44 Ophiuchi

44 Ophiuchi is a single[10] star in the constellation Ophiuchus. It has the Bayer designation b Ophiuchi, while 44 Ophiuchi is the Flamsteed designation. It is visible to the naked eye as a faint, white-hued star with an apparent visual magnitude of 4.16.[2] The distance to this object is approximately 83.2 light years based on parallax.[1] It is drifting closer to the Earth with a heliocentric radial velocity of -37.2 km/s,[5] and is predicted to come within 30 light-years around 585,000 years from now.[11]

This article is about b Ophiuchi. It is not to be confused with β (Beta) Ophiuchi.
44 Ophiuchi
Location of 44 Ophiuchi (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Ophiuchus
Right ascension  17h 26m 22.21749s[1]
Declination −24° 10′ 31.1190″[1]
Apparent magnitude (V) 4.16[2]
Characteristics
Spectral type kA5hA9mF1III[3]
U−B color index +0.12[4]
B−V color index +0.28[4]
Astrometry
Radial velocity (Rv)−37.20[5] km/s
Proper motion (μ) RA: +0.10[1] mas/yr
Dec.: −118.18[1] mas/yr
Parallax (π)39.22 ± 0.24[1] mas
Distance83.2 ± 0.5 ly
(25.5 ± 0.2 pc)
Absolute magnitude (MV)2.13[2]
Details
Mass1.77[6] M☉
Radius1.9[7] R☉
Luminosity13[6] L☉
Surface gravity (log g)4.15[8] cgs
Temperature7,559[8] K
Metallicity [Fe/H]+0.30[2] dex
Rotational velocity (v sin i)78[6] km/s
Age1.028[8] Gyr
Other designations
b Oph, 44 Oph, CD−24°13337, FK5 1457, GC 23597, GJ 9591, HD 157792, HIP 85340, HR 6486, SAO 185401[9]
Database references
SIMBADdata

This is an Am star with a stellar classification of kA5hA9mF1III,[3] indicating it has the luminosity class of a giant star with a spectrum that matches an A5 star based on the calcium K line, and an A9 star from the hydrogen and metal lines. It is around a billion years old[8] with 1.77[6] times the mass of the Sun and 1.9[7] times the Sun's girth. The star is radiating 13[6] times the Sun's luminosity from its photosphere at an effective temperature of 7,559 K.[8] It retains a moderately high rotation rate, showing a projected rotational velocity of 78 km/s.[6]

References
  1. Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. Vizier catalog entry
  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. Gray, R. O.; Corbally, C. J.; Garrison, R. F.; McFadden, M. T.; Bubar, E. J.; McGahee, C. E.; O'Donoghue, A. A.; Knox, E. R. (2006). "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 pc--The Southern Sample". The Astronomical Journal. 132: 161. arXiv:astro-ph/0603770. Bibcode:2006AJ....132..161G. doi:10.1086/504637.
  4. Mallama, A. (2014). "Sloan Magnitudes for the Brightest Stars". The Journal of the American Association of Variable Star Observers. 42: 443. Bibcode:2014JAVSO..42..443M.Vizier catalog entry
  5. Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065.
  6. Zorec, J.; Royer, F. (2012). "Rotational velocities of A-type stars". Astronomy & Astrophysics. 537: A120. arXiv:1201.2052. Bibcode:2012A&A...537A.120Z. doi:10.1051/0004-6361/201117691. Vizier catalog entry
  7. Allende Prieto, C.; Lambert, D. L. (1999). "Fundamental parameters of nearby stars from the comparison with evolutionary calculations: Masses, radii and effective temperatures". Astronomy and Astrophysics. 352: 555. arXiv:astro-ph/9911002. Bibcode:1999A&A...352..555A. Vizier catalog entry
  8. David, Trevor J.; Hillenbrand, Lynne A. (2015). "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets". The Astrophysical Journal. 804 (2): 146. arXiv:1501.03154. Bibcode:2015ApJ...804..146D. doi:10.1088/0004-637X/804/2/146. Vizier catalog entry
  9. "b Oph". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-06-21.
  10. Eggleton, P. P.; Tokovinin, A. A. (September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society. 389 (2): 869–879. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x.
  11. Bailer-Jones, C. A. L. (March 2015). "Close encounters of the stellar kind". Astronomy & Astrophysics. 575: 13. arXiv:1412.3648. Bibcode:2015A&A...575A..35B. doi:10.1051/0004-6361/201425221. A35.
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