Xi1 Sagittarii
Star in the constellation Sagittarius
From Wikipedia, the free encyclopedia
Xi1 Sagittarii (ξ1 Sagittarii) is a solitary,[11] blue-white hued star in the zodiac constellation of Sagittarius. It is visible to the naked eye with an apparent visual magnitude of +5.06.[2] Based upon a small annual parallax shift of 1.58 mas as seen from Earth,[1] this system is located roughly 2,100 light years from the Sun.
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Sagittarius |
| Right ascension | 18h 57m 20.47670s[1] |
| Declination | −20° 39′ 22.8539″[1] |
| Apparent magnitude (V) | +5.06[2] |
| Characteristics | |
| Spectral type | B9/A0 Ib[3] |
| U−B color index | −0.14[2] |
| B−V color index | +0.12[2] |
| Astrometry | |
| Proper motion (μ) | RA: −1.46[1] mas/yr Dec.: −5.75[1] mas/yr |
| Parallax (π) | 1.58±0.26 mas[1] |
| Distance | approx. 2,100 ly (approx. 600 pc) |
| Absolute magnitude (MV) | −3.92[4] |
| Details | |
| Mass | 7.8±0.1[5] M☉ |
| Radius | 15[6] R☉ |
| Luminosity | 2,753[7] L☉ |
| Surface gravity (log g) | 2.3[8] cgs |
| Temperature | 9,400[8] K |
| Metallicity [Fe/H] | −0.20[8] dex |
| Rotational velocity (v sin i) | 10[9] km/s |
| Age | 39.8±4.9[5] Myr |
| Other designations | |
| ξ1 Sgr, 36 Sgr, BD−20°5339, HD 175687, HIP 93057, HR 7145, SAO 187498[10] | |
| Database references | |
| SIMBAD | data |
This is a massive supergiant star[6] with a stellar classification of B9/A0 Ib.[3] With an estimated 7.8[5] times the mass of the Sun and an age of about 40[5] million years it has depleted the hydrogen at its core, causing it to expand to about 15 times the Sun's radius.[6] It is radiating 2,753[7] times the Sun's luminosity from its photosphere at an effective temperature of about 9,400 K.[8]