FY Canis Majoris
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  | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Canis Major |
| Right ascension | 07h 26m 59.48269s[1] |
| Declination | −23° 05′ 09.6897″[1] |
| Apparent magnitude (V) | 4.8 - 6.25[2] |
| Characteristics | |
| Spectral type | B0.5 IVe[3] |
| Variable type | γ Cas[2] |
| Astrometry | |
| Proper motion (μ) | RA: −6.692±0.038[1] mas/yr Dec.: +4.054±0.078[1] mas/yr |
| Parallax (π) | 1.7919 ± 0.0645 mas[1] |
| Distance | 1,820 ± 70 ly (560 ± 20 pc) |
| Absolute magnitude (MV) | −2.23[4] |
| Orbit[5] | |
| Primary | Be star |
| Companion | hot subdwarf |
| Period (P) | 37.257±0.003 d |
| Inclination (i) | >66[6]° |
| Periastron epoch (T) | 2448529.64±0.15 |
| Semi-amplitude (K1) (primary) | 14.4±0.9 km/s |
| Semi-amplitude (K2) (secondary) | 128.2±2.2 km/s |
| Details | |
| Be star | |
| Mass | 10-13[6] M☉ |
| Radius | 6.8[6] R☉ |
| Luminosity | 26,915[6] L☉ |
| Temperature | 27,500±3,000[5] K |
| Rotational velocity (v sin i) | 340±40[5] km/s |
| hot subdwarf | |
| Mass | 1.1-1.5[6] M☉ |
| Radius | 0.81[6] R☉ |
| Luminosity | 2,399[6] L☉ |
| Temperature | 45,000±5,000[5] K |
| Rotational velocity (v sin i) | 41±5[5] km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
FY Canis Majoris (FY CMa), also known as HD 58978, is a star about 1,800 light years from the Earth, in the constellation Canis Major (very near the border of Puppis). It is usually a 5th magnitude star, so it will be visible to the naked eye of an observer far from city lights. It is a Gamma Cassiopeiae variable star, whose brightness varies from magnitude 4.8 to 6.25.
In 1967, Alejandro Feinstein detected low amplitude (0.14 magnitude) variability in HD 58978's brightness, from photoelectric observations at La Plata Observatory.[10] The star was given the variable star designation FY Canis Majoris in 1973.[11] During an outburst in 2009, the star brightened to magnitude 4.8, its historical peak brightness.[2] TESS data show that FY CMa pulsates at many different frequencies, with periods ranging from 1.07 hours to 5.8 days.[12]
In 1905, Edward King noted that FY CMa has a peculiar spectrum with an unusually bright Hβ (and other) emission lines.[13] Paul Merrill et al. listed it as a Be star in 1925.[14] Spectra taken by various observers over several decades of the 20th century showed that the strength and relative intensities of the star's emission line are variable,[3] and could change on a timescale of just a few days.[15]
In 2008, Geraldine Peters et al. obtained high resolution spectra from the IUE and found that the Be star has hot, far less massive subdwarf companion star, with which it forms a spectroscopic binary.[5]
Hui-Lau Cao calculated that FY CMa is losing mass at a rate of about 6 × 10−8 M☉/year via a stellar wind with a terminal velocity of about 750 km/sec.[16]
References[edit]
- ^ a b c d e Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
- ^ a b c "FY CMa". The International Variable Star Index. AAVSO. Retrieved 1 February 2023.
- ^ a b Slettebak, A. (September 1982). "Spectral types and rotational velocities of the brighter Be stars and A-F type shell stars". Astrophysical Journal Supplement Series. 50: 55–83. Bibcode:1982ApJS...50...55S. doi:10.1086/190820.
- ^ Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331–346. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. eISSN 1562-6873. ISSN 1063-7737. S2CID 119257644.
- ^ a b c d e f Peters, Geraldine J.; Gies, Douglas R.; Grundstrom, Erika D.; McSwain, M. Virginia (October 2008). "Detection of a Hot Subdwarf Companion to the Be Star FY Canis Majoris". Astrophysical Journal. 686 (2): 1280–1291. arXiv:0806.3004. Bibcode:2008ApJ...686.1280P. doi:10.1086/591145.
- ^ a b c d e f g Nazé, Yaël; Rauw, Gregor; Smith, Myron A.; Motch, Christian (2022). "The X-ray emission of Be+stripped star binaries★". Monthly Notices of the Royal Astronomical Society. 516 (3): 3366. arXiv:2208.03990. Bibcode:2022MNRAS.516.3366N. doi:10.1093/mnras/stac2245.
- ^ "HD 58978 -- Be Star". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2023-02-01.
- ^ "ASAS All Star Catalogue". The All Sky Automated Survey. Retrieved 1 February 2023.
- ^ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 1 February 2023.
- ^ Feinstein, A. (1968). "A Survey of Southern Be Stars. II. Photometric data". Zeitschrift für Astrophysik. 68: 29–47. Bibcode:1968ZA.....68...29F.
- ^ Kukarkin, B. V.; Kholopov, P. N.; Kukarkina, N. P.; Perova, N. B. (October 1973). "59th Name-List of Variable Stars" (PDF). Information Bulletin on Variable Stars. 834 (1): 1. Bibcode:1973IBVS..834....1K. Retrieved 2 February 2023.
- ^ Balona, L. A.; Ozuyar, D. (April 2020). "TESS observations of Be stars: a new interpretation". Monthly Notices of the Royal Astronomical Society. 493 (2): 2528–2544. arXiv:1911.03068. Bibcode:2020MNRAS.493.2528B. doi:10.1093/mnras/staa389.
- ^ Pickering, Edward C.; Fleming, W. P. (July 1905). "Stars having peculiar spectra. Spectra of known variables". Astrophysical Journal. 22: 87–90. Bibcode:1905ApJ....22...87P. doi:10.1086/141242.
- ^ Merrill, P. W.; Humason, M. L.; Burwell, C. G. (June 1925). "Discovery and Observations of Stars of Class Be". Astrophysical Journal. 61: 389–417. Bibcode:1925ApJ....61..389M. doi:10.1086/142899.
- ^ Peters, G. J. (May 1987). "FY Canis Majoris". IAU Circ. 4391: 2. Bibcode:1987IAUC.4391....2P. Retrieved 1 February 2023.
- ^ Cao, Hui-Lai (December 2001). "Infall and Outflow Activities in the Be star FY CMa". Chinese Journal of Astronomy & Astrophysics. 1 (6): 514–524. Bibcode:2001ChJAA...1..514C. doi:10.1088/1009-9271/1/6/514.
