Omega2 Aquarii
Star in the constellation Aquarius
From Wikipedia, the free encyclopedia
Omega2 Aquarii is a star[12] system in the equatorial constellation of Aquarius. Its name is a Bayer designation that is Latinised from Ï2 Aquarii, and abbreviated Omega2 Aqr or Ï2 Aqr. The system can be seen with the naked eye as a faint point of light, having an apparent visual magnitude of 4.49.[3] The approximate distance to this star, 149 light-years (46 parsecs), is known from parallax measurements.[2]
 | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aquarius[1] |
| Right ascension | 23h 42m 43.345s[2] |
| Declination | â14° 32â² 41.66â³[2] |
| Apparent magnitude (V) | 4.49[3] |
| Characteristics | |
| Spectral type | B9 V[4] + A5V[5] |
| UâB color index | â0.12[3] |
| BâV color index | â0.04[3] |
| Astrometry | |
| Radial velocity (Rv) | +3.2±2.3[6] km/s |
| Proper motion (μ) | RA: +98.578 mas/yr[2] Dec.: â66.231 mas/yr[2] |
| Parallax (Ï) | 20.8948±0.1589 mas[2] |
| Distance | 156 ± 1 ly (47.9 ± 0.4 pc) |
| Absolute magnitude (MV) | +1.20[1] |
| Details | |
| A | |
| Mass | 2.6+0.15 â0.14[7] Mâ |
| Radius | 1.94±0.06[8] Râ |
| Luminosity | 37[1] Lâ |
| Surface gravity (log g) | 4.22±0.03[8] cgs |
| Temperature | 10,504±91[8] K |
| Rotation | 10.6546 h[9] |
| Rotational velocity (v sin i) | 148[10] km/s |
| Age | 109+90 â70[7] Myr |
| Other designations | |
| Ï2 Aqr, 105 Aquarii, BDâ15 6476, FK5 894, GC 32931, GJ 9836, HD 222661, HIP 116971, HR 8988, SAO 165842, PPM 242001, WDS J23427-1433A[11] | |
| Database references | |
| SIMBAD | data |
This is a B-type main-sequence star with a stellar classification of B9 V.[4] In 1953, astronomers H. L. Johnson and W. W. Morgan selected it as the MK standard for stars of class B9.5V.[13] It has an estimated age of 109[7] million years and is spinning rapidly with a projected rotational velocity of 148 km/s,[10] giving it a rotation period of 10.6546 h.[9] The star has 2.6[7] times the Sun's mass and nearly double the radius of the Sun.[8] It is radiating 37[1] times the luminosity of the Sun from its photosphere at an effective temperature of 10,504 K,[8] giving it the blue-white hue of a B-type star.[14]
In 1983, this was catalogued as a spectroscopic binary star system with components classed B9V and B9.5V.[5] However, a 2012 survey by R. Chini et al found the star to have a constant radial velocity.[12] There is a companion star at an angular separation of 5.7 arcseconds that shares a common proper motion with the primary. It is an A-type main-sequence star with a visual magnitude of 9.5.[5] This system is among the 100 strongest stellar X-ray sources within 163 light-years (50 parsecs) of the Sun. It is emitting an X-ray luminosity of 1.2Ã1030 erg·sâ1. The source for this X-ray emission is unknown.[15]