Epsilon Sagittarius (υ Sgr / υ Sagittarii) is a spectrally-binary star system in the constellation Sagittarius . Sagittarius Epsilon is the prototype of hydrogen-deficient double stars (HdB), one of four currently known. The unusual spectrum of such binaries makes their spectral classification extremely difficult.
| υ Sagittarius | |||
|---|---|---|---|
| Star | |||
| Observational data ( Age J2000.0) | |||
| Right ascension | |||
| Declination | |||
| Distance | 1800 St. years (550 pc ) | ||
| Visible magnitude ( V ) | from +4.57 to +4.61 | ||
| Constellation | Sagittarius | ||
| Astrometry | |||
| Radial velocity ( R v ) | +13.3 km / s | ||
| Own movement (μ) | RA: 1.86 mas per year Dec: -6.27 mas per year | ||
| Parallax (π) | 1.83 ± 0.23 mas | ||
| Absolute magnitude (V) | from -4.02 to -3.94 | ||
| Specifications | |||
| Spectral class | B2Vpe + A2IaShell | ||
| Color Index ( B - V ) | 0.06 | ||
| Variability | EB (β lyr) / GS | ||
| physical characteristics | |||
| Weight | ~ 25 M ☉ | ||
| Radius | 60 R ☉ | ||
| Temperature | |||
| Luminosity | from 3222 to 3468 L ☉ | ||
| |||
| Database Information | |||
| SIMBAD | data | ||
The main component of Epsilon Sagittarius A is most likely a supergiant of spectral class A. Its radius is estimated at 60 solar , and the mass is ~ 25 [3] solar . The average apparent brightness of the star is +4.52 m , however, the star belongs to the class of irregular variables and therefore its magnitude varies from +4.51 m to +4.65 m with a period of about 20 days.
The companion Epsilon Sagittarius B is massive, but so weak in the visible range that it cannot be viewed with optical telescopes. Most likely, he is a blue-white star of the main sequence of the spectral class O or B. He acquired his mass, estimated at ~ 19 [3] solar , by accretion from the main component.
The entire system belongs to eclipsing variables of the type of β Lyrae , has a period of variability of 137.939 days and is about 1800 light-years distant from Earth . Given the mass of the star, it can be predicted that Sagittarius Epsilon will end his life as a supernova .
Notes
- ↑ 1 2 3 4 Gaia Data Release 2 - 2018.
- ↑ 1 2 The chemical composition of the atmospheres of Beta Lyrae and Upsilon Sagittarii // Proceedings of the International Astronomical Union - Cambridge University Press , 1964. - ISSN 1743-9221
- ↑ 1 2 Hohle MM, Neuhäuser R., Schutz BF Masses and luminosities of O- and B-type stars and red supergiants (Eng.) // Astronomische Nachrichten: journal. - Wiley-VCH , 2010 .-- April ( vol. 331 , no. 4 ). - P. 349 . - DOI : 10.1002 / asna.200911355 . - . - arXiv : 1003.2335 .