V915 Scorpii is surrounded by the sparse
OB association Moffat 2.[12] It is also surrounded by an envelope of dust and gas, producing a significant
infrared excess.[13]
V915 Scorpii has been classified as a triple star. 15" away is the
Wolf-Rayet star WR 85, one of the
most luminous stars known, but still
visually four magnitudes fainter than V915 Scorpii.[14] Component C is a 10th magnitude K class star 17" away.[15] There is also a 14th magnitude star 22" away. Photometry and space motions suggest that only V915 Scorpii and WR 85 lie at the same distance, while the other two stars are foreground objects. Assumptions about the brightness of each star suggest a distance of 2,600 pc, and a projected separation of 0.2 pc.[16]
Four arc minutes distant are two other assumed members of the association, a 10th magnitude B0 giant and an 11th magnitude OB star. Fitting the association members to a main sequence gives a highly uncertain distance of 1.8 kpc.[12] A kinematical distance has been calculated for the bubble around WR 85 at 2.8 kpc.[17] The distance to V915 Scorpii derived assuming minimal interstellar extinction is 7,300 pc.[13] However, the star is considerably reddened and this results in a distance of 2,630 pc.[16] Analysis of WR 85 as a luminous hydrogen-rich star gives a distance of 6,600 pc.[14] Bailer-Jones et al. 2018 estimates a distance of 1,720 pc.[8] The parallax for WR 85 is considerably reliable and suggests a distance of around 2,400 pc.[18]
Variability
V915 Scorpii is classified as a
semiregular variable, with an
apparent magnitude that varies between 6.22 and 6.64.[6] Any period associated with the variation is longer than 600 days.[20]
The spectral type of V915 Scorpii was determined to be G5Ia in 1954,[25] G5Ia-0 in 1973,[26] G8Ia in 1977,[12] K0Ia in 1982,[27] and K0Ia-0 in 1989,[3] all indicative of a luminous supergiant or hypergiant.
^Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1.
Bibcode:
2009yCat....102025S.
^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: 0.
Bibcode:
2002yCat.2237....0D.
^Barbier-Brossat, M.; Petit, M.; Figon, P. (1994). "Third bibliographic catalogue of stellar radial velocities (Text in French)". Astronomy and Astrophysics Supplement Series. 108: 603.
Bibcode:
1994A&AS..108..603B.
^
abcMoffat, A. F. J.; Fitzgerald, M. P. (1977). "Some very luminous supergiants associated with compact groups of luminous OB stars". Astronomy and Astrophysics. 54: 263.
Bibcode:
1977A&A....54..263M.
^ESA (1997). "The HIPPARCOS and TYCHO catalogues. Astrometric and photometric star catalogues derived from the ESA HIPPARCOS Space Astrometry Mission". The Hipparcos and Tycho Catalogues. Astrometric and Photometric Star Catalogues Derived from the ESA Hipparcos Space Astrometry Mission. 1200.
Bibcode:
1997ESASP1200.....E.
^Kholopov, P. N.; Kukarkina, N. P.; Perova, N. B. (1979-04-01). "64th Name-List of Variable Stars". Information Bulletin on Variable Stars. 1581: 1.
Bibcode:
1979IBVS.1581....1K.
ISSN0374-0676.
^Houk, N. (1982). "Michigan Catalogue of Two-dimensional Spectral Types for the HD stars. Volume_3. Declinations -40_ƒ0 to -26_ƒ0". Michigan Catalogue of Two-dimensional Spectral Types for the HD stars. Volume_3. Declinations -40_ƒ0 to -26_ƒ0.
Bibcode:
1982mcts.book.....H.