Tau Cancri

Tau Cancri (τ Cancri) is a solitary,[3] yellow-hued star in the zodiac constellation of Cancer. With an apparent visual magnitude of +5.42,[2] it is faintly visible to the naked eye. Based upon an annual parallax shift of 11.92 mas as seen from Earth,[1] it is located around 274 light years from the Sun.

Tau Cancri
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Cancer
Right ascension 09h 08m 00.04963s[1]
Declination +29° 39′ 15.2428″[1]
Apparent magnitude (V) +5.42[2]
Characteristics
Spectral type G8 III[3]
U−B color index +0.57[2]
B−V color index +0.89[2]
Astrometry
Radial velocity (Rv)−13.90±0.14[4] km/s
Proper motion (μ) RA: −32.51[1] mas/yr
Dec.: +2.79[1] mas/yr
Parallax (π)11.92 ± 0.39[1] mas
Distance274 ± 9 ly
(84 ± 3 pc)
Absolute magnitude (MV)+0.81[5]
Details[4]
Mass2.42±0.09 M☉
Radius7.76±0.51 R☉
Luminosity40 L☉
Surface gravity (log g)3.21 cgs
Temperature5,153 K
Metallicity [Fe/H]−0.06 dex
Rotational velocity (v sin i)1.95±0.45 km/s
Age620±60 Myr
Other designations
τ Cnc, 72 Cancri, BD+30° 1817, FK5 2719, HD 78235, HIP 44818, HR 3621, SAO 80650[6]
Database references
SIMBADdata

With an age of about 620[4] million years and a stellar classification of G8 III,[3] this is a red clump giant star,[7] which indicates that it has evolved onto the horizontal branch and is generating energy through helium fusion at its core. It is a microvariable, showing a luminosity variation of 0.04 in magnitude.[8] Tau Cancri has an estimated 2.4 times the mass of the Sun and 7.8 times the Sun's radius. The star radiates 40 times the solar luminosity from its photosphere at an effective temperature of 5,153 K.[4]

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, S2CID 18759600.
  2. Argue, A. N. (1963), "UBV photometry of 300 G and K type stars", Monthly Notices of the Royal Astronomical Society, 125 (6): 557–570, Bibcode:1963MNRAS.125..557A, doi:10.1093/mnras/125.6.557
  3. Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
  4. Jofré, E.; et al. (2015), "Stellar parameters and chemical abundances of 223 evolved stars with and without planets", Astronomy & Astrophysics, 574: A50, arXiv:1410.6422, Bibcode:2015A&A...574A..50J, doi:10.1051/0004-6361/201424474, S2CID 53666931.
  5. Da Silva, Ronaldo; et al. (2015), "Homogeneous abundance analysis of FGK dwarf, subgiant, and giant stars with and without giant planets", Astronomy & Astrophysics, 580: A24, arXiv:1505.01726, Bibcode:2015A&A...580A..24D, doi:10.1051/0004-6361/201525770, S2CID 119216425.
  6. "tau Cnc". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-06-11.
  7. Adelman, Saul J. (2001), "On the Photometric Variability of Red Clump Giants", Baltic Astronomy, 10 (4): 593–597, Bibcode:2001BaltA..10..593A, doi:10.1515/astro-2001-0404, S2CID 118317147.
  8. Adelman, S. J.; et al. (December 2000), "On the Variability of G0-G9 Stars", Information Bulletin on Variable Stars, 4993: 1, Bibcode:2000IBVS.4993....1A.
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