Lambda Aurigae

Lambda Aurigae is a Sun-like^[10] star in the northern constellation of Auriga.^[14] Its name is a Bayer designation that is Latinized from λ Aurigae, and abbreviated Lambda Aur or λ Aur. This star is visible to the naked eye with an apparent visual magnitude of 4.71.^[2] Based upon parallax measurements, it is 41 light-years (13 parsecs) distant from the Earth.^[1] The star is drifting further away with a high radial velocity of +66.5 km/s,^[5] having come to within 24.4 ly (7.5 pc) some 117,300 years ago.^[15] It has a high proper motion, traversing the celestial sphere at the rate of 0.844″ per year.^[16]

λ Aurigae

Location of λ Aurigae (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Auriga
Right ascension	05h 19m 08.475s[1]
Declination	+40° 05′ 56.59″[1]
Apparent magnitude (V)	4.71[2]
Characteristics
Spectral type	G1 V[3] or G1.5 IV-V Fe-1[4]
U−B color index	+0.13[2]
B−V color index	+0.62[2]
R−I color index	0.32
Astrometry
Radial velocity (Rv)	+66.53±0.14[5] km/s
Proper motion (μ)	RA: +520.569 mas/yr[1] Dec.: −664.488 mas/yr[1]
Parallax (π)	79.6021±0.1005 mas[5]
Distance	40.97 ± 0.05 ly (12.56 ± 0.02 pc)
Absolute magnitude (MV)	4.20[6]
Details
Mass	1.081+0.054 −0.029[7] M☉
Radius	1.331±0.021[3] R☉
Luminosity	1.732±0.022[3] L☉
Surface gravity (log g)	4.02[8] cgs
Temperature	5,890±4.3[9] K
Metallicity [Fe/H]	+0.12[10] dex
Rotational velocity (v sin i)	2[11] km/s
Age	4,[10] 5.0–7.9[12] Gyr
Other designations
λ Aur, 15 Aurigae, BD+39°1248, FK5 1145, GC 6494, GJ 197, HD 34411, HIP 24813, HR 1729, SAO 40233, PPM 47977, WDS J05191+4006A, LFT 403, LHS 1753, LTT 11625[13]
Database references
SIMBAD	data
ARICNS	data

Properties

This is a G-type main sequence star with a stellar classification of G1 V.^[3] It is sometimes listed with a class of G1.5 IV-V Fe-1,^[4] which indicates the spectrum is showing some features of a more evolved subgiant star along with a noticeable underabundance of iron. In terms of composition it is similar to the Sun, while the mass and radius are slightly larger.^[7] It is 73% more luminous than the Sun^[3] and radiates this energy from its outer atmosphere at an effective temperature of 5890 K.^[9] At this heat, the star glows with the yellow hue of a G-type star.^[17] It has a low level of magnetic activity and is a candidate Maunder minimum analog.^[18]

Lambda Aurigae has been examined for the presence of excess infrared emission that may indicate the presence of a circumstellar disk of dust, but no significant surplus has been observed.^[10] It is a possible member of the Epsilon Indi Moving Group of stars that share a common motion through space. The space velocity components of this star are [U, V, W] = [+76, –39, –6] km/s.^[19]

Name

This star may have been called by the name Al Hurr, meaning the fawn in Arabic.^[20] Lambda Aurigae, along with μ Aur and σ Aur, were Kazwini's Al Ḣibāʽ (ألحباع), the Tent.^[20] According to the catalogue of stars in the Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars, Al Ḣibāʽ were the title for three stars : λ Aur as Al Ḣibāʽ I, μ Aur as Al Ḣibāʽ II and σ Aur as Al Ḣibāʽ III.^[21]

In Chinese, 咸池 (Xián Chí), meaning Pool of Harmony, refers to an asterism consisting of λ Aurigae, ρ Aurigae and HD 36041.^[22] Consequently, the Chinese name for λ Aurigae itself is 咸池三 (Xián Chí sān, English: the Third Star of Pool of Harmony.)^[23]

Observation

From Earth, Lambda Aurigae has an apparent magnitude of 4.71. The closest large neighboring star to Lambda Aurigae is Capella, located 4.5 light-years (1.4 parsecs) away.^[24] Hypothetically viewed from Lambda Aurigae, Capella's quadruple star system would have an apparent magnitude of approximately -5.48,^[25] about 40 times brighter than Sirius can be seen at maximum brightness from Earth.^[26]