HD 4308

HD 4308 is a single[2] star in the southern constellation of Tucana.[9] It has a yellow hue and is a challenge to view with the naked eye even under good seeing conditions, having an apparent visual magnitude of 6.54.[2] This object is located at a distance of 72 light years, as determined from parallax measurements. It is a population II star[2] and is considered to be a member of the thick disk.[10] The star is receding from the Sun with a radial velocity of +95 km/s.[6]

HD 4308
Observation data
Epoch J2000      Equinox J2000
Constellation Tucana
Right ascension  00h 44m 39.2675s[1]
Declination –65° 38′ 58.2825″[1]
Apparent magnitude (V) 6.544±0.005[2]
Characteristics
Evolutionary stage main sequence
Spectral type G6VFe-0.9[3]
Apparent magnitude (B) 7.193[4]
Apparent magnitude (V) 6.552[4]
Apparent magnitude (J) 5.366±0.024[5]
Apparent magnitude (H) 5.101±0.016[5]
Apparent magnitude (K) 4.945±0.020[5]
Astrometry
Radial velocity (Rv)+95.251±0.0162[6] km/s
Proper motion (μ) RA: 157.504±0.041[1] mas/yr
Dec.: −741.599±0.040[1] mas/yr
Parallax (π)45.3930 ± 0.0220[1] mas
Distance71.85 ± 0.03 ly
(22.03 ± 0.01 pc)
Details[7]
Mass0.95±0.05 M☉
Radius1.04±0.03 R☉
Luminosity1.03±0.01 L☉
Surface gravity (log g)4.38±0.02 cgs
Temperature5,714±61 K
Metallicity [Fe/H]−0.35±0.07[2] dex
Rotational velocity (v sin i)1.0±1.0[2] km/s
Age1.6±4.0[7] or 10.0+0.5
−1.0[8] Gyr
Other designations
BD−27°223, GC 897, GJ 9028, HD 4308, HIP 3497, SAO 248244, PPM 352003, LFT 71, LHS 1139, LPM 40, LTT 416, TYC 8847-598-1, 2MASS J00443925-6538581[9]
Database references
SIMBADdata
ARICNSdata
Extrasolar Planets
Encyclopaedia		data

This is a Sun-like G-type main-sequence star with a stellar classification of G6VFe-0.9,[3] where the suffix notation indicates an underabundance of iron in the spectrum. The age of the star is poorly constrained, with estimated ranging from 1.6[7] billion years up to 10 billion.[8] It has 95% of the mass of the Sun but 104% of the Sun's radius. The star is radiating nearly the same luminosity as the Sun from its photosphere at an effective temperature of 5,714 K.[7]

Planetary system

In 2005, a low-mass planet was found in orbit around this star using the radial velocity method with the HARPS spectrograph. It is following a circular orbit close to its host star with a period of just 15.6 days. Unusual for a star with planets, HD 4308 has a metallicity lower than that of the Sun.[11]

The HD 4308 planetary system[11]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b >0.0442 MJ 0.115 15.56±0.02 0.00±0.01 — —
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See also

References
  1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. Fuhrmann, K.; et al. (2017). "Multiplicity among Solar-type Stars". The Astrophysical Journal. 836 (1): 139. Bibcode:2017ApJ...836..139F. doi:10.3847/1538-4357/836/1/139.
  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. Koen, C.; Kilkenny, D.; van Wyk, F.; Marang, F. (April 21, 2010). "UBV(RI)CJHK 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.
  5. Cutri, R. M.; et al. (June 2003). "2MASS All Sky Catalog of point sources". NASA/IPAC. Bibcode:2003tmc..book.....C. Cite journal requires |journal= (help)
  6. 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.
  7. 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.
  8. Ge, Z. S.; et al. (December 2016). "Ages of 70 Dwarfs of Three Populations in the Solar Neighborhood: Considering O and C Abundances in Stellar Models". The Astrophysical Journal. 833 (2): 13. arXiv:1612.01622. Bibcode:2016ApJ...833..161G. doi:10.3847/1538-4357/833/2/161. 161.
  9. "HD 4308". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-11-05.
  10. Neves, V.; et al. (April 2009). "Chemical abundances of 451 stars from the HARPS GTO planet search program. Thin disc, thick disc, and planets". Astronomy and Astrophysics. 497 (2): 563–581. arXiv:0902.3374. Bibcode:2009A&A...497..563N. doi:10.1051/0004-6361/200811328.
  11. Udry, S.; et al. (2006). "The HARPS search for southern extra-solar planets V. A 14 Earth-masses planet orbiting HD 4308". Astronomy and Astrophysics. 447 (1): 361–367. arXiv:astro-ph/0510354. Bibcode:2006A&A...447..361U. doi:10.1051/0004-6361:20054084.

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