Thabit, a blue main-sequence star in Orion
Thabit is a blue main-sequence star in the constellation Orion. At 1,328 light years away, it shines at an apparent visual magnitude of 4.63.
Thabit (HIP 25923)
Thabit is a blue main-sequence star in the constellation Orion. At 1,328 light years away, it shines at an apparent visual magnitude of 4.63. It is moving through the Galaxy at a speed of 18.6 km/s relative to the Sun.
Sky position: RA 5h 31.9m, Dec -7° 18.1'
Common designations: Thabit, Upsilon Orionis, 36 Orionis, HR 1855, HD 36512, Gaia DR3 3016424530632449280, HIP 25923
Thabit has the spectral type O9.7V. O-type stars are the hottest and most massive stars, with surface temperatures above 30,000 K. They burn through their fuel in only a few million years and flood their surroundings with ultraviolet light. Its luminosity class V means it is a main-sequence (dwarf) star, still fusing hydrogen into helium in its core like the Sun.
How to find Thabit in the sky
Thabit lies in Orion. With a declination of -7° 18.1', it is visible from the entire Southern Hemisphere and from the Northern Hemisphere up to about latitude 83° N. It is bright enough to see with the naked eye under dark skies. 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 Thabit
Astrometry and spectroscopy
| Right Ascension (J2000) | 82.98274983° (5h 31.9m) |
| Declination (J2000) | -7.30153775° (-7° 18.1') |
| Galactic Longitude | 210.43562700° |
| Galactic Latitude | -20.98304268° |
| Proper motion RA | -0.70 mas/yr |
| Proper motion Dec | -4.88 mas/yr |
| Parallax | 2.46 ± 0.14 mas |
| Spectral Type | O9.7V |
| Radial Velocity | 16.00 km/s |
Photometry
| Band | Magnitude | Abs. Mag. |
|---|---|---|
| U | 3.30 | -4.75 |
| B | 4.36 | -3.69 |
| V | 4.63 | -3.42 |
| R | 4.75 | -3.30 |
| I | 5.01 | -3.04 |
| J | 5.23 | -2.82 |
| H | 5.35 | -2.70 |
| K | 5.38 | -2.67 |
Colour index B-V: -0.27
Derivations
- Heliocentric distance: 407.05 pc (1,328 light years) (5.7% margin of error)
- Absolute visual magnitude: -3.42
- Transverse velocity: 9.5 km/s
- Space velocity relative to the Sun: 18.6 km/s
- Galactic position (X, Y, Z): -327.7 pc, -192.5 pc, -145.8 pc
- Galactic velocity (U, V, W): -7.2 km/s, -13.4 km/s, -10.8 km/s
Data: Extended Hipparcos Compilation (XHIP) and SIMBAD.