30 Monocerotis

30 Monocerotis is a single[9] star in the equatorial constellation of Hydra,[8] located 122 light years away from the Sun.[1] It has the Bayer designation C Hydrae;[8] 30 Monocerotis is the Flamsteed designation and was assigned when it belonged to the Monoceros constellation. The object is visible to the naked eye as a white-hued star with an apparent visual magnitude of 3.90.[2] It is moving away from the Earth with a heliocentric radial velocity of +10 km/s.[5]

30 Monocerotis
Observation data
Epoch J2000      Equinox J2000
Constellation Hydra
Right ascension 08h 25m 39.63201s[1]
Declination −03° 54′ 23.1178″[1]
Apparent magnitude (V) 3.90[2]
Characteristics
Spectral type A0 Va[3]
B−V color index −0.012±0.003[4]
Astrometry
Radial velocity (Rv)+10.00±1.78[5] km/s
Proper motion (μ) RA: −66.43[1] mas/yr
Dec.: −23.41[1] mas/yr
Parallax (π)26.66 ± 0.19 mas[1]
Distance122.3 ± 0.9 ly
(37.5 ± 0.3 pc)
Absolute magnitude (MV)1.04[4]
Details
Mass2.36[6] M☉
Radius2.7[7] R☉
Luminosity40.05[4] L☉
Surface gravity (log g)4.20[6] cgs
Temperature10,281±350[6] K
Rotational velocity (v sin i)129[6] km/s
Age162[6] Myr
Other designations
C Hya, 30 Mon, BD−03°2339, HD 71155, HIP 41307, HR 3314, SAO 135896[8]
Database references
SIMBADdata

This is an A-type main-sequence star with a stellar classification of A0 Va.[3] It is around 162[6] million years old with a high rate of spin, showing a projected rotational velocity of 129 km/s.[6] The star has 2.36[6] times the mass of the Sun and about 2.7[7] times the Sun's radius. It is radiating 40[4] times the luminosity of the Sun from its photosphere at an effective temperature of 10,281 K.[6]

A statistically significant infrared excess has been detected, indicating a debris disk is orbiting 2.0±0.1 AU from the host star with a blackbody temperature of 499±3 K. It is comparable in size to the asteroid belt.[10] An unexplained X-ray emission has also been detected coming from these coordinates – stars of this class are not normally expected to show X-ray emission, so it may be coming from a background source or an unseen companion.[11]

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. Baines, Ellyn K.; et al. (2018), "Fundamental Parameters of 87 Stars from the Navy Precision Optical Interferometer", The Astronomical Journal, 155 (1), 30, arXiv:1712.08109, Bibcode:2018AJ....155...30B, doi:10.3847/1538-3881/aa9d8b, S2CID 119427037.
  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. 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, S2CID 119257644.
  5. de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, S2CID 59451347, A61.
  6. David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146, S2CID 33401607.
  7. Pasinetti Fracassini, L. E.; et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy and Astrophysics (Third ed.), 367 (2): 521–524, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451, S2CID 425754.
  8. "30 Mon". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved May 7, 2019.
  9. 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.
  10. Moerchen, Margaret M.; et al. (November 2010), "High Spatial Resolution Imaging of Thermal Emission from Debris Disks", The Astrophysical Journal, 723 (2): 1418–1435, arXiv:1011.1410, Bibcode:2010ApJ...723.1418M, doi:10.1088/0004-637X/723/2/1418, S2CID 118648798.
  11. Schröder, C.; Schmitt, J. H. M. M. (November 2007), "X-ray emission from A-type stars", Astronomy and Astrophysics, 475 (2): 677–684, Bibcode:2007A&A...475..677S, doi:10.1051/0004-6361:20077429.
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