Astronomy:HD 186756

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Short description: K-type giant; Telescopium
HD 186756
Telescopium constellation map.svg
Red circle.svg
Location of HD 186756 (circled)
Observation data
Epoch J2000.0   Equinox (celestial coordinates)
Constellation Telescopium
Right ascension  19h 48m 55.08814s[1]
Declination −52° 53′ 17.1953″[1]
Apparent magnitude (V) 6.25[2]
Characteristics
Spectral type K1 III[3]
U−B color index +1.12[2]
B−V color index +1.13[2]
Astrometry
Radial velocity (Rv)−21.2±0.4[4] km/s
Proper motion (μ) RA: +14.802[1] mas/yr
Dec.: −48.522[1] mas/yr
Parallax (π)4.3872 ± 0.0275[1] mas
Distance743 ± 5 ly
(228 ± 1 pc)
Absolute magnitude (MV)−0.96[5]
Details
Mass1.23[6] M☉
Radius21.01±1.07[7] R☉
Luminosity177±2[8] L☉
Surface gravity (log g)1.83[6] cgs
Temperature4,747±122[9] K
Metallicity [Fe/H]−0.13[6] dex
Rotational velocity (v sin i)<1[10] km/s
Other designations
CD−53°8294, CPD−53°9678, FK5 3581, GC 27384, HD 186756, HIP 97491, HR 7521, SAO 246277[11]
Database references
SIMBADdata

HD 186756, also known as HR 7521 or rarely 68 G. Telescopii, is a solitary orange hued star located in the southern constellation Telescopium. It has an apparent magnitude of 6.25,[2] placing it near the limit for naked eye visibility, even under ideal conditions. Gaia DR3 parallax measurements imply a distance of 743 light years;[1] it is currently approaching with a heliocentric radial velocity of −21.2 km/s.[4] At its current distance, HD 186756's brightness is diminished by 0.34 magnitudes due to extinction from interstellar dust[12] and it has an absolute magnitude of −0.96.[5]

This is an evolved red giant star with a stellar classification of K1 III. It has 123% the mass of the Sun[6] but it has expanded to 21.01 times the radius of the Sun.[7] The object radiates 177 times the luminosity of the Sun[8] from its enlarged photosphere at an effective temperature of 4,747 K.[9] HD 186756 is slightly metal deficient with an iron abundance of [Fe/H] = −0.13 (74% solar) and it spins too slowly for its projected rotational velocity to be measured accurately.[10]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 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 2.2 2.3 Oja, T. (1970). "UBV-Fotometri danska Tel (ESO)". Private Communication: 0. Bibcode: 1970Priv.........0O. 
  3. ↑ Houk, Nancy (1978). Michigan catalogue of two-dimensional spectral types for the HD stars: Declinations −53° to −40°. 2. Bibcode: 1978mcts.book.....H. 
  4. ↑ 4.0 4.1 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. 
  5. ↑ 5.0 5.1 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. 
  6. ↑ 6.0 6.1 6.2 6.3 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. 
  7. ↑ 7.0 7.1 Kervella, P.; Thévenin, F.; Di Folco, E.; Ségransan, D. (October 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. 
  8. ↑ 8.0 8.1 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.
  9. ↑ 9.0 9.1 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. 
  10. ↑ 10.0 10.1 De Medeiros, J. R.; Alves, S.; Udry, S.; Andersen, J.; Nordström, B.; Mayor, M. (January 2014). "A catalog of rotational and radial velocities for evolved stars V: Southern stars *". Astronomy & Astrophysics 561: A126. doi:10.1051/0004-6361/201220762. ISSN 0004-6361. Bibcode: 2014A&A...561A.126D. 
  11. ↑ "HD 186756". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+186756. 
  12. ↑ 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. 
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