Gliese 221

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Gliese 221
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Orion
Right ascension 05h 53m 00.285s[1]
Declination −05° 59′ 41.44″[1]
Apparent magnitude (V) 9.70[2]
Characteristics
Spectral type K7V/M0V[3]
B−V color index 1.321±0.001[2]
Astrometry
Radial velocity (Rv)+22.9±0.4[1] km/s
Proper motion (μ) RA: −1.170 mas/yr[1]
Dec.: −346.762 mas/yr[1]
Parallax (π)49.2485 ± 0.0185 mas[1]
Distance66.23 ± 0.02 ly
(20.305 ± 0.008 pc)
Absolute magnitude (MV)8.154±0.077[4]
Details
Mass0.72±0.21[5] M☉
Radius0.613±0.064[4] R☉
Luminosity0.095±0.01[5] L☉
Surface gravity (log g)4.74±0.02[5] cgs
Temperature4,324±100[5] K
Metallicity [Fe/H]−0.34±0.08[5] dex
Age4.4±4[5] Gyr
Other designations
BD−06 1339, GJ 221, HIP 27803, PPM 188554, LTT 2396, 2MASS J05530028-0559410,[6] Gaia EDR3 3022099969137163904
Database references
SIMBADdata
Exoplanet Archivedata

Gliese 221 (GJ 221), also known as BD-06 1339, is a star with an exoplanetary companion in the equatorial constellation of Orion. It is too faint to be visible to the naked eye, having an apparent visual magnitude of 9.70[2] and an absolute magnitude of 8.15.[4] Using parallax measurements, the distance to this system can be estimated as 66.2 light-years. It is receding from the Sun with a radial velocity of +23 km/s.[1] This is a high proper motion star, traversing the celestial sphere at an angular rate of 0.333″·yr−1.[7]

This is a late K-type or early M-type main-sequence star with a stellar classification of K7V/M0V.[3] It has 72% of the mass and 61% of the radius of the Sun.[5] The star is roughly 4.4[5] billion years old and is depleted in heavy elements, containing just 46% of solar abundance of iron.[5] It is an active star and the level of chromospheric activity has been found to vary significantly over time.[3] The star is radiating 10%[5] of the luminosity of the Sun from its photosphere at an effective temperature of 4,324 K.[5]

Planetary system[edit]

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.

A super-Venus planet, and an eccentric Neptune / Saturn in the habitable zone, were deduced by radial velocity in January 2013.[8] They were confirmed in May 2013.[9] In January 2014, a candidate planet d was proposed.[10]

The planet Gliese 221b (BD-06 1339 b) is not transiting the disk of the parent star,[11] and its existence was disputed in 2022.[12]

The Gliese 221 planetary system[13][8]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
b (disputed[12]) >8.5806 ± 1.2712 M⊕ 0.0428 ± 0.0007 3.8728 ± 0.0004 — — —
c >54.026 ± 9.534 M🜨 0.435 ± 0.007 125.94 ± 0.44 0.31 ± 0.11 — —
d (unconfirmed) 22.246 M⊕ 1.0947 500 — — —

References[edit]

  1. ^ a b c d e f Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  2. ^ a b c Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
  3. ^ a b c Lo Curto, G.; et al. (March 2013), "The HARPS search for southern extra-solar planets. XXXII. New multi-planet systems in the HARPS volume limited sample: a super-Earth and a Neptune in the habitable zone", Astronomy & Astrophysics, 551: 7, arXiv:1301.2741, Bibcode:2013A&A...551A..59L, doi:10.1051/0004-6361/201220415, S2CID 116916728, A59.
  4. ^ a b c Houdebine, E. R.; et al. (2016). "Rotation-Activity Correlations in K and M Dwarfs. I. Stellar Parameters and Compilations of v sin I and P/Sin I for a Large Sample of Late-K and M Dwarfs". The Astrophysical Journal. 822 (2): 97. arXiv:1604.07920. Bibcode:2016ApJ...822...97H. doi:10.3847/0004-637X/822/2/97. S2CID 119118088.
  5. ^ a b c d e f g h i j k Sousa, S. G.; et al. (2018), "SWEET-Cat updated", Astronomy & Astrophysics, 620: A58, arXiv:1810.08108, Bibcode:2018A&A...620A..58S, doi:10.1051/0004-6361/201833350, S2CID 119374557.
  6. ^ "BD-06 1339". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-11-18.
  7. ^ Luyten, W. J. (June 1995), "NLTT Catalogue", VizieR On-line Data Catalog: I/98A. Originally published in: 1979nltt.book.....L, Bibcode:1995yCat.1098....0L.
  8. ^ a b Lo Curto, G.; 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, S2CID 116916728.
  9. ^ Arriagada, Pamela; et al. (2013), "Two Planetary Companions Around the K7 Dwarf Gj 221: A Hot Super-Earth and a Candidate in the Sub-Saturn Desert Range", The Astrophysical Journal, 771 (1): 42, arXiv:1305.2203, Bibcode:2013ApJ...771...42A, doi:10.1088/0004-637X/771/1/42, S2CID 119212312.
  10. ^ Tuomi, Mikko (2014), "A new cold sub-Saturnian candidate planet orbiting GJ 221", Monthly Notices of the Royal Astronomical Society: Letters, 440: L1–L5, arXiv:1401.4000, doi:10.1093/mnrasl/slu014
  11. ^ Gillon, M.; et al. (2017), "The Spitzer search for the transits of HARPS low-mass planets", Astronomy & Astrophysics, 601: A117, arXiv:1701.01303, Bibcode:2017A&A...601A.117G, doi:10.1051/0004-6361/201629270, S2CID 86862862.
  12. ^ a b Simpson, Emilie R.; Fetherolf, Tara; Kane, Stephen R.; Li, Zhexing; Pepper, Joshua; Močnik, Teo (2022). "Revisiting BD-06 1339b: A Likely False Positive Caused by Stellar Activity". The Astronomical Journal. 163 (5): 215. arXiv:2203.06191. Bibcode:2022AJ....163..215S. doi:10.3847/1538-3881/ac5d41. S2CID 247446960.
  13. ^ "Planet BD-06 1339 c", Extrasolar Planets Encyclopaedia.
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