HD 197630

HD 197630, also known as HR 7933 or rarely 23 G. Microscopii, is a probable astrometric binary located in the southern constellation Microscopium. The visible component is a bluish-white hued star that is faintly visible to the naked eye with an apparent magnitude of 5.47.[2] Based on parallax measurements from the Gaia satellite, the system is estimated to be 328 light years away.[1] However, it is drifting closer with a heliocentric radial velocity of −30 km/s. At its current distance, HD 197630's brightness is diminished by 0.11 magnitudes due to interstellar dust.[17] A 2012 multiplicity survey failed to confirm the velocity variations.[18]

HD 197630
HD 197630 is the star circled in red
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Microscopium
Right ascension 20h 46m 20.06779s[1]
Declination −39° 11′ 57.3590″[1]
Apparent magnitude (V) 5.47±0.01[2]
Characteristics
Evolutionary stage main sequence star[3]
Spectral type B8/9 V[4]
B−V color index −0.10[5]
Variable type suspected SPB[6]
Astrometry
Radial velocity (Rv)−30±7.4[7] km/s
Proper motion (μ) RA: +50.451 mas/yr[1]
Dec.: −27.196 mas/yr[1]
Parallax (π)9.9354 ± 0.1022 mas[1]
Distance328 ± 3 ly
(101 ± 1 pc)
Absolute magnitude (MV)+0.49[8]
Details
Mass2.83±0.04[3] M☉
Radius2.56±0.13[9] R☉
Luminosity73.5[10] L☉
Surface gravity (log g)4.11±0.14[11] cgs
Temperature10,965+255
−250[12] K
Metallicity59% solar
Metallicity [Fe/H]−0.23[13] dex
Rotational velocity (v sin i)290[14] km/s
Age113[11] Myr
Other designations
23 G. Microscopii[15], CD−39°13960, CPD−39°8771, FK5 3658, GC 28927, HD 197630, HIP 102497, HR 7933, SAO 212416[16]
Database references
SIMBADdata

HD 197630 has a stellar classification of B8/9 V,[4] indicating that it is a B-type star with the characteristics of a B8 and B9 main sequence star. It has 2.83 times the mass of the Sun[3] and 2.56 times the Sun's radius. It radiates 73.5 times the luminosity of the Sun[10] from its photosphere at an effective temperature of 10,965 K.[12] The star is estimated to be 113 million years old,[11] having completed roughly half of its main sequence lifetime.[3] HD 19730 is spinning rapidly with a projected rotational velocity of 290 km/s.[14]

A light curve for HD 197630, plotted from TESS data[19]

The object was in a 2002 Hipparcos variability survey and as a result,[20] the AAVSO cataloged HD 197630 as a suspected variable star that fluctuates by 0.005 magnitudes within 7.71 hours.[21] However, subsequent observations have not confirmed this. Further data from the Transiting Exoplanet Survey Satellite suggests that HD 197630 may be a slowly pulsating B-type star plus a variable star with rotation modulations.[6]

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. 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.
  3. Zorec, J.; Royer, F. (January 2012). "Rotational velocities of A-type stars IV: Evolution of rotational velocities". Astronomy & Astrophysics. 537: A120. arXiv:1201.2052. Bibcode:2012A&A...537A.120Z. doi:10.1051/0004-6361/201117691. eISSN 1432-0746. ISSN 0004-6361. S2CID 55586789.
  4. Houk, N. (1982). Michigan Catalogue of Two-dimensional Spectral Types for the HD stars. Volume III: Declinations −40° to −26°. Bibcode:1982mcts.book.....H.
  5. Corben, P. M. (April 1971). "Photoelectric Magnitudes and Colours for Bright Southern Stars". Monthly Notes of the Astronomical Society of South Africa. 30 (4): 37. Bibcode:1971MNSSA..30...37C. ISSN 0024-8266.
  6. Pedersen, May G.; et al. (8 February 2019). "Diverse Variability of O and B Stars Revealed from 2-minute Cadence Light Curves in Sectors 1 and 2 of the TESS Mission: Selection of an Asteroseismic Sample". The Astrophysical Journal. 872 (1): L9. arXiv:1901.07576. Bibcode:2019ApJ...872L...9P. doi:10.3847/2041-8213/ab01e1. eISSN 2041-8213.
  7. Kharchenko, N.V.; Scholz, R.-D.; Piskunov, A.E.; Röser, S.; Schilbach, E. (November 2007). "Astrophysical supplements to the ASCC-2.5: Ia. Radial velocities of ~55000 stars and mean radial velocities of 516 Galactic open clusters and associations". Astronomische Nachrichten. 328 (9): 889–896. arXiv:0705.0878. Bibcode:2007AN....328..889K. doi:10.1002/asna.200710776. eISSN 1521-3994. ISSN 0004-6337. S2CID 119323941.
  8. 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.
  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. McDonald, I.; Zijlstra, A. A.; Boyer, M. L. (21 November 2012). "Fundamental parameters and infrared excesses of Hipparcos stars: Parameters and IR excesses from Hipparcos". Monthly Notices of the Royal Astronomical Society. 427 (1): 343–357. arXiv:1208.2037. Bibcode:2012MNRAS.427..343M. doi:10.1111/j.1365-2966.2012.21873.x. eISSN 1365-2966. ISSN 0035-8711.
  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. 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.
  13. Anders, F.; et al. (August 2019). "Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18". Astronomy & Astrophysics. 628: A94. arXiv:1904.11302. Bibcode:2019A&A...628A..94A. doi:10.1051/0004-6361/201935765. eISSN 1432-0746. ISSN 0004-6361.
  14. Levato, H.; Grosso, M. (June 2004). "New Projected Rotational Velocities of All Southern B-type Stars of the Bright Star Catalogue". Astronomical Society of the Pacific. 215: 51. Bibcode:2004IAUS..215...51L.
  15. 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.
  16. "HD 197360". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved December 20, 2022.
  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. arXiv:1709.01160. Bibcode:2017MNRAS.472.3805G. doi:10.1093/mnras/stx2219. eISSN 1365-2966. ISSN 0035-8711.
  18. Chini, R.; Hoffmeister, V. H.; Nasseri, A.; Stahl, O.; Zinnecker, H. (10 July 2012). "A spectroscopic survey on the multiplicity of high-mass stars". Monthly Notices of the Royal Astronomical Society. 424 (3): 1925–1929. arXiv:1205.5238. Bibcode:2012MNRAS.424.1925C. doi:10.1111/j.1365-2966.2012.21317.x. ISSN 0035-8711.
  19. "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 8 December 2021.
  20. Koen, Chris; Eyer, Laurent (March 2002). "New periodic variables from the Hipparcos epoch photometry". Monthly Notices of the Royal Astronomical Society. 331 (1): 45–59. arXiv:astro-ph/0112194. Bibcode:2002MNRAS.331...45K. doi:10.1046/j.1365-8711.2002.05150.x. eISSN 1365-2966. ISSN 0035-8711.
  21. "VSX : Detail for HIP 102497". www.aavso.org. Retrieved 20 December 2022.
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