HD 104304

HD 104304 (24 G. Virginis) is a binary star system in the zodiac constellation Virgo. It has a combined apparent visual magnitude of 5.54,^[2] making it visible to the unaided eye under suitable viewing conditions. The system is located at a distance of 41 light-years from the Sun based on parallax measurements.^[1] The primary component has a stellar classification of G8 IV,^[3] which means that this is a subgiant star that has left the main sequence and has begun to evolve into a giant star. The secondary is a faint red dwarf star with a class of M4V.^[4]

HD 104304

Observation data Epoch J2000      Equinox J2000
Constellation	Virgo
Right ascension	12h 00m 44.461s[1]
Declination	–10° 26′ 46.06″[1]
Apparent magnitude (V)	5.54[2]
Characteristics
Spectral type	G8 IV[3] + M4V[4]
U−B color index	+0.43[2]
B−V color index	+0.76[2]
Astrometry
Radial velocity (Rv)	0.14±0.14[1] km/s
Proper motion (μ)	RA: 82.841 mas/yr[1] Dec.: −482.807 mas/yr[1]
Parallax (π)	78.7565 ± 0.1206 mas[1]
Distance	41.41 ± 0.06 ly (12.70 ± 0.02 pc)
Absolute magnitude (MV)	5.15±0.009[5]
Orbit[4]
Period (P)	48.5 yr
Semi-major axis (a)	10.4 AU
Eccentricity (e)	0.29
Inclination (i)	35°
Details
A
Mass	0.98[6] M☉
Radius	1.01[6] R☉
Surface gravity (log g)	4.43[6] cgs
Temperature	5,538[3] K
Metallicity [Fe/H]	0.18[7] dex
Rotational velocity (v sin i)	4.5[8] km/s
Age	8.48[6] Gyr
B
Mass	0.21+0.03 −0.02[4] M☉
Other designations
BD−09°3413, GJ 454, HD 104304, HIP 58576, HR 4587, SAO 157041, G 24 G. Virginis, LTT 4476[9]
Database references
SIMBAD	data

In 2007, a candidate planet was announced orbiting the primary. This was updated in 2010 when two independent papers announced the discovery of a common proper motion companion red dwarf.^[4][10] It is believed to have a mass of 0.21 M_☉ and spectral type of M4V although the spectrum has not been directly observed. The most likely orbit has a period of 48.5 years and an eccentricity of 0.29.^[4][11] Further measurement will be needed to determine whether the star has a planetary companion, but further companions with masses above 83 M_J and separated by at least 3.9 au can be ruled out.^[4]

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. Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99): 99, Bibcode:1966CoLPL...4...99J
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, S2CID 119476992
4. Schnupp, C.; et al. (June 2010), "Discovery of a stellar companion to the nearby solar-analogue HD 104304", Astronomy and Astrophysics, 516: A21, arXiv:1005.0620, Bibcode:2010A&A...516A..21S, doi:10.1051/0004-6361/201014740, S2CID 54984741
5. Park, Sunkyung; et al. (2013), "Wilson-Bappu Effect: Extended to Surface Gravity", The Astronomical Journal, 146 (4): 73, arXiv:1307.0592, Bibcode:2013AJ....146...73P, doi:10.1088/0004-6256/146/4/73, S2CID 119187733.
6. Takeda, Genya; et al. (2007). "Structure and Evolution of Nearby Stars with Planets. II. Physical Properties of ~1000 Cool Stars from the SPOCS Catalog". The Astrophysical Journal Supplement Series. 168 (2): 297. arXiv:astro-ph/0607235. Bibcode:2007ApJS..168..297T. doi:10.1086/509763. S2CID 18775378.
7. Hearnshaw, J. B. (1972), "The abundances of the elements in the oldest disk stars", Memoirs of the Royal Astronomical Society, 77: 55, Bibcode:1972MmRAS..77...55H
8. Schröder, C.; et al. (January 2009), "Ca II HK emission in rapidly rotating stars. Evidence for an onset of the solar-type dynamo" (PDF), Astronomy and Astrophysics, 493 (3): 1099–1107, Bibcode:2009A&A...493.1099S, doi:10.1051/0004-6361:200810377^{[permanent dead link]}
9. "HD 104304". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-10-11.
10. Tanner, Angelle M.; et al. (2010), "A High-Contrast Imaging Survey of SIM Lite Planet Search Targets", Publications of the Astronomical Society of the Pacific, 122 (896): 1195, arXiv:1007.4315, Bibcode:2010PASP..122.1195T, doi:10.1086/656481, S2CID 118459054.
11. Schneider, Jean, "Star : HD 104304", Extrasolar Planets Encyclopaedia, archived from the original on November 13, 2007, retrieved 2011-12-21