Spectroscopy is a powerful tool to study and understand stars. With the continuous development of high-precision spectrographs and new analysis methods, we can now precisely characterize stars and their physical properties. As is too often the case, while our detailed observations have given us important answers, they have also raised some interesting questions.

During the last decade, noticeable advances were made in the characterization of atmospheric properties (e.g. effective temperature, metallicity, surface gravity) and chemical abundances of cool stars. The extremely high precision allowed observers to study very subtle chemical peculiarities in stars that had initially appeared Sun-like. The quintessential example is the so-called Tc-trend – a trend of individual chemical abundances with the condensation temperature of the elements. While terrestrial planet formation, Galactic chemical evolution and stellar formation/evolution were proposed to explain the observed Tc-trend in Sun-like stars, the real nature is still debated.

Other stellar variations have also arisen, such as those seen within planetary hosts and the variations found in Li abundances. Given the nature of the detailed chemical abundance derivations, it is likely that many physical processes determine the chemical peculiarities of the stars. Understanding the origin of these anomalies is very important for the further advancement of Galactic and stellar astronomy, as well as the emerging field of exoplanetary research.

The purpose of this Splinter Session is to bring together experts of stellar, Galactic and planetary astrophysics to highlight the latest results and discuss what makes Sun-like stars unlike the Sun. The initial plan is to have several talks on the highest achievable (to-date) precision for solar-type stars, different explanations of the origins of chemical peculiarities of stars, and then move to an open discussion between the speakers and audience. We found that this format worked very well for Satellite Meeting 8 at the Pathways Towards Habitable Planets conference in Bern, Switzerland. If more interesting suggestions are received from the participants on the format of the session we will gladly adapt for it.

Conveners
Vardan Adibekyan (IA,Porto)
Elisa Delgado Mena (IA, Porto)
Sofia Feltzing (Lund, Sweden)
Jonay González Hernández (IAC, Spain)
Natalie Hinkel (ASU, US)
Andreas Korn (Uppsala, Sweden)