63 Ophiuchi

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63 Ophiuchi
Diagram showing star positions and boundaries of the Sagittarius constellation and its surroundings
Cercle rouge 100%.svg

The location of 63 Ophiuchi (circled) in the constellation Sagittarius
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Sagittarius
Right ascension 17h 54m 54.04380s[1]
Declination −24° 53′ 13.5413″[1]
Apparent magnitude (V) 6.18[2]
Spectral type O8III[2]
U−B color index –0.89[3]
B−V color index +0.04[3]
Radial velocity (Rv) –11[4] km/s
Proper motion (μ) RA: 1.66[1] mas/yr
Dec.: –2.63[1] mas/yr
Parallax (π) −0.77 ± 0.40[2] mas
Rotational velocity (v sin i) 86[5] km/s
Other designations
63 Oph, HD 162978, HIP 87706, SAO 185928.[2]

63 Ophiuchi is an O-type giant star in the constellation Sagittarius, despite its name. During a 2009 survey for companions of massive stars, it was observed using speckle interferometry but no companion was found.[6] Uncertain negative parallax measurements of –0.77 ± 0.40 mas[2] suggest that this extremely luminous star may be located about 4000 light-years away. An estimate of the distance based on the strength of the Ca II line yields a more modest value of 2,605 ly (799 pc).[7] The star lies only 0.3° north of the galactic plane.[2]

In 1983, astronomers from the Sternberg Astronomical Institute in Moscow, Russia identified a faint, shell-shaped nebula surrounding the star that was being excited by the star's energy. Named Sharpless 22, this ring-shaped nebula has a double-shell structure with an inner envelope spanning 45–50 (9–18 pc), surrounded by a diffuse envelope some 65–80′ (14–29 pc) across. At an estimated mass loss rate of (6–8) × 10−6 M/yr, it would take the star about (1–5) × 105 years to produce such a nebula from the outflow of its stellar wind.[8]


  1. ^ a b c d van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357 
  2. ^ a b c d e f "63 Oph -- Star", SIMBAD (Centre de Données astronomiques de Strasbourg), retrieved 2011-12-01 
  3. ^ a b Schild, R. E. et al. (April 1983), "UBV photometry for southern OB stars", Astrophysical Journal Supplement Series 51: 321–336, Bibcode:1983ApJS...51..321S, doi:10.1086/190852 
  4. ^ Wilson, Ralph Elmer (1953), General catalogue of stellar radial velocities, Carnegie Institution of Washington, Bibcode:1953QB901.W495..... 
  5. ^ Hubrig, S. et al. (November 2008), "Magnetic field measurements of O stars with FORS 1 at the VLT", Astronomy and Astrophysics 490 (2): 793–800, arXiv:0808.2039, Bibcode:2008A&A...490..793H, doi:10.1051/0004-6361:200810171 
  6. ^ Mason, Brian D. et al. (February 2009), "The High Angular Resolution Multiplicity of Massive Stars", The Astronomical Journal 137 (2): 3358–3377, arXiv:0811.0492, Bibcode:2009AJ....137.3358M, doi:10.1088/0004-6256/137/2/3358 
  7. ^ Megier, A. et al. (November 2009), "The interstellar Ca II distance scale", Astronomy and Astrophysics 507 (2): 833–840, Bibcode:2009A&A...507..833M, doi:10.1051/0004-6361/20079144 
  8. ^ Lozinskaya, T. A. et al. (June 1983), "A New Search for Ring Nebulae around Of-Stars - SHARPLESS22", Soviet Astronomy Letters 9 (6): 344–345, Bibcode:1983SvAL....9..344L