Rho Coronae Borealis

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**ρ Coronae Borealis**
Observation data Epoch 2000
Constellation	Corona Borealis
Right ascension	16^h 1^m 2.66^s
Declination	+33° 18' 12.63"
Apparent magnitude (V)	5.40
Distance	56.81 ly (17.43 pc)
Spectral type	G0Va
Other designations
15 CrB, GJ 606.2, BD+33°2663, HR 5968, HD 143761, HIP 78459

Rho Coronae Borealis (ρ CrB / ρ Coronae Borealis) is a 6th magnitude star in the constellation of Corona Borealis. It is, like our Sun, a yellow dwarf (spectral type G0 V or G2 V) and only slightly brighter. It may be much older than the Sun, 10,000 million years old.

In 1997 the AFOE planet search team announced the discovery of an extrasolar planet orbiting the star. Furthermore, in 1997 the star was observed radiating excessively in certain infrared wavelengths indicating a circumstellar disk around the star, similar to the Kuiper belt in our Solar system.

A stellar companion has been listed for ρ Coronae Borealis in the Washington Visual Double Star Catalog, but no further information is available on it. It may be just a line-of-sight optical companion.

[edit] ρ Coronae Borealis b

**ρ Coronae Borealis b**
Orbital elements

Semi-major axis	(a)	0.22 AU
Eccentricity	(e)	0.04 ± 0.15
Orbital period	(P)	39.945 d
Inclination	(i)	?°
Longitude of periastron	(ω)	311°
Time of periastron	(τ)	2,450,085.93 JD
Physical characteristics
Mass		>1.04 M_J
Radius		? R_J
Density		? kg/m³
Temperature		620 K
Discovery
Discovery date		1997
Detection method(s)
Discoverer(s)		Noyes, Jha, Korzennik et al.

The planet, one of the first discovered, is designated as ρ Coronae Borealis b. The planet's distance to the star is only about one fifth Earth's distance from the Sun. The orbit is circular and it takes 40 days to complete one revolution around the star. The planet has a mass about that of Jupiter. However, the inclination of the orbital plane is not known, so the value is only a minimum. If the planet orbits in the same plane as the circumstellar disk, the inclination would be about 46° and mass of the planet 1.5 times Jupiter.

In 2000 group of scientist claimed, based on preliminary Hipparcos astrometrical satellite data, that the inclination of the planet would be 0.5° and mass as much as 115 times Jupiter. Such a massive body would be nothing else but a dim red dwarf. However, this is statistically very unprobable, and the claim has not been backed up.