Astronomy:BM Scorpii
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| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Scorpius[1] |
| Right ascension | 17h 40m 58.54640s[2] |
| Declination | −32° 12′ 52.0644″[2] |
| Apparent magnitude (V) | 5.25 – 6.46[3] |
| Characteristics | |
| Spectral type | K2Ib Hδ1[4] |
| Variable type | SRd[5] |
| Astrometry | |
| Radial velocity (Rv) | −7.39[2] km/s |
| Proper motion (μ) | RA: −0.895[2] mas/yr Dec.: −6.073[2] mas/yr |
| Parallax (π) | 2.0344 ± 0.0681[2] mas |
| Distance | 1,600 ± 50 ly (490 ± 20 pc) |
| Absolute magnitude (MV) | −2.57[6] |
| Details | |
| Mass | 5-9[7] M☉ |
| Radius | 129[7] R☉ |
| Luminosity | 3,388[7] L☉ |
| Surface gravity (log g) | 1.1[7] cgs |
| Temperature | 3,888[7] K |
| Metallicity [Fe/H] | −0.22[8] dex |
| Other designations | |
| Database references | |
| SIMBAD | data |
BM Scorpii (BM Sco) is a red supergiant and a semiregular variable star located in the constellation Scorpius. It lies approximately 490 parsecs (1,600 ly) away in the open cluster Messier 6, the Butterfly Cluster. Although its brightness varies, it is at least occasionally visible to the naked eye of an observer with dark skies far from city lights.
Characteristics
BM Scorpii is a red supergiant of spectral type K2Ib. While it is listed as a standard star for that spectral class, it is also considered to have somewhat stronger Hδ absorption lines than normal. Its luminosity and mass are considered to be borderline for a supergiant star, and its spectral class has been given as K3III, which would indicate a giant star.[7]
BM Scorpii is a confirmed member of the open cluster Messier 6 (M6) and the brightest star in the cluster.[10] The brightest other stars in the cluster are late B- and A-class main sequence stars. A search has been made for other cool supergiant members, but none were found.[11]
With an effective temperature of 3,900 K and a radius of 129 R☉, BM Scorpii has a bolometric luminosity of 3,388 L☉. Its angular diameter has been measured at 2.5 mas.[7]
Variability
In 1920 Annie Cannon discovered that BM Scorpii is a variable star,[13] and it was included in the first edition of the General Catalogue of Variable Stars.[14] The brightness variations between apparent magnitudes 5.25 and 6.46 are not entirely regular, but were reported to show a primary period of 815 days.[5] In Hipparcos satellite photometry, the dominant variation period is 4.6 days with an amplitude of 0.05 magnitudes.[15] No secondary period longer than 815 days was detected.[16]
References
- ↑ Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 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.
- ↑ "BM Sco". https://www.aavso.org/vsx/index.php?view=detail.top&oid=32906.
- ↑ Keenan, Philip C.; McNeil, Raymond C. (1989). "The Perkins Catalog of Revised MK Types for the Cooler Stars". The Astrophysical Journal Supplement Series 71: 245. doi:10.1086/191373. Bibcode: 1989ApJS...71..245K.
- ↑ 5.0 5.1 Samus', N. N.; Kazarovets, E. V.; Durlevich, O. V.; Kireeva, N. N.; Pastukhova, E. N. (2017). "General catalogue of variable stars: Version GCVS 5.1". Astronomy Reports 61 (1): 80. doi:10.1134/S1063772917010085. Bibcode: 2017ARep...61...80S.
- ↑ Massey, Philip; Silva, David R.; Levesque, Emily M.; Plez, Bertrand; Olsen, Knut A. G.; Clayton, Geoffrey C.; Meynet, Georges; Maeder, Andre (2009). "Red Supergiants in the Andromeda Galaxy (M31)". The Astrophysical Journal 703 (1): 420. doi:10.1088/0004-637X/703/1/420. Bibcode: 2009ApJ...703..420M.
- ↑ 7.0 7.1 7.2 7.3 7.4 7.5 7.6 Wittkowski, M.; Arroyo-Torres, B.; Marcaide, J. M.; Abellan, F. J.; Chiavassa, A.; Guirado, J. C. (2017). "VLTI/AMBER spectro-interferometry of the late-type supergiants V766 Cen (=HR 5171 A), σ Oph, BM Sco, and HD 206859". Astronomy and Astrophysics 597: A9. doi:10.1051/0004-6361/201629349. Bibcode: 2017A&A...597A...9W.
- ↑ Khalatyan, A.; Anders, F.; Chiappini, C.; Queiroz, A. B. A.; Nepal, S.; Dal Ponte, M.; Jordi, C.; Guiglion, G. et al. (2024). "Transferring spectroscopic stellar labels to 217 million Gaia DR3 XP stars with SHBoost". Astronomy and Astrophysics 691: A98. doi:10.1051/0004-6361/202451427. Bibcode: 2024A&A...691A..98K.
- ↑ "BM Sco". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=BM+Sco.
- ↑ Rohlfs, K.; Schrick, K. W.; Stock, J. (1959). "Lichtelektrische Dreifarben-Photometrie von NGC 6405 (M6). Mit 3 Textabbildungen". Zeitschrift für Astrophysik 47: 15. Bibcode: 1959ZA.....47...15R.
- ↑ Warner, J. W.; Wing, R. F. (1977). "Supergiants in the field of the cluster M6, and the distribution of interstellar matter in the direction of the galactic center". The Astrophysical Journal 218: 105. doi:10.1086/155662. Bibcode: 1977ApJ...218..105W.
- ↑ EAS (1997). "The HIPPARCOS and TYCHO catalogues". Astrometric and Photometric Star Catalogues Derived from the ESA Hipparcos Space Astrometry Mission. ESA SP Series (Noordwijk, Netherlands: ESA Publications Division) 1200. ISBN 9290923997. Bibcode: 1997ESASP1200.....E. https://cdsarc.cds.unistra.fr/viz-bin/ftp-index?/ftp/cats/more/HIP/cdroms/cats. Retrieved 24 Mar 2025.
- ↑ Müller, Hartwig (1921). "Benennung von neu entdeckten veränderlichen Sternen". Astronomische Nachrichten 212 (19): 353. doi:10.1002/asna.19202121902. Bibcode: 1921AN....212..353..
- ↑ Kukarkin, B. V. (1949). General Catalog of Variable Stars. Akademii NAUK SSSR.
- ↑ Koen, Chris; Eyer, Laurent (2002). "New periodic variables from the Hipparcos epoch photometry". Monthly Notices of the Royal Astronomical Society 331 (1): 45. doi:10.1046/j.1365-8711.2002.05150.x. Bibcode: 2002MNRAS.331...45K.
- ↑ Percy, J. R.; Ursprung, C. (2006). "Do Yellow Semiregular (SRD) Variables Show Long Secondary Periods?". Journal of the American Association of Variable Star Observers (Jaavso) 34 (2): 125. Bibcode: 2006JAVSO..34..125P.
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