Astronomy:HD 196917

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Short description: Suspected variable star in Microscopium
HD 196917
Microscopium constellation map.svg
Red circle.svg
Location of HD 196917 on the map (circled)
Observation data
Epoch J2000.0   Equinox (celestial coordinates)
Constellation Microscopium
Right ascension  20h 41m 23.65766s[1]
Declination −31° 35′ 53.8334″[1]
Apparent magnitude (V) 5.74[2] (5.75 - 5.76)[3]
Characteristics
Evolutionary stage AGB[4]
Spectral type M1 III[5] or M0 III[6]
B−V color index +1.53[7]
Variable type suspected[8]
Astrometry
Radial velocity (Rv)−97.3±2.3[9] km/s
Proper motion (μ) RA: +109.914[1] mas/yr
Dec.: −60.256[1] mas/yr
Parallax (π)7.6563 ± 0.0891[1] mas
Distance426 ± 5 ly
(131 ± 2 pc)
Absolute magnitude (MV)+0.04[10]
Details
Mass1.27[11] M☉
Radius44.2±2.2[12] R☉
Luminosity620+45−20[1] L☉
Surface gravity (log g)1.40[11] cgs
Temperature3,908±122[13] K
Metallicity [Fe/H]−0.28[11] dex
Other designations
NSV 25227, CD−32°16130, CPD−32°6177, FK5 3652, GC 28808, HD 196917, HIP 102092, HR 7909, SAO 212345[14]
Database references
SIMBADdata

HD 196917 (HR 7909; 17 G. Microscopii; NSV 25227) is a solitary star[15] located in the southern constellation Microscopium. It is faintly visible to the naked eye as a red-hued point of light with an apparent magnitude of 5.74.[2] Gaia DR3 parallax measurements imply a distance of 426 light-years and[1] it is rapidly approaching the Solar System with a heliocentric radial velocity of −97.3 km/s.[9] At its current distance, HD 196917's brightness is diminished by 0.13 magnitudes due to interstellar extinction[16] and it has an absolute magnitude of +0.04.[10]

HD 196917 has a stellar classification of either M1 III[5] or M0 III,[6] indicating that it is an evolved M-type giant. It is currently on the asymptotic giant branch,[4] fusing hydrogen and helium shells around an inert carbon core. It has 1.27 times the mass of the Sun[11] but it has expanded to 44.2 times the radius of the Sun.[12] It radiates 620 times the luminosity of the Sun[1] from its enlarged photosphere at an effective temperature of 3,908 K.[13] HD 196917 is metal deficient with an iron abundance of [Fe/H] = −0.28 or 52.5% of the Sun's.[11]

The variability of the star was first detected in 1997 by the Hipparcos mission.[17] It found variations between 5.82 and 5.86 in the Hipparcos passband. Koen & Lyer (2002) observed visual variations from the star and found that HD 196917 varies by 0.009 magnitudes within 21.01 hours.[18] As of 2004, its variability has not been confirmed.[19]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 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 NSV 25227". https://www.aavso.org/vsx/index.php?view=detail.top&oid=63662. 
  4. ↑ 4.0 4.1 Eggen, Olin J. (July 1992). "Asymptotic giant branch stars near the sun". The Astronomical Journal 104: 275. doi:10.1086/116239. ISSN 0004-6256. Bibcode: 1992AJ....104..275E. 
  5. ↑ 5.0 5.1 Houk, N. (1982). Michigan Catalogue of Two-dimensional Spectral Types for the HD stars. Declinations −40° to −26°. 3. Bibcode: 1982mcts.book.....H. 
  6. ↑ 6.0 6.1 Evans, D. S.; Menzies, A.; Stoy, R. H. (October 1, 1957). "Fundamental Data for Southern Stars (First List)". Monthly Notices of the Royal Astronomical Society (Oxford University Press (OUP)) 117 (5): 534–561. doi:10.1093/mnras/117.5.534. ISSN 0035-8711. Bibcode: 1957MNRAS.117..534E. 
  7. ↑ 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. 
  8. ↑ 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. 
  9. ↑ 9.0 9.1 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. 
  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 11.4 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. doi:10.1051/0004-6361/201935765. ISSN 0004-6361. Bibcode: 2019A&A...628A..94A. 
  12. ↑ 12.0 12.1 Kervella, P.; Thévenin, F.; Di Folco, E.; Ségransan, D. (April 8, 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 Stassun, Keivan G. et al. (9 September 2019). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal 158 (4): 138. doi:10.3847/1538-3881/ab3467. Bibcode: 2019AJ....158..138S. 
  14. ↑ "HD 196917". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+196917. 
  15. ↑ 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. doi:10.1111/j.1365-2966.2008.13596.x. ISSN 0035-8711. Bibcode: 2008MNRAS.389..869E. 
  16. ↑ 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. 
  17. ↑ Perryman, M. A. C.; Lindegren, L.; Kovalevsky, J.; Hoeg, E.; Bastian, U.; Bernacca, P. L.; Crézé, M.; Donati, F. et al. (July 1997). "The HIPPARCOS Catalogue". Astronomy and Astrophysics 323: L49–L52. ISSN 0004-6361. Bibcode: 1997A&A...323L..49P. 
  18. ↑ 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. doi:10.1046/j.1365-8711.2002.05150.x. ISSN 0035-8711. Bibcode: 2002MNRAS.331...45K. 
  19. ↑ Samus, N. N.; Durlevich, O. V. (November 2004). "VizieR Online Data Catalog: Combined General Catalogue of Variable Stars (Samus+ 2004)". VizieR Online Data Catalog: II/250. Bibcode: 2004yCat.2250....0S. 
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