Gliese 42

Gliese 42 is a star in the southern constellation of Sculptor. It is too faint to be seen with the naked eye, having an apparent visual magnitude of +7.3.[1] The annual parallax shift of 70.56 mas provides a distance estimate of 46 light years. It has a relatively high proper motion, advancing 0.62[9] arcseconds across the sky per anum, and is moving closer to the Sun with a radial velocity of −13 km/s.[3]

Gliese 42
Observation data
Epoch J2000      Equinox J2000
Constellation Pisces
Right ascension  00h 53m 00.71555s[1]
Declination −30° 21′ 25.1677″[1]
Apparent magnitude (V) +7.3029[1]
Characteristics
Spectral type K2.5 V (k)[2]
B−V color index 0.936[1]
Astrometry
Radial velocity (Rv)−13.021±0.0064[3] km/s
Proper motion (μ) RA: +620.35[1] mas/yr
Dec.: +30.26[1] mas/yr
Parallax (π)70.56 ± 0.61[1] mas
Distance46.2 ± 0.4 ly
(14.2 ± 0.1 pc)
Absolute magnitude (MV)+6.39[4]
Details
Radius0.660[5] R☉
Luminosity0.29[4] L☉
Surface gravity (log g)4.55[2] cgs
Temperature4,822[2] K
Metallicity [Fe/H]−0.21[2] dex
Rotational velocity (v sin i)3.52[6] km/s
Age6.67±4.74[7] Gyr
Other designations
BD−31° 325, GJ 42, HD 5133, HIP 4148, SAO 192793, LTT 498[8]
Database references
SIMBADdata

The spectrum of the star matches a stellar classification of K2.5 V (k),[2] indicating it is an ordinary K-type main-sequence star that is generating energy through hydrogen fusion at its core. It is radiating 29%[4] of the Sun's luminosity from its photosphere at an effective temperature of 4,822 K.[2] The star has 66%[5] of the Sun's radius. An infrared excess has been detected around this star,[10] most likely indicating the presence of a circumstellar disk at a radius of 45.7 astronomical units (6.84×109 km; 4.25×109 mi). The temperature of this dust is 30 K (−243.2 °C; −405.7 °F).[5]

References
  1. van Leeuwen, F. (November 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.
  2. 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.
  3. Soubiran, C.; et al. (April 2013). "The catalogue of radial velocity standard stars for Gaia. I. Pre-launch release". Astronomy & Astrophysics. 552: 11. arXiv:1302.1905. Bibcode:2013A&A...552A..64S. doi:10.1051/0004-6361/201220927. A64.
  4. 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.
  5. Cotten, Tara H.; Song, Inseok (July 2016), "A Comprehensive Census of Nearby Infrared Excess Stars", The Astrophysical Journal Supplement Series, 225 (1): 24, arXiv:1606.01134, Bibcode:2016ApJS..225...15C, doi:10.3847/0067-0049/225/1/15, 15.
  6. Martínez-Arnáiz, R.; et al. (September 2010), "Chromospheric activity and rotation of FGK stars in the solar vicinity. An estimation of the radial velocity jitter" (PDF), Astronomy and Astrophysics, 520: A79, arXiv:1002.4391, Bibcode:2010A&A...520A..79M, doi:10.1051/0004-6361/200913725.
  7. Pace, G. (March 2013), "Chromospheric activity as age indicator. An L-shaped chromospheric-activity versus age diagram", Astronomy & Astrophysics, 551: 4, arXiv:1301.5651, Bibcode:2013A&A...551L...8P, doi:10.1051/0004-6361/201220364, L8.
  8. "HD 5133". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-01-01.
  9. Bakos, Gáspár Á.; et al. (July 2002), "Revised Coordinates and Proper Motions of the Stars in the Luyten Half-Second Catalog", The Astrophysical Journal Supplement Series, 141 (1): 187–193, arXiv:astro-ph/0202164, Bibcode:2002ApJS..141..187B, doi:10.1086/340115.
  10. Eiroa, C.; et al. (July 2013). "DUst around NEarby Stars. The survey observational results". Astronomy & Astrophysics. 555: A11. arXiv:1305.0155. Bibcode:2013A&A...555A..11E. doi:10.1051/0004-6361/201321050.
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