A Multi-Year Search For Transits Of Proxima Centauri. I: Light Curves Corresponding To Published Ephemerides

TL;DR

This study conducted an extensive multi-year photometric monitoring of Proxima Centauri to search for transits of its planet, but found no conclusive evidence of transits despite confirming the star's intrinsic variability.

Contribution

It provides the first comprehensive, multi-year light curve dataset for Proxima Centauri, enabling a more thorough search for transits and analysis of stellar variability.

Findings

No independent verification of previous tentative transit claims.

Confirmed complex and ubiquitous stellar variability.

Data set spans 2006-2017 with 329 observations.

Abstract

Proxima Centauri has become the subject of intense study since the radial-velocity discovery by Anglada-Escud\'e et al. 2016 of a planet orbiting this nearby M-dwarf every ~ 11.2 days. If Proxima Centauri b transits its host star, independent confirmation of its existence is possible, and its mass and radius can be measured in units of the stellar host mass and radius. To date, there have been three independent claims of possible transit-like event detections in light curve observations obtained by the MOST satellite (in 2014-15), the BSST telescope in Antarctica (in 2016), and the Las Campanas Observatory (in 2016). The claimed possible detections are tentative, due in part to the variability intrinsic to the host star, and in the case of the ground-based observations, also due to the limited duration of the light curve observations. Here, we present preliminary results from an extensive photometric monitoring campaign of Proxima Centauri, using telescopes around the globe and spanning from 2006 to 2017, comprising a total of 329 observations. Considering our data that coincide directly and/or phased with the previously published tentative transit detections, we are unable to independently verify those claims. We do, however, verify the previously reported ubiquitous and complex variability of the host star. We discuss possible interpretations of the data in light of the previous claims, and we discuss future analyses of these data that could more definitively verify or refute the presence of transits associated with the radial-velocity discovered planet.