About 32 light years from Earth, practically in our backyard, lies a dramatic young star called AU Microscopii or AU Mic for short. This star is only 20 to 30 million years old. That may sound ancient, but according to star standards it is a baby – our sun is 150 times older for reference.
The orbit of this baby star is a planet of dramatic events, AU Mic b, that was recently discovered using data from NASA's Transiting Exoplanet Survey Satellite (TESS) and the now retired Spitzer Space Telescope.
A year on this Neptune-sized planet takes a little more than an Earth week because it orbits extremely close to its star. And it is constantly bombarded with torches of the star caused by the star's strong magnetic fields. The star is often covered with star spots – similar to sun spots – that erupt with torches that bathe the planet in radiation.
This portrayal of the young planet AU Mic b is part of NASA's entertaining but informative poster series Galaxy of Horrors. The star of the planet, AU Microscopii, emits powerful, fiery torches that would likely terrorize all life forms that are looking for a home here. NASA exoplanet exploration program
Because the star AU Mic is so young, both it and its planet are still surrounded by the dust and gas disk from which they formed. This makes this system the ideal place for researchers to observe how planetary systems evolve over time.
"We believe AU Mic b has formed far from the star and has moved inward into its current orbit. This can happen when planets gravitationally interact with a gas disk or with other planets," said co-author Thomas Barclay, Associate Project Scientist at TESS in NASA Flight Center's Goddard Space, explains in a statement.
The concept of this artist shows the dusty disk that surrounds the star AU MIcroscopii. Astronomers have studied this system extensively, but have only recently identified the presence of a planet there. The find offers a laboratory to study the evolution and formation of planets. NASA's Goddard Space Flight Center / Chris Smith (USRA)
Barclay and his team also compared the system to planets in another nearby system, the Beta Pictoris Moving Group. “In contrast, the orbit of Beta Pictoris b doesn't seem to have moved much at all. The differences between these similar aged systems can tell us a lot about how planets form and migrate, ”he said.
There may even be more planets hiding in AU Mic's orbit, so scientists are returning to this system to examine it more closely and see if they can find it.
"There is an additional transit event for candidates in the TESS data, and hopefully TESS will revisit AU Mic later this year in its expanded mission," said lead researcher Peter Plavchan. "We continue to monitor the star with precise radial speed measurements, so keep up to date."
The research is published in the journal Nature.