Astronomy:HD 187086

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Short description: Astrometric binary and uspected variable star
HD 187086
HD187086LightCurve.png
A light curve for HD 187086, plotted from Hipparcos data[1]
Observation data
Epoch J2000.0   Equinox (celestial coordinates)
Constellation Telescopium
Right ascension  19h 50m 14.05959s[2]
Declination −47° 33′ 26.6014″[2]
Apparent magnitude (V) 5.95 - 6.07[3]
Characteristics
Evolutionary stage AGB[4]
Spectral type M1 III[5]
B−V color index +1.67[6]
Variable type suspected[3]
Astrometry
Radial velocity (Rv)−64±1[7] km/s
Proper motion (μ) RA: +9.424[2] mas/yr
Dec.: −10.867[2] mas/yr
Parallax (π)3.1998 ± 0.0655[2] mas
Distance1,020 ± 20 ly
(313 ± 6 pc)
Absolute magnitude (MV)−0.80[8]
Details
Mass1.76±0.09[9] M☉
Radius111±6[10] R☉
Luminosity1,031±56[11] L☉
Surface gravity (log g)1.5±1[2] cgs
Temperature3,821±122[12] K
Metallicity [Fe/H]+0.24[2] dex
Other designations
NSV 12432, CD−47°13103, CPD−47°9366, GC 27427, HD 187086, HIP 95798, HR 7537, SAO 229887[13]
Database references
SIMBADdata

HD 187086, also known as HR 7537, is a probable astrometric binary[14] (87% chance[15]) located in the southern constellation Telescopium. It has an average apparent magnitude of 5.9, making it faintly visible to the naked eye. The star is located relatively far at a distance of 1,020 light years based on Gaia DR3 parallax measurements[2] but is rapidly drifting closer with a heliocentric radial velocity of −64 km/s.[7] At its current distance, HD 187086's brightness is diminished by 0.27 magnitudes due to interstellar dust.[16] It has an absolute magnitude of −0.8.[8]

The primary has a stellar classification of M1 III,[5] indicating that it is a red giant. It is currently on the asymptotic giant branch, fusing hydrogen and helium shells around an inert carbon core. It has 1.76 times the mass of the Sun[9] but it has expanded to 111 times the solar radius.[10] It radiates 1,031 times the luminosity of the Sun[11] from its enlarged photosphere at an effective temperature of 3,821 K,[12] giving it a red hue. HD 187086 is particularly metal enriched ([Fe/H] = +0.24).[2]

HD 187086 fluctuates between 5.95 and 6.07[3] and its variability was first noticed by P.M. Corben in 1971 after being listed as an ordinary M-type giant a year prior.[6][17] In 2002, Chris Koen and Laurent Eyer reported that the Hipparcos data shows periodic fluctuations with an amplitude of 0.023 magnitudes, and a period of 7.6805 days.[18] As of 2004 however, it is not confirmed to be variable.[19]

References

  1. ↑ 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: 1997ESASP1200.....E. https://cdsarc.cds.unistra.fr/viz-bin/ftp-index?/ftp/cats/more/HIP/cdroms/cats. Retrieved 15 October 2022. 
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 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.
  3. ↑ 3.0 3.1 3.2 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. doi:10.1134/S1063772917010085. ISSN 1063-7729. Bibcode: 2017ARep...61...80S. 
  4. ↑ 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, Nancy (1978). Michigan catalogue of two-dimensional spectral types for the HD stars: Declinations −53° to −40°. 2. Bibcode: 1978mcts.book.....H. 
  6. ↑ 6.0 6.1 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. ISSN 0024-8266. Bibcode: 1971MNSSA..30...37C. 
  7. ↑ 7.0 7.1 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. 
  8. ↑ 8.0 8.1 Corbally, C. J.; Garrison, R. F. (1984). "Which Map of Absolute Magnitudes: Keenan or Schmidt-Kaler?". The Mk Process and Stellar Classification: 277. Bibcode: 1984mpsc.conf..277C. 
  9. ↑ 9.0 9.1 Kervella, Pierre; Arenou, Frédéric; Thévenin, Frédéric (2022). "Stellar and substellar companions from Gaia EDR3". Astronomy & Astrophysics 657: A7. doi:10.1051/0004-6361/202142146. ISSN 0004-6361. Bibcode: 2022A&A...657A...7K. 
  10. ↑ 10.0 10.1 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. 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 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. 
  13. ↑ "HD 187086". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+187086. 
  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. ↑ Frankowski, A.; Jancart, S.; Jorissen, A. (19 December 2006). "Proper-motion binaries in the Hipparcos catalogue". Astronomy & Astrophysics 464 (1): 377–392. doi:10.1051/0004-6361:20065526. ISSN 0004-6361. Bibcode: 2007A&A...464..377F. 
  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. ↑ Eggen, O. J.; Stokes, N. R. (July 1970). "Narrow-Band and Broad-Band Photometry of Red Stars. III. Southern Giants". The Astrophysical Journal 161: 199. doi:10.1086/150525. ISSN 0004-637X. Bibcode: 1970ApJ...161..199E. 
  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. Bibcode: 2002MNRAS.331...45K. https://academic.oup.com/mnras/article/331/1/45/1034740. Retrieved 4 February 2023. 
  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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