24 Scorpii

24 Scorpii is a star that was originally placed by John Flamsteed within the constellation of Scorpius but in now placed within the southeastern constellation of Ophiuchus. It is visible to the naked eye as a faint, yellow-hued point of light with an apparent visual magnitude of 4.91.[2] Based on the trigonometric parallax published in Gaia Data Release 2, the star lies approximately 121 parsecs or 390 light years away.[1] It is positioned near the ecliptic and thus is subject to lunar occultations.[10]

24 Scorpii
Location of 24 Scorpii (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Ophiuchus
Right ascension  16h 41m 34.38407s[1]
Declination −17° 44′ 31.8047″[1]
Apparent magnitude (V) 4.91[2]
Characteristics
Spectral type G7.5IICN1Ba0.4[3]
U−B color index +0.85[4]
B−V color index +1.11[4]
Astrometry
Radial velocity (Rv)−25.20[5] km/s
Proper motion (μ) RA: −21.670[1] mas/yr
Dec.: −1.224[1] mas/yr
Parallax (π)8.2914 ± 0.2626[1] mas
Distance390 ± 10 ly
(121 ± 4 pc)
Absolute magnitude (MV)−0.60[2]
Details[6]
Mass2.51 M☉
Radius22 R☉
Luminosity208 L☉
Surface gravity (log g)2.15 cgs
Temperature4,667 K
Metallicity [Fe/H]−0.13[7] dex
Rotational velocity (v sin i)5.3[8] km/s
Age692 Myr
Other designations
24 Sco, BD−17°4618, FK5 624, GC 22449, GJ 9574, HD 150416, HIP 81724, HR 6196, SAO 160046[9]
Database references
SIMBADdata

This object is a luminous giant star that is classified by spectral and luminosity class as G7.5II[3] or G7.5II-IIICN1Ba0.5.[9] 24 Sco is associated with the faint reflection nebulae RfN VDB 109[9] or GN 16.36.7,[11] but may just lie along the same line of sight.[12] It is a very mild Barium star, but the enhanced barium lines in the spectrum may be a simple luminosity effect rather than a true abundance anomaly.[13] It is a probable horizontal branch star, fusing helium in its core, with just a 13% likelihood that it is still on the red giant branch.[6] The star has 2.51 times the mass of the Sun and has expanded to 22 times the Sun's radius. It is radiating 208 times the Sun's luminosity from its photosphere at an effective temperature of 4,667 K.[6]

References
  1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. Vizier catalog entry
  3. Hoffleit, D.; Warren, W. H. (1995). "VizieR Online Data Catalog: Bright Star Catalogue, 5th Revised Ed. (Hoffleit+, 1991)". VizieR On-line Data Catalog: V/50. Originally Published in: 1964BS....C......0H. 5050. Bibcode:1995yCat.5050....0H.
  4. Mermilliod, J. C. (2006). "VizieR Online Data Catalog: Homogeneous Means in the UBV System (Mermilliod 1991)". VizieR On-line Data Catalog: II/168. Originally Published in: Institut d'Astronomie. 2168. Bibcode:2006yCat.2168....0M.Vizier catalog entry
  5. Wilson, R. E. (1953). General Catalogue of Stellar Radial Velocities. Carnegie Institution for Science. Bibcode:1953GCRV..C......0W. LCCN 54001336.
  6. Stock, Stephan; Reffert, Sabine; Quirrenbach, Andreas (2018). "Precise radial velocities of giant stars. X. Bayesian stellar parameters and evolutionary stages for 372 giant stars from the Lick planet search". Astronomy and Astrophysics. 616: A33. arXiv:1805.04094. Bibcode:2018A&A...616A..33S. doi:10.1051/0004-6361/201833111. Vizier catalog entry
  7. Reffert, Sabine; Bergmann, Christoph; Quirrenbach, Andreas; Trifonov, Trifon; Künstler, Andreas (2015). "Precise radial velocities of giant stars". Astronomy & Astrophysics. 574: A116. arXiv:1412.4634. Bibcode:2015A&A...574A.116R. doi:10.1051/0004-6361/201322360. hdl:10722/215277. Vizier catalog entry
  8. De Medeiros, J. R.; Alves, S.; Udry, S.; Andersen, J.; Nordström, B.; Mayor, M. (2014). "A catalog of rotational and radial velocities for evolved stars". Astronomy & Astrophysics. 561: A126. arXiv:1312.3474. Bibcode:2014A&A...561A.126D. doi:10.1051/0004-6361/201220762. Vizier catalog entry
  9. "HD 150416". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2014-05-11.
  10. Richichi, A.; et al. (January 2016), "Lunar Occultations of 18 Stellar Sources from the 2.4 m Thai National Telescope", The Astronomical Journal, 151 (1): 5, Bibcode:2016AJ....151...10R, doi:10.3847/0004-6256/151/1/10, 10
  11. "GN 16.36.7 - Reflection Nebula". Retrieved 12 June 2019.
  12. van den Bergh, S. (December 1966). "A study of reflection nebulae". Astronomical Journal. 71: 990–998. Bibcode:1966AJ.....71..990V. doi:10.1086/109995.
  13. Escorza, A.; Boffin, H. M. J.; Jorissen, A.; Van Eck, S.; Siess, L.; Van Winckel, H.; Karinkuzhi, D.; Shetye, S.; Pourbaix, D. (2017). "Hertzsprung-Russell diagram and mass distribution of barium stars". Astronomy and Astrophysics. 608: A100. arXiv:1710.02029. Bibcode:2017A&A...608A.100E. doi:10.1051/0004-6361/201731832.
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