Eta Aurigae

η Aurigae

Template:Location mark Location of η Aurigae (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Auriga
Right ascension	Template:RA
Declination	Template:DEC
Apparent magnitude (V)	3.18
Characteristics
Spectral type	B3 V
U−B Template:Engvar	−0.66
B−V Template:Engvar	−0.18
R−I Template:Engvar	−0.17
Variable type	SPB
Astrometry
Radial velocity (Rv)	+7.3 km/s
Proper motion (μ)	RA: +31.45 mas/yr Dec.: −67.87 mas/yr
Parallax (π)	13.40±0.20 mas
Distance	Template:Rnd ± Template:Rnd ly (Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)	−1.18
Details
Mass	Template:Val Template:Solar mass
Radius	Template:Val Template:Solar radius
Luminosity	Template:Val Template:Solar luminosity
Surface gravity (log g)	4.13±0.04 cgs
Temperature	Template:Val K
Rotational velocity (v sin i)	95 km/s
Age	Template:Val Myr
Metallicity [Fe/H]	{{{metal_fe2}}} dex
Other designations
Template:Odlist
Database references
SIMBAD	data

Eta Aurigae is a star in the northern constellation of Auriga. Its identifier is a Bayer designation that is Latinized from η Aurigae, and abbreviated Eta Aur or η Aur. The star is officially named Haedus, pronounced Template:IPAc-en. With an apparent visual magnitude of 3.18, it is visible to the naked eye. Based upon parallax measurements made during the Hipparcos mission, this star is approximately Template:Convert distant from the Sun. It is receding with a radial velocity of +7 km/s.

Nomenclature

File:Eta Aurigae.jpg

η Aurigae in optical light

η Aurigae (Latinised to Eta Aurigae) is the star's Bayer designation.

Along with Zeta Aurigae it represents one of the kids of the she-goat Capella, from which it derived its Latin traditional name Haedus II or Hoedus II, from the Latin haedus "kid" (Zeta Aurigae was Haedus I). It also had the less common traditional name Mahasim, from the Arabic المِعْصَم al-miʽşam "the wrist" (of the charioteer), which it shared with Theta Aurigae. In 2016, the IAU organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN approved the names Haedus for Eta Aurigae and Saclateni for Zeta Aurigae A on 30 June 2017 and they are both now so included in the List of IAU-approved Star Names.

In Chinese, (), meaning Pillars, refers to an asterism consisting of Eta Aurigae, Epsilon Aurigae, Zeta Aurigae, Upsilon Aurigae, Nu Aurigae, Tau Aurigae, Chi Aurigae and 26 Aurigae. Consequently, the Chinese name for Eta Aurigae itself is (, Template:Langx).

Properties

File:EtaAurLightCurve.png

A light curve for Eta Aurigae, plotted from TESS data. The 1.29 day primary period is marked in red.

Since 1943, the spectrum of Eta Aurigae has served as one of the stable anchor points by which other stars are classified.

Eta Aurigae is larger than the Sun, with more than five times the Sun's mass and over three times its radius. The spectrum of this star matches a stellar classification of B3 V, which is a B-type main-sequence star that is generating its energy through the nuclear fusion of hydrogen at its core. It is a chemically peculiar star and a slowly pulsating B-type star with a primary period of 1.29 days. This star is radiating 1,450 times the Sun's luminosity from its photosphere at an effective temperature of Template:Val. Based upon its projected rotational velocity of 95 km/s, it is spinning with a rotation period of only 1.8 days. Eta Aurigae is around 39 million years old.

External links

• HR 1641
• Image Eta Aurigae