63 Ophiuchi

63 Ophiuchi
Diagram showing star positions and boundaries of the Sagittarius constellation and its surroundings


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]
Characteristics
Spectral type O8III[2]
U−B color index –0.89[3]
B−V color index +0.04[3]
Astrometry
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
Distanceapprox. −4,000 ly
(approx. −1,300 pc)
Details
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]

References

  1. ↑ 1.0 1.1 1.2 1.3 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. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 "63 Oph -- Star", SIMBAD (Centre de Données astronomiques de Strasbourg), retrieved 2011-12-01
  3. ↑ 3.0 3.1 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