40 Aurigae
Binary star in the constellation Auriga
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40 Aurigae is a binary star in the constellation Auriga. Its apparent magnitude is 5.345,[3] meaning it can just barely be seen with the naked eye. Based on parallax estimates made by the Hipparcos spacecraft, the system is located some 340 light-years (104 parsecs) away.
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Auriga[1] |
| Right ascension | 06h 06m 35.09752s[2] |
| Declination | +38° 28′ 57.5285″[2] |
| Apparent magnitude (V) | 5.345[3] |
| Characteristics | |
| Evolutionary stage | main sequence[2] |
| Spectral type | A4m[4] |
| U−B color index | +0.11[5] |
| B−V color index | +0.23[5] |
| Astrometry | |
| Radial velocity (Rv) | 16.90±7.4[6] km/s |
| Proper motion (μ) | RA: +9.452[2] mas/yr Dec.: −54.087[2] mas/yr |
| Parallax (π) | 9.1085±0.0728 mas[2] |
| Distance | 358 ± 3 ly (109.8 ± 0.9 pc) |
| Absolute magnitude (MV) | +0.26[1] |
| Orbit[4] | |
| Period (P) | 28.28 d |
| Eccentricity (e) | 0.56 |
| Periastron epoch (T) | JD 2420468.197 |
| Argument of periastron (ω) (secondary) | 178.4° |
| Semi-amplitude (K1) (primary) | 51.4 km/s |
| Semi-amplitude (K2) (secondary) | 62.5 km/s |
| Details | |
| Mass | 1.81[7] M☉ |
| Radius | 4.62[7] R☉ |
| Luminosity | 68[7] L☉ |
| Surface gravity (log g) | 3.88±0.08[8] cgs |
| Temperature | 7,838±52[8] K |
| Metallicity [Fe/H] | +0.35±0.05[8] dex |
| Rotational velocity (v sin i) | 71[9] km/s |
| Age | 559[2] Myr |
| Other designations | |
| AG+38°663, BD+38°1377, FK5 2465, GC 7723, HD 41357, HIP 28946, HR 2143, SAO 58749, PPM 71223, PLX 1403, TYC 2925-806-1, GCRV 3828, GSC 02925-00806, IRAS 06031+3829, 2MASS J06063509+3828578 | |
| Database references | |
| SIMBAD | data |
40 Aurigae is a spectroscopic binary, meaning the two stars are too close to be individually resolved, but periodic Doppler shifts in their spectra indicate there must be orbital motion. In this case, light from both stars can be detected and it is a double-lined spectroscopic binary.[4] The two have an orbital period of 28.28 days and a fairly high eccentricity of 0.56.[4] The primary star is an A-type main-sequence star and shows unusual absorption lines in its spectrum, so it is an Am star[4] with an effective temperature of 7,838 K.[8]