Alpha Lacertae

α Lacertae
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Lacerta
Right ascension 22h 31m 17.5010s[1]
Declination +50° 16′ 56.969″[1]
Apparent magnitude (V) 3.777[1]
Characteristics
Spectral type A1 V[1]
U−B color index 0.00[2]
B−V color index +0.01[2]
R−I color index −0.03[2]
Astrometry
Radial velocity (Rv)−4.0 ± 2[1] km/s
Proper motion (μ) RA: 137.22[1] mas/yr
Dec.: 17.15[1] mas/yr
Parallax (π)31.86 ± 0.54[1] mas
Distance102 ± 2 ly
(31.4 ± 0.5 pc)
Absolute magnitude (MV)1.29[3]
Details
Mass~2[4] M☉
Radius2.143 ± 0.074[5] R☉
Luminosity28.552 ± 0.678[5] L☉
Luminosity (bolometric)27[4] L☉
Temperature9131 ± 167[5] K
Rotational velocity (v sin i)146[2] km/s
Other designations
α Lac, Alpha Lacertae, Alpha Lac, 7 Lacertae, 7 Lac, ADS 16021 A, BD+49°3875, CCDM J22313+5017A, FK5 848, GC 31471, HD 213558, HIP 111169, HR 8585, SAO 34542, WDS 22131+5017A.[1][6]
Database references
SIMBADdata

Alpha Lacertae (Alpha Lac, α Lacertae, α Lac) is an A-type main sequence star in the constellation of Lacerta.[1] It is the brightest star in Lacerta and has an apparent visual magnitude of approximately 3.777.[1][4]

The star has a visual companion, CCDM J22313+5017B, of spectral type A and apparent visual magnitude 11.8, approximately 36 arcseconds away.[6] The companion is optical, a chance line-of-sight coincidence.[2]

Naming

In Chinese, 螣蛇 (Téng Shé), meaning Flying Serpent, refers to an asterism consisting of α Lacertae, 4 Lacertae, π2 Cygni, π1 Cygni, HD 206267, ε Cephei, β Lacertae, σ Cassiopeiae, ρ Cassiopeiae, τ Cassiopeiae, AR Cassiopeiae, 9 Lacertae, 3 Andromedae, 7 Andromedae, 8 Andromedae, λ Andromedae, κ Andromedae, ι Andromedae, and ψ Andromedae. Consequently, α Lacertae itself is known as 螣蛇一 (Téng Shé yī, English: the First Star of Flying Serpent)[7]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 1.10 * alf Lac -- Star in double system, database entry, SIMBAD. Accessed on line September 3, 2008.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 HR 8585, database entry, The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version), D. Hoffleit and W. H. Warren, Jr., CDS ID V/50. Accessed on line September 3, 2008.
  3. ↑ From apparent magnitude and parallax.
  4. ↑ 4.0 4.1 4.2 Alpha Lac, Jim Kaler, Stars. Accessed on line September 3, 2008.
  5. ↑ 5.0 5.1 5.2 Boyajian, Tabetha S. et al. (February 2012), "Stellar Diameters and Temperatures. I. Main-sequence A, F, and G Stars", The Astrophysical Journal 746 (1): 101, arXiv:1112.3316, Bibcode:2012ApJ...746..101B, doi:10.1088/0004-637X/746/1/101. See Table 10.
  6. ↑ 6.0 6.1 Entry 22313+5017, discoverer code BU 703, The Washington Double Star Catalog, United States Naval Observatory. Accessed on line September 3, 2008.
  7. ↑ (Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 7 日