4 Lacertae
Star in the constellation Lacerta
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4 Lacertae is a single[11] blue supergiant star in the northern constellation Lacerta, located about 2,600 light years away.[1] This object visible to the naked eye as a white-hued star with an apparent visual magnitude of 4.55.[2] It is moving closer to the Earth with a heliocentric radial velocity of −26 km/s.[2] This star is a suspected member of the Lac OB1 association.[3][5]
 | |
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Lacerta |
| Right ascension | 22h 24m 30.99149s[1] |
| Declination | +49° 28′ 35.0106″[1] |
| Apparent magnitude (V) | 4.55[2] |
| Characteristics | |
| Evolutionary stage | Blue supergiant (blue loop)[3] |
| Spectral type | A0 Ib[4] |
| B−V color index | 0.092±0.034[2] |
| Astrometry | |
| Radial velocity (Rv) | −26.0±1.7[2] km/s |
| Proper motion (μ) | RA: −5.274(82)[1] mas/yr Dec.: −3.303(96)[1] mas/yr |
| Parallax (π) | 1.2656±0.0891 mas[1] |
| Distance | 2,600 ± 200 ly (790 ± 60 pc) |
| Absolute magnitude (MV) | −4.42[5] |
| Details | |
| Mass | 19+13 −8[6] M☉ |
| Radius | 36 ± 5[7][a] R☉ |
| Luminosity | 17,000+3,000 −2,500[7] L☉ |
| Surface gravity (log g) | 2.18[6] cgs |
| Temperature | 11,000±600[7] K |
| Metallicity [Fe/H] | 0.28±0.04[8] dex |
| Rotational velocity (v sin i) | 28±3[6] km/s |
| Age | 25.1±2.5[9] Myr |
| Other designations | |
| 4 Lac, BD+48°3715, HD 212593, HIP 110609, HR 8541, SAO 51970, 2MASS J22243097+4928351[10] | |
| Database references | |
| SIMBAD | data |
This blue supergiant star has a stellar classification of A0 Ib.[4] The surface abundances show evidence of material that has been processed via the CNO cycle at the core.[3] It has ten[9] times the mass of the Sun and has expanded to about 36 times the Sun's radius.[7][a] The star is around 25 million years old[9] and is spinning with a projected rotational velocity of 28 km/s.[6][1] It is believed to be a blue loop star that has already spent time as a red supergiant after fusing the hydrogen within its core.
Notes
- Applying the Stefan–Boltzmann law with a nominal solar effective temperature of 5,772 K:
- .
