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Supermoon! Red Blood Lunar Eclipse! It’s All Happening At Once, but What Does That Mean?

A series of images taken aboard the amphibious assault ship USS Boxer (LHD 4) shows the moon during a full lunar eclipse. U.S. Navy/Joshua Valcarcel/WikimediaCommons

By | The Conversation

The first lunar eclipse of 2021 is going to happen during the early hours of May 26. But this is going to be an especially superlunar event, as it will be a supermoon, a lunar eclipse, and a red blood moon all at once. So what does this all mean?

What’s a super moon?

supermoon occurs when a full or new moon coincides with the Moon’s closest approach to the Earth.

White lines showing the oblong shape of the moon's orbit.

The Moon’s orbit is not a perfect circle as it slowly rotates around Earth. Rfassbind/WikimediaCommons

 

The Moon’s orbit around Earth is not perfectly circular. This means the Moon’s distance from Earth varies as it goes around the planet. The closest point in the orbit, called the perigee, is roughly 28,000 miles closer to Earth than the farthest point of the orbit. A full moon that happens near the perigee is called a supermoon.

So why is it super? The relatively close proximity of the Moon makes it seem a little bit bigger and brighter than usual, though the difference between a supermoon and a normal moon is usually hard to notice unless you’re looking at two pictures side by side.

How does a lunar eclipse work?

A lunar eclipse happens when the Earth’s shadow covers all or part of the Moon. This can only happen during a full moon, so first, it helps to understand what makes a full moon.

Like the Earth, half of the Moon is illuminated by the sun at any one time. A full moon happens when the Moon and the Sun are on opposite sides of the Earth. This allows you to see the entire lit-up side, which looks like a round disc in the night sky.

If the Moon had a totally flat orbit, every full moon would be a lunar eclipse. But the Moon’s orbit is tilted by about 5 degrees relative to Earth’s orbit. So, most of the time a full moon ends up a little above or below the shadow cast by the Earth.

A diagram showing the orbits of the Earth and the moon and Earth's shadow.

A lunar eclipse occurs when the Moon passes through Earth’s shadow. Sagredo/WikimediaCommons

But twice in each lunar orbit, the Moon is on the same horizontal plane as both the Earth and Sun. If this corresponds to a full moon, the Sun, the Earth and the Moon will form a straight line and the Moon will pass through the Earth’s shadow. This results in a total lunar eclipse.

To see a lunar eclipse, you need to be on the night side of the Earth while the Moon passes through the shadow. The best place to see the eclipse on May 26, 2021, will be the middle of the Pacific Ocean, Australia, the East Coast of Asia, and the West Coast of the Americas. It will be visible on the eastern half of the U.S., but only in the very earliest stages before the Moon sets.

Why does the moon look red?

When the Moon is completely covered by Earth’s shadow it will darken, but doesn’t go completely black. Instead, it takes on a red color, which is why total lunar eclipses are sometimes called red or blood moons.

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Sunlight contains all colors of visible light. The particles of gas that makeup Earth’s atmosphere are more likely to scatter blue wavelengths of light while redder wavelengths pass through. This is called Rayleigh scattering, and it’s why the sky is blue and sunrises and sunsets are often red.

In the case of a lunar eclipse, red light can pass through the Earth’s atmosphere and is refracted – or bent – toward the Moon, while blue light is filtered out. This leaves the moon with a pale reddish hue during an eclipse.

Hopefully, you will be able to go see this super lunar eclipse. When you do, now you will know exactly what makes for such a special sight.




New Evidence of How and When the Milky Way Came Together

Spiral galaxy illustration.
Credit: © AlexMit / 123RF.com

By Jeff Grabmeier | Science Daily

New research provides the best evidence to date into the timing of how our early Milky Way came together, including the merger with a key satellite galaxy.

Using relatively new methods in astronomy, the researchers were able to identify the most precise ages currently possible for a sample of about a hundred red giant stars in the galaxy.

With this and other data, the researchers were able to show what was happening when the Milky Way merged with an orbiting satellite galaxy, known as Gaia-Enceladus, about 10 billion years ago.

Their results were published today (May 17, 2021) in the journal Nature Astronomy.

“Our evidence suggests that when the merger occurred, the Milky Way had already formed a large population of its own stars,” said Fiorenzo Vincenzo, co-author of the study and a fellow in The Ohio State University’s Center for Cosmology and Astroparticle Physics.

Many of those “homemade” stars ended up in the thick disc in the middle of the galaxy, while most that were captured from Gaia-Enceladus are in the outer halo of the galaxy.

“The merging event with Gaia-Enceladus is thought to be one of the most important in the Milky Way’s history, shaping how we observe it today,” said Josefina Montalban, with the School of Physics and Astronomy at the University of Birmingham in the U.K., who led the project.

By calculating the age of the stars, the researchers were able to determine, for the first time, that the stars captured from Gaia-Enceladus have similar or slightly younger ages compared to the majority of stars that were born inside the Milky Way.

A violent merger between two galaxies can’t help but shake things up, Vincenzo said. Results showed that the merger changed the orbits of the stars already in the galaxy, making them more eccentric.

Vincenzo compared the stars’ movements to a dance, where the stars from the former Gaia-Enceladus move differently than those born within the Milky Way. The stars even “dress” differently, Vincenzo said, with stars from outside showing different chemical compositions from those born inside the Milky Way.

The researchers used several different approaches and data sources to conduct their study.

The researchers were able to get such precise ages of the stars through the use of asteroseismology, a relatively new field that probes the internal structure of stars.

Asteroseismologists study oscillations in stars, which are sound waves that ripple through their interiors, said Mathieu Vrard, a postdoctoral research associate in Ohio State’s Department of Astronomy.

“That allows us to get very precise ages for the stars, which are important in determining the chronology of when events happened in the early Milky Way,” Vrard said.

The study also used a spectroscopic survey, called APOGEE, which provides the chemical composition of stars — another aid in determining their ages.

“We have shown the great potential of asteroseismology, in combination with spectroscopy, to age-date individual stars,” Montalban said.

This study is just the first step, according to the researchers.

“We now intend to apply this approach to larger samples of stars, and to include even more subtle features of the frequency spectra,” Vincenzo said.

“This will eventually lead to a much sharper view of the Milky Way’s assembly history and evolution, creating a timeline of how our galaxy developed.”

The work is the result of the collaborative Asterochronometry project, funded by the European Research Council.


Story Source:

Materials provided by Ohio State University. Originally written by Jeff Grabmeier.


Journal Reference:

  1. Josefina Montalbán, J. Ted Mackereth, Andrea Miglio, Fiorenzo Vincenzo, Cristina Chiappini, Gael Buldgen, Benoît Mosser, Arlette Noels, Richard Scuflaire, Mathieu Vrard, Emma Willett, Guy R. Davies, Oliver J. Hall, Martin Bo Nielsen, Saniya Khan, Ben M. Rendle, Walter E. van Rossem, Jason W. Ferguson, William J. Chaplin. Chronologically dating the early assembly of the Milky WayNature Astronomy, 2021; DOI: 10.1038/s41550-021-01347-7



White Dwarfs Going Supernova Detonate Like a Nuclear Bomb, Study Suggests

A new study published in the Physical Review Letters suggests that the remnant cores of dead average-size stars can explode like a nuclear bomb.

Known as white dwarfs, these dense cores are packed with heavy radioactive elements called actinides that can spontaneously undergo nuclear fission – the splitting of atoms. Depending on certain conditions, these cores can eventually undergo uncontrolled fission, culminating in a massive stellar explosion known as a supernova.

“The conditions to build and set off an atomic bomb seemed very difficult. I was surprised that these conditions might be satisfied in a natural way inside a very dense white dwarf,” Charles Horowitz, a nuclear astrophysicist from Indiana University Bloomington and one of the study’s researchers, told Space.

“If true, this provides a very new way to think about thermonuclear supernovae, and perhaps other astrophysical explosions,” he added.

Nuclear reactions can trigger supernova of white dwarfs

White dwarfs are the dim, Earth-size cores of dead stars. They form when average-sized stars have exhausted their fuel and shed their outer layers. The sun will one day become a white dwarf, as will more than 90 percent of the stars in the Milky Way galaxy.

Past studies show that white dwarfs can die in type Ia supernovae, a type of stellar explosion. Much remains unknown about what triggers type Ia supernovae, but prior research suggests that they can happen when a white dwarf absorbs material from another star. These two celestial objects orbit each other in an arrangement called a binary star system.

In their study, Horowitz and co-author Matt Caplan, a theoretical physicist from Illinois State University, proposed that type Ia supernovae might also occur when a white dwarf undergoes the processes behind the explosion of a hydrogen bomb.

As a white dwarf cools, actinides such as uranium crystallize within its core. The atoms of these elements can spontaneously undergo nuclear fission, which releases energy and neutrons. Neutrons can collide with other atoms and break them up, repeating the process.

If the amount of actinides exceeds a critical mass, these elements can set off an explosive runaway nuclear fission chain reaction. This, in turn, can trigger nuclear fusion, where atomic nuclei fuse with each other and generate enormous amounts of energy in the process. (Related: Gold and elements heavier than iron were formed on Earth after neutron stars collided billions of years ago: Study.)

The pair’s calculations and computer simulations showed that a critical mass of uranium could indeed crystallize from the mixture of elements in a white dwarf. If this heavy uranium were to explode due to a nuclear chain reaction, the white dwarf would become so hot and pressurized as to trigger the fusion of lighter elements, resulting in a supernova. A hydrogen bomb also works the same way – a nuclear chain reaction is initiated to set off a nuclear fusion explosion.

Horowitz said that this mechanism could be responsible for around half of all Type Ia supernovae in the cosmos. These stellar explosions should occur within a billion years of a white dwarf’s formation since uranium takes a very long time to decay.

The pair recommended running more computer simulations to definitively answer whether fission chain reactions in white dwarfs could indeed trigger nuclear fusion. Though the study was compelling, Horowitz admitted that there were plenty of physical processes that occur during a supernova, which meant there were many potential uncertainties.

For more fascinating studies about stars and space, visit Cosmic.news.

Sources include:

LiveScience.com

Space.com

By  | Science.News




A New Super-Earth Detected Orbiting a Red Dwarf Star

By Instituto de Astrofísica de Canarias (IAC) | Science Daily

In recent years there has been an exhaustive study of red dwarf stars to find exoplanets in orbit around them. These stars have effective surface temperatures between 2400 and 3700 K (over 2000 degrees cooler than the Sun), and masses between 0.08 and 0.45 solar masses. In this context, a team of researchers led by Borja Toledo Padrón, a Severo Ochoa-La Caixa doctoral student at the Instituto de Astrofísica de Canarias (IAC), specializing in the search for planets around this type of stars, has discovered a super-Earth orbiting the star GJ 740, a red dwarf star situated some 36 light years from Earth.

The planet orbits its star with a period of 2.4 days and its mass is around 3 times the mass of Earth. Because the star is so close to the Sun, and the planet so close to the star, this new super-Earth could be the object of future researches with very large diameter telescopes towards the end of this decade. The results of the study were recently published in the journal Astronomy & Astrophysics.

“This is the planet with the second shortest orbital period around this type of star. The mass and the period suggest a rocky planet, with a radius of around 1.4 Earth radii, which could be confirmed in future observations with the TESS satellite,” explains Borja Toledo Padrón, the first author of the article. The data also indicate the presence of a second planet with an orbital period of 9 years, and a mass comparable to that of Saturn (close to 100 Earth masses), although its radial velocity signal could be due to the magnetic cycle of the star (similar to that of the Sun), so that more data are needed to confirm that the signal is really due to a planet.

The Kepler mission, recognised at one of the most successful in detecting exoplanets using the transit method (which is the search for small variations in the brightness of a star caused by the transit between it and ourselves of planets orbiting around it), has discovered a total of 156 new planets around cool stars. From its data it has been estimated that this type of stars harbours an average of 2.5 planets with orbital periods of less than 200 days. “The search for new exoplanets around cool stars is driven by the smaller difference between the planet’s mass and the star’s mass compared with stars in warmer spectral classes (which facilitates the detection of the planets’ signals), as well as the large number of this type of stars in our Galaxy,” comments Borja Toledo Padrón.

Cool stars are also an ideal target for the search for planets via the radial velocity method. This method is based on the detection of small variations in the velocity of a star due to the gravitational attraction of a planet in orbit around it, using spectroscopic observations. Since the discovery in 1998 of the first radial velocity signal of an exoplanet around a cool star, until now, a total of 116 exoplanets has been discovered around this class of stars using the radial velocity method. “The main difficulty of this method is related to the intense magnetic activity of this type of stars, which can produce spectroscopic signals very similar to those due to an exoplanet,” says Jonay I. González Hernández, an IAC researcher who is a co-author of this article.

The study is part of the project HADES (HArps-n red Dwarf Exoplanet Survey), in which the IAC is collaborating with the Institut de Ciències de l’Espai (IEEC-CSIC) of Catalonia, and the Italian programme GAPS (Global Architecture of Planetary Systems), whose objective is the detection and characterization of exoplanets round cool stars, in which are being used HARPS-N, on the Telescopio Nazionale Galileo (TNG) at the Roque de los Muchachos Observatory (Garafía, La Palma). This detection was possible due to a six year observing campaign with HARPS-N, complemented with measurements with the CARMENES spectrograph on the 3.5m telescope at the Calar Alto Observatory (Almería) and HARPS, on the 3.6m telescope at the La Silla Observatory (Chile), as well as photometric support from the ASAP and EXORAP surveys. Also participating in this work are IAC researchers Alejandro Suárez Mascareño, and Rafael Rebolo.


Story Source:

Materials provided by Instituto de Astrofísica de Canarias (IAC).


Journal Reference:

  1. B. Toledo-Padrón, A. Suárez Mascareño, J. I. González Hernández, R. Rebolo, M. Pinamonti, M. Perger, G. Scandariato, M. Damasso, A. Sozzetti, J. Maldonado, S. Desidera, I. Ribas, G. Micela, L. Affer, E. González-Alvarez, G. Leto, I. Pagano, R. Zanmar Sánchez, P. Giacobbe, E. Herrero, J. C. Morales, P. J. Amado, J. A. Caballero, A. Quirrenbach, A. Reiners, M. Zechmeister. A super-Earth on a close-in orbit around the M1V star GJ 740Astronomy & Astrophysics, 2021; 648: A20 DOI: 10.1051/0004-6361/202040099



WATCH Awesome Clips of the First Supermoon of 2021 As It Lights Up Skies Around the World

Video Source: The Telegraph

Skygazers were treated to a glimpse of a “pink supermoon” as the celestial event lit up the skies across the globe. See what they saw. The image of the supermoon above the Statue of Liberty is particularly spectacular.



Astronomers Release New All-Sky Map of Milky Way’s Outer Reaches

By NASA/Jet Propulsion Laboratory | Science Daily

Astronomers using data from NASA and ESA (European Space Agency) telescopes have released a new all-sky map of the outermost region of our galaxy. [Editor’s note: See Related Multimedia link below.] Known as the galactic halo, this area lies outside the swirling spiral arms that form the Milky Way’s recognizable central disk and is sparsely populated with stars. Though the halo may appear mostly empty, it is also predicted to contain a massive reservoir of dark matter, a mysterious and invisible substance thought to make up the bulk of all the mass in the universe.

The data for the new map comes from ESA’s Gaia mission and NASA’s Near-Earth Object Wide-Field Infrared Survey Explorer, or NEOWISE, which operated from 2009 to 2013 under the moniker WISE. The study makes use of data collected by the spacecraft between 2009 and 2018.

The new map reveals how a small galaxy called the Large Magellanic Cloud (LMC) — so named because it is the larger of two dwarf galaxies orbiting the Milky Way — has sailed through the Milky Way’s galactic halo like a ship through water, its gravity creating a wake in the stars behind it. The LMC is located about 160,000 light-years from Earth and is less than one-quarter the mass of the Milky Way.

Though the inner portions of the halo have been mapped with a high level of accuracy, this is the first map to provide a similar picture of the halo’s outer regions, where the wake is found — about 200,000 light-years to 325,000 light-years from the galactic center. Previous studies have hinted at the wake’s existence, but the all-sky map confirms its presence and offers a detailed view of its shape, size, and location.

This disturbance in the halo also provides astronomers with an opportunity to study something they can’t observe directly: dark matter. While it doesn’t emit, reflect, or absorb light, the gravitational influence of dark matter has been observed across the universe. It is thought to create a scaffolding on which galaxies are built, such that without it, galaxies would fly apart as they spin. Dark matter is estimated to be five times more common in the universe than all the matter that emits and/or interacts with light, from stars to planets to gas clouds.

Although there are multiple theories about the nature of dark matter, all of them indicate that it should be present in the Milky Way’s halo. If that’s the case, then as the LMC sails through this region, it should leave a wake in the dark matter as well. The wake observed in the new star map is thought to be the outline of this dark matter wake; the stars are like leaves on the surface of this invisible ocean, their position shifting with the dark matter.

The interaction between the dark matter and the Large Magellanic Cloud has big implications for our galaxy. As the LMC orbits the Milky Way, the dark matter’s gravity drags on the LMC and slows it down. This will cause the dwarf galaxy’s orbit to get smaller and smaller until the galaxy finally collides with the Milky Way in about 2 billion years. These types of mergers might be a key driver in the growth of massive galaxies across the universe. In fact, astronomers think the Milky Way merged with another small galaxy about 10 billion years ago.

“This robbing of a smaller galaxy’s energy is not only why the LMC is merging with the Milky Way, but also why all galaxy mergers happen,” said Rohan Naidu, a doctoral student in astronomy at Harvard University and a co-author of the new paper. “The wake in our map is a really neat confirmation that our basic picture for how galaxies merge is on point!”

A Rare Opportunity

The authors of the paper also think the new map — along with additional data and theoretical analyses — may provide a test for different theories about the nature of dark matter, such as whether it consists of particles, like regular matter, and what the properties of those particles are.

“You can imagine that the wake behind a boat will be different if the boat is sailing through water or through honey,” said Charlie Conroy, a professor at Harvard University and an astronomer at the Center for Astrophysics | Harvard & Smithsonian, who co-authored the study. “In this case, the properties of the wake are determined by which dark matter theory we apply.”

Conroy led the team that mapped the positions of over 1,300 stars in the halo. The challenge arose in trying to measure the exact distance from Earth to a large portion of those stars: It’s often impossible to figure out whether a star is faint and closes by or bright and far away. The team used data from ESA’s Gaia mission, which provides the location of many stars in the sky but cannot measure distances to the stars in the Milky Way’s outer regions.

After identifying stars most likely located in the halo (because they were not obviously inside our galaxy or the LMC), the team looked for stars belonging to a class of giant stars with a specific light “signature” detectable by NEOWISE. Knowing the basic properties of the selected stars enabled the team to figure out their distance from Earth and create a new map. It charts a region starting about 200,000 light-years from the Milky Way’s center, or about where the LMC’s wake was predicted to begin and extends about 125,000 light-years beyond that.

Conroy and his colleagues were inspired to hunt for LMC’s wake after learning about a team of astrophysicists at the University of Arizona in Tucson that makes computer models predicting what dark matter in the galactic halo should look like. The two groups worked together on the new study.

One model by the Arizona team, included in the new study, predicted the general structure and specific location of the star wake revealed in the new map. Once the data had confirmed that the model was correct, the team could confirm what other investigations have also hinted at: that the LMC is likely on its first orbit around the Milky Way. If the smaller galaxy had already made multiple orbits, the shape and location of the wake would be significantly different from what has been observed. Astronomers think the LMC formed in the same environment as the Milky Way and another nearby galaxy, M31, and that it is close to completing a long first orbit around our galaxy (about 13 billion years). Its next orbit will be much shorter due to its interaction with the Milky Way.

“Confirming our theoretical prediction with observational data tells us that our understanding of the interaction between these two galaxies, including the dark matter, is on the right track,” said University of Arizona doctoral student in astronomy Nicolás Garavito-Camargo, who led work on the model used in the paper.

The new map also provides astronomers with a rare opportunity to test the properties of the dark matter (the notional water or honey) in our own galaxy. In the new study, Garavito-Camargo and colleagues used a popular dark matter theory called cold dark matter that fits the observed star map relatively well. Now the University of Arizona team is running simulations that use different dark matter theories to see which one best matches the wake observed in the stars.

“It’s a really special set of circumstances that came together to create this scenario that lets us test our dark matter theories,” said Gurtina Besla, a co-author of the study and an associate professor at the University of Arizona. “But we can only realize that test with the combination of this new map and the dark matter simulations that we built.”

Launched in 2009, the WISE spacecraft was placed into hibernation in 2011 after completing its primary mission. In September 2013, NASA reactivated the spacecraft with the primary goal of scanning for near-Earth objects, or NEOs, and the mission and spacecraft were renamed NEOWISE. NASA’s Jet Propulsion Laboratory in Southern California managed and operated WISE for NASA’s Science Mission Directorate. The mission was selected competitively under NASA’s Explorers Program managed by the agency’s Goddard Space Flight Center in Greenbelt, Maryland. NEOWISE is a project of JPL, a division of Caltech, and the University of Arizona, supported by NASA’s Planetary Defense Coordination Office.


Story Source:

Materials provided by NASA/Jet Propulsion LaboratoryNote: Content may be edited for style and length.


Journal Reference:

  1. Charlie Conroy, Rohan P. Naidu, Nicolás Garavito-Camargo, Gurtina Besla, Dennis Zaritsky, Ana Bonaca, Benjamin D. Johnson. All-sky dynamical response of the Galactic halo to the Large Magellanic CloudNature, 2021; 592 (7855): 534 DOI: 10.1038/s41586-021-03385-7



Telescopes Unite in Unprecedented Observations of Famous Black Hole

By Harvard-Smithsonian Center for Astrophysics | Science Daily

In April 2019, scientists released the first image of a black hole in galaxy M87 using the Event Horizon Telescope (EHT). However, that remarkable achievement was just the beginning of the science story to be told.

Data from 19 observatories released today promise to give unparalleled insight into this black hole and the system it powers, and to improve tests of Einstein’s General Theory of Relativity.

“We knew that the first direct image of a black hole would be groundbreaking,” says Kazuhiro Hada of the National Astronomical Observatory of Japan, a co-author of a new study published in The Astrophysical Journal Letters that describes the large set of data. “But to get the most out of this remarkable image, we need to know everything we can about the black hole’s behavior at that time by observing over the entire electromagnetic spectrum.”

The immense gravitational pull of a supermassive black hole can power jets of particles that travel at almost the speed of light across vast distances. M87’s jets produce light spanning the entire electromagnetic spectrum, from radio waves to visible light to gamma rays. This pattern is different for each black hole. Identifying this pattern gives crucial insight into a black hole’s properties — for example, its spin and energy output — but is a challenge because the pattern changes with time.

Scientists compensated for this variability by coordinating observations with many of the world’s most powerful telescopes on the ground and in space, collecting light from across the spectrum. These 2017 observations were the largest simultaneous observing campaign ever undertaken on a supermassive black hole with jets.

Three observatories managed by the Center for Astrophysics | Harvard & Smithsonian participated in the landmark campaign: the Submillimeter Array (SMA) in Hilo, Hawaii; the space-based Chandra X-ray Observatory; and the Very Energetic Radiation Imaging Telescope Array System (VERITAS) in southern Arizona.

Beginning with the EHT’s now-iconic image of M87, a new video takes viewers on a journey through the data from each telescope. Each consecutive frame shows data across many factors often in scale, both of wavelengths of light and physical size.

The sequence begins with the April 2019 image of the black hole. It then moves through images from other radio telescope arrays from around the globe (SMA), moving outward in the field of view during each step. Next, the view changes to telescopes that detect visible light, ultraviolet light, and X-rays (Chandra). The screen splits to show how these images, which cover the same amount of the sky at the same time, compare to one another. The sequence finishes by showing what gamma-ray telescopes on the ground (VERITAS), and Fermi in space, detect from this black hole and its jet.

Each telescope delivers different information about the behavior and impact of the 6.5-billion-solar-mass black hole at the center of M87, which is located about 55 million light-years from Earth.

“There are multiple groups eager to see if their models are a match for these rich observations, and we’re excited to see the whole community use this public data set to help us better understand the deep links between black holes and their jets,” says co-author Daryl Haggard of McGill University in Montreal, Canada.

The data were collected by a team of 760 scientists and engineers from nearly 200 institutions, spanning 32 countries or regions, and using observatories funded by agencies and institutions around the globe. The observations were concentrated from the end of March to the middle of April 2017.

“This incredible set of observations includes many of the world’s best telescopes,” says co-author Juan Carlos Algaba of the University of Malaya in Kuala Lumpur, Malaysia. “This is a wonderful example of astronomers around the world working together in the pursuit of science.”

The first results show that the intensity of the light produced by material around M87’s supermassive black hole was the lowest that had ever been observed. This produced ideal conditions for viewing the ‘shadow’ of the black hole, as well as being able to isolate the light from regions close to the event horizon from those tens of thousands of light-years away from the black hole.

The combination of data from these telescopes, and current (and future) EHT observations, will allow scientists to conduct important lines of investigation into some of the astrophysics’ most significant and challenging fields of study. For example, scientists plan to use this data to improve tests of Einstein’s Theory of General Relativity. Currently, uncertainties about the material rotating around the black hole and being blasted away in jets, in particular the properties that determine the emitted light, represent a major hurdle for these General Relativity tests.

A related question that is addressed by today’s study concerns the origin of energetic particles called “cosmic rays,” which continually bombard the Earth from outer space. Their energies can be a million times higher than what can be produced in the most powerful accelerator on Earth, the Large Hadron Collider. The huge jets launched from black holes, like the ones shown in today’s images, are thought to be the most likely source of the highest energy cosmic rays, but there are many questions about the details, including the precise locations where the particles get accelerated. Because cosmic rays produce light via their collisions, the highest-energy gamma rays can pinpoint this location, and the new study indicates that these gamma rays are likely not produced near the event horizon — at least not in 2017. A key to settling this debate will be a comparison to the observations from 2018, and the new data being collected this week.

“Understanding the particle acceleration is really central to our understanding of both the EHT image as well as the jets, in all their ‘colors’,” says co-author Sera Markoff from the University of Amsterdam. “These jets manage to transport energy released by the black hole out to scales larger than the host galaxy, like a huge power cord. Our results will help us calculate the amount of power carried, and the effect the black hole’s jets have on its environment.”

The release of this new treasure trove of data coincides with the EHT’s 2021 observing run, which leverages a worldwide array of radio dishes, the first since 2018. Last year’s campaign was canceled because of the COVID-19 pandemic, and the previous year was suspended because of unforeseen technical problems. This very week, for six nights, EHT astronomers are targeting several supermassive black holes: the one in M87 again, the one in our Galaxy called Sagittarius A*, and several more distant black holes. Compared to 2017, the array has been improved by adding three more radio telescopes: the Greenland Telescope, the Kitt Peak 12-meter Telescope in Arizona, and the Northern Extended Millimeter Array (NOEMA) in France.

“With the release of these data, combined with the resumption of observing and an improved EHT, we know many exciting new results are on the horizon,” says co-author Mislav Balokovi? of Yale University.

“I’m really excited to see these results come out, along with my fellow colleagues working on the SMA, some of whom were directly involved in collecting some of the data for this spectacular view into M87,” says co-author Garrett Keating, a Submillimeter Array project scientist. “And with the results of Sagittarius A* — the massive black hole at the center of the Milky Way — coming out soon, and the resumption of observing this year, we are looking forward to even more amazing results with the EHT for years to come.”


Story Source:

Materials provided by Harvard-Smithsonian Center for AstrophysicsNote: Content may be edited for style and length.


Journal Reference:

  1. The EHT MWL Science Working Group et al. Broadband Multi-wavelength Properties of M87 during the 2017 Event Horizon Telescope CampaignThe Astrophysical Journal Letters, 2021; 911 (1): L11 DOI: 10.3847/2041-8213/abef71



A Giant, Sizzling Planet May Be Orbiting the Star Vega

By University of Colorado at Boulder | Science Daily

Astronomers have discovered new hints of a giant, scorching-hot planet orbiting Vega, one of the brightest stars in the night sky.

The research, published this month in The Astrophysical Journal, was led by University of Colorado Boulder student Spencer Hurt, an undergraduate in the Department of Astrophysical and Planetary Sciences.

It focuses on an iconic and relatively young star, Vega, which is part of the constellation Lyra and has a mass twice that of our own sun. This celestial body sits just 25 light-years, or about 150 trillion miles, from Earth — pretty close, astronomically speaking.

Scientists can also see Vega with telescopes even when it’s light out, which makes it a prime candidate for research, said study coauthor Samuel Quinn.

“It’s bright enough that you can observe it at twilight when other stars are getting washed out by sunlight,” said Quinn, an astronomer at the Harvard and Smithsonian Center for Astrophysics (CfA).

Despite the star’s fame, researchers have yet to find a single planet in orbit around Vega. That might be about to change: Drawing on a decade of observations from the ground, Hurt, Quinn, and their colleagues unearthed a curious signal that could be the star’s first-known world.

If the team’s findings bear out, the alien planet would orbit so close to Vega that its years would last less than two-and-a-half Earth days. (Mercury, in contrast, takes 88 days to circle the sun). This candidate planet could also rank as the second hottest world known to science — with surface temperatures averaging a searing 5,390 degrees Fahrenheit.

Hurt said the group’s research also helps to narrow down where other, exotic worlds might be hiding in Vega’s neighborhood.

“This is a massive system, much larger than our own solar system,” Hurt said. “There could be other planets throughout that system. It’s just a matter of whether we can detect them.”

Youthful energy

Quinn would like to try. Scientists have discovered more than 4,000 exoplanets, or planets beyond Earth’s solar system, to date. Few of those, however, circle stars that are as bright or as close to Earth as Vega. That means that, if there are planets around the star, scientists could get a really detailed look at them.

“It would be really exciting to find a planet around Vega because it offers possibilities for future characterization in ways that planets around fainter stars wouldn’t,” Quinn said.

There’s just one catch: Vega is what scientists call an A-type star, the name for objects that tend to be bigger, younger, and much faster-spinning than our own sun. Vega, for example, rotates around its axis once every 16 hours — much faster than the sun with a rotational period that clocks in at 27 Earth days. Such a lightning-fast pace, Quinn said, can make it difficult for scientists to collect precise data on the star’s motion and, by extension, any planets in orbit around it.

To take on that game of celestial hide-and-seek, he and colleagues pored through roughly 10 years of data on Vega collected by the Fred Lawrence Whipple Observatory in Arizona. In particular, the team was looking for a tell-tale signal of an alien planet — a slight jiggle in the star’s velocity.

“If you have a planet around a star, it can tug on the star, causing it to wobble back and forth,” Quinn said.

Hot and puffy

The search may have paid off, said Hurt, who began the study as a summer research fellow working for Quinn at the CFA. The team discovered a signal that indicates that Vega might host what astronomers call a “hot Neptune” or maybe a “hot Jupiter.”

“It would be at least the size of Neptune, potentially as big as Jupiter, and would be closer to Vega than Mercury is to the sun,” Hurt said.

That close to Vega, he added, the candidate world might puff up like a balloon, and even iron would melt into gas in its atmosphere.

The researchers have a lot more work to do before they can definitively say that they’ve discovered this sizzling planet. Hurt noted that the easiest way to look for it might be to scan the stellar system directly to look for light emitted from the hot, bright planet.

For now, the student is excited to see his hard work reflected in the constellations: “Whenever I get to go outside and look at the night sky and see Vega, I say ‘Hey, I know that star.”

Other co-authors on the new study include David Latham, Gilbert Esquerdo, Michael Calkins, Perry Berlind, Christian Latham, and George Zhou at the CfA; Andrew Vanderburg at the University of Wisconsin-Madison; and Ruth Angus at the American Museum of Natural History.


Story Source:

Materials provided by the University of Colorado at Boulder. Originally written by Daniel Strain. Note: Content may be edited for style and length.


Journal Reference:

  1. Spencer A. Hurt, Samuel N. Quinn, David W. Latham, Andrew Vanderburg, Gilbert A. Esquerdo, Michael L. Calkins, Perry Berlind, Ruth Angus, Christian A. Latham, George Zhou. A Decade of Radial-velocity Monitoring of Vega and New Limits on the Presence of PlanetsThe Astronomical Journal, 2021; 161 (4): 157 DOI: 10.3847/1538-3881/abdec8



Scientists Discover X-Rays Coming From Uranus For Very First Time

By | TheMindUnleashed.com

Scientists are seeing X-rays being emitted from Uranus for the very first time, according to new research.

On Wednesday, the study was published in the Journal of Geophysical Research that lays out how a comparison of two images of the planet taken by the Chandra Observatory in 2002 and 2017 show a clear detection of X-rays in the first image, while the second shows a possible flare of X-rays on the enigmatic and icy planet.

According to NASA, the reason for these X-rays is “mainly the sun.”

However, “there are tantalizing hints that at least one other source of X-rays is present,” the space agency noted.

“One possibility is that the rings of Uranus are producing X-rays themselves, which is the case for Saturn’s rings,” NASA said. “Another possibility is that at least some of the X-rays come from auroras on Uranus, a phenomenon that has previously been observed on this planet at other wavelengths.”

X-rays can provide a crucial window into the processes and characteristics of our universe. In the case of Uranus, these characteristics can include “atmospheric, surface and planetary ring composition.”

And while X-ray lights given off by the sun have been previously observed by astronomers on Jupiter and Saturn, this hasn’t been the case for icy giants like Uranus and Neptune.

The agency hopes that by figuring out the origin of the X-rays observed at Uranus, researchers can better grasp how mysterious objects including black holes and neutron stars emit X-rays.

Uranus is roughly four times the diameter of Earth and is the seventh planet from the sun, and is known for its distinct pair of rings around its equator and its unique side rotation.




From Stardust to Pale Blue Dot: Carbon’s Interstellar Journey to Earth

By University of Michigan | ScienceDaily

We are made of stardust, the saying goes, and a pair of studies including University of Michigan research finds that may be more true than we previously thought.

The first study, led by U-M researcher Jie (Jackie) Li and published in Science Advances, finds that most of the carbon on Earth was likely delivered from the interstellar medium, the material that exists in space between stars in a galaxy. This likely happened well after the protoplanetary disk, the cloud of dust and gas that circled our young sun and contained the building blocks of the planets, formed and warmed up.

Carbon was also likely sequestered into solids within one million years of the sun’s birth — which means that carbon, the backbone of life on earth, survived an interstellar journey to our planet.

Previously, researchers thought carbon in the Earth came from molecules that were initially present in nebular gas, which then accreted into a rocky planet when the gases were cool enough for the molecules to precipitate. Li and her team, which includes U-M astronomer Edwin Bergin, Geoffrey Blake of the California Institute of Technology, Fred Ciesla of the University of Chicago, and Marc Hirschmann of the University of Minnesota, point out in this study that the gas molecules that carry carbon wouldn’t be available to build the Earth because once carbon vaporizes, it does not condense back into a solid.

“The condensation model has been widely used for decades. It assumes that during the formation of the sun, all of the planet’s elements got vaporized, and as the disk cooled, some of these gases condensed and supplied chemical ingredients to solid bodies. But that doesn’t work for carbon,” said Li, a professor in the U-M Department of Earth and Environmental Sciences.

Much of carbon was delivered to the disk in the form of organic molecules. However, when carbon is vaporized, it produces much more volatile species that require very low temperatures to form solids. More importantly, carbon does not condense back again into an organic form. Because of this, Li and her team inferred most of Earth’s carbon was likely inherited directly from the interstellar medium, avoiding vaporization entirely.

To better understand how Earth acquired its carbon, Li estimated the maximum amount of carbon Earth could contain. To do this, she compared how quickly a seismic wave travels through the core to the known sound velocities of the core. This told the researchers that carbon likely makes up less than half a percent of Earth’s mass. Understanding the upper bounds of how much carbon the Earth might contain tells the researchers information about when the carbon might have been delivered here.

“We asked a different question: We asked how much carbon could you stuff in the Earth’s core and still be consistent with all the constraints,” Bergin said, professor and chair of the U-M Department of Astronomy. “There’s uncertainty here. Let’s embrace the uncertainty to ask what are the true upper bounds for how much carbon is very deep in the Earth, and that will tell us the true landscape we’re within.”

A planet’s carbon must exist in the right proportion to support life as we know it. Too much carbon, and the Earth’s atmosphere would be like Venus, trapping heat from the sun and maintaining a temperature of about 880 degrees Fahrenheit. Too little carbon and Earth would resemble Mars: an inhospitable place unable to support water-based life, with temperatures around minus 60.

In a second study by the same group of authors, but led by Hirschmann of the University of Minnesota, the researchers looked at how carbon is processed when the small precursors of planets, known as planetesimals, retain carbon during their early formation. By examining the metallic cores of these bodies, now preserved as iron meteorites, they found that during this key step of planetary origin, much of the carbon must be lost as the planetesimals melt, form cores, and lose gas. This upends previous thinking, Hirschmann says.

“Most models have the carbon and other life-essential materials such as water and nitrogen going from the nebula into primitive rocky bodies, and these are then delivered to growing planets such as Earth or Mars,” said Hirschmann, professor of earth and environmental sciences. “But this skips a key step, in which the planetesimals lose much of their carbon before they accrete to the planets.”

Hirschmann’s study was recently published in Proceedings of the National Academy of Sciences.

“The planet needs carbon to regulate its climate and allow life to exist, but it’s a very delicate thing,” Bergin said. “You don’t want to have too little, but you don’t want to have too much.”

Bergin says the two studies both describe two different aspects of carbon loss — and suggest that carbon loss appears to be a central aspect in constructing the Earth as a habitable planet.

“Answering whether or not Earth-like planets exist elsewhere can only be achieved by working at the intersection of disciplines like astronomy and geochemistry,” said Ciesla, a U. of C. professor of geophysical sciences. “While approaches and the specific questions that researchers work to answer differ across the fields, building a coherent story requires identifying topics of mutual interest and finding ways to bridge the intellectual gaps between them. Doing so is challenging, but the effort is both stimulating and rewarding.”

Blake, a co-author on both studies and a Caltech professor of cosmochemistry and planetary science, and of chemistry, says this kind of interdisciplinary work is critical.

“Over the history of our galaxy alone, rocky planets like the Earth or a bit larger have been assembled hundreds of millions of times around stars like the Sun,” he said. “Can we extend this work to examine carbon loss in planetary systems more broadly? Such research will take a diverse community of scholars.”

Funding sources for this collaborative research include the National Science Foundation, NASA’s Exoplanets Research Program, NASA’s Emerging Worlds Program, and the NASA Astrobiology Program.


Story Source:

Materials provided by the University of MichiganNote: Content may be edited for style and length.


Journal References:

  1. J. Li, E. A. Bergin, G. A. Blake, F. J. Ciesla, M. M. Hirschmann. Earth’s carbon deficit caused by early loss through irreversible sublimationScience Advances, 2021; 7 (14): eabd3632 DOI: 10.1126/sciadv.abd3632
  2. Marc M. Hirschmann, Edwin A. Bergin, Geoff A. Blake, Fred J. Ciesla, Jie Li. Early volatile depletion on planetesimals inferred from C–S systematics of iron meteorite parent bodiesProceedings of the National Academy of Sciences, 2021; 118 (13): e2026779118 DOI: 10.1073/pnas.2026779118



Breathtaking New Image of Black Hole Reveals Ultrapowerful Magnetic Fields

By | TheMindUnleashed.com

Two years after the first-ever image of a black hole was produced, an international team of scientists has released an updated view of the magnetic fields surrounding it, saying that the groundbreaking new development allows us to understand the Messier 87 (M87) galaxy’s ability to “launch energetic jets from its core.”

In a press release, the Event Horizon Telescope (EHT) said that over 300 researchers collaborated on the project and the findings were published Wednesday in two separate papers in The Astrophysical Journal.

In April 2019, scientists from EHT captured the world’s attention by releasing an image of the supermassive black hole lying at the center of M87, which is located 55 million light-years away from Earth.

The striking image showed a dark central region outlined by a ring-like structure, which scientists described at the time as “emission from hot gas swirling around it under the influence of strong gravity near its event horizon.” In the new image captured through polarized light, brightly colored streaks of light can be seen corresponding with its magnetic field.

“We are now seeing the next crucial piece of evidence to understand how magnetic fields behave around black holes, and how activity in this very compact region of space can drive powerful jets that extend far beyond the galaxy,” said Monika Mościbrodzka, coordinator of the EHT Polarimetry Working Group and a professor at Radboud Universiteit in the Netherlands.

The new observations, which are based on data collected by EHT researchers, should provide crucial insights on how a galaxy can project streams of energy thousands of light-years outward from its core.




Scientists Develop Model for Faster-Than-Light Warp Drive That Bends Spacetime to Send Ships to the Stars

‘A class of subluminal, spherically symmetric warp drive spacetimes, at least in principle, can be constructed based on the physical principles known to humanity today,’ the scientists say

Scientists claim they have developed a physical model for a warp drive – a device that would allow spacecraft to travel at faster-than-light speeds.

“We present the first general model for subliminal positive-energy, spherically symmetric warp drives”, the paper’s abstract states.

“Conceptually, we demonstrate that any warp drive, including the Alcubierre drive, is a shell of regular or exotic material moving inertially with a certain velocity. Therefore, any warp drive requires propulsion. We show that a class of subluminal, spherically symmetric warp drive spacetimes, at least in principle, can be constructed based on the physical principles known to humanity today.”

The scientists’ theories are based on the Alcubierre warp drive, named after theoretical physicist Miguel Alcubierre. In his paper’s abstract, published in 2000, he wrote that the drive world work by modifying spacetime.

“By a purely local expansion of spacetime behind the spaceship and an opposite contraction in front of it, motion faster than the speed of light as seen by observers outside the disturbed region is possible,” Alcubierre wrote.

“The resulting distortion is reminiscent of the ‘warp drive’ of science fiction. However, just as it happens with wormholes, the exotic matter will be needed in order to generate a distortion of spacetime”.

In theory, a warp drive would be able to work within the boundaries of Albert Einstein’s theory of general relativity. Faster-than-light travel would usually require an infinite amount of energy, but that restriction only applies to objects in spacetime rather than spacetime itself – which is how the universe could expand faster than the speed of light after the Big Bang.

The new paper, as Popular Mechanics reports, makes a key distinction between Alcubierre’s notions and its own: rather than using “negative energy”, a substance that does not exist in the universe, bubbles of spacetime could be used to make the drive possible.

The inside of the bubble would contain a passenger area, where the passage of time could operate differently from that outside the craft. “You cannot break the speed of light barrier for the passengers themselves relative to spacetime, so instead you keep them moving normally in the bubble [but] you move the bubble itself superluminally”, Professor and Research Fellow at the Frankfurt Institute for Advanced Studies, Sabine Hossenfelder, explains.

Professor Hossenfelder goes on to say that to move faster than light, the spacecraft itself would require negative energy densities, and acceleration needs energy and momentum – although the paper does not explain how this could be managed, it assumes that it is possible because it fits with the scientific theory.

The paper does go on to explain other designs the craft could take, such as seating passengers next to each other rather than behind each other – in contrast to traditional spacecraft.

This is because the amount of energy required depends on the shape of the bubble, and the flatter it is in the direction of travel (in the design of this warp drive) the less energy is needed.

The development of a warp drive has been a dream of space agencies for many years but is difficult to achieve tangible results. Nasa has been attempting to research novel propulsion methods for space travel but is clear in stating that it is not working on ‘warp drive’ technology.

In 2014 the agency published a design for a craft with a warp-drive, which would be able to travel to the nearest star in four weeks as opposed to the current time of 80,000 years.

By Adam Smith | Independent



How Fast is the Universe Expanding? Galaxies Provide One Answer

By University of California – Berkeley | ScienceDaily

Determining how rapidly the universe is expanding is key to understanding our cosmic fate, but with more precise data has come to a conundrum: Estimates based on measurements within our local universe don’t agree with extrapolations from the era shortly after the Big Bang 13.8 billion years ago.

A new estimate of the local expansion rate — the Hubble constant, or H0 (H-naught) — reinforces that discrepancy.

Using a relatively new and potentially more precise technique for measuring cosmic distances, which employs the average stellar brightness within giant elliptical galaxies as a rung on the distance ladder, astronomers calculate a rate — 73.3 kilometers per second per megaparsec, give or take 2.5 km/sec/Mpc — that lies in the middle of three other good estimates, including the gold standard estimate from Type Ia supernovae. This means that for every megaparsec — 3.3 million light-years, or 3 billion trillion kilometers — from Earth, the universe is expanding an extra 73.3 ±2.5 kilometers per second. The average from the three other techniques is 73.5 ±1.4 km/sec/Mpc.

Perplexingly, estimates of the local expansion rate based on measured fluctuations in the cosmic microwave background and, independently, fluctuations in the density of normal matter in the early universe (baryon acoustic oscillations), give a very different answer: 67.4 ±0.5 km/sec/Mpc.

Astronomers are understandably concerned about this mismatch because the expansion rate is a critical parameter in understanding the physics and evolution of the universe and is key to understanding dark energy — which accelerates the rate of expansion of the universe and thus causes the Hubble constant to change more rapidly than expected with increasing distance from Earth. Dark energy comprises about two-thirds of the mass and energy in the universe but is still a mystery.

For the new estimate, astronomers measured fluctuations in the surface brightness of 63 giant elliptical galaxies to determine the distance and plotted distance against velocity for each to obtain H0. The surface brightness fluctuation (SBF) technique is independent of other techniques and has the potential to provide more precise distance estimates than other methods within about 100 Mpc of Earth, or 330 million light-years. The 63 galaxies in the sample are at distances ranging from 15 to 99 Mpc, looking back in time a mere fraction of the age of the universe.

“For measuring distances to galaxies out to 100 megaparsecs, this is a fantastic method,” said cosmologist Chung-Pei Ma, the Judy Chandler Webb Professor in the Physical Sciences at the University of California, Berkeley, and professor of astronomy and physics. “This is the first paper that assembles a large, homogeneous set of data, on 63 galaxies, for the goal of studying H-naught using the SBF method.”

Ma leads the MASSIVE survey of local galaxies, which provided data for 43 of the galaxies — two-thirds of those employed in the new analysis.

The data on these 63 galaxies were assembled and analyzed by John Blakeslee, an astronomer with the National Science Foundation’s NOIRLab. He is the first author of a paper now accepted for publication in The Astrophysical Journal that he co-authored with colleague Joseph Jensen of Utah Valley University in Orem. Blakeslee, who heads the science staff that supports NSF’s optical and infrared observatories, is a pioneer in using SBF to measure distances to galaxies, and Jensen was one of the first to apply the method at infrared wavelengths. The two worked closely with Ma on the analysis.

“The whole story of astronomy is, in a sense, the effort to understand the absolute scale of the universe, which then tells us about the physics,” Blakeslee said, harkening back to James Cook’s voyage to Tahiti in 1769 to measure a transit of Venus so that scientists could calculate the true size of the solar system. “The SBF method is more broadly applicable to the general population of evolved galaxies in the local universe, and certainly if we get enough galaxies with the James Webb Space Telescope, this method has the potential to give the best local measurement of the Hubble constant.”

The James Webb Space Telescope, 100 times more powerful than the Hubble Space Telescope, is scheduled for launch in October.

Giant elliptical galaxies

The Hubble constant has been a bone of contention for decades, ever since Edwin Hubble first measured the local expansion rate and came up with an answer seven times too big, implying that the universe was actually younger than its oldest stars. The problem, then and now, lies in pinning down the location of objects in space that gives few clues about how far away they are.

Astronomers over the years have laddered up to greater distances, starting with calculating the distance to objects close enough that they seem to move slightly, because of parallax, as the Earth orbits the sun. Variable stars called Cepheids get you farther, because their brightness is linked to their period of variability, and Type Ia supernovae get you even farther because they are extremely powerful explosions that, at their peak, shine as bright as a whole galaxy. For both Cepheids and Type Ia supernovae, it’s possible to figure out the absolute brightness from the way they change over time, and then the distance can be calculated from their apparent brightness as seen from Earth.

The best current estimate of H0 comes from distances determined by Type Ia supernova explosions in distant galaxies, though newer methods — time delays caused by gravitational lensing of distant quasars and the brightness of water masers orbiting black holes — all give around the same number.

The technique using surface brightness fluctuations is one of the newest and relies on the fact that giant elliptical galaxies are old and have a consistent population of old stars — mostly red giant stars — that can be modeled to give an average infrared brightness across their surface. The researchers obtained high-resolution infrared images of each galaxy with the Wide Field Camera 3 on the Hubble Space Telescope and determined how much each pixel in the image differed from the “average” — the smoother the fluctuations over the entire image, the farther the galaxy, once corrections are made for blemishes like bright star-forming regions, which the authors excluded from the analysis.

Neither Blakeslee nor Ma was surprised that the expansion rate came out close to that of the other local measurements. But they are equally confounded by the glaring conflict with estimates from the early universe — a conflict that many astronomers say means that our current cosmological theories are wrong, or at least incomplete.

The extrapolations from the early universe are based on the simplest cosmological theory — called lambda cold dark matter, or?CDM — which employs just a few parameters to describe the evolution of the universe. Does the new estimate drive a stake into the heart of?CDM?

“I think it pushes that stake in a bit more,” Blakeslee said. “But it (?CDM) is still alive. Some people think, regarding all these local measurements, (that) the observers are wrong. But it is getting harder and harder to make that claim — it would require there to be systematic errors in the same direction for several different methods: supernovae, SBF, gravitational lensing, water masers. So, as we get more independent measurements, that stake goes a little deeper.”

Ma wonders whether the uncertainties astronomers ascribe to their measurements, which reflect both systematic errors and statistical errors, are too optimistic, and that perhaps the two ranges of estimates can still be reconciled.

“The jury is out,” she said. “I think it really is in the error bars. But assuming everyone’s error bars are not underestimated, the tension is getting uncomfortable.”

In fact, one of the giants of the field, astronomer Wendy Freedman, recently published a study pegging the Hubble constant at 69.8 ±1.9 km/sec/Mpc, roiling the waters even further. The latest result from Adam Riess, an astronomer who shared the 2011 Nobel Prize in Physics for discovering dark energy, reports 73.2 ±1.3 km/sec/Mpc. Riess was a Miller Postdoctoral Fellow at UC Berkeley when he performed this research, and he shared the prize with UC Berkeley and Berkeley Lab physicist Saul Perlmutter.

MASSIVE galaxies

The new value of H0 is a byproduct of two other surveys of nearby galaxies — in particular, Ma’s MASSIVE survey, which uses space and ground-based telescopes to exhaustively study the 100 most massive galaxies within about 100 Mpc of Earth. A major goal is to weigh the supermassive black holes at the centers of each one.

To do that, precise distances are needed, and the SBF method is the best to date, she said. The MASSIVE survey team used this method last year to determine the distance to a giant elliptical galaxy, NGC 1453, in the southern sky constellation of Eridanus. Combining that distance, 166 million light-years, with extensive spectroscopic data from the Gemini and McDonald telescopes — which allowed Ma’s graduate students Chris Liepold and Matthew Quenneville to measure the velocities of the stars near the center of the galaxy — they concluded that NGC 1453 has a central black hole with a mass nearly 3 billion times that of the sun.

To determine H0, Blakeslee calculated SBF distances to 43 of the galaxies in the MASSIVE survey, based on 45 to 90 minutes of HST observing time for each galaxy. The other 20 came from another survey that employed HST to image large galaxies, specifically ones in which Type Ia supernovae have been detected.

Most of the 63 galaxies are between 8 and 12 billion years old, which means that they contain a large population of old red stars, which are key to the SBF method and can also be used to improve the precision of distance calculations. In the paper, Blakeslee employed both Cepheid variable stars and a technique that uses the brightest red giant stars in a galaxy — referred to as the tip of the red giant branch, or TRGB technique — to ladder up to galaxies at large distances. They produced consistent results. The TRGB technique takes account of the fact that the brightest red giants in galaxies have about the same absolute brightness.

“The goal is to make this SBF method completely independent of the Cepheid-calibrated Type Ia supernova method by using the James Webb Space Telescope to get a red giant branch calibration for SBFs,” he said.

“The James Webb telescope has the potential to really decrease the error bars for SBF,” Ma added. But for now, the two discordant measures of the Hubble constant will have to learn to live with one another.

“I was not setting out to measure H0; it was a great product of our survey,” she said. “But I am a cosmologist and am watching this with great interest.”

Co-authors of the paper with Blakeslee, Ma, and Jensen are Jenny Greene of Princeton University, who is a leader of the MASSIVE team, and Peter Milne of the University of Arizona in Tucson, who leads the team studying Type Ia supernovae. The work was supported by the National Aeronautics and Space Administration (HST-GO-14219, HST-GO-14654, HST GO-15265) and the National Science Foundation (AST-1815417, AST-1817100).


Story Source:

Materials provided by University of California – Berkeley. Originally written by Robert Sanders. Note: Content may be edited for style and length.


Journal Reference:

  1. John P. Blakeslee, Joseph B. Jensen, Chung-Pei Ma, Peter A. Milne, Jenny E. Greene. The Hubble Constant from Infrared Surface Brightness Fluctuation DistancesThe Astrophysical Journal, 2021 [abstract]



New Study Suggests Supermassive Black Holes Could Form from Dark Matter

By Royal Astronomical Society | ScienceDaily

A new theoretical study has proposed a novel mechanism for the creation of supermassive black holes from dark matter. The international team find that rather than the conventional formation scenarios involving ‘normal’ matter, supermassive black holes could instead form directly from dark matter in high density regions in the centers of galaxies. The result has key implications for cosmology in the early Universe, and is published in Monthly Notices of the Royal Astronomical Society.

Exactly how supermassive black holes initially formed is one of the biggest problems in the study of galaxy evolution today. Supermassive black holes have been observed as early as 800 million years after the Big Bang, and how they could grow so quickly remains unexplained.

Standard formation models involve normal baryonic matter — the atoms and elements that that make up stars, planets, and all visible objects — collapsing under gravity to form black holes, which then grow over time. However the new work investigates the potential existence of stable galactic cores made of dark matter, and surrounded by a diluted dark matter halo, finding that the centers of these structures could become so concentrated that they could also collapse into supermassive black holes once a critical threshold is reached.

According to the model this could have happened much more quickly than other proposed formation mechanisms, and would have allowed supermassive black holes in the early Universe to form before the galaxies they inhabit, contrary to current understanding.

Carlos R. Argüelles, the researcher at Universidad Nacional de La Plata and ICRANet who led the investigation comments: “This new formation scenario may offer a natural explanation for how supermassive black holes formed in the early Universe, without requiring prior star formation or needing to invoke seed black holes with unrealistic accretion rates.”

Another intriguing consequence of the new model is that the critical mass for collapse into a black hole might not be reached for smaller dark matter halos, for example those surrounding some dwarf galaxies. The authors suggest that this then might leave smaller dwarf galaxies with a central dark matter nucleus rather than the expected black hole. Such a dark matter core could still mimic the gravitational signatures of a conventional central black hole, whilst the dark matter outer halo could also explain the observed galaxy rotation curves.

“This model shows how dark matter haloes could harbor dense concentrations at their centers, which may play a crucial role in helping to understand the formation of supermassive black holes,” added Carlos.

“Here we’ve proven for the first time that such core-halo dark matter distributions can indeed form in a cosmological framework, and remain stable for the lifetime of the Universe.”

The authors hope that further studies will shed more light on supermassive black hole formation in the very earliest days of our Universe, as well as investigating whether the centers of non-active galaxies, including our own Milky Way, may play host to these dense dark matter cores.


Story Source:

Materials provided by Royal Astronomical SocietyNote: Content may be edited for style and length.


Journal Reference:

  1. Carlos R Argüelles, Manuel I Díaz, Andreas Krut, Rafael Yunis. On the formation and stability of fermionic dark matter haloes in a cosmological frameworkMonthly Notices of the Royal Astronomical Society, 2021; 502 (3): 4227 DOI: 10.1093/mnras/staa3986



As New Mars Rover Lands This Week, NASA Sees Evidence of Ancient Alien Life Within Reach

By   | TheMindUnleashed.com

NASA’s Perseverance rover is en route to Mar and expected to arrive on Thursday on the surface of the Red Planet, where it will land near the dried-out lakebed Jezero Crater.

NASA is hoping to finally find solid evidence of alien life in our solar system at the ancient lakebed and will be deploying its six-wheeled Perserverence rover for this purpose. The Perseverance rover will be the first rover to land on the Martian surface since 2012 and will include two major upgrades: a microphone and its very own helicopter.

The researchers at the U.S. space agency chose the ancient Jezero Crater as a landing site due to its significance as a once-thriving home to Martian life that was swimming with microbes and potentially other forms of life.

According to the NASA science team, over 3.5 billion years ago Mars was a major water world that teemed with rivers and lakes. Among these bodies of water was the lakebed at Jezero Crater, which was filled with water and formed a deep lake roughly the same size as Lake Tahoe.

During this period, rivers fed Lake Jezero with the rich clay minerals of the region, likely also feeding microbes into the lake where they were trapped. However, as the climate of the Red Planet changed, Lake Jezero eventually dried up while surface water across Mars vanished.

However, NASA scientists believe that due to the likelihood that microbes dwelled in the ancient lakebed, there is a strong likelihood that they will find fossil rocks known as stromatolites along what was once the shoreline of the lake, as well as the dried-up river delta in the area.

Mars remains inhospitable for any form of life to exist on its planetary surface. However, the Mars 2020 mission is to learn whether life ever existed on the planet. For this purpose, the Perseverance rover will be studying rocks, taking pictures with its nearly two dozen cameras, and bring samples back to Earth.

 “The science team identified Jezero Crater as basically an ancient lakebed,” said Mars 2020 flight director of cruise operations Matt Smith in a video released by NASA“And one of the most promising places to look for evidence of ancient microbial life and to collect samples for a future return to Earth. The problem is it’s a much more hazardous place to land.”

One of the most challenging aspects of the mission will be the actual landing of the rover at the site, which will include an upgraded rocket pack known as the sky crane as well as advanced technologies dubbed the Range Trigger and Terrain-Relative Navigation, which will detect any potential hazards in the landing zone. Perseverance will also be equipped with a miniature helicopter drone equipped with cameras that will fly over the site later in the year.

The space agency will also be sharing the dramatic scene of the rover being lowered to the Martian surface by the sky crane before its wheels drop into place, NASA engineer David Gruel told NPR.

“And then the jet engines start to kick up dust from the surface of Mars,” Gruel said. “As the vehicle disappears into that dust and gets ready to land on Mars, it’s going to be awesome.”