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Rho1 Arae

Rho1 Arae is a star in the southern constellation of Ara. Its name is a Bayer designation that is Latinized from ρ1 Arae, and abbreviated Rho1 Ara or ρ1 Ara. Unusually for a star with a Bayer designation, it was not catalogued by Bayer in his Uranometria. It was instead first catalogued by Nicolas Lacaille, in his Coelum Australe Stelliferum published in 1763. This star gained the designation of Rho1 Arae in Bode's Uranographia, published in 1801. Rho1 Arae is one of the dimmest stars with a Bayer designation, having an apparent visual magnitude of just +6.275.[2] According to the Bortle Dark-Sky Scale, this means the star is just barely visible to the naked eye in dark rural skies. Based upon parallax measurements, it is about 990 light-years (302 parsecs) distant from the Sun.[1] It is receding from the Sun with a radial velocity of +19 km/s.[5]

A light curve for V846 Arae, plotted from TESS data[13]

Hipparcos data revealed that Rho1 Arae is a variable star. It was given its variable star designation, V846 Arae, in 1999.[14] This is a spectroscopic binary system, which means that the presence of an orbiting companion is indicated by shifts in the spectrum. The primary star is a Be star, while the secondary star is a subdwarf O star; they orbit each other with a period of about 236.50 days.[7]

The combined spectrum of this system matches a stellar classification of B3 Vnpe, which may indicate the primary is a B-type main-sequence star. The 'e' suffix indicates the presence of emission lines from the primary Be star. The primary star is spinning rapidly with a projected rotational velocity of 370±10 km/s, which makes it difficult to obtain reliable orbital elements.[4] For Rho1 Arae, the emission lines are prominent and variable.[4] The observed variability may be the result of a magnetized stellar wind that is flowing close to the circumstellar disk.[15]

Rho1 Arae has a peculiar velocity of 27.4±4.9 km/s relative to its neighbors,[11] making it a runaway star system. A scenario that it was ejected from the Scorpius–Centaurus OB association as a result of a past supernova explosion seems unlikely because of its binarity.[4]

References

  1. ^ 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.
  2. ^ a b c d Kozok, J. R. (September 1985), "Photometric observations of emission B-stars in the southern Milky Way", Astronomy and Astrophysics Supplement Series, 61: 387–405, Bibcode:1985A&AS...61..387K.
  3. ^ Levenhagen, R. S.; Leister, N. V. (2006), "Spectroscopic Analysis of Southern B and Be Stars", Monthly Notices of the Royal Astronomical Society, 371 (1): 252–62, arXiv:astro-ph/0606149, Bibcode:2006MNRAS.371..252L, doi:10.1111/j.1365-2966.2006.10655.x, S2CID 16492030.
  4. ^ a b c d e Jilinski, E.; et al. (September 2010), "A Dynamical Study of Suspected Runaway Stars as Traces of Past Supernova Explosions in the Region of the Scorpius–Centaurus OB Association", The Astrophysical Journal, 721 (1): 469–477, Bibcode:2010ApJ...721..469J, doi:10.1088/0004-637X/721/1/469.
  5. ^ a b Evans, D. S. (June 20–24, 1966), "The Revision of the General Catalogue of Radial Velocities", in Batten, Alan Henry; Heard, John Frederick (eds.), Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30, vol. 30, University of Toronto: International Astronomical Union, p. 57, Bibcode:1967IAUS...30...57E.
  6. ^ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
  7. ^ a b c d Wang, Luqian; et al. (April 2023), "The Orbital and Physical Properties of Five Southern Be+sdO Binary Systems", The Astronomical Journal, 165 (5): 203, arXiv:2303.12616, Bibcode:2023AJ....165..203W, doi:10.3847/1538-3881/acc6ca, ISSN 1538-3881.
  8. ^ a b c d Wang, Luqian; et al. (2021), "The Detection and Characterization of Be+sdO Binaries from HST/STIS FUV Spectroscopy", The Astronomical Journal, 161 (5): 248, arXiv:2103.13642, Bibcode:2021AJ....161..248W, doi:10.3847/1538-3881/abf144.
  9. ^ Hohle, M. M.; et al. (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, S2CID 111387483.
  10. ^ a b Soubiran, C.; et al. (June 2010), "The PASTEL catalogue of stellar parameters", Astronomy and Astrophysics, 515: A111, arXiv:1004.1069, Bibcode:2010A&A...515A.111S, doi:10.1051/0004-6361/201014247, S2CID 118362423.
  11. ^ a b 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, arXiv:1007.4883, Bibcode:2011MNRAS.410..190T, doi:10.1111/j.1365-2966.2010.17434.x, S2CID 118629873.
  12. ^ "rho01 Ara", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2012-08-01.
  13. ^ MAST: Barbara A. Mikulski Archive for Space Telescopes, Space Telescope Science Institute, retrieved 8 December 2021.
  14. ^ 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.
  15. ^ Pogodin, M. A.; et al. (December 2012), Carciofi, A.; Rivinius, Th. (eds.), "Long-Term Variability of Emission Lines in the Spectrum of the Be Star HD 152478", Circumstellar Dynamics at High Resolution. Proceedings of a Joint ESP/Brazilian Workshop held at Foz do Iguacu, Brazil, 27 February-2 March, 2012, ASP Conference Proceedings, vol. 464, San Francisco: Astronomical Society of the Pacific, p. 227, Bibcode:2012ASPC..464..227P.