Astronomy:Alpha Monocerotis
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| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Monoceros |
| Right ascension | 07h 41m 14.832s[1] |
| Declination | −09° 33′ 04.08″[1] |
| Apparent magnitude (V) | 3.94[2] |
| Characteristics | |
| Evolutionary stage | red clump[3] |
| Spectral type | G9.5 III-IIIb Fe-0.5[4] |
| B−V color index | 1.022[2] |
| Astrometry | |
| Radial velocity (Rv) | 11.66±0.06[5] km/s |
| Proper motion (μ) | RA: −74.989[1] mas/yr Dec.: −19.838[1] mas/yr |
| Parallax (π) | 22.3839 ± 0.1348[1] mas |
| Distance | 145.7 ± 0.9 ly (44.7 ± 0.3 pc) |
| Absolute magnitude (MV) | 0.71±0.08[6] |
| Details | |
| Mass | 2.25±0.13[5] M☉ |
| Radius | 10.42±0.12[7] R☉ |
| Luminosity | 63.7±1.3[7] L☉ |
| Surface gravity (log g) | 2.79±0.04[5] cgs |
| Temperature | 5049±32[7] K |
| Metallicity [Fe/H] | −0.04±0.03[5] dex |
| Rotation | 326 days[8] |
| Rotational velocity (v sin i) | 0.92±0.45[5] km/s |
| Age | 890±180[5] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Alpha Monocerotis, Latinised from α Monocerotis, is the Bayer designation for a star in the equatorial constellation of Monoceros. It can be viewed with the naked eye, having an apparent visual magnitude of 3.94.[2] Despite being labeled "alpha", it is not the brightest star in the constellation; Beta Monocerotis is, though the individual stars of the latter are fainter.[10] Based upon an annual parallax shift of 22.4 mas as seen from Earth,[1] it is located 146 light-years away from the Sun. The star is moving away from the Sun with a radial velocity of +11.7 km/s.[5]
The stellar classification of G9.5 III-IIIb Fe-0.5[4] indicates this is an evolved giant star of type G, which means the hydrogen has been depleted at its core and the outer envelope has expanded and cooled. The 'Fe−0.5' notation indicates the spectrum displays a slight underabundance of iron relative to other stars of this temperature. It is a red clump giant, which means it is generating energy through helium fusion at its core.[3] At the age of 890 million years, this yellow-hued star has an estimated 2.2 times the mass of the Sun[5] and 10 times the Sun's radius.[7] It is spinning sedately with a rotation period of about 326 days.[8]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940 Gaia DR3 record for this source at VizieR.
- ↑ 2.0 2.1 2.2 Hekker, S. et al. (August 2006), "Precise radial velocities of giant stars. I. Stable stars", Astronomy and Astrophysics 454 (3): 943–949, doi:10.1051/0004-6361:20064946, Bibcode: 2006A&A...454..943H.
- ↑ 3.0 3.1 Laney, C. D.; Joner, M. D.; Pietrzyński, G. (2012), "A new Large Magellanic Cloud K-band distance from precision measurements of nearby red clump stars", Monthly Notices of the Royal Astronomical Society 419 (2): 1637, doi:10.1111/j.1365-2966.2011.19826.x, Bibcode: 2012MNRAS.419.1637L.
- ↑ 4.0 4.1 Keenan, Philip C; McNeil, Raymond C (1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series 71: 245, doi:10.1086/191373, Bibcode: 1989ApJS...71..245K.
- ↑ 5.0 5.1 5.2 5.3 5.4 5.5 5.6 5.7 Jofré, E. et al. (2015), "Stellar parameters and chemical abundances of 223 evolved stars with and without planets", Astronomy & Astrophysics 574: A50, doi:10.1051/0004-6361/201424474, A50, Bibcode: 2015A&A...574A..50J. Alpha Monocerotis' database entry at VizieR.
- ↑ da Silva, L. et al. (November 2006), "Basic physical parameters of a selected sample of evolved stars", Astronomy and Astrophysics 458 (2): 609–623, doi:10.1051/0004-6361:20065105, Bibcode: 2006A&A...458..609D.
- ↑ 7.0 7.1 7.2 7.3 Baines, Ellyn K.; Armstrong, J. Thomas; Clark, James H.; Gorney, Jim; Hutter, Donald J.; Jorgensen, Anders M.; Kyte, Casey; Mozurkewich, David et al. (October 2021), "Angular Diameters and Fundamental Parameters of Forty-four Stars from the Navy Precision Optical Interferometer" (in en), The Astronomical Journal 162 (5): 198, doi:10.3847/1538-3881/ac2431, ISSN 1538-3881, Bibcode: 2021AJ....162..198B.
- ↑ 8.0 8.1 Setiawan, J. et al. (July 2004), "Precise radial velocity measurements of G and K giants. Multiple systems and variability trend along the Red Giant Branch", Astronomy and Astrophysics 421 (1): 241–254, doi:10.1051/0004-6361:20041042-1, Bibcode: 2004A&A...421..241S.
- ↑ "alf Mon". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=alf+Mon.
- ↑ Ridpath, Ian. "Star Tales - Monoceros". http://www.ianridpath.com/startales/monoceros.html.
External links
- Kaler, James B. (March 23, 2007), "Alpha Monocerotis", STARS (University of Illinois), http://stars.astro.illinois.edu/sow/alphamon.html, retrieved 2017-11-08.
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