Astronomy:27 Canis Majoris
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| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Canis Major |
| Right ascension | 07h 14m 15.21192s[1] |
| Declination | −26° 21′ 09.0312″[1] |
| Apparent magnitude (V) | +4.62 – 4.82[2] (+4.92 + 5.39)[3] |
| Characteristics | |
| Spectral type | B3 IIIpe[4] |
| B−V color index | −0.17±0.16[5] |
| Variable type | γ Cas + β Cep:[2] |
| Astrometry | |
| Radial velocity (Rv) | 16.3±3.6[5] km/s |
| Proper motion (μ) | RA: −6.91[1] mas/yr Dec.: +3.17[1] mas/yr |
| Parallax (π) | 1.88 ± 0.32[1] mas |
| Distance | approx. 1,700 ly (approx. 530 pc) |
| Absolute magnitude (MV) | −4.13[5] |
| Orbit[6] | |
| Period (P) | 118.54±11.14 yr |
| Semi-major axis (a) | 0.178±0.012″ |
| Eccentricity (e) | 0.747±0.094 |
| Inclination (i) | 80.2±1.0° |
| Longitude of the node (Ω) | 131.3±3.0° |
| Periastron epoch (T) | 1,971.01±0.74 |
| Argument of periastron (ω) (secondary) | 85.0±3.6° |
| Details | |
| 27 CMa A | |
| Mass | 12.5±2.5[7] M☉ |
| Luminosity (bolometric) | 15,610[8] L☉ |
| Surface gravity (log g) | 3.514[9] cgs |
| Temperature | 21,061[9] K |
| Rotational velocity (v sin i) | 290[9] km/s |
| Age | 0.1±0.1[7] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
27 Canis Majoris is a binary star[3] system in the northern constellation of Canis Major,[10] located approximately 1,700 light years away from the Sun.[1] It has the variable star designation EW Canis Majoris;[2] 27 Canis Majoris is the Flamsteed designation. This system is visible to the naked eye as a 4th-magnitude,[2] blue-white hued star. It is moving away from the Earth with a heliocentric radial velocity of 16 km/s.[5]
The pair of stars in this system were first resolved by W. S. Finsen in 1953, and the split has been widening since that time.[13] The system has an orbital period of around 119 years with an eccentricity of 0.7 and a semimajor axis of 0.178″.[6] The magnitude 4.92[3] primary, designated component A, is a Be star with a stellar classification of B3 IIIpe.[4] It is spinning rapidly with a projected rotational velocity of 290 km/s, compared to a critical velocity of 389 km/s.[9] The star appears to be a Beta Cephei variable[14] with a pulsation period of 0.0919 days and an amplitude of 0.0080 in magnitude.[15]
The magnitude 5.39[3] secondary, component B, is classified as a Gamma Cassiopeiae type variable star. Due to its variable nature, the brightness of the system varies from magnitude +4.42 to +4.82.[2]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, doi:10.1051/0004-6361:20078357, Bibcode: 2007A&A...474..653V.
- ↑ 2.0 2.1 2.2 2.3 2.4 Samus, N. N. et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, 5.1 61 (1): 80–88, doi:10.1134/S1063772917010085, Bibcode: 2017ARep...61...80S.
- ↑ 3.0 3.1 3.2 3.3 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, doi:10.1111/j.1365-2966.2008.13596.x, Bibcode: 2008MNRAS.389..869E.
- ↑ 4.0 4.1 Woods, M. L. (1958), "Spectral types of bright southern stars", Memoirs of the Mount Stromlo Observatory 12: 125, Bibcode: 1955MmMtS..12..125W.
- ↑ 5.0 5.1 5.2 5.3 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A.
- ↑ 6.0 6.1 Hartkopf, W. I. et al. (June 30, 2006), Sixth Catalog of Orbits of Visual Binary Stars, United States Naval Observatory, http://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/wds/orb6, retrieved 2017-06-02.
- ↑ 7.0 7.1 Tetzlaff, N. et al. (January 2011), "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun", Monthly Notices of the Royal Astronomical Society 410 (1): 190–200, doi:10.1111/j.1365-2966.2010.17434.x, Bibcode: 2011MNRAS.410..190T.
- ↑ Hohle, M. M. et al. (April 2010), "Masses and luminosities of O- and B-type stars and red supergiants", Astronomische Nachrichten 331 (4): 349, doi:10.1002/asna.200911355, Bibcode: 2010AN....331..349H.
- ↑ 9.0 9.1 9.2 9.3 Frémat, Y.; Zorec, J.; Hubert, A.-M.; Floquet, M. (2005), "Effects of gravitational darkening on the determination of fundamental parameters in fast-rotating B-type stars", Astronomy and Astrophysics 440 (1): 305, doi:10.1051/0004-6361:20042229, Bibcode: 2005A&A...440..305F.
- ↑ 10.0 10.1 "27 CMa". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=27+CMa.
- ↑ Mennickent, R. E.; Vogt, N.; Sterken, C. (November 1994). "Long-term photometry of Be stars. I. Fading events and variations on time scales of years". Astronomy & Astrophysics Supplement Series 108: 237–250. Bibcode: 1994A&AS..108..237M.
- ↑ Balona, Luis A.; Rozowsky, Joel (August 1991). "Appearance of beta cephei pulsations in the Be star 27 CMa". Monthly Notices of the Royal Astronomical Society 251: 66–68. doi:10.1093/mnras/251.1.66P. Bibcode: 1991MNRAS.251P..66B.
- ↑ Mason, Brian D. et al. (November 1997), "ICCD Speckle Observations of Binary Stars. XVIII. An Investigation of Be Stars", Astronomical Journal 114: 2112, doi:10.1086/118630, Bibcode: 1997AJ....114.2112M.
- ↑ Balona, L. A.; Krisciunas, K. (May 1994), "Further Confirmation that the Be Star 27 CMa is a beta Cep Variable", Information Bulletin on Variable Stars 4022 (4022): 1, Bibcode: 1994IBVS.4022....1B.
- ↑ Stankov, Anamarija; Handler, Gerald (2005), "Catalog of Galactic β Cephei Stars", The Astrophysical Journal Supplement Series 158 (2): 193–216, doi:10.1086/429408, ISSN 0067-0049, Bibcode: 2005ApJS..158..193S.
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