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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 Think They’ve Detected Radio Emissions from an Alien World

© Provided by Space An artist’s depiction of the exoplanet Tau Boötes b shows a magnetic field, which may cause the radio emissions…

The astronomers behind the new research used a radio telescope in the Netherlands to study three different stars known to host exoplanets. The researchers compared what they saw to observations of Jupiter, diluted as if being seen from a star system dozens of light-years away. And the one-star system stood out: Tau Boötes, which contains at least one exoplanet. If the detection holds up, it could open the door to better understanding the magnetic fields of exoplanets and therefore the exoplanets themselves, the researchers hope.

“We present one of the first hints of detecting an exoplanet in the radio realm,” Jake Turner, an astronomer at Cornell University and lead author of the new research, said in a statement. “We make the case for emission by the planet itself. From the strength and polarization of the radio signal and the planet’s magnetic field, it is compatible with theoretical predictions.”

However, Turner and his colleagues aren’t yet positive that the signal they detected really is coming from the planet, dubbed Tau Boötes b; the researchers called for additional observations of the system, which is about 51 light-years away from Earth in the constellation Boötes.

The new research actually began at Jupiter; the researchers had previously studied that planet’s radio emissions and then tweaked those measurements to reflect the effect they expected closeness to the host star and distance from Earth would have had on their observations of an exoplanet.

Then, the scientists consulted observations made in 2016 and 2017 by the Low-Frequency Array (LOFAR) in the Netherlands. In addition to the potential signal from Tau Boötes b, the researchers also report that they may have picked up a signal from the star Upsilon Andromedae or its planet, but that detection was even fainter than the one from Tau Boötes b.

The researchers are interested in detecting radio emissions from planets because such information may help scientists decipher what’s happening in the same worlds’ magnetic fields. Those magnetic fields, in turn, influence conditions on the surface of the planet — Earth’s magnetic field protects the atmosphere that makes the world one we can survive, for example. Such magnetic fields can also tell scientists about other qualities of a world, like its structure and history.

But so far, studying those magnetic fields directly has been difficult for scientists to manage, despite the fact that nearly every planet in our solar system has had one at some point in its history. Hence the interest in using radio emissions as an intermediate.

“We learned from our own Jupiter what this kind of detection looks like,” Turner said. “We went searching for it and we found it.”

But that’s just the beginning of the story, not the end of it, he emphasized, since the radio emissions could still be coming from the stars or another source instead of the planet. “There remains some uncertainty that the detected radio signal is from the planet. The need for follow-up observations is critical.”

By Meghan Bartels / Senior Writer, Space.com
Meghan Bartels graduated from Georgetown University with a major in classics and a minor in biology. After college, she worked at a small environmental book publisher, where she learned that writing about science is fun when you get to use sentences that include both nouns and verbs. She also enjoys learning about history, drinking tea, and cheering on the Georgetown men’s basketball team.

@meghanbartels