A Multi-year Search for Transits of Proxima Centauri. I. Light Curves Corresponding to Published Ephemerides

Abstract

Proxima Centauri has become the subject of intense study since the radial-velocity discovery by Anglada-Escudé 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.

Stellar and substellar companions of nearby stars from Gaia DR2

“…It hosts the nearest exoplanet, Proxima b (Anglada-Escudé et al 2016), a telluric mass planet with a very short orbital period (11.2 d) and orbital distance (0.05 au) that place it inside the habitable zone of its parent star. The search for transiting exoplanet signals have been unsuccessful up to now (Blank et al 2018;Feliz et al 2019). Proxima is an active star, with frequent flares that were detected over a broad range of wavelengths (MacGregor et al 2018;Howard et al 2018).…”

Predicted Yield of Transits of Known Radial Velocity Exoplanets from the TESS Primary and Extended Missions

“…TERMS, and other similar efforts, have thoroughly ruled out transits for the exoplanet hosts GJ 581 (e.g. (Kane et al 2011c), and Proxima Cen b (e.g., Kipping et al 2017;Blank et al 2018). However, resources for individual efforts such as those listed here are limited.…”

Proxima Centauri b is not a transiting exoplanet

“…Using the Bright Star Survey Telescope in Antartica, Liu et al (2018) report a number of transit-like events that could be ascribed to Proxima b, and assuming large transit timing variations (TTV), they could phase with the event reported in Kipping et al (2017). On the contrary, Blank et al (2018) were unable to confirm any of the previously reported transit events using optical data spanning 11 years, albeit with heterogeneous and noncontinuous data sets. They do, however, confirm the impact of high stellar activity on optical light curves.…”