Lambda Pavonis
Star in the constellation Pavo
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λ Pavonis, Latinized as Lambda Pavonis, is a single,[13] variable star in the southern constellation of Pavo. It is a blue-white hued star that is faintly visible to the naked eye with an apparent visual magnitude that fluctuates around 4.22.[2] This object is located approximately 1,400 light years from the Sun, based upon parallax. It is a member of the Scorpius–Centaurus association.[14]
  | |
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Pavo |
| Right ascension | 18h 52m 13.03427s[1] |
| Declination | −62° 11′ 15.3324″[1] |
| Apparent magnitude (V) | 4.22[2] (4.00 - 4.26)[3] |
| Characteristics | |
| Spectral type | B2Ve[4] or B2II–IIIe[5] |
| U−B color index | −0.88[6] |
| B−V color index | −0.15[2] |
| Variable type | γ Cas[3] |
| Astrometry | |
| Radial velocity (Rv) | +9.0±4.1[7] km/s |
| Proper motion (μ) | RA: −1.86[1] mas/yr Dec.: −13.02[1] mas/yr |
| Parallax (π) | 2.28±0.18 mas[1] |
| Distance | 1,400 ± 100 ly (440 ± 30 pc) |
| Absolute magnitude (MV) | −3.97[2] |
| Details | |
| Mass | 12.5[8] M☉ |
| Radius | 9±1[9] (polar) R☉ |
| Luminosity | 8,450[2] L☉ |
| Temperature | 20,300[10] K |
| Rotational velocity (v sin i) | 190[11] km/s |
| Other designations | |
| λ Pav, CD−62°1254, FK5 704, GC 25823, HD 173948, HIP 92609, HR 7074, SAO 254393, CCDM J18522-6212A, WDS J18522-6211[12] | |
| Database references | |
| SIMBAD | data |
This is a massive Be star, a rapidly rotating hot blue star which has developed a gas disk around it. It is a γ Cassiopeiae variable or shell star which has occasionally brightened to magnitude 4.0.[3] The stellar classification of B2Ve[4] suggests it is a B-type main-sequence star that is generating energy through core hydrogen fusion. This star is spinning rapidly with a projected rotational velocity of 190 km/s.[11] This is giving the star an oblate shape with an equatorial bulge that is an estimated 10% larger than the polar radius.[16] Lambda Pavonis has 12.5[8] times the mass of the Sun and nine times the Sun's polar radius.[9] It is radiating 8,450[2] times the luminosity of the Sun from its photosphere at an effective temperature of 20,300 K.[10]
Variations in signals coming from Lambda Pavonis have led to a debate on whether it is a binary, single or pulsating variable star.[14]