CoRoT-7 (TYC 4799-1733-1) is a binary star system. The primary, CoRoT-7A is a G-type main sequence star, slightly smaller, cooler, and younger than the

Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...

. It has an

apparent magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's ...

of 11.67, fainter than Proxima Centauri (mag. 11.05), the nearest star to the Sun. This star is approximately 520 light-years away from the

Solar System The Solar System Capitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar ...

in the constellation

Monoceros Monoceros (Greek: Μονόκερως, "unicorn") is a faint constellation on the celestial equator. Its definition is attributed to the 17th-century Dutch cartographer Petrus Plancius. It is bordered by Orion to the west, Gemini to the north, ...

(the Unicorn). The comoving companion CoRoT-7B was discovered in 2021. It is a red dwarf star.

Location and properties

The star is located in the LRa01 field of view of the CoRoT spacecraft. It is about 500 light years from Earth. According to the project website, this field is in the Monoceros constellation. Published data lists the stellar properties as being a G9V yellow dwarf with a temperature of 5250 K, a radius of about 82% of the Sun and a mass of about 91% of the Sun. But other sources have listed it as a (K0V) orange dwarf. The metallicity is 0.12 ± 0.06. The star is estimated to be about 150 parsecs away and with an age in the range 1.2 – 2.3 billion years, is younger than our own star which has an age of 4.6 billion years. The rotation period of the star, inferred by the lightcurve obtained by

CoRoT CoRoT (French: ; English: Convection, Rotation and planetary Transits) was a space telescope mission which operated from 2006 to 2013. The mission's two objectives were to search for extrasolar planets with short orbital periods, particularly th ...

, is around 23 days.

Planetary system

The primary star is orbited by the

super-Earth A super-Earth is an extrasolar planet with a mass higher than Earth's, but substantially below those of the Solar System's ice giants, Uranus and Neptune, which are 14.5 and 17 times Earth's, respectively. The term "super-Earth" refers only to ...

exoplanets

CoRoT-7b CoRoT-7b (previously named CoRoT-Exo-7b) is an exoplanet orbiting the star CoRoT-7 in the constellation of Monoceros (constellation), Monoceros, from Earth. It was first detected Methods of detecting extrasolar planets#Transit photometry, photome ...

and CoRoT-7c, both discovered in 2009. A third planet CoRoT-7d, initially proposed in a 2010 study, was confirmed in 2022. The discovery of the inner planet was made using the

transit Transit may refer to: Arts and entertainment Film * ''Transit'' (1979 film), a 1979 Israeli film * ''Transit'' (2005 film), a film produced by MTV and Staying-Alive about four people in countries in the world * ''Transit'' (2006 film), a 2006 ...

method by the

program. CoRoT-7b is notable for its relatively small size, compared to other exoplanets known at the time. Because of their closeness to their star, these exoplanets cannot be seen in a

telescope A telescope is a device used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. Originally meaning only an optical instrument using lenses, curved mirrors, or a combination of both to observ ...

; only their gravitational effect can be detected by the Doppler effect on the star's electromagnetic spectrum (radial velocity method), as well as transits of planet b. This star was reported to have stellar activity, making the confirmation process for CoRoT-7b more difficult. In fact, mass estimates are affected by large uncertainty due to stellar activity that perturbs the radial velocity measurements needed to "weigh" the planets. CoRoT-7d was first proposed by A. P. Hatzes et al in 2010 by the

radial velocity method Doppler spectroscopy (also known as the radial-velocity method, or colloquially, the wobble method) is an indirect method for finding extrasolar planets and brown dwarfs from radial-velocity measurements via observation of Doppler shifts in t ...

. The existence of CoRoT-7d was disputed by a 2014 study, which concluded that the radial velocity signal was more likely to be an artifact of the stellar rotation. However, a 2022 study provided strong evidence for the existence of this planet, and it is now listed as a confirmed planet in the

NASA Exoplanet Archive The NASA Exoplanet Archive is an online astronomical exoplanet catalog and data service that collects and serves public data that support the search for and characterization of extra-solar planets (exoplanets) and their host stars. It is part of ...

. CoRoT-7d's mass is 17.1 times that of

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

, but its volume and diameter are unknown. One year on CoRoT-7d would be equivalent to 8.966 days on Earth.

References

External links

* {{DEFAULTSORT:CoRoT-7 G-type main-sequence stars M-type main-sequence stars Binary stars Planetary transit variables Planetary systems with three confirmed planets Monoceros (constellation)