Gliese 221

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Gliese 221
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Orion
Right ascension 05h 53m 00.0s
Declination −05° 59′ 41″
Apparent magnitude (V) 9.69 ± 0.01
Characteristics
Spectral type K7V/M0V
Astrometry
Parallax (π) 49.23±1.65 mas
Distance 66 ly
(20 ± 1 pc)
Details
Mass 0.7 M
Radius R
Luminosity 0.095 ± 0.01 L
Surface gravity (log g) 4.74 ± 0.02 cgs
Temperature 4324 ± 100 K
Metallicity -0.14 ± 0.17
Age 4.4 ± 4 × 109 years
Other designations
BD-061339, HIP 27803, LTT 2396
Database references
SIMBAD data
Exoplanet Archive data
Extrasolar Planets
Encyclopaedia
data

Gliese 221 is an orange-red dwarf star.

Planetary system[edit]

From 2003 to 2012, the star was under observance from HARPS. It is becoming less active and this reduced activity allowed for lower-mass planetary measurements to be made.

In 2012, a super-Venus planet, and an eccentric Neptune / Saturn in the habitable zone,[1] were deduced by radial velocity. They were published in January 2013. In January of 2014, a new, sub-Saturn planet candidate was reported. [2]

The Gliese 221 planetary system[3][4]
Companion
(in order from star)
Mass Semimajor axis
(AU)
Orbital period
(days)
Eccentricity Inclination Radius
b >0.027 ± 0.004 MJ 0.0428 ± 0.0007 3.8728 ± 0.0004 -
c >0.17 ± 0.03 MJ 0.435 ± 0.007 125.94 ± 0.44 0.31 ± 0.11
d (unconfirmed) >0.07 MJ 1.0947 500

References[edit]

  1. ^ The preprint defined the star's HZ to 0.5-0.9 AU. Square root of luminosity would put an Earth analogue at 0.31 AU. The planet's semimajor is 0.435 AU.
  2. ^ A new cold sub-Saturnian candidate planet orbiting GJ 221: Mikko Tuomi, January 16, 2014
  3. ^ "Planet BD-061339b". 
  4. ^ G. Lo Curto et al. (2013). "The HARPS search for southern extrasolar planets: XXXVI. New multi-planet systems in the HARPS volume limited sample: a super-Earth and a Neptune in the habitable zone". arXiv:1301.2741. Bibcode:2013arXiv1301.2741L.