STEREO observations of stars and the search for exoplanets

TL;DR

This study demonstrates the potential of NASA STEREO data for variable star research and exoplanet detection, revealing new eclipsing binaries and a possible substellar companion through high-precision photometry.

Contribution

It develops a data analysis pipeline for the entire STEREO star database and identifies new variable stars and exoplanet candidates, expanding the utility of STEREO observations.

Findings

Discovered 122 new eclipsing binaries not in SIMBAD.

Detected a potential substellar companion with 5-sigma significance.

Showed STEREO data's suitability for long-term variable star and exoplanet studies.

Abstract

The feasibility of using data from the NASA STEREO mission for variable star and asteroseismology studies has been examined. A data analysis pipeline has been developed that is able to apply selected algorithms to the entire database of nearly a million stars to search for signs of variability. An analysis limited to stars of magnitude 10.5 has been carried out, which has resulted in the extraction of 263 eclipsing binaries (EBs), of which 122 are not recorded as such in the SIMBAD online database. The characteristics of the STEREO observations are shown to be extremely well-suited to variable star studies with the ability to provide continuous phase coverage for extended periods as well as repeated visits that allow both short and long term variability to be observed. This will greatly inform studies of particular stars, such as the pre-cataclysmic variable V471 Tau, as well as entire classes of stars, including many forms of rotational variability. The high-precision photometry has also revealed a potentially substellar companion to a bright (R = 7.5 mag) nearby star (HD 213597), detected with 5-sigma significance. This would provide a significant contribution to exoplanet research if follow-up observations ascertain the mass to be within the planetary domain. Some particularly unusual EBs from the recovered sample are discussed, including a possible reclassification of a well-known star as an EB rather than a rotational variable (HR 7355) and several particularly eccentric systems, including very long-period EBs.