Searching for the Transit of the Earth--mass exoplanet Proxima~Centauri~b in Antarctica: Preliminary Result

Abstract

Proxima Centauri is known as the closest star from the Sun. Recently, radial velocity observations revealed the existence of an Earth-mass planet around it. With an orbital period of ~11 days, the surface of Proxima Centauri b is temperate and might be habitable. We took a photometric monitoring campaign to search for its transit, using the Bright Star Survey Telescope at the Zhongshan Station in Antarctica. A transit-like signal appearing on 2016 September 8th, is identified tentatively. Its midtime, $T_C=2,457,640.1990\pm 0.0017$ HJD, is consistent with the predicted ephemeris based on RV orbit in a 1$\sigma$ confidence interval. Time-correlated noise is pronounced in the light curve of Proxima Centauri, affecting detection of transits. We develop a technique, in a Gaussian process framework, to gauge the statistical significance of potential transit detection. The tentative transit signal reported here, has a confidence level of $2.5\sigma$. Further detection of its periodic signals is necessary to confirm the planetary transit of Proxima Centauri b. We plan to monitor Proxima Centauri in next Polar night at Dome A in Antarctica, taking the advantage of continuous darkness. \citet{Kipping17} reported two tentative transit-like signals of Proxima Centauri b, observed by the Microvariability and Oscillation of Stars space Telescope in 2014 and 2015, respectively. The midtransit time of our detection is 138 minutes later than that predicted by their transit ephemeris. If all the signals are real transits, the misalignment of the epochs plausibly suggests transit timing variations of Proxima Centauri b induced by an outer planet in this system.

17 pages, 8 figures, 2 tables, accepted by The Astronomical Journal

References in corpus (16)

• Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1
• A terrestrial planet candidate in a temperate orbit around Proxima Centauri
• DHP Framework: Digital Health Passports Using Blockchain -- Use case on international tourism during the COVID-19 pandemic
• The effect of red noise on planetary transit detection
• The Solar Neighborhood XVII: Parallax Results from the CTIOPI 0.9m Program -- Twenty New Members of the RECONS 10 Parsec Sample
• Proxima's orbit around Alpha Centauri
• The habitability of Proxima Centauri b II. Possible climates and Observability
• Exoplanet Orbital Eccentricities Derived From LAMOST-Kepler Analysis
• The habitability of Proxima Centauri b. I. Irradiation, rotation and volatile inventory from formation to the present
• The Mass of Kepler-93b and The Composition of Terrestrial Planets
• MOST Observations of our Nearest Neighbor: Flares on Proxima Centauri
• Prospects for Characterizing the Atmosphere of Proxima Centauri b
• Close stellar conjunctions of alpha Centauri A and B until 2050 - An mK = 7.8 star may enter the Einstein ring of alpha Cen A in 2028
• Planetary Transit Candidates in the CSTAR Field: Analysis of the 2008 Data
• No Conclusive Evidence for Transits of Proxima b in MOST photometry
• Hubble Space Telescope search for the transit of the Earth-mass exoplanet Alpha Centauri Bb

Cited by in corpus (5)

• Toward Extremely Precise Radial Velocities: II. A Tool For Using Multivariate Gaussian Processes to Model Stellar Activity
• Proxima Centauri b is not a transiting exoplanet
• Large Interferometer For Exoplanets (LIFE). X. Detectability of currently known exoplanets and synergies with future IR/O/UV reflected-starlight imaging missions
• 3-D climate simulations for the detectability of Proxima Centauri b
• Astronomy from Dome A in Antarctica