Astronomy:HD 85709

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Short description: Suspected variable in Sextans
HD 85709
Location of HD 85709 on the map (circled)
Observation data
Epoch J2000.0   Equinox (celestial coordinates)
Constellation Sextans
Right ascension  09h 53m 42.92424s[1]
Declination +05° 57′ 30.8742″[1]
Apparent magnitude (V) 5.95[2] (5.89 - 5.95)[3]
Characteristics
Evolutionary stage AGB[4]
Spectral type M2.5 III[5]
U−B color index +1.93[6]
B−V color index +1.66[6]
Variable type suspected[7]
Astrometry
Radial velocity (Rv)−0.66±0.40[8] km/s
Proper motion (μ) RA: −3.026[1] mas/yr
Dec.: +1.315[1] mas/yr
Parallax (π)2.9474 ± 0.107[1] mas
Distance1,110 ± 40 ly
(340 ± 10 pc)
Absolute magnitude (MV)−1.30[9]
Details
Radius133±7[10] R☉
Luminosity1,918±144[11] L☉
Surface gravity (log g)0.469[12] cgs
Temperature3,622±125[12] K
Metallicity [Fe/H]+0.23[13] dex
Other designations
NSV 18292, BD+06°2224, GC 13608, HD 85709, HIP 48519, HR 3915, SAO 117975
Database references
SIMBADdata

HD 85709 (HR 3915; 14 G. Sextantis; NSV 18292) is a solitary star[14] located in the equatorial constellation Sextans. It is faintly visible to the naked eye as a red-hued point of light with an apparent magnitude of 5.95.[2] The object is located relatively far at a distance of 1,100 light-years based on Gaia DR3 parallax measurements but it is slowly drifting closer with a heliocentric radial velocity of −0.66 km/s.[8] At its current distance, HD 85709's brightness is diminished with an interstellar extinction of two-tenths of a magnitude[15] and it has an absolute magnitude of −1.30.[9]

HD 85709 has a stellar classification of M2.5 III,[5] indicating that it is an evolved M-type giant star. It is currently on the asymptotic giant branch,[4] the point where it is generating energy via the fusion of hydrogen and helium shells around an inert carbon core. Having expanded to 133 times the radius of the Sun,[10] it now radiates 1,918 times the luminosity of the Sun[11] from its enlarged photosphere at an effective temperature of 3,622 K.[12] HD 85709 is metal enriched with an iron abundance 1.58 times that of the Sun's.[13]

In 1991, astronomer V.G. Kornilov and colleagues observed that HD 85709 fluctuated between magnitudes 5.89 and 5.95 in optical light during a photometry survey.[3] As of 2004 however, its variability has not been confirmed.[16]

References

  1. ↑ 1.0 1.1 1.2 1.3 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 Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system.". VizieR Online Data Catalog 2237. Bibcode: 2002yCat.2237....0D. 
  3. ↑ 3.0 3.1 Kornilov, V. G.; Volkov, I. M.; Zakharov, A. I.; Kozyreva, V. S.; Kornilova, L. N.; Krutyakov, A. N.; Krylov, A. V.; Kusakin, A. V. et al. (1991). "Catalogue of WBVR-magnitudes of bright stars of the northern sky.". Trudy Gosudarstvennogo Astronomicheskogo Instituta 63: 4–399. ISSN 0371-6791. Bibcode: 1991TrSht..63....1K. 
  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 Wilson, Ralph E.; Joy, Alfred H. (March 1950). "Radial Velocities of 2111 Stars.". The Astrophysical Journal 111: 221. doi:10.1086/145261. ISSN 0004-637X. Bibcode: 1950ApJ...111..221W. 
  6. ↑ 6.0 6.1 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. ↑ 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 Famaey, B.; Jorissen, A.; Luri, X.; Mayor, M.; Udry, S.; Dejonghe, H.; Turon, C. (January 2005). "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters". Astronomy and Astrophysics 430: 165. doi:10.1051/0004-6361:20041272. Bibcode: 2005A&A...430..165F. 
  9. ↑ 9.0 9.1 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. 
  10. ↑ 10.0 10.1 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. 
  11. ↑ 11.0 11.1 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G.  Gaia DR2 record for this source at VizieR.
  12. ↑ 12.0 12.1 12.2 McDonald, I.; Zijlstra, A. A.; Watson, R. A. (15 June 2017). "Fundamental parameters and infrared excesses of Tycho–Gaia stars". Monthly Notices of the Royal Astronomical Society 471 (1): 770–791. doi:10.1093/mnras/stx1433. ISSN 0035-8711. Bibcode: 2017MNRAS.471..770M. 
  13. ↑ 13.0 13.1 Zhou, Xu (August 1991). "The near-IR NA I doublet and CA II triplet in late-type stars and the determination of stellar atmosphere parameters.". Astronomy and Astrophysics 248: 367. ISSN 0004-6361. Bibcode: 1991A&A...248..367Z. 
  14. ↑ 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. 
  15. ↑ 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. 
  16. ↑ 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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