Epsilon Reticuli

From Wikipedia, the free encyclopedia

Our inner solar system superimposed behind the orbits of the planets HD 179949 b, HD 164427 b, Epsilon Reticuli ab, and Mu Arae b (each planet has its parent star labeled next to it -- all parent stars are in the center)

Epsilon Reticuli (ε Ret / ε Reticuli) is a 4th magnitude star in the constellation Reticulum. The system is a binary, the primary component being an orange subgiant, and the secondary is probably a red dwarf. The primary star should be easily visible without optical aid under dark skies in southern hemisphere.

The primary star is known to have an extrasolar planet orbiting it.

1 ε Reticuli A
- 1.1 ε Reticuli Ab
2 ε Reticuli B
3 References
4 External links

[edit] ε Reticuli A

**ε Reticuli A**
Observation data Equinox 2000
Constellation	Reticulum
Right ascension	4^h 16^m 29.03^s
Declination	-59° 18' 07.76"
Apparent magnitude (V)	4.44
Distance	59.45 ly (18.23 pc)
Spectral type	K2IVa
Other designations
HR 1355, HD 27442, HIP 19921

The primary star, ε Reticuli A, is a yellow subgiant 20% more massive than our Sun. Being a subgiant it is ceasing or has already ceased fusing hydrogen in its core. Soon the star will swell up and become a red giant. Despite its advanced stage, it cannot be much older than the Sun.

[edit] ε Reticuli Ab

**ε Reticuli Ab**
Orbital elements
Extrasolar planet		Lists of extrasolar planets
Semimajor axis	(a)	1.271±0.073 AU
Eccentricity	(e)	0.060±0.043
Orbital period	(P)	428.1±1.1 d
Inclination	(i)	?°
Longitude of periastron	(ω)	216°
Time of periastron	(τ)	2,451,963±55 JD
Physical characteristics
Mass	(m)	>1.56±0.14 M_J
Radius	(r)	? R_J
Density	(ρ)	? kg/m³
Temperature	(T)	? K
Discovery information
Discovery date		2001
Discoverer(s)		Butler, Tinney, Marcy et al.
Detection method		Radial velocity
Discovery status		Published

The planet, designated as ε Reticuli Ab, was discovered in 2001 by the Anglo-Australian Planet Search Team using the highly successful radial velocity method. The planet's mass is at least 28% greater than Jupiter's, a more accurate estimate requiring its inclination to be known.

The planet orbits the star in a very Earth-like orbit. However, the planet is certainly a gas giant and life as we know it may not flourish there. The planet might have massive moons (they cannot be detected with current technology) that could have supported life, but as the star aged they became too hot for life.

[edit] ε Reticuli B

**ε Reticuli B**
Observation data Equinox 2000
Constellation	Reticulum
Right ascension	4^h 16^m 30.2^s
Declination	-59° 17' 45"
Apparent magnitude (V)	12.5
Distance	59.45? ly (18.23? pc)
Spectral type	?
Other designations
n/a