V701 Coronae Australis

V701 Coronae Australis (HD 176723; HR 7197; 40 G. Coronae Australis), or simply V701 CrA, is a solitary,^[16] yellowish-white hued variable star located in the southern constellation Corona Australis. It has an average apparent magnitude of 5.72,^[17] making it faintly visible to the naked eye under ideal conditions. The object is located relatively close at a distance of 213 light-years based on Gaia DR3 parallax measurements,^[1] and it is currently receding with a poorly constrained heliocentric radial velocity of 4 km/s.^[6] At its current distance, V701 CrA's brightness is diminished by a quarter of a magnitude due to extinction^[18] and it has an absolute magnitude of +1.55.^[7]

A light curve for V701 Coronae Australis, plotted from TESS data^[19]

V701 Coronae Australis

Location of HD 168592 (circled)
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Corona Australis
Right ascension	19h 03m 17.69619s[1]
Declination	−38° 15′ 11.3335″[1]
Apparent magnitude (V)	5.69 to 5.73[2]
Characteristics
Spectral type	F2 III/IV[3] or F0 IIIn[4]
B−V color index	+0.32[5]
Variable type	δ Scuti[2]
Astrometry
Radial velocity (Rv)	4±7.4[6] km/s
Proper motion (μ)	RA: +12.794 mas/yr[1] Dec.: +14.271 mas/yr[1]
Parallax (π)	15.2952 ± 0.0559 mas[1]
Distance	213.2 ± 0.8 ly (65.4 ± 0.2 pc)
Absolute magnitude (MV)	+1.55[7]
Details
Mass	1.83+0.07 −0.06[8] M☉
Radius	2.85±0.14[9] R☉
Luminosity	17.5+0.2 −0.1[1] L☉
Surface gravity (log g)	3.75±0.12[10] cgs
Temperature	7,046±240[11] K
Metallicity [Fe/H]	−0.21[12] dex
Rotational velocity (v sin i)	265[13] km/s
Age	1.25[11] Gyr
Other designations
40 G. Coronae Australis[14], V701 CrA, CD−38°13300, CPD−38°7685, GC 26177, HD 176723, HIP 93552, HR 7197, SAO 210859[15]
Database references
SIMBAD	data

The object was first suspected to be variable in 1990. The variations matched that of δ Scuti variables.^[20] Three years later, it was confirmed to be variable and was given the variable star designation V701 Coronae Australis.^[21] It ranges from magnitude 5.69 to 5.73^[2] within 3.25 hours.^[22]

V701 CrA has a stellar classification of F2 III/IV,^[3] indicating that it is an evolved F-type star with the blended luminosity class of a subgiant and giant star. It has also been given a class of F0 IIIn,^[4] indicating broad or nebulous absorption lines due to rapid rotation. It has 1.83 times the mass of the Sun^[8] and a slightly enlarged radius of 2.85 R_☉.^[9] It radiates 17.5 times the luminosity of the Sun^[1] from its photosphere at an effective temperature of 7,046 K.^[11] The star spins rapidly with a projected rotational velocity of 265 km/s,^[13] which causes it to have an equatorial bulge that is 26% larger than the poles.^[23] It is metal deficient with an iron abundance 62% that of the Sun ([Fe/H] = −0.21)^[12] and it is estimated to be 1.25 billion years old.^[11] V701 CrA was considered to be a chemically peculiar star and was given a class of FpSr. Its peculiarity is now considered to be doubtful.^[24]

References

1. 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. 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. Bibcode:2017ARep...61...80S. doi:10.1134/S1063772917010085. eISSN 1562-6881. ISSN 1063-7729. S2CID 125853869.
3. Houk, N. (1982). Michigan Catalogue of Two-dimensional Spectral Types for the HD stars. Declinations −40° to −26°. Vol. 3. Bibcode:1982mcts.book.....H.
4. Evans, D. S.; Laing, J. D.; Menzies, A.; Stoy, R. H. (1964). "Fundamental data for southern stars (fifth list)". Royal Greenwich Observatory Bulletins. 85: 207–224. Bibcode:1964RGOB...85..207E.
5. 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.
6. Holmberg, J.; Nordström, B.; Andersen, J. (6 August 2007). "The Geneva-Copenhagen survey of the Solar neighbourhood II". Astronomy & Astrophysics. 475 (2): 519–537. arXiv:0707.1891. Bibcode:2007A&A...475..519H. doi:10.1051/0004-6361:20077221. eISSN 1432-0746. ISSN 0004-6361.
7. 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.
8. Nordström, B.; Mayor, M.; Andersen, J.; Holmberg, J.; Pont, F.; Jørgensen, B. R.; Olsen, E. H.; Udry, S.; Mowlavi, N. (16 April 2004). "The Geneva-Copenhagen survey of the Solar neighbourhood". Astronomy & Astrophysics. 418 (3): 989–1019. arXiv:astro-ph/0405198. Bibcode:2004A&A...418..989N. doi:10.1051/0004-6361:20035959. eISSN 1432-0746. ISSN 0004-6361.
9. Kervella, P.; Thévenin, F.; Di Folco, E.; Ségransan, D. (October 2004). "The angular sizes of dwarf stars and subgiants". Astronomy & Astrophysics. 426 (1): 297–307. arXiv:astro-ph/0404180. Bibcode:2004A&A...426..297K. doi:10.1051/0004-6361:20035930. eISSN 1432-0746. ISSN 0004-6361.
10. Allende Prieto, C.; Lambert, D. L. (December 1999). "Fundamental parameters of nearby stars from the comparison with evolutionary calculations: masses, radii and effective temperatures". Astronomy and Astrophysics. 352: 555–562. arXiv:astro-ph/9911002. Bibcode:1999A&A...352..555A. ISSN 0004-6361. S2CID 13365201.
11. David, Trevor J.; Hillenbrand, Lynne A. (12 May 2015). "The Ages of Early-type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets". The Astrophysical Journal. 804 (2): 146. arXiv:1501.03154. Bibcode:2015ApJ...804..146D. doi:10.1088/0004-637X/804/2/146. eISSN 1538-4357.
12. Casagrande, L.; Schönrich, R.; Asplund, M.; Cassisi, S.; Ramírez, I.; Meléndez, J.; Bensby, T.; Feltzing, S. (26 May 2011). "New constraints on the chemical evolution of the solar neighbourhood and Galactic disc(s): Improved astrophysical parameters for the Geneva-Copenhagen Survey⋆". Astronomy & Astrophysics. 530: A138. arXiv:1103.4651. Bibcode:2011A&A...530A.138C. doi:10.1051/0004-6361/201016276. eISSN 1432-0746. ISSN 0004-6361. S2CID 56118016.
13. Huang, Su-Shu (September 1953). "A Statistical Study of the Rotation of the Stars". The Astrophysical Journal. 118: 285. Bibcode:1953ApJ...118..285H. doi:10.1086/145751. eISSN 1538-4357. ISSN 0004-637X. S2CID 120328179.
14. Gould, Benjamin Apthorp (1878). "Uranometria Argentina : brillantez y posicion de las estrellas fijas, hasta la septima magnitud, comprendidas dentro de cien grados del polo austral : con atlas". Resultados del Observatorio Nacional Argentino. 1. Bibcode:1879RNAO....1.....G.
15. "V* V701 Coronae Australis". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved May 22, 2023.
16. Eggleton, P. P.; Tokovinin, A. A. (11 September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society. 389 (2): 869–879. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x. eISSN 1365-2966. ISSN 0035-8711. S2CID 14878976.
17. Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (March 2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27–L30. Bibcode:2000A&A...355L..27H. ISSN 0004-6361. S2CID 17128864.
18. 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. arXiv:1709.01160. Bibcode:2017MNRAS.472.3805G. doi:10.1093/mnras/stx2219. eISSN 1365-2966. ISSN 0035-8711. S2CID 118879856.
19. "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 24 May 2023.
20. Lampens, P.; Rufener, F. (April 1990). "Study of delta Scuti stars in the Geneva photometric system. I. New photometric data and period analysis for nine stars". Astronomy and Astrophysics Supplement Series. 83: 145–182. Bibcode:1990A&AS...83..145L. ISSN 0365-0138. S2CID 116966422.
21. Kazarovets, E. V.; Samus, N. N.; Goranskij, V. P. (February 1993). "The 71st Name-List of Variable Stars". Information Bulletin on Variable Stars. 3840: 1. Bibcode:1993IBVS.3840....1K. ISSN 0374-0676.
22. Rodriguez, E.; Lopez de Coca, P.; Rolland, A.; Garrido, R.; Costa, V. (July 1994). "δ Scuti stars: a new revised list". Astronomy and Astrophysics Supplement Series. 106: 21–28. Bibcode:1994A&AS..106...21R. ISSN 0365-0138. S2CID 124872236.
23. van Belle, Gerard T. (14 March 2012). "Interferometric observations of rapidly rotating stars". The Astronomy and Astrophysics Review. 20 (1): 51. arXiv:1204.2572. Bibcode:2012A&ARv..20...51V. doi:10.1007/s00159-012-0051-2. eISSN 1432-0754. ISSN 0935-4956.
24. Renson, P.; Manfroid, J. (19 March 2009). "Catalogue of Ap, HgMn and Am stars". Astronomy & Astrophysics. 498 (3): 961–966. Bibcode:2009A&A...498..961R. doi:10.1051/0004-6361/200810788. eISSN 1432-0746. ISSN 0004-6361. S2CID 55849045.