HD 7924 b is an
extrasolar planet located approximately 55
light year
A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...
s away in the
constellation
A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object.
The origins of the e ...
of
Cassiopeia, orbiting the 7th
magnitude K-type main sequence
In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Her ...
(slightly metal poor)
star
A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...
HD 7924.
It was published on January 28, 2009 and is the second planet discovered in the constellation Cassiopeia. Two additional planets in this system were discovered in 2015.
Super-Earth
HD 7924 b is a
super-Earth exoplanet with a
minimum mass 9.2 times that of Earth and takes only about 129.5 hours to orbit the star, at an average distance of . When HD 7924 b was discovered in 2009, it was one of only eight planets known with a minimum mass less than 10 Earths.
Also a super-Earth discovery makes 2009 the fifth year in a row since 2005 to have super-Earth planets discovered.
Characteristics
While the radius of HD 7924 b is unknown, depending on its composition, it will be between 1.4–6 times the diameter of the Earth.
It is unknown whether this planet is rocky or
gaseous. Since the
true mass of this planet is not known, it might be gaseous if the true mass is considerably more than minimum mass. If the true mass is near the minimum mass of 9.2
ME, then this planet could be rocky.
References
External links
*
{{Sky, 01, 21, 59.1153, +, 76, 42, 37.024, 54.8
Exoplanets discovered in 2009
Terrestrial planets
Super-Earths
Cassiopeia (constellation)
Exoplanets detected by radial velocity