Exploring the Impact of Substellar Objects on Late Stellar Evolution

点击翻译按钮获取中文摘要

Recently, planets and brown dwarfs (objects intermediate in size between planets and stars) have been discovered around very old stars that have ejected most of their material, leaving a small hot star known as a "subdwarf B" (sdB). Prior to ejecting material, the sdB stars were large red giant stars. Thus, their planets and brown dwarfs must have been engulfed as the red giant star expanded. The PI plans to use small telescopes to search for more of these sdB stars and determine whether they have companion planets or brown dwarfs. He will determine the masses of the stars and their companions, and compare the new data set with theories for how stars change near the end of their lifetimes. He will establish an integrated research and education program that will, first, teach university students to observe with robotic telescopes. The students will then teach high school teachers and students to use the telescopes to discover and analyze sdB stars. This will strengthen the students' interest and active participation in STEM research.Finding the companion masses in a large number of post-common envelope sdB binaries will provide the first robust tests of models involving red giant-engulfed companion interactions. The lower mass limits resulting from this work will help constrain model parameters relating to tidal effects and angular momentum conservation. Determination of orbital periods, eccentricities, and component masses will provide constraints on hot subdwarf formation models and improve understanding of this stage of stellar evolution. The PI, through collaborations with other astronomers, has access to Evryscope data, SKYNET, and the SOAR/Goodman telescopes.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.