Lambda Persei
Star in the constellation Perseus
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λ Persei, Latinized as Lambda Persei, is a star in the northern constellation of Perseus. It is visible to the naked eye as a faint, white-hued point of light with an apparent visual magnitude of 4.29.[2] This object is located approximately 422 light years from the Sun based on parallax,[1] and is drifting further away with a radial velocity of +6 km/s.[4]
  | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Perseus |
| Right ascension | 04h 06m 35.04360s[1] |
| Declination | +50° 21′ 04.5500″[1] |
| Apparent magnitude (V) | 4.29[2] |
| Characteristics | |
| Spectral type | A0IVn[3] |
| U−B color index | −0.04[2] |
| B−V color index | +0.02[2] |
| Astrometry | |
| Radial velocity (Rv) | +6.1±2.0[4] km/s |
| Proper motion (μ) | RA: −12.75[1] mas/yr Dec.: −35.60[1] mas/yr |
| Parallax (π) | 7.73±0.22 mas[1] |
| Distance | 420 ± 10 ly (129 ± 4 pc) |
| Absolute magnitude (MV) | −1.31[5] |
| Details | |
| Radius | 3.1[6] R☉ |
| Luminosity | 348[5] L☉ |
| Surface gravity (log g) | 4.05[7] cgs |
| Temperature | 10,585[7] K |
| Metallicity [Fe/H] | +0.01[7] dex |
| Rotational velocity (v sin i) | 196[8] km/s |
| Age | 345[9] Myr |
| Other designations | |
| λ Per, 47 Persei, BD+49°1101, FK5 1113, GC 4924, HD 25642, HIP 19167, HR 1261, SAO 24412[10] | |
| Database references | |
| SIMBAD | data |
This object has a stellar classification of A0IVn,[3] matching an A-type subgiant star with "nebulous" lines due to rapid rotation. It is spinning with a projected rotational velocity of 196 km/s,[8] which is giving the star an equatorial bulge that is an estimated 16% larger than the polar radius.[11] Unusually for a star of this type, spectra show weak emission features among the Hydrogen lines, which may be due to plage regions on the surface caused by an implied magnetic field.[12] The star is 345[9] million years old and is radiating 348[5] times the luminosity of the Sun from its photosphere at an effective temperature of 10,585 K.[7]
In Chinese astronomy, Lambda Persei is called 積水, Pinyin: Jīshuǐ, meaning Stored Water, because this star is marking itself and stand alone in Stored Water asterism, Stomach mansion (see : Chinese constellation).[13] This name has also been applied to Omicron Geminorum and was approved by the IAU Working Group on Star Names as the name of that star.[14]