CoRoT-1b

Lore & Background

CoRoT-1b was identified as the best planetary candidate from the CoRoT spacecraft's initial observation run from February 6 to April 2, 2007. Follow-up photometry with the Wise Observatory's 1.0 m telescope and at the Canada–France–Hawaii Telescope eliminated many possible false positives for the transit signal. Nine radial velocity measurements of CoRoT-1 were made at Haute-Provence Observatory in March–April and October 2007 with the SOPHIE échelle spectrograph, which matched the CoRoT light curve and supported the planetary nature of CoRoT-1b, eliminating other possibilities such as background stars, grazing eclipsing binaries, or a triple system. The discovery was publicly announced on May 3, 2007.

The planet is a large hot Jupiter, about 1.49 times the radius of Jupiter and approximately 1.03 times as massive, based on ground observations of the star. Its large size is due to its low density combined with the intense heating of its parent star, causing the outer layers of the atmosphere to bloat. In May 2009, CoRoT-1b became the first extrasolar planet for which optical observations of phases were reported, suggesting that there is not significant heat transfer between the tidally locked night and day sides of the planet.

Reader's Guide

CoRoT-1b holds a significant place in exoplanet science as the first discovery of the CoRoT mission, a French-led space telescope designed to detect transiting planets. Its detection demonstrated the effectiveness of the transit method combined with radial velocity follow-up to confirm a planetary candidate and rule out false positives such as background stars or grazing eclipsing binaries. The planet's large radius relative to its mass, characteristic of a bloated hot Jupiter, provided early evidence of how intense stellar irradiation can inflate a gas giant's atmosphere. More notably, in May 2009, CoRoT-1b became the first exoplanet for which optical phase variations were observed, revealing that the planet's day side is significantly hotter than its night side with little heat redistribution. This finding offered direct observational insight into the atmospheric dynamics of a tidally locked hot Jupiter, influencing subsequent studies of exoplanet atmospheres and phase curves. The planet's legacy includes serving as a benchmark for understanding the properties of close-in giant planets and the capabilities of space-based transit surveys.

Did You Know?

• CoRoT-1b was the first planet discovered by the French-led CoRoT Mission.
• It is located approximately 2,630 light-years away in the constellation of Monoceros.
• The planet's large size is due to its low density combined with intense heating from its parent star.