Holmberg IX V1
| Observation data Epoch J2000.0 Equinox J2000.0 | ||
|---|---|---|
| Constellation | Ursa Major | |
| Right ascension | 09h 57m 37.14s | |
| Declination | +69° 02′ 11.0″ | |
| Apparent magnitude (V) | 20.7 | |
| Characteristics | ||
| A | ||
| Evolutionary stage | Yellow supergiant | |
| Spectral type | G | |
| B | ||
| Evolutionary stage | Yellow supergiant | |
| Spectral type | G | |
| Astrometry | ||
| Distance | 13 million ly | |
| Absolute magnitude (MV) | -7.1 | |
| Orbit | ||
| Primary | Holmberg IX V1 A | |
| Name | Holmberg IX V1 B | |
| Period (P) | 270.7 days | |
| Semi-major axis (a) | 547 R☉ | |
| Eccentricity (e) | 0 | |
| Inclination (i) | 55.7° | |
| Details | ||
| A | ||
| Mass | 15-20 M☉ | |
| Radius | 337 R☉ | |
| Luminosity | 54,450 L☉ | |
| Temperature | 4,800 K | |
| Metallicity [Fe/H] | -0.328 dex | |
| Age | 10-15 Myr | |
| B | ||
| Mass | 15-20 M☉ | |
| Radius | 306 R☉ | |
| Luminosity | 54,450 L☉ | |
| Temperature | 5,040 K | |
| Metallicity [Fe/H] | -0.328 dex | |
| Age | 10-15 Myr | |
| Other designations | ||
| EQ J095737+690211 | ||
| Database references | ||
| SIMBAD | data | |
Holmberg IX V1, also known as EQ J095737+690211 is a W Ursae Majoris type eclipsing contact binary star system in the constellation of Ursa Major. The binary system is located in the dwarf galaxy Holmberg IX, roughly 13 million light years (or 4 million parsecs) away. The binary system has a maximum visual magnitude of 20.7, and is one of most extreme and rarest systems discovered.