Astronomy:27 Canis Majoris
 Blue band light curves for EW Canis Majoris. The main plot shows the long term variability, and the inset plot shows the short term variability. Adapted from Mennickent et al. (1994) and Balona & Rozowsky (1991).[1][2] | |
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Canis Major |
| Right ascension | 07h 14m 15.21192s[3] |
| Declination | −26° 21′ 09.0312″[3] |
| Apparent magnitude (V) | +4.65[4] (+4.92 + 5.39)[5] |
| Characteristics | |
| Spectral type | B3 IIIpe[6] |
| B−V color index | −0.17±0.16[7] |
| Variable type | γ Cas + β Cep:[8] |
| Astrometry | |
| Radial velocity (Rv) | 16.3±3.6[7] km/s |
| Proper motion (μ) | RA: −6.91[3] mas/yr Dec.: +3.17[3] mas/yr |
| Parallax (π) | 1.88 ± 0.32[3] mas |
| Distance | approx. 1,700 ly (approx. 530 pc) |
| Absolute magnitude (MV) | −4.13[7] |
| Orbit[9] | |
| 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[10] M☉ |
| Luminosity (bolometric) | 15,610[4] L☉ |
| Surface gravity (log g) | 3.514[11] cgs |
| Temperature | 21,061[11] K |
| Rotational velocity (v sin i) | 290[11] km/s |
| Age | 0.1±0.1[10] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
27 Canis Majoris is a binary star[5] system in the northern constellation of Canis Major,[12] located approximately 1,700 light years away from the Sun.[3] It has the variable star designation EW Canis Majoris;[8] 27 Canis Majoris is the Flamsteed designation. This system is visible to the naked eye as a dim, blue-white hued star with an apparent visual magnitude of +4.65.[4] It is moving away from the Earth with a heliocentric radial velocity of 16 km/s.[7]
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″.[9] The magnitude 4.92[5] primary, designated component A, is a Be star with a stellar classification of B3 IIIpe.[6] It is spinning rapidly with a projected rotational velocity of 290 km/s, compared to a critical velocity of 389 km/s.[11] 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[5] 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.[8]
References
- ↑ 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.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 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.
- ↑ 4.0 4.1 4.2 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.
- ↑ 5.0 5.1 5.2 5.3 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.
- ↑ 6.0 6.1 Woods, M. L. (1958), "Spectral types of bright southern stars", Memoirs of the Mount Stromlo Observatory 12: 125, Bibcode: 1955MmMtS..12..125W.
- ↑ 7.0 7.1 7.2 7.3 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A.
- ↑ 8.0 8.1 8.2 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.
- ↑ 9.0 9.1 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.
- ↑ 10.0 10.1 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.
- ↑ 11.0 11.1 11.2 11.3 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.
- ↑ 12.0 12.1 "27 CMa". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=27+CMa.
- ↑ 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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