Sigma Herculis
 σ Herculis in optical light | ||
| Observation data ICRS )
| ||
|---|---|---|
| Constellation | Hercules | |
| Right ascension | 16h 34m 06.18334s[1] | |
| Declination | +42° 26′ 13.3455″[1] | |
| Apparent magnitude (V) | 4.18[2] (4.20 + 7.70)[3] | |
| Characteristics | ||
| Spectral type | B9 V[4] (B7 + A9)[3] | |
| U−B color index | −0.14[2] | |
| B−V color index | −0.03[2] | |
| Absolute magnitude (MV) | −0.72[6] | |
Argument of periastron (ω)(secondary) | 184.97±0.40° | |
| Details | ||
| σ Her A | ||
Myr | ||
| σ Her B | ||
| Mass | 1.5±0.5[4] M☉ | |
| Luminosity | 7.4[4] L☉ | |
| Database references | ||
| SIMBAD | data | |
Sigma Herculis,
The components of this binary system have a separation of 7
oblate shape with an equatorial bulge that is an estimated 18% larger than the polar radius.[10] The star has an estimated 2.60 times the mass of the Sun,[8] 4.91 times the Sun's radius,[9] and is radiating 230[4] times the solar luminosity from its photosphere at an effective temperature of 9,794 K.[8]
The primary is emitting an
AU.[9] There may be a second disk orbiting between 7 and 30 AU with a temperature of 300±100. The Poynting–Robertson lifetime of the dust grains in this inner belt is around 46,000 years − much less than the age of the star. Hence the grains are being replenished, presumably through collisions between larger objects.[4] Circumstellar gas is visible in ultraviolet images from the FUSE satellite, which is likely being emitted by the circumstellar matter then driven outward by the star's radiation.[4]
The secondary, component B, has a magnitude of 7.70 and is an A-type main-sequence star.[3] It has around 1.5 times the mass of the Sun and 7.4 times the Sun's luminosity.[4]
References
- ^ S2CID 18759600.
- ^ Bibcode:1986EgUBV........0M.
- ^ .
- ^ S2CID 119465913.
- S2CID 59451347, A61.
- S2CID 119257644.
- ^ S2CID 118803592.
- ^ S2CID 33401607.
- ^ S2CID 11879505.
- ^ S2CID 119273474.
- ^ "sig Her". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-04-05.
{{cite web}}: CS1 maint: postscript (link)