I study stars and their spectra (rainbows) to learn about their overall characteristics and in particular their chemical composition.

Sun’s Siblings

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.

Star map showing the location of the star HD 162826 in the Hercules constellation. Also shown are the Cygnus and Lyra constellations, the latter including a label to the bright star Vega.

Credit: Ivan Ramirez/Tim Jones/McDonald Observatory

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.

Picture of the wide binary star system XO-2.