- Upsilon Sagittarii
Starbox short
name=υ Sagittarii
epoch=J2000.0
constell=Sagittarius
ra=19h 21m 43.6s
dec=-15° 57' 18"
spectral=B2Vpe+A2IaShell
appmag_v=+4.52
absmag_v=-4.03
dist_ly=1672 ± 618
dist_pc=513 ± 189
names=46 Sagittarii, HR 7342,
HD 181615, SAO 162518,
HIP 95176Upsilon Sagittarii (υ Sgr / υ Sagittarii) is a
spectroscopic binary star system in theconstellation Sagittarius. Upsilon Sagittarii is the prototypicalhydrogen-deficient binary (HdB), and one of only four such systems known. The unusualspectrum of hydrogen-deficient binaries has madestellar classification of Upsilon Sagittarii difficult.The primary component, Upsilon Sagittarii A, is most likely an A type
supergiant . The radius of the primary is estimated at 60 solar radii, and its mass is estimated to be between one and thirteensolar mass es. A is classified as anirregular variable and experiencesapparent magnitude fluctuations between +4.51 and +4.65 with a period of approximately 20 days. Its mean apparent magnitude is +4.52.The companion, Upsilon Sagittarii B, is more massive, but so dim at visible frequencies as to be undetectable by optical telescopes. It is likely an O or B type
main sequence dwarf, which has accreted much of the original mass of the primary. It is estimated to have a mass of three to elevensolar mass es.The binary system has an orbital period of 137.939 days and is approximately 1672
light years fromEarth . It is predicted that Upsilon Sagittarii will end its life in asupernova .References
Dudley, R. E., Jeffery, C. S., 1990. "Mon. Not. R. astr. Soc." 247, 400
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