Astronomy:V692 Coronae Australis

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Short description: SX Areits variable; Corona Australis
V692 Coronae Australis
Corona Australis constellation map.svg
Red circle.svg
Location of V692 CrA (circled)
Observation data
Epoch J2000.0   Equinox (celestial coordinates)
Constellation Corona Australis
Right ascension  18h 13m 12.69843s[1]
Declination −41° 20′ 09.9972″[1]
Apparent magnitude (V) 5.46[2] (5.46 - 5.51)[3]
Characteristics
Spectral type B2 III[4] or B1.5 IIIp[5]
B−V color index −0.17[6]
Variable type SX Arietis[7]
Astrometry
Radial velocity (Rv)−15.3±2.8[8] km/s
Proper motion (μ) RA: −2.050[1] mas/yr
Dec.: −6.210[1] mas/yr
Parallax (π)1.7423 ± 0.0977[1] mas
Distance1,900 ± 100 ly
(570 ± 30 pc)
Absolute magnitude (MV)−6.44[9] or −2.26[10]
Details
Mass7.35±0.48[11] M☉
Radius12.6±0.7[12] R☉
Luminosity (bolometric)4,181[11] L☉
Surface gravity (log g)3.52+0.33−0.14[1] cgs
Temperature17,061+1,474−1,357[13] K
Rotational velocity (v sin i)212±9[14] km/s
Age31.6±5.1[15] Myr
Other designations
V692 CrA, CD−41°12534, CPD−41°8620, GC 24824, HD 166596, HIP 89290, HR 6804, SAO 228815[16]
Database references
SIMBADdata

V692 Coronae Australis (HD 166596; HR 6804; 3 G. CrA), or simply V692 CrA, is a whitish-blue hued variable star located in the southern constellation Corona Australis. It has a maximum apparent magnitude of 5.46,[2] making it faintly visible to the naked eye. The object is located relatively far at a distance of approximately 1,900 light years based on Gaia DR3 parallax measurements,[1] but it is approaching the Solar System with a fairly constrained heliocentric radial velocity of −15.3 km/s.[8] At its current distance, V692 CrA's brightness is heavily diminished by 0.46 magnitudes due to extinction due to interstellar dust.[17] Its absolute magnitude depends on the source: Westin (1985) gave a value of −6.44[9] while the extended Hipparcos catalogue gave a value of −2.26.[10]

A light curve for V692 Coronae Australis, plotted from Hipparcos data[18]

Astronomers Carlos and Mercedes Jaschek along with a colleague listed HD 166596 as a Be star in 1964.[19] However, its status as an Ap star was not observed until 1979 by astronomers N. Vogt and A.M Faundez.[20] A year later, HD 166596 was observed to be variable and it had a period of 1.67 days.[21] In 1981, its variability was confirmed and it was given the variable star designation V692 Coronae Australis—the 692nd variable star in Corona Australis.[22] The star might have a shorter period of 49.8 hours.[7]

V692 CrA has a stellar classification of B2 III[4] or B1.5 IIIp,[5] both indicating that it is a slightly evolved B-type giant star. The second classification indicates that V692 CrA has peculiarities in its spectrum. It has 7.35 times the mass of the Sun[11] and 12.6 times the Sun's radius.[12] It radiates at a bolometric luminosity 4,181 times that of the Sun[11] from its photosphere at an effective temperature of 17,061 K.[13] V692 CrA is estimated to be 31.6 million years old[15] and it spins rapidly with a projected rotational velocity of 212 km/s.[14]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 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.
  2. ↑ 2.0 2.1 Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P. et al. (March 2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics 355: L27–L30. ISSN 0004-6361. Bibcode: 2000A&A...355L..27H. 
  3. ↑ "VSX : Detail for V0692 CrA". https://www.aavso.org/vsx/index.php?view=detail.top&oid=10563. 
  4. ↑ 4.0 4.1 Houk, Nancy (1978). Michigan catalogue of two-dimensional spectral types for the HD stars: Declinations −53° to −40°. 2. Bibcode: 1978mcts.book.....H. 
  5. ↑ 5.0 5.1 Rountree, Janet; Sonneborn, George (March 1991). "Criteria for the spectral classification of B stars in the ultraviolet". The Astrophysical Journal 369: 515. doi:10.1086/169781. ISSN 0004-637X. Bibcode: 1991ApJ...369..515R. 
  6. ↑ Johnson, H. L.; Mitchell, R. I.; Iriarte, B.; Wisniewski, W. Z. (1966). "UBVRIJKL Photometry of the Bright Stars". Communications of the Lunar and Planetary Laboratory 4: 99–110. Bibcode: 1966CoLPL...4...99J. 
  7. ↑ 7.0 7.1 Samus’, N. N.; Kazarovets, E. V.; Durlevich, O. V.; Kireeva, N. N.; Pastukhova, E. N. (January 2017). "General catalogue of variable stars: Version GCVS 5.1". Astronomy Reports 61 (1): 80–88. doi:10.1134/S1063772917010085. ISSN 1063-7729. Bibcode: 2017ARep...61...80S. 
  8. ↑ 8.0 8.1 Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35,495 Hipparcos stars in a common system". Astronomy Letters 32 (11): 759–771. doi:10.1134/S1063773706110065. ISSN 1063-7737. Bibcode: 2006AstL...32..759G. 
  9. ↑ 9.0 9.1 Westin, T. N. G. (April 1985). "The local system of early type stars. Spatial extent and kinematics.". Astronomy and Astrophysics Supplement Series 60: 99–134. ISSN 0365-0138. Bibcode: 1985A&AS...60...99W. 
  10. ↑ 10.0 10.1 Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331–346. doi:10.1134/S1063773712050015. ISSN 1063-7737. Bibcode: 2012AstL...38..331A. 
  11. ↑ 11.0 11.1 11.2 11.3 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): 349–360. doi:10.1002/asna.200911355. ISSN 0004-6337. Bibcode: 2010AN....331..349H. 
  12. ↑ 12.0 12.1 Kervella, P.; Thévenin, F.; Di Folco, E.; Ségransan, D. (October 2004). "The angular sizes of dwarf stars and subgiants. Surface brightness relations calibrated by interferometry". Astronomy & Astrophysics 426 (1): 297–307. doi:10.1051/0004-6361:20035930. ISSN 0004-6361. Bibcode: 2004A&A...426..297K. 
  13. ↑ 13.0 13.1 Gulati, R. K.; Malagnini, M. L.; Morossi, C. (October 1989). "Empirical temperature calibrations for early-type stars.". Astronomy and Astrophysics Supplement Series 80: 73–88. ISSN 0365-0138. Bibcode: 1989A&AS...80...73G. 
  14. ↑ 14.0 14.1 Brown, A. G. A.; Verschueren, W. (March 1997). "High S/N Echelle spectroscopy in young stellar groups. II. Rotational velocities of early-type stars in SCO OB2.". Astronomy & Astrophysics 319: 811–838. ISSN 0004-6361. Bibcode: 1997A&A...319..811B. 
  15. ↑ 15.0 15.1 Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (October 12, 2010). "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun". Monthly Notices of the Royal Astronomical Society (Oxford University Press (OUP)) 410 (1): 190–200. doi:10.1111/j.1365-2966.2010.17434.x. ISSN 0035-8711. Bibcode: 2011MNRAS.410..190T. 
  16. ↑ "V* V692 CrA". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=V%2A+V692+CrA. 
  17. ↑ Gontcharov, George A.; Mosenkov, Aleksandr V. (28 September 2017). "Verifying reddening and extinction for Gaia DR1 TGAS main sequence stars". Monthly Notices of the Royal Astronomical Society 472 (4): 3805–3820. doi:10.1093/mnras/stx2219. ISSN 0035-8711. Bibcode: 2017MNRAS.472.3805G. 
  18. ↑ 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: 1997HIP...C......0E. https://cdsarc.cds.unistra.fr/viz-bin/ftp-index?/ftp/cats/more/HIP/cdroms/cats. Retrieved 15 October 2022. 
  19. ↑ Jaschek, C.; Jaschek, M.; Kucewicz, B. (1964). "A Survey of Southern Be Stars". Zeitschrift für Astrophysik 59: 108. ISSN 0372-8331. Bibcode: 1964ZA.....59..108J. 
  20. ↑ Vogt, N.; Faundez, A. M. (1 June 1979). "Photoelectric observations of peculiar A and related stars I: Strömgren photometry of 341 Ap stars.". Astronomy and Astrophysics Supplement Series 36: 477–484. ISSN 0365-0138. Bibcode: 1979A&AS...36..477V. 
  21. ↑ Renson, P.; Manfroid, J. (March 1980). "Nouvelle Recherche de Periodes d'etoiles Ap Observees a l'ESO-IV". Information Bulletin on Variable Stars 1755: 1. ISSN 0374-0676. Bibcode: 1980IBVS.1755....1R. 
  22. ↑ Kholopov, P. N.; Samus', N. N.; Kukarkina, N. P.; Medvedeva, G. I.; Perova, N. B. (November 1981). "66th Name-List of Variable Stars". Information Bulletin on Variable Stars 2042: 1. ISSN 0374-0676. Bibcode: 1981IBVS.2042....1K. 
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