Epsilon Apodis
| |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Apus |
| Right ascension | 14h 22m 23.16467s[1] |
| Declination | –80° 06′ 32.2053″[1] |
| Apparent magnitude (V) | 5.06[2] |
| Characteristics | |
| Spectral type | B3 V[3] |
| U−B color index | –0.610[2] |
| B−V color index | –0.121[2] |
| Variable type | γ Cas[4] |
| Astrometry | |
| Radial velocity (Rv) | +4.5[5] km/s |
| Proper motion (μ) | RA: –9.51[1] mas/yr Dec.: –14.34[1] mas/yr |
| Parallax (π) | 5.06 ± 0.22[1] mas |
| Distance | 640 ± 30 ly (198 ± 9 pc) |
| Details | |
| Mass | 6.15 ± 0.71[6] M☉ |
| Radius | 3.9[7] R☉ |
| Luminosity | 1,614[6] L☉ |
| Surface gravity (log g) | 4.18[8] cgs |
| Temperature | 17,050[6] K |
| Metallicity [Fe/H] | –0.02[8] dex |
| Rotational velocity (v sin i) | 255[9] km/s |
| Age | 38.3 ± 4.4[10] Myr |
| Other designations | |
Epsilon Apodis (ε Aps, ε Apodis) is the Bayer designation for a star in the southern circumpolar constellation of Apus. It has an apparent visual magnitude of 5.06,[2] which is bright enough to be viewed from dark suburban skies. Based upon parallax measurements, it is at a distance of roughly 640 light-years (200 parsecs) from Earth.[1]
Based upon a stellar classification of B3 V,[3] this is a massive, B-type main sequence star that is generating energy through the fusion of hydrogen at its core. Epsilon Apodis has more than six[6] times the mass of the Sun and nearly four[7] times the Sun's radius. It is radiating 1,614[6] times as much luminosity as the Sun from its outer envelope at an effective temperature of 17,050 K.[6] At this heat, it has a blue-white glow that is a characteristic of B-type stars.[12]
It is spinning rapidly, with a projected rotational velocity of 255 km/s [9] giving a lower bound for the azimuthal velocity along the equator. Epsilon Apodis is classified as a Gamma Cassiopeiae type[4] variable star and its brightness varies between magnitudes 4.99 and 5.04.[13]
Naming
In Chinese caused by adaptation of the European southern hemisphere constellations into the Chinese system, 異雀 (Yì Què), meaning Exotic Bird, refers to an asterism consisting of ε Apodis, ζ Apodis, ι Apodis, β Apodis, γ Apodis, δ Octantis, δ1 Apodis, η Apodis and α Apodis. Consequently, ε Apodis itself is known as 異雀九 (Yì Què jiǔ, English: the Ninth Star of Exotic Bird.)[14]
References
- 1 2 3 4 5 6 van Leeuwen, F. (November 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.
- 1 2 3 4 Gutierrez-Moreno, Adelina; Moreno, Hugo (June 1968), "A photometric investigation of the Scorpio-Centaurus association", Astrophysical Journal Supplement 15: 459, Bibcode:1968ApJS...15..459G, doi:10.1086/190168.
- 1 2 Houk, Nancy (1979), Michigan catalogue of two-dimensional spectral types for the HD stars 1, Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan, Bibcode:1978mcts.book.....H.
- 1 2 Kazarovets, E. V.; et al. (January 1999), "The 74th Special Name-list of Variable Stars", Information Bulletin on Variable Stars 4659: 1, Bibcode:1999IBVS.4659....1K.
- ↑ Evans, D. S. (June 20–24, 1966), "The Revision of the General Catalogue of Radial Velocities", in Batten, Alan Henry; Heard, John Frederick, Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30, University of Toronto: International Astronomical Union, Bibcode:1967IAUS...30...57E.
- 1 2 3 4 5 6 Hohle, M. M.; Neuhäuser, R.; Schutz, B. F. (April 2010), "Masses and luminosities of O- and B-type stars and red supergiants", Astronomische Nachrichten 331 (4): 349, arXiv:1003.2335, Bibcode:2010AN....331..349H, doi:10.1002/asna.200911355.
- 1 2 Pasinetti Fracassini, L. E.; Pastori, L.; Covino, S.; Pozzi, A. (February 2001). "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics". Astronomy and Astrophysics 367 (2): 521–524. arXiv:astro-ph/0012289. Bibcode:2001A&A...367..521P. doi:10.1051/0004-6361:20000451.
- 1 2 Saffe, C.; et al. (October 2008), "Spectroscopic metallicities of Vega-like stars", Astronomy and Astrophysics 490 (1): 297–305, arXiv:0805.3936, Bibcode:2008A&A...490..297S, doi:10.1051/0004-6361:200810260.
- 1 2 Uesugi, Akira; Fukuda, Ichiro (1970), "Catalogue of rotational velocities of the stars", Contributions from the Institute of Astrophysics and Kwasan Observatory (University of Kyoto), Bibcode:1970crvs.book.....U.
- ↑ Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (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, arXiv:1007.4883, Bibcode:2011MNRAS.410..190T, doi:10.1111/j.1365-2966.2010.17434.x.
- ↑ "eps Aps -- Be Star", SIMBAD (Centre de Données astronomiques de Strasbourg), retrieved 2012-07-08.
- ↑ "The Colour of Stars", Australia Telescope, Outreach and Education (Commonwealth Scientific and Industrial Research Organisation), December 21, 2004, retrieved 2012-01-16.
- ↑ Samus, N. N.; Durlevich, O. V.; Kazarovets, R. V., "eps Aps", General Catalogue of Variable Stars (Sternberg Astronomical Institute), retrieved 2012-07-09.
- ↑ (Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 29 日
External links
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