30 Ophiuchi, an orange giant star in Ophiuchus
30 Ophiuchi is an orange giant star in the constellation Ophiuchus. At 365 light years away, it shines at an apparent visual magnitude of 4.81.
30 Ophiuchi (HIP 83262)
30 Ophiuchi is an orange giant star in the constellation Ophiuchus. At 365 light years away, it shines at an apparent visual magnitude of 4.81. It is moving through the Galaxy at a speed of 47.6 km/s relative to the Sun.
Sky position: RA 17h 1.1m, Dec -4° 13.4'
Common designations: 30 Ophiuchi, HR 6318, HD 153687, HIP 83262, Gaia DR3 4365395040146977408
30 Ophiuchi has the spectral type K4III. K-type stars are orange stars with surface temperatures of about 3,900 to 5,300 K. Their spectra are rich in neutral metal lines and, in the cooler examples, molecular bands. 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 30 Ophiuchi in the sky
30 Ophiuchi lies in Ophiuchus. With a declination of -4° 13.4', it is visible from the entire Southern Hemisphere and from the Northern Hemisphere up to about latitude 86° N. It is bright enough to see with the naked eye under dark skies. It is highest in the sky at local midnight around July, which makes the weeks around that month the best time to observe it.
Tabulated data for 30 Ophiuchi
Astrometry and spectroscopy
| Right Ascension (J2000) | 255.26500741° (17h 1.1m) |
| Declination (J2000) | -4.22264385° (-4° 13.4') |
| Galactic Longitude | 15.57942131° |
| Galactic Latitude | 22.18247618° |
| Proper motion RA | -40.37 mas/yr |
| Proper motion Dec | -78.45 mas/yr |
| Parallax | 8.93 ± 0.12 mas |
| Spectral Type | K4III |
| Radial Velocity | -8.26 km/s |
Photometry
| Band | Magnitude | Abs. Mag. |
|---|---|---|
| B | 6.30 | 1.06 |
| V | 4.81 | -0.43 |
| J | 2.11 | -3.13 |
| H | 1.43 | -3.81 |
| K | 1.27 | -3.98 |
Colour index B-V: +1.49
Derivations
- Heliocentric distance: 112.01 pc (365 light years) (1.3% margin of error)
- Absolute visual magnitude: -0.43
- Transverse velocity: 46.9 km/s
- Space velocity relative to the Sun: 47.6 km/s
- Galactic position (X, Y, Z): 99.9 pc, 27.9 pc, 42.3 pc
- Galactic velocity (U, V, W): 6.5 km/s, -46.7 km/s, -6.4 km/s
Data: Extended Hipparcos Compilation (XHIP) and SIMBAD.