63 Ophiuchi is an
O-type giantstar 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.[9] The small
parallax measurement of 0.91±0.09
mas suggest that this extremely luminous star may be located about 3,600
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).[10] The star lies only 0.3° north of the
galactic plane.
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) × 10−6M☉/yr, it would take the star about (1–5) × 105 years to produce such a nebula from the outflow of its
stellar wind.[11]
^Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237.
Bibcode:
2002yCat.2237....0D.
^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