1 Lacertae

1 Lacertae is a solitary[9] star in the northern constellation of Lacerta. It is visible to the naked eye with an apparent visual magnitude of 4.15.[2] Based upon measurements by the Hipparcos spacecraft, this star is located at a distance of roughly 420 light years.[1] It is moving further from the Earth with a heliocentric radial velocity of −8.6 km/s.[4]

1 Lacertae

1 Lacertae in optical light
Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Lacerta
Right ascension	22^h 15^m 58.17673^s[1]
Declination	+37° 44′ 55.4385″[1]
Apparent magnitude (V)	4.15[2]
Characteristics
Spectral type	K3 II-III[3]
U−B color index	+1.70[2]
B−V color index	+1.43[2]
Astrometry
Radial velocity (Rv)	−8.58[4] km/s
Proper motion (μ)	RA: +8.85[1] mas/yr Dec.: –0.72[1] mas/yr
Parallax (π)	5.25 ± 0.23[1] mas
Distance	620 ± 30 ly (190 ± 8 pc)
Absolute magnitude (MV)	−2.61+0.27 −0.24[5]
Details[6]
Mass	4.16±0.28 M☉
Radius	69.01+3.32 −3.07 R☉
Luminosity	1,453±147 L☉
Surface gravity (log g)	2.15 cgs
Temperature	4,288±62 K
Metallicity [Fe/H]	−0.01 dex
Rotational velocity (v sin i)	10[7] km/s
Age	170±30 Myr
Other designations
1 Lac, NSV 25864, BD+37° 4526, HD 211388, HIP 109937, HR 8498, SAO 72191[8]
Database references
SIMBAD	data

A stellar classification of K3 II-III[3] suggests this is an evolved giant star/bright giant hybrid. It is 170 million years old with around four times the mass of the Sun and has expanded to an estimated 69 times the Sun's radius. The star is radiating 1,453 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4288 K, giving it the orange-hued glow of a K-type star.[10] The star was once a suspected variable, but this was later rescinded.[11]

References

1. van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357.
2. Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data, SIMBAD, Bibcode:1986EgUBV........0M.
3. Herbig, George H.; Spalding, John F., Jr. (January 1955), "Axial Rotation and Line Broadening in Stars of Spectral Types F0-K5", Astrophysical Journal, 121: 118, Bibcode:1955ApJ...121..118H, doi:10.1086/145969.
4. Famaey, B.; et al. (2005), "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters", Astronomy and Astrophysics, 430: 165–186, arXiv:astro-ph/0409579, Bibcode:2005A&A...430..165F, doi:10.1051/0004-6361:20041272.
5. Carney, Bruce W.; et al. (March 2008), "Rotation and Macroturbulence in Metal-Poor Field Red Giant and Red Horizontal Branch Stars", The Astronomical Journal, 135 (3): 892–906, arXiv:0711.4984, Bibcode:2008AJ....135..892C, doi:10.1088/0004-6256/135/3/892.
6. Baines, E.; Schmitt, H. R.; Zavala, R. T.; Hutter, D.; van Belle, G. T. (2017), "Fundamental Parameters of 87 Stars from the Navy Precision Optical Interferometer", The Astronomical Journal, 155 (1): 30, arXiv:1712.08109, Bibcode:2018AJ....155...30B, doi:10.3847/1538-3881/aa9d8b
7. Bernacca, P. L.; Perinotto, M. (1970). "A catalogue of stellar rotational velocities". Contributi Osservatorio Astronomico di Padova in Asiago. 239. Bibcode:1970CoAsi.239....1B.
8. "1 Lac -- Variable Star", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2016-03-07.
9. Eggleton, P. P.; Tokovinin, A. A. (2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x.
10. "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on March 10, 2012, retrieved 2012-01-16.
11. Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S, retrieved 2019-01-27.