astro.wikisort.org - Meteorite

CoRoT-7c is an extrasolar planet which orbits the G-type main sequence star CoRoT-7, located approximately 489 light years away in the constellation Monoceros. It's either a super-Earth or a Neptune-like planet, orbiting at 0.046 AU from the star, taking 3.7 days or 89 hours to make one round trip around the star.

CoRoT-7c

Discovery
Discovered by	Queloz et al.
Discovery site	La Silla Observatory, Chile
Discovery date	August 24, 2009
Detection method	Radial Velocity (HARPS)
Orbital characteristics
Semi-major axis	0.046 AU (6,900,000 km)[1]
Eccentricity	0
Orbital period (sidereal)	3.698 ± 0.003[1] d
Semi-amplitude	unknown[1]
Star	CoRoT-7
Physical characteristics
Mass	unknown[1] MEarth

Discovery

The discovery of the planet was announced in February 2009, during the First Corot Symposium. It was discovered during the follow-up started in order to confirm the existence of CoRoT-7b, a super-Earth uncovered by the CoRoT mission. However, unlike CoRoT-7b, it was not detected by the transit method from the CoRoT satellite, but only by the radial velocity method using HARPS from La Silla Observatory, Chile. A posteriori search of transits of CoRoT-7c in the lightcurve of the star CoRoT-7 yielded a negative result, confirming the planet is not transiting. As a consequence no radius measurement is available, and no density and structure models of the planet can be established.

Characteristics

Like CoRoT-7b, the mass of CoRoT-7c is weakly constrained, since the radial velocity data is noisy due to the presence of stellar activity. Published mass measurements range from 8.4 Earth masses[1] to 13.5 Earth masses,[2] passing through 12.4 Earth masses[3] and 13.1 Earth masses.[4] This mass range encompasses the Super-Earths to Neptunes transition, so the nature of CoRoT-7c, either a rocky planet or an ice giant, remains unclear. However, if the larger mass estimates are correct, CoRoT-7c is probably a hot Uranus-like planet. Chances are high that planet's rotation is tidally locked to the orbital period, with one side of the planet always facing the star CoRoT-7 and the other one in permanent darkness. A possible third planet, CoRoT-7d, may be present in the system, but pending further observations its status remains unconfirmed. If this planet is confirmed, strong mutual gravitational forces could be exchanged between these planets, leading to powerful tidal forces.

Doubts about existence

A published study[5] cast doubt on CoRoT-7c's existence, arguing that the combined presence of stellar activity and additional errors on HARPS radial velocity measurements preclude a meaningful search for additional companions besides CoRoT-7b. However, all the other studies seem to confirm the planet's existence: the signal in the HARPS data of CoRoT-7c is detected in analysis of different type, does not seem to be correlated with stellar activity and is stronger than the signal associated with the confirmed CoRoT-7b. The remarkable stability and precision showed by the HARPS spectrograph[6] also speaks in favour of the detection. The status of CoRoT-7c seems very well confirmed.

References

На других языках

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- [en] CoRoT-7c

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[es] COROT-7c

COROT-7c es un planeta extrasolar que orbita la estrella de tipo G de la secuencia principal COROT-7, localizado aproximadamente a 489 años luz en la constelación de Monoceros. Se trata de una supertierra con una masa 8,4 veces la de la Tierra y que orbita a 0,046 UA de su estrella. Este planeta tarda 3,7 días en completar su periodo orbital. Sin embargo, a diferencia de COROT-7b este planeta no fue detectado por el método de tránsito desde el satélite COROT, fue detectado usando el HARPS desde el observatorio de La Silla (Chile). Fue descubierto el 24 de agosto de 2009.

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[ru] CoRoT-7 c

COROT-7c — экзопланета (сверхземля), обнаруженная возле звезды COROT-7 с помощью спектрографа HARPS (а не спутника COROT) 24 августа 2009 года. Планета стала второй известной в системе COROT-7, которая представляет собой жёлтый карлик класса G9. Масса планеты оценивается в 8,4 массы Земли, а большая полуось — 0,046 а. е.. Планета находится дальше от родительской звезды, чем экстремально горячая планета COROT-7b, но всё же явно слишком горяча, чтобы на ней была жизнь. Период обращения вокруг звезды составляет порядка 3,5 земных суток[2].

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