HD 42845, a blue-white giant star in Orion
HD 42845 is a blue-white giant star in the constellation Orion. At 1,052 light years away, it shines at an apparent visual magnitude of 7.49.
HD 42845 (HIP 29516)
HD 42845 is a blue-white giant star in the constellation Orion. At 1,052 light years away, it shines at an apparent visual magnitude of 7.49. It is moving through the Galaxy at a speed of 34.8 km/s relative to the Sun.
Sky position: RA 6h 13.1m, Dec +3° 30.5'
Common designations: HD 42845, HIP 29516, Gaia DR3 3317122475291169920
HD 42845 has the spectral type B8II/III. B-type stars are hot (about 10,000 to 30,000 K), luminous and blue-white. They are massive, short-lived stars, typically only tens of millions of years old, and are common in young clusters and OB associations. Its luminosity class III marks it as a giant: an evolved star that has left the main sequence and swollen to many times its original size.
How to find HD 42845 in the sky
HD 42845 lies in Orion. With a declination of +3° 30.5', it is visible from the entire Northern Hemisphere and from the Southern Hemisphere down to about latitude 86° S. It is just beyond naked-eye visibility; binoculars will show it easily. It is highest in the sky at local midnight around January, which makes the weeks around that month the best time to observe it.
Tabulated data for HD 42845
Astrometry and spectroscopy
| Right Ascension (J2000) | 93.26569190° (6h 13.1m) |
| Declination (J2000) | 3.50905135° (+3° 30.5') |
| Galactic Longitude | 205.38857709° |
| Galactic Latitude | -6.90017577° |
| Proper motion RA | -4.19 mas/yr |
| Proper motion Dec | -3.56 mas/yr |
| Parallax | 3.10 ± 0.04 mas |
| Spectral Type | B8II/III |
| Radial Velocity | 33.80 km/s |
Photometry
| Band | Magnitude | Abs. Mag. |
|---|---|---|
| B | 7.40 | -0.14 |
| V | 7.49 | -0.05 |
| J | 7.64 | 0.10 |
| H | 7.71 | 0.17 |
| K | 7.72 | 0.17 |
Colour index B-V: -0.09
Derivations
- Heliocentric distance: 322.42 pc (1,052 light years) (1.2% margin of error)
- Absolute visual magnitude: -0.05
- Transverse velocity: 8.4 km/s
- Space velocity relative to the Sun: 34.8 km/s
- Galactic position (X, Y, Z): -289.2 pc, -137.2 pc, -38.7 pc
- Galactic velocity (U, V, W): -28.6 km/s, -15.6 km/s, -12.2 km/s
Data: Extended Hipparcos Compilation (XHIP) and SIMBAD.