Gliese 221
Gliese 221 is an orange-red dwarf star 66 light years from Earth.
| 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 | |
| Proper motion (μ) | RA: −1.045±0.070[1] mas/yr Dec.: −346.721±0.070[1] mas/yr |
| Parallax (π) | 49.3062 ± 0.0529[1] mas |
| Distance | 66.15 ± 0.07 ly (20.28 ± 0.02 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 |
Planetary system
From 2003 to 2012, the star was under observance from the High Accuracy Radial Velocity Planet Searcher (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,[2] were deduced by radial velocity. They were published in January 2013. In January 2014, a new, sub-Saturn planet candidate was reported.[3]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | >0.027 ± 0.004 MJ
(>8.5806 M⊕ ± 1.2712 M⊕) MJ |
0.0428 ± 0.0007 | 3.8728 ± 0.0004 | - | — | — |
| c | >0.17 ± 0.03 MJ
(>54.026 M⊕ ± 9.534 M⊕) MJ |
0.435 ± 0.007 | 125.94 ± 0.44 | 0.31 ± 0.11 | — | — |
| d (unconfirmed) | >0.07 MJ
(>22.246 M⊕) MJ |
1.0947 | 500 | — | — | — |
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References
- Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
- 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.
- A new cold sub-Saturnian candidate planet orbiting GJ 221: Mikko Tuomi, January 16, 2014
- "Planet BD-061339b".
- 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". Astronomy & Astrophysics. 551: A59. arXiv:1301.2741. Bibcode:2013A&A...551A..59L. doi:10.1051/0004-6361/201220415.
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