I study stars and their spectra (rainbows) to learn about their overall characteristics and in particular their chemical composition.
Stars are born in clusters of thousands to tens of thousands of stars, and our Sun was no exception. Where are the stars that were born together with the Sun now? These “siblings” of the Sun are difficult to find in the solar neighborhood. Nevertheless, a combination of kinematics and chemical abundance analysis has made it possible for us to find them. The star map below shows the location of HD162826, the first, and so far only, sibling of the Sun identified.
Credit: Ivan Ramirez/Tim Jones/McDonald Observatory
- Press release: Astronomers Find Sun’s “Long-Lost Brother,” Pave Way for Family Reunion
- YouTube video: Does the Sun Have Long-Lost Siblings?
- Paper: Elemental Abundances of Solar Sibling Candidates
Stellar Twins and their Planets
When planets form, they retain heavy elements (“metals”) that would otherwise end up in the star. Thus, small “metallicity” deficiences are expected in stars that host planets. We have detected this signature in a number of twin-star binaries (systems of two nearly identical stars that orbit each other) where one or both of the stars are known to host planets, supporting our hypothesis. That is the case of the binary star system XO-2, which is shown in the picture below.