Two amateur astronomers found a new candidate planet, and the object could shed light on planetary evolution around red dwarf stars.
The discovery was confirmed by Andrew Mann, an astronomer at the University of Texas at Austin, and colleagues. The planet, called K2-25b, orbits a star in the Hyades star cluster located 153 light-years from Earth. K2-25b has approximately four times the mass of Earth, and is about the size of Neptune.
The planet is significantly larger than any previously detected planet around a red dwarf; such worlds are usually less than twice the size of Earth. The discovery is important for two reasons: Red dwarfs are the most common stars in the Milky Way, and the system is in a young open cluster of stars. This is a window into how the most common star systems form.
“This could even give us a glimpse into what our Solar System looked like,” said Dr. Mann in a statement.
The Hyades cluster is between 650 and 800 million years old, making K2-25b a very young planet.
“We can compare those to planets orbiting older stars elsewhere to see if they are different in some fundamental way – to see how planets change with time,” added Dr. Mann.
The paper, published in the Astrophysical Journal, reports that K2-25b's star is less than one-third the mass of our Sun, and that the planet orbits very close to it, with a period of about 3.5 days. The vicinity indicates that the atmosphere of K2-25b is being blown off into space, a process that might have been going on for hundreds of millions of years.
“This could have major implications for our understanding of how planets evolve, including Earth-like planets, as we need to know how well a planet can hold an atmosphere given a certain set of conditions to tell how long it remains habitable,” Mann said.
The discovery of this planet was initally made by Thomas Jacobs and Daryll LaCourse, two amateur astronomers who were able to find this planet candidate in the freely available K2 data from the Kepler space telescope’s extended mission.
The red dwarf star K2-25 is indicated in this view of part of the Hyades open star cluster from the Digitized Sky Survey. A. Mann/McDonald Obs./DSS