HD 121504

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**HD 121504**
Observation data Epoch 2000
Constellation	Centaurus
Right ascension	13^h 57^m 17.24^s
Declination	-56° 2' 24.53"
Apparent magnitude (V)	7.6
Distance	144.6 ly (44.57 pc)
Spectral type	G2V
Other designations
CD-55°5427, HIP 68162

HD 121504 is an 8th magnitude star in the constellation of Centaurus. It is a yellow dwarf (spectral type G2 V) and remarkably similar to our Sun, only slightly brighter like α Centauri A. However, it is located at a distance fo about 140 light years and thus is not visible to the unaided eye; binoculars or small telescope is required to see this star.

Another component, designated as SAO 241323 has been proposed as a component of the system. However, the star is an optical binary component and in reality is a white giant star located thousands of light years away.

In 2000 the Geneva Extrasolar Planet Search Team announced the discovery of an extrasolar planet orbiting the star.

[edit] HD 121504 b

**HD 121504 b**
Orbital elements

Semi-major axis	(a)	0.32 AU
Eccentricity	(e)	0.13
Orbital period	(P)	64.6 d
Inclination	(i)	?°
Longitude of periastron	(ω)	199 ± 20°
Time of periastron	(τ)	2,451,563.0 ± 3.5 JD
Physical characteristics
Mass		>0.89 M_J
Radius		? R_J
Density		? kg/m³
Temperature		? K
Discovery
Discovery date		2000
Detection method(s)
Discoverer(s)		Urdy, Mayor, Queloz

The planet, designated as HD 121504 b is likely slightly less massive than Jupiter. The radial velocity method, that was used to detect the planet, can only measure the minimum mass of the planet. Still, it is very unlikely that its true mass would be much higher.

HD 121504 b orbits the star at a distance of about one third Earth's distance from the Sun, and has a slightly eccentric orbit.