Iota Sagittarii
Astrometric binary star in the constellation Sagittarius / From Wikipedia, the free encyclopedia
Iota Sagittarii (Iota Sgr, ι Sagittarii, ι Sgr) is a star in the zodiac constellation of Sagittarius. With an apparent visual magnitude of +4.118, it is bright enough to be viewed with the naked eye.[2] Based upon an annual parallax shift of 17.94 mas as seen from Earth,[1] this star is located 182 light years from the Sun. It is moving away from the Earth with a radial velocity of +35.8 km/s.[3]
Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
---|---|
Constellation | Sagittarius |
Right ascension | 19h 55m 15.69691s[1] |
Declination | −41° 52′ 05.8388″[1] |
Apparent magnitude (V) | +4.118[2] |
Characteristics | |
Spectral type | K0 II-III[3] |
U−B color index | +0.911[2] |
B−V color index | +1.084[2] |
Astrometry | |
Radial velocity (Rv) | +35.8[3] km/s |
Proper motion (μ) | RA: +22.61[1] mas/yr Dec.: +51.40[1] mas/yr |
Parallax (π) | 17.94 ± 0.21 mas[1] |
Distance | 182 ± 2 ly (55.7 ± 0.7 pc) |
Absolute magnitude (MV) | +0.39[4] |
Details | |
Mass | 1.40[3] M☉ |
Radius | 14[5] R☉ |
Luminosity | 87[3] L☉ |
Surface gravity (log g) | 1.89[6] cgs |
Temperature | 4,594±41[3] K |
Metallicity [Fe/H] | −0.26[6] dex |
Age | 4.74[3] Gyr |
Other designations | |
Database references | |
SIMBAD | data |
This is a probable astrometric binary,[8] based upon proper motion data collected during the Hipparcos mission.[9] The visible component shows the spectrum of an evolved K-type giant or bright giant star with a stellar classification of K0 II-III.[3] The measured angular diameter, after correction for limb darkening, is 2.32±0.02 mas.[10] At an estimated distance of this star, this yields a physical size of about 14 times the radius of the Sun.[5] It has 1.4[3] times the mass of the Sun and is radiating 87[3] times the Sun's luminosity from its photosphere at an effective temperature of about 4,594 K.[3]