Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Sagittarius |
Right ascension | 17h 59m 47.55132s[1] |
Declination | −23° 48′ 58.0269″[1] |
Apparent magnitude (V) | 4.74[2] |
Characteristics | |
Spectral type | B9V[3] |
U−B color index | −0.03[4] |
B−V color index | -0.05[4] |
Astrometry | |
Radial velocity (Rv) | −18.00[5] km/s |
Proper motion (μ) | RA: +3.673[1] mas/yr Dec.: −50.327[1] mas/yr |
Parallax (π) | 8.3677 ± 0.4521 mas[1] |
Distance | 390 ± 20 ly (120 ± 6 pc) |
Absolute magnitude (MV) | −0.77[2] |
Details | |
Mass | 3.23[6] M☉ |
Luminosity | 240[6] L☉ |
Temperature | 9,661[6] K |
Rotational velocity (v sin i) | 149[6] km/s |
Other designations | |
Database references | |
SIMBAD | data |
4 Sagittarii is a suspected astrometric binary[8] star system in the zodiac constellation of Sagittarius, located approximately 390 light years away based on parallax.[1] It is visible to the naked eye as a faint, blue-white hued star with an apparent visual magnitude of 4.74,[2] The system is moving closer to the Earth with a heliocentric radial velocity of −18 km/s.[5]
The visible component is a B-type main-sequence star with a stellar classification of B9 V.[3] It has a high rate of spin, displaying a projected rotational velocity of 149 km/s.[6] This is giving it an oblate shape with an equatorial bulge that is an estimated 14% larger than the polar radius.[9] 4 Sagittarii has 3.23 times the mass of the Sun and is radiating 240 times the Sun's luminosity from its photosphere at an effective temperature of 9,661 K.[6]