Tau1 Gruis

Tau1 Gruis, Latinized from τ1 Gruis, and catalogued as HD 216435 and HR 8700, is a yellow-hued star approximately 106 light-years away[1] in the constellation of Grus (the Crane). The star is visible to the naked eye for some people, placing it in the Bright Star Catalogue. In 2002, one extrasolar planet was confirmed to orbit the star.

For other stars with this Bayer designation, see τ Gruis.
Tau1 Gruis
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Grus
Right ascension  22h 53m 37.932s[1]
Declination –48° 35′ 53.83″[1]
Apparent magnitude (V) +6.02[2]
Characteristics
Spectral type G0 V[3]
U−B color index 0.17[2]
B−V color index 0.62[2]
Variable type None
Astrometry
Radial velocity (Rv)–1.1[4] km/s
Proper motion (μ) RA: 217.04±0.37[1] mas/yr
Dec.: −81.76±0.29[1] mas/yr
Parallax (π)30.66 ± 0.39[1] mas
Distance106 ± 1 ly
(32.6 ± 0.4 pc)
Absolute magnitude (MV)+3.46[5]
Details
Mass1.28±0.04[6] M☉
Radius1.71±0.04[6] R☉
Luminosity3.39±0.02[6] L☉
Surface gravity (log g)4.07±0.03[6] cgs
Temperature5,996±56[6] K
Metallicity [Fe/H]0.27±0.02[7] dex
Rotational velocity (v sin i)5.13[8] km/s
Age4.2±0.6[6] Gyr
Other designations
τ1 Gru, CD−49° 13988, GJ 9802, HD 216435, HIP 113044, HR 8700, SAO 231343, GSC 09340-01818
Database references
SIMBADdata
ARICNSdata

Characteristics

Tau1 Gruis is a G-type main-sequence star of spectral type G0 V. It is estimated that the star has about 1.28 times the mass of the Sun, 1.71 times the Sun's radius, and about 3.6 times the luminosity. Due to its unusual brightness, at least one source suspects that the star may be a highly evolved subgiant star.[9] It is thought that Tau1 Gruis is about 1.4 times more enriched with elements heavier than hydrogen, making a high abundance of iron likely. The Ca-II H line of the star suggests that it is chromospherically inactive, making it significantly older than previously predicted.

Planetary system

On September 17, 2002, a team of astronomers led by Geoffrey Marcy announced the discovery of a giant planet around Tau1 Gruis.[9] The radial velocity measurements suggest that the star has a companion with at least 1.23 times the mass of Jupiter. The planet's orbit stays inside the system's habitable zone for most of its revolution around the star, though at apoapsis, the planet falls outside of this zone.

The Tau1 Gruis planetary system[10]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b >1.26 ± 0.13 MJ 2.56 ± 0.17 1311 ± 49 0.070 ± 0.078 — —
gollark: Try repeatedly hitting yourself until you become unconscious.
gollark: I can be differentiated wrt. unified electroapiomagnetonucleic field tensors.
gollark: "GTech™ experimental tetrahedral apioform #908411" is highly serious.
gollark: No, their real name is "GTech™ experimental tetrahedral apioform #908411".
gollark: I made an IQ test once. The sequel is pending.

See also

References
  1. van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.Vizier catalog entry
  2. Corben, P. M.; et al. (1972), "U, B, V photometry of 500 southern stars", Monthly Notes of the Astronomical Society of South Africa, 31: 7–22, Bibcode:1972MNSSA..31....8C.
  3. Gray, R. O.; et al. (July 2006), "Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample", The Astronomical Journal, 132 (1): 161–170, arXiv:astro-ph/0603770, Bibcode:2006AJ....132..161G, doi:10.1086/504637.
  4. Nordström, B.; et al. (May 2014), "The Geneva-Copenhagen survey of the Solar neighbourhood. Ages, metallicities, and kinematic properties of ~14000 F and G dwarfs", Astronomy and Astrophysics, 418 (3): 989–1019, arXiv:astro-ph/0405198, Bibcode:2004A&A...418..989N, doi:10.1051/0004-6361:20035959.
  5. 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.
  6. Bonfanti, A.; et al. (2015). "Revising the ages of planet-hosting stars". Astronomy and Astrophysics. 575: A18. arXiv:1411.4302. Bibcode:2015A&A...575A..18B. doi:10.1051/0004-6361/201424951.
  7. Tsantaki, M.; et al. (July 2013), "Deriving precise parameters for cool solar-type stars. Optimizing the iron line list", Astronomy & Astrophysics, 555: A150, arXiv:1304.6639, Bibcode:2013A&A...555A.150T, doi:10.1051/0004-6361/201321103.
  8. Delgado Mena, E.; et al. (April 2015), "Li abundances in F stars: planets, rotation, and Galactic evolution", Astronomy & Astrophysics, 576: 24, arXiv:1412.4618, Bibcode:2015A&A...576A..69D, doi:10.1051/0004-6361/201425433, A69.
  9. Jones, R. Paul; et al. (2003). "An exoplanet in orbit around τ1 Gruis". Monthly Notices of the Royal Astronomical Society. 341 (3): 948–952. arXiv:astro-ph/0209302. Bibcode:2003MNRAS.341..948J. doi:10.1046/j.1365-8711.2003.06481.x.
  10. Butler, R. P.; et al. (2006). "Catalog of Nearby Exoplanets". The Astrophysical Journal. 646 (1): 505–522. arXiv:astro-ph/0607493. Bibcode:2006ApJ...646..505B. doi:10.1086/504701.

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