HD 16955
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aries |
| Right ascension | 02h 43m 51.24421s |
| Declination | +25° 38′ 18.0493″ |
| Apparent magnitude (V) | 6.376 |
| Characteristics | |
| Evolutionary stage | main sequence |
| Spectral type | A3 V |
| B−V color index | 0.089±0.002 |
| Astrometry | |
| Radial velocity (Rv) | −10.3±3.1 km/s |
| Proper motion (μ) | RA: −4.98±0.70 mas/yr Dec.: +6.04±0.52 mas/yr |
| Parallax (π) | 9.59±0.76 mas |
| Distance | 340 ± 30 ly (104 ± 8 pc) |
| Absolute magnitude (MV) | +1.18±0.13 |
| Details | |
| HD 16955 A | |
| Mass | 2.25±0.08 M☉ |
| Radius | 2.4 R☉ |
| Luminosity | 26.9+3.3 −2.9 L☉ |
| Surface gravity (log g) | 3.97 cgs |
| Temperature | 8,450±164 K |
| Rotational velocity (v sin i) | 175 km/s |
| Age | 1.6 Gyr |
| Other designations | |
| BD+25°441, HD 16955, HIP 12744, HR 803, SAO 75539 | |
| Database references | |
| SIMBAD | data |
HD 16955, also known as HR 803, is a double or multiple star. With an apparent visual magnitude of 6.376, is lies at or below the nominal limit for visibility with a typical naked eye. The measured annual parallax shift is 9.59 milliarcseconds, which yields an estimated distance of around 340 light years. The star is moving closer to the Sun with a heliocentric radial velocity of around -10 km/s.
This is an A-type main-sequence star with a stellar classification of A3 V. Hauck et al. (1995) identified this as a Lambda Boötis star with a circumstellar shell, but this now appears to be unlikely. It has 2.25 times the mass of the Sun and is spinning rapidly with a projected rotational velocity of 175 km/s. The star is radiating about 27 times the Sun's luminosity from its photosphere at an effective temperature of roughly 8,450 K.
HD 16955 has a magnitude 10.36 companion, component B, which is located, as of 2015, at an angular separation of 3.0 arcseconds along a position angle of 19°. This is the likely source for the detected X-ray emission with a luminosity of 262.5×1020 W coming from these coordinates, since A-type stars are not expected to emit X-rays. Component C is a more distant magnitude 12.94 companion located at a separation of 51.10 arcseconds along a position angle of 92°, as of 2015.