Eta Coronae Borealis (η Coronae Borealis, η CrB) is a stellar system that lies approximately 58
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. The primary component is a mid-wide binary, while a brown dwarf component is located at a wide separation.
Components
Eta Coronae Borealis has been known since the late 18th century to be a moderate-separation binary. The orbit of the two components takes approximately 42 years, which when combined with the distance to the system makes the two stars fairly easily resolvable with a larger telescope. The two stars have similar physical parameters, though the secondary is slightly cooler than the primary and has approximately 90% of the primary's mass. Possible stable planetary orbits in the
habitable zone were calculated for the system in 1996.
At present the angular separation between both stars is 0.5 arcseconds, so a telescope with a diameter of over 25 centimetres is required to resolve i
A
brown dwarf companion was detected in 2001. The source 2MASSW J1523226+301456 in the
2MASS
The Two Micron All-Sky Survey, or 2MASS, was an astronomical survey of the whole sky in infrared light. It took place between 1997 and 2001, in two different locations: at the U.S. Fred Lawrence Whipple Observatory on Mount Hopkins, Arizona, and ...
working database was identified as having a similar proper motion to the AB binary, and subsequent observations confirmed its relationship to the system. The new component, Eta Coronae Borealis C, was found to have a spectral type of L8. The brown dwarf has a minimum separation of 3600 AU, and considering a cooling age of 1–2.5 gigayears, the brown dwarf has a mass of , or .
See also
*
81 Cancri
References
{{DEFAULTSORT:Eta Coronae Borealis
Corona Borealis
G-type main-sequence stars
Coronae Borealis, Eta
Coronae Borealis, 02
075312
Brown dwarfs
5727
0584
137107 8
Triple star systems
Durchmusterung objects