University of Hawai‘i Astronomers Help Discover "Infant’" Planet

Pablo Tucker
June 26, 2020

The Neptune-sized exoplanet has been found orbiting a young star which, astronomers say, is relatively close to Earth. But don't expect habitability here: The star throws epic temper tantrum-like storms.

Thanks to these observations and in large part to NASA's Transiting Exoplanet Survey Satellite (TESS) and the Spitzer Space Telescope, scientists were able to observe a planetary transit occurring once every eight and a half days.

The planet was discovered around the star AU Microscopii (AU Mic), a 20 to 30 million-year-old star about 32 light-years away from Earth. They are the correct size and correct orbit for their star to withstand surface water and, at least theoretically, for Life Support. Planetary gravitational tugs on M dwarfs are also easier to spot, which can teach scientists more about a newly spotted world.

Espace pour la vie | Newswire
Espace pour la vie | Newswire

AU Mic is in the Microscopium constellation and is a part of the Beta Pictoris Moving Group, which NASA notes is an A-type star and "harbors two planets and is likewise surrounded by a debris disk". "It's surrounded by a vast debris disk in which moving clumps of dust have been tracked, and now, thanks to TESS and Spitzer, it has a planet with a direct size measurement", said Bryson Cale, a doctoral student at George Mason University in Fairfax, Virginia. No there is another known system that ticks all these important boxes.

"There is an additional candidate transit event seen in the TESS data, and TESS will hopefully revisit AU Mic later this year in its extended mission", said Dr. Peter Plavchan, an astronomer at George Mason University. "One of the fun things and one of the most frustrating things about studying the stars is that we can never go to them", says Barclay. But Beta Pictoris and AU Mic have markedly different planets, despite being neighbors.

The team determined that AU Mic b is the size of Neptune, has a mass of no more than 58 Earths, and completes an orbit of AU Mic every 8.5 days.

NASA's research of the method has been described as a one particular-of-a-form laboratory for learning how planets and their atmospheres kind, evolve and interact with their stars.

Dr Barclay, who is also an associate project scientist for Tess, said: "Dips in brightness tell you about the size of the planet, and measuring how regularly spaced the transits are tells us how long it takes the planet to go around the star".

This would provide clues about how it had moved since it first came into being - offering insights on how planets form and migrate in a new star system.

AU Mic and its planet are about 25 million years young. In fact, some of the flares were actually more powerful than some of the strongest ones our own sun has released.

Since first spying the flaring behaviour of the star in the 1970s, space experts had debated whether AU Mic hosted its own worlds. The observing team won time on NASA's Spitzer Space Telescope to follow up on their find.

Spitzer was a multipurpose infrared observatory operating from 2003 until its decommissioning on January 30, 2020.

An global team of scientists have discovered an exoplanet that is 8 percent larger than Neptune, the fourth-largest planet in our Solar System. "Analysis of these measurements show that the planet is about 8 percent larger than Neptune", NASA notes. Sensitive spectrographs such as the one on the IRTF can detect the star's radial velocity, its motion to-and-fro along our line of sight.

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