Innes' star

Innes' star /ˈɪnɪs/ (Gliese 422) is an M3.5-type red dwarf,[1][5] located in constellation Carina.[6] It has around 35% of the mass of the Sun, yet only 1.1% of its luminosity, and an estimated surface temperature of 3,323 K.[5]

Innes' star
Observation data
Epoch J2000      Equinox J2000
Constellation Carina
Right ascension 11h 16m 00.20551s[1]
Declination −57° 32′ 51.5988″[1]
Apparent magnitude (V) 11.516[2]
Characteristics
Spectral type M3.5[1]
U−B color index +0.92[3]
B−V color index -0.22[3]
Astrometry
Radial velocity (Rv)-35.00[1] km/s
Proper motion (μ) RA: -2466.98[1] mas/yr
Dec.: 1180.09[1] mas/yr
Parallax (π)78.941 ± 0.045[2][4] mas
Distance41.32 ± 0.02 ly
(12.668 ± 0.007 pc)
Absolute magnitude (MV)11.00[2]
Details[5]
Mass0.35 M☉
Luminosity0.011 L☉
Temperature3,323 K
Other designations
HD 304043, HIP 55042, SAO 112775, Gliese 422, LTT 4167, TYC 8624-3387-1
Database references
SIMBADdata

Discovery

Innes' star was discovered in 1920 by Robert T. A. Innes in Union Observatory, Union of South Africa, who had discerned its large proper motion and a parallax of 0.337 arcsec.[7] The discovery was published in Circular of the Union Observatory No. 49, hence its discovery name is UO 49,[8] or In UOC 49.[9] However, UO designations should be used with caution since they are often not unique for each star: the number in the name is the number of Circular, so all stars published in one Circular have identical names. So, all other newfound stars, published in the 49th Circular, may be named UO 49 too.

Erroneous parallax

It is known for the fact that it had once been considered one of the nearest stars to Earth, due to erroneously measured parallax. The estimated distance was less than 10 light-years in the following studies:

  • In List of stars nearer than 5 parsecs by Ejnar Hertzsprung (1922) its parallax is 0.339 arcsec (distance is 2.95 pc or 9.62 ly), and it is the 4th-closest star system after Alpha Centauri ABC, Barnard's Star and Sirius AB;[10]
  • In A study of the near-by stars by Willem Jacob Luyten and Harlow Shapley (1930) its parallax is 0.337 arcsec (distance is 2.97 pc or 9.68 ly), and it is the 4th-closest star system after Alpha Centauri ABC, Barnard's Star and 22 H Camelopardalis (Sirius is further);[11]
  • In List of stars nearer than five parsecs by Peter van de Kamp (1930) its parallax is 0.34 arcsec (distance is 2.94 pc or 9.59 ly), and it is the 7th-closest star system after Alpha Centauri ABC, Barnard's Star, Wolf 359, Lalande 21185, Sirius AB and BD-12 4523;[12]
  • In Stars within ten parsecs of the Sun by Louise Freeland Jenkins (1937) its parallax is 0.34 arcsec (distance is 2.94 pc or 9.59 ly), and it is the 6th-closest star system after Alpha Centauri, Barnard's Star, Wolf 359, Lalande 21185 and Sirius.[9]

Its actual distance is 12.667 parsecs, or 41.32 light-years, based on parallax by van Leeuwen (2007) and Gaia DR2:[4] 0.0784±0.0004 arcsec.[1]

Planetary system

In 2014, a Mega-Earth or a mini-Neptune, GJ 422 b, of approximately ten Earth-masses, was discovered in the system of this star, orbiting the star every 20 days and lying at a distance of around 0.11 astronomical units (AU)—11% of the distance between our Earth and Sun—on the inner edge of the stellar system's habitable zone, which for this star has been calculated to lie between 0.11 and 0.21 AU.[5]

The discovery of GJ 422 b was confirmed in 2020.[13]

The Innes' star planetary system[13]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
GJ 422 b ≥ 11.07 ± 1.128 M⊕ 0.111 ±0.004 20.129 ± 0.005 0.13 ± 0.04 — —

Name

Innes' Star is one of a few stars named after people—named after a scientist, whereas the majority of proper names of stars have ancient origins or medieval, in the main Arabic, ones. Certain stars, found to be nearby due to their large proper motion, also fall into this class and are named after their discoverers: Barnard's Star, Kapteyn's Star, Luyten's Star, van Maanen's Star, van Biesbroeck's Star, and Teegarden's Star. Innes is also known as the discoverer of Proxima Centauri.

References
  1. "LHS 40". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 1 April 2014.
  2. Koen, C.; Kilkenny, D.; van Wyk, F.; Marang, F. (2010). "UBV(RI)C JHK observations of Hipparcos-selected nearby stars". Monthly Notices of the Royal Astronomical Society. 403 (4): 1949–1968. Bibcode:2010MNRAS.403.1949K. doi:10.1111/j.1365-2966.2009.16182.x.
  3. Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
  4. Gaia DR2 parallaxes archive
  5. Tuomi, Mikko; Jones, Hugh R. A.; Barnes, John R.; Anglada-Escudé, Guillem; Jenkins, James S. (2014-03-03). "Bayesian search for low-mass planets around nearby M dwarfs. Estimates for occurrence rate based on global detectability statistics". Monthly Notices of the Royal Astronomical Society. 441 (2): 1545. arXiv:1403.0430. Bibcode:2014MNRAS.441.1545T. doi:10.1093/mnras/stu358. S2CID 32965505.
  6. Enter 11 16 00.20551 -57 32 51.5988
  7. Worssell, W. M. (1920). "Parallax and Proper Motion of a Faint Star in the Sydney Zone". Circular of the Union Observatory Johannesburg. 49: 55. Bibcode:1920CiUO...49...55W.
  8. Porter, J. G.; Yowell, E. J.; Smith, E. S. (1930). "A catalogue of 1474 stars with proper motion exceeding four-tenths year". Publications of the Cincinnati Observatory. 20: 1. Bibcode:1930PCinO..20....1P.
  9. Jenkins, Louise F. (1937). "Stars within ten parsecs of the sun". Astronomical Journal. 46: 95. Bibcode:1937AJ.....46...95J. doi:10.1086/105404.
  10. Hertzsprung, E. (1922). "Remark on the period of VV Orionis". Bulletin of the Astronomical Institutes of the Netherlands. 1: 22. Bibcode:1922BAN.....1...22H.
  11. Luyten, Willem Jacob; Shapley, Harlow (1930). "A study of the near-by stars". Annals of the Astronomical Observatory of Harvard College. 85 (5): 73. Bibcode:1930AnHar..85...73L.
  12. Van De Kamp, P. (1930). "List of stars nearer than five parsecs". Popular Astronomy. 38: 17. Bibcode:1930PA.....38...17V.
  13. Feng, Fabo; Butler, R. Paul; Shectman, Stephen A.; Crane, Jeffrey D.; Vogt, Steve; Chambers, John; Jones, Hugh R. A.; Wang, Sharon Xuesong; Teske, Johanna K.; Burt, Jenn; Díaz, Matías R.; Thompson, Ian B. (2020). "Search for Nearby Earth Analogs. II. Detection of Five New Planets, Eight Planet Candidates, and Confirmation of Three Planets around Nine Nearby M Dwarfs". The Astrophysical Journal Supplement Series. 246 (1): 11. arXiv:2001.02577. Bibcode:2020ApJS..246...11F. doi:10.3847/1538-4365/ab5e7c. S2CID 210064560.
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