Adam Rains

I currently am part of the CRIRES+ Consortium and work as part of the Planetary Atmospheres Working Group to understand planets through high-resolution transmission spectroscopy. More broadly, however, my research interests sit somewhere at the intersection of cool stars, exoplanet demographics, stellar benchmarks, and non-traditional analysis techniques.

This largely centres on cool dwarf stars of spectral type M or K, which are the most common kind of star in the Universe, and the most likely to host planets. These stars possess complicated spectra dominated by intense molecular absorption, something which is not well reproduced by current libraries of model spectra—especially at optical wavelengths.

This greatly limits the ability to chemically characterise these stars and their planets, and currently they are arguably best understood via empirical relations, comparison to benchmark systems, or through non-traditional analysis techniques like data-driven methods. My PhD research was focused on providing solutions to some of these challenging topics.

My first project in Rains et al. 2020 used PIONIER, the highest resolution beam combiner on the VLTI, to broaden and verify the existing library of ~1% precision temperature and radius benchmark stars suitable to calibrate current and future surveys in Galactic archaeology.

Rains et al. 2021 involved working to characterise a set of 92 cool TESS candidate exoplanet hosts and their 100 candidate planets and in so doing conduct an investigation into the systematics associated with model cool dwarf spectra, develop a new photometric [Fe/H] relation for isolated cool dwarfs, and broaden the currently small sample of planets around cool stars suitable for studies in exoplanet demographics.

The main extension to my PhD work has been to use the cool dwarf spectra observed as part of Rains et al. 2021 in a data-driven capacity to recover stellar chemistry. When trained on a hand-selected set of benchmarks, my Cannon model is able to recover T_eff, log g, [Fe/H], and [Ti/H], as well as gain insight into the giant planet—[Fe/H] correlation for my sample of TESS candidate planet hosts. For preliminary results, see my poster from Cool Stars 21.