30 Ophiuchi is a single[10] star in the equatorial constellation of Ophiuchus, and figures 0.99° east (specifically E½S) of the heart of cluster Messier 10.[11] It is visible to the naked eye as a faint, orange-hued point of light with an apparent visual magnitude of 4.82.[2] The distance to this star is approximately 350 light years based on parallax.[6] Its present motion is, net, one of approaching rather than parting, at −6.7 km/s, its "radial velocity".[5]
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Ophiuchus |
Right ascension | 17h 01m 03.60142s[1] |
Declination | −4° 13′ 21.5308″[1] |
Apparent magnitude (V) | 4.82[2] |
Characteristics | |
Spectral type | K4III[3] |
U−B color index | +1.80[4] |
B−V color index | +1.48[4] |
Astrometry | |
Radial velocity (Rv) | −6.70[5] km/s |
Proper motion (μ) | RA: −39.13[6] mas/yr Dec.: −78.09[6] mas/yr |
Parallax (π) | 9.3138 ± 0.1676 mas[1] |
Distance | 350 ± 6 ly (107 ± 2 pc) |
Absolute magnitude (MV) | −0.65[2] |
Details | |
Radius | 35.89+0.54 −2.12[1] R☉ |
Luminosity | 299.8±6.2[1] L☉ |
Surface gravity (log g) | 1.73[7] cgs |
Temperature | 4,009.00+126.67 −29.67[1] K |
Metallicity [Fe/H] | −0.03[2] dex |
Rotational velocity (v sin i) | 1.4[8] km/s |
Other designations | |
Database references | |
SIMBAD | data |
This is an aging giant star with a stellar classification of K4III,[3] having exhausted the supply of hydrogen at its core and expanded to 36[1] times the Sun's radius. It is a suspected variable star.[12] The star is radiating 300[1] times the luminosity of the Sun from its swollen photosphere at an effective temperature of 4,009 K.[1] It is emitting a far infrared excess due to circumstellar dust,[13] which extends out to a diameter of 240 AU and has a mass of 62×1025 g.[14]
The primary presents with two visual companions: B, at magnitude 9.71 and separation 99.8″, and C, at magnitude 8.75 and separation 220.9″ (3′ 40.9″).[15]