Proxima Centauri b is not a transiting exoplanet

DOI: 
10.1093/mnras/stz1268
Publication date: 
01/05/2019
Main author: 
Jenkins, James S.
IAA authors: 
Rodríguez, Eloy;Amado, Pedro J.;Rodríguez-López, Cristina
Authors: 
Jenkins, James S.;Harrington, Joseph;Challener, Ryan C.;Kurtovic, Nicolás T.;Ramirez, Ricardo;Peña, Jose;McIntyre, Kathleen J.;Himes, Michael D.;Rodríguez, Eloy;Anglada-Escudé, Guillem;Dreizler, Stefan;Ofir, Aviv;Rojas, Pablo A. Peña;Ribas, Ignasi;Rojo, Patricio;Kipping, David;Butler, R. Paul;Amado, Pedro J.;Rodríguez-López, Cristina;Kempton, Eliza M. -R.;Palle, Enric;Murgas, Felipe
Journal: 
Monthly Notices of the Royal Astronomical Society
Refereed: 
Yes
Publication type: 
Article
Pages: 
268-274
Abstract: 
We report Spitzer Space Telescope observations during predicted transits of the exoplanet Proxima Centauri b. As the nearest terrestrial habitable-zone planet we will ever discover, any potential transit of Proxima b would place strong constraints on its radius, bulk density, and atmosphere. Subsequent transmission spectroscopy and secondary-eclipse measurements could then probe the atmospheric chemistry, physical processes, and orbit, including a search for biosignatures. However, our photometric results rule out planetary transits at the 200 ppm level at 4.5 μm, yielding a 3σ upper radius limit of 0.4 R<SUB>⊕</SUB> (Earth radii). Previous claims of possible transits from optical ground- and space-based photometry were likely correlated noise in the data from Proxima Centauri's frequent flaring. Follow-up observations should focus on planetary radio emission, phase curves, and direct imaging. Our study indicates dramatically reduced stellar activity at near-to-mid infrared wavelengths, compared to the optical. Proxima b is an ideal target for space-based infrared telescopes, if their instruments can be configured to handle Proxima's brightness.
Database: 
ADS
SCOPUS
URL: 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85071157345&doi=10.1093%2fmnras%2fstz1268&partnerID=40&md5=bad05b6be472686a09abecf210d6e9c0
ADS Bibcode: 
2019MNRAS.487..268J
Keywords: 
stars: planetary systems;stars: planetary systems: formation;stars: activity;Astrophysics - Earth and Planetary Astrophysics;Astrophysics - Instrumentation and Methods for Astrophysics;Astrophysics - Solar and Stellar Astrophysics