Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
---|---|
Constellation | Delphinus |
Right ascension | 20h 39m 04.9681s[1] |
Declination | +15° 50′ 17.5112″[1] |
Apparent magnitude (V) | 5.98[2] |
Characteristics | |
Spectral type | B3 V[3] |
U−B color index | −0.71[2] |
B−V color index | −0.16[2] |
Astrometry | |
Radial velocity (Rv) | −4.6±1[4] km/s |
Proper motion (μ) | RA: −0.868 mas/yr[1] Dec.: −15.290 mas/yr[1] |
Parallax (π) | 3.1211 ± 0.0617 mas[1] |
Distance | 1,050 ± 20 ly (320 ± 6 pc) |
Absolute magnitude (MV) | −2.05[5] |
Details | |
Mass | 7±0.4[6] M☉ |
Radius | 4.13±0.14[7] R☉ |
Luminosity | 1,507[8] L☉ |
Surface gravity (log g) | 3.97[9] cgs |
Temperature | 18,100[9] K |
Rotational velocity (v sin i) | 145±6[10] km/s |
Age | 36.1±9.5[6] Myr |
Other designations | |
Database references | |
SIMBAD | data |
HD 196775 (HR 7899) is a solitary star in the equatorial constellation Delphinus. It has an apparent magnitude of 5.98, allowing it to be faintly seen with the naked eye. The object is relatively far at a distance of 1,050 light years but is approaching the Solar System with a heliocentric radial velocity of −4.6 km/s. HD 196775 has a high peculiar velocity of 21.8+1.9
−4.1 km/s[6] compared to neighboring stars, indicating that it may be a runaway star.
HD 196775 has a general stellar classification of B3 V,[3] indicating that it is an ordinary B-type main-sequence star. However, once source gives it a class of B4 Vn,[11] making it slightly cooler and having broad absorption lines due to rapid rotation. It has an angular diameter of 0.12 mas,[12] yielding a radius 4.13 times that of the Sun.[7] At present it has 7 times the mass of the Sun[6] and shines at 1507 L☉[8] from its photosphere at an effective temperature of 18,100 K,[9] giving it a whitish blue hue. HD 196775 is 36 million years old[6] and is spinning rapidly with a projected rotational velocity of 145 km/s.[10]
HD 196775 has four faint optical companions whose parameters are listed below.
Companion | mv | PA (°) | Year | Sep. (″) |
---|---|---|---|---|
B | 12.40 | 154 | 2006 | 5.2 |
C | 11.31 | 122 | 2012 | 39.9 |
D | 14.40 | 146 | 2012 | 28.8 |
E | 14.40 | 33 | 2012 | 23.3 |