Rho Indi

ρ Indi, Latinised as Rho Indi, (Bright Star designation HR 8701) is a yellow-hued star in the constellation Indus. With an apparent visual magnitude of +6.05[2] it is, barely, a naked eye star, not visible in the northern hemisphere outside the tropics. Based upon an annual parallax shift of 37.39 mas, it is located about 160 light years from the Sun. The star is moving closer to the Sun with a radial velocity of −4 km/s.[5]

ρ Indi
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Indus
Right ascension  22h 54m 39.482s[1]
Declination –70° 04′ 25.35″[1]
Apparent magnitude (V) +6.05[2]
Characteristics
Spectral type G1 V Fe+0.3[3]
U−B color index +0.22[4]
B−V color index +0.66[4]
Astrometry
Radial velocity (Rv)−4.00±0.92[5] km/s
Proper motion (μ) RA: −43.89±0.26[1] mas/yr
Dec.: +73.04±0.24[1] mas/yr
Parallax (π)37.39 ± 0.36[1] mas
Distance87.2 ± 0.8 ly
(26.7 ± 0.3 pc)
Absolute magnitude (MV)+3.90[6]
Details[5]
Mass1.317±0.083 M☉
Radius1.456±0.024 R☉
Luminosity2.24 L☉
Surface gravity (log g)4.23 cgs
Temperature5,849 K
Metallicity [Fe/H]0.18 dex
Rotational velocity (v sin i)3.1 km/s
Age4.6 (4.2 - 5.6) Gyr
Other designations
ρ Ind, CPD–70° 2971, FK5 865, HR 8701, HD 216437, HIP 113137, SAO 258084.
Database references
SIMBADdata
Exoplanet Archivedata
Extrasolar Planets
Encyclopaedia		data

The stellar classification of Rho Indi is G1 V Fe+0.3,[3] which indicates it is a G-type main-sequence star with a mild overabundance of iron in its outer atmosphere. However, Houk and Cowley (1975) classified it as G2.5 IV,[7] suggesting it is instead a somewhat more evolved subgiant star. It has an estimated 1.32 times the mass of the Sun and 1.46 times the Sun's radius. The star is radiating about 2.24 times the Sun's luminosity from its photosphere at an effective temperature of 5,849 K. It is around 4.6 billion years old and is spinning with a leisurely projected rotational velocity of 3.1 km/s.[5]

Planetary system

On September 17, 2002, this star was found to have a planetary companion, designated Rho Indi b.[8] The discovery was made by measuring variations in the host star's radial velocity, thereby indicating the presence of a perturbing object. Based upon the data, the object is orbiting the host star with a period of about 3.7 years at an eccentricity of 0.32. The semimajor axis for this orbit is around 2.5 times the distance from the Earth to the Sun. Since the inclination of the orbit to the line-of-sight is unknown, only a lower bound on the planet's mass can be determined. It has at least 2.3 times Jupiter's mass.[8]

The Rho Indi planetary system[9]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b >2.26 ± 0.19 MJ 2.54 ± 0.15 1353 ± 25 0.319 ± 0.025 — —
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See also
  • Tau1 Gruis, a separate exoplanet discovery by the same team

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. Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.
  3. Gray, R. O.; Corbally, C. J.; Garrison, R. F.; McFadden, M. T.; Bubar, E. J.; McGahee, C. E.; O'Donoghue, A. A.; Knox, E. R. (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. Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
  5. Valenti, Jeff A.; Fischer, Debra A. (2005). "Spectroscopic Properties of Cool Stars (SPOCS). I. 1040 F, G, and K Dwarfs from Keck, Lick, and AAT Planet Search Programs". The Astrophysical Journal Supplement Series. 159 (1): 141–166. Bibcode:2005ApJS..159..141V. doi:10.1086/430500.
  6. 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.
  7. Houk, N.; Cowley, A. P. (1975), Michigan catalogue of two-dimensional spectral types for the HD stars, 1, Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan, Bibcode:1975mcts.book.....H.
  8. Jones, Hugh R. A.; et al. (2002). "Extrasolar planets around HD 196050, HD 216437 and HD 160691". Monthly Notices of the Royal Astronomical Society. 337 (4): 1170–1178. arXiv:astro-ph/0206216. Bibcode:2002MNRAS.337.1170J. doi:10.1046/j.1365-8711.2002.05787.x.
  9. 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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