Blue main-sequence star · Ophiuchus
ζ Ophiuchi
Also known as: ζ Oph, HIP 81377
mag 2.5370 light-years
About
ζ Ophiuchi is a blue main-sequence star of magnitude 2.5 in Ophiuchus, about 370 light-years away.
How to find it
- ζ Ophiuchi is in the constellation Ophiuchus.
- Best evenings: around mid-July it is highest at about 9 pm (10 pm in summer time); a month earlier, two hours later.
- Where on Earth: it is seen well, at least 10° up, from south of 69° N.
When it rises and sets tonight, how high it climbs and how much the Moon gets in the way are worked out in your browser for your place.
What you will see
- EyesEasy, even from town.
- Binoculars (10×50)A sharp point; binoculars bring out its colour and the fainter stars around it.
- Telescope (6–8 inch)Still a point of light at any magnification — stars are too far away to show a disc. Low in the sky, bright stars twinkle and flash colours.
Stars look the same in any instrument: brighter and sharper, but never bigger.
Facts
| Designation | ζ Ophiuchi (ζ Oph) |
|---|---|
| Hipparcos number | HIP 81377 |
| Type | Blue main-sequence star |
| Spectral type | O9.5V |
| Colour | WhiteB−V colour index 0.04 |
| Magnitude | 2.5The smaller the number, the brighter. |
| Distance | 370 light-yearsThe light you see left it around 1660. |
| Proper motion | 0.029″ per year across the sky |
| Constellation | Ophiuchus |
| Right ascension (J2000) | 16h 37m 09.5s |
| Declination (J2000) | −10° 34′ 02″ |
Sources and credits
Star data: HYG Database by David Nash, CC BY-SA 4.0. All data sources →