AR Aurigae
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Auriga |
| Right ascension | 05h 18m 18.896s |
| Declination | +33° 46′ 02.52″ |
| Apparent magnitude (V) | 6.144 |
| Characteristics | |
| Spectral type | B9V + B9.5V |
| U−B color index | −0.18 |
| B−V color index | −0.06 |
| Variable type | Algol |
| Astrometry | |
| Radial velocity (Rv) | 25.4±0.9 km/s |
| Proper motion (μ) | RA: +15.254 mas/yr Dec.: −29.225 mas/yr |
| Parallax (π) | 7.0735±0.0461 mas |
| Distance | 461 ± 3 ly (141.4 ± 0.9 pc) |
| Absolute magnitude (MV) | 1.11/1.17 |
| Details | |
| AR Aur A | |
| Mass | 2.552±0.008 M☉ |
| Radius | 1.781 R☉ |
| Luminosity | 41 L☉ |
| Surface gravity (log g) | 4.33 cgs |
| Temperature | 10,950±150 K |
| Rotational velocity (v sin i) | 10 km/s |
| AR Aur B | |
| Mass | 2.367±0.008 M☉ |
| Radius | 1.816 R☉ |
| Luminosity | 34 L☉ |
| Surface gravity (log g) | 4.28 cgs |
| Temperature | 10,350±150 K |
| Rotational velocity (v sin i) | 11 km/s |
| Other designations | |
| 17 Aur, BD+33°1002, HD 34364, HIP 24740, HR 1728, SAO 57858, PPM 70158 | |
| Database references | |
| SIMBAD | data |
AR Aurigae (AR Aur), also known by its Flamsteed designation 17 Aurigae, is a binary star in the constellation Auriga. Based on parallax measurements made by the Hipparcos spacecraft, it is approximately 461 light-years from Earth.
Both components are blue-white B-type main-sequence stars that do not fill their Roche lobes. The system has a mean apparent magnitude of +6.15. However, the orbit of the stars are oriented in such a way that they periodically eclipse each other, so AR Aurigae is a variable star and its brightness varies from magnitude +6.15 to +6.82 with a period of 4.13 days. In 1931, H. N. Pendersen and J. C. Steensgard became the first persons to detect these eclipses. When an eclipse is not occurring, the star will be faintly visible to the naked eye under very good observing conditions.
The primary component of AR Aurigae is known to be a mercury-manganese star, also known as an HgMn star. As the name implies, these stars have over-abundances of the elements mercury and manganese, and also often xenon and other elements. Because AR Aurigae is an eclipsing binary (in fact, it is the only known eclipsing binary with a mercury-manganese star), accurate characterization of its parameters has been made possible. Based on the light-time effect observed from the stars, it is inferred that there is a third star with a mass of 0.54 M☉, orbiting at a separation of 13 AU every 23.7 years.