| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Lyra |
| Right ascension | 18h36m 37.34437s[1] |
| Declination | 33° 28′ 08.5352″[1] |
| Apparent magnitude (V) | 5.41[2] + 10.7[3] |
| Characteristics | |
| Spectral type | B8IIpHgMn[4] |
| U−B color index | −0.509[2] |
| B−V color index | −0.101±0.003[2] |
| Astrometry | |
| A | |
| Radial velocity (Rv) | −32.5±0.8[5] km/s |
| Proper motion (μ) | RA: −7.966[1] mas/yr Dec.: +0.690[1] mas/yr |
| Parallax (π) | 6.0990 ± 0.0893 mas[1] |
| Distance | 535 ± 8 ly (164 ± 2 pc) |
| Absolute magnitude (MV) | −0.53[2] |
| B | |
| Proper motion (μ) | RA: −7.403[6] mas/yr Dec.: +0.479[6] mas/yr |
| Parallax (π) | 6.2391 ± 0.0221 mas[6] |
| Distance | 523 ± 2 ly (160.3 ± 0.6 pc) |
| Orbit[7] | |
| Period (P) | 1675 d |
| Semi-major axis (a) | ≥71.6×108 km |
| Eccentricity (e) | 0.16 |
| Periastron epoch (T) | 2,420,438.5 JD |
| Argument of periastron (ω) (secondary) | 120° |
| Semi-amplitude (K1) (primary) | 3.2 km/s |
| Details | |
| A | |
| Mass | 3.65±0.50[8] M☉ |
| Luminosity | 262.17[2] L☉ |
| Surface gravity (log g) | 3.90[9] cgs |
| Temperature | 14,500[9] K |
| Metallicity [Fe/H] | −0.25[2] dex |
| Rotational velocity (v sin i) | 34[9] km/s |
| Other designations | |
BD+33°3154, GC 25443, HD 172044, HIP 91235, HR 6997, SAO 67164, CCDM J18366+3328, WDS J18366+3328, GSC 02641-02396[10] | |
| Database references | |
| SIMBAD | data |
HD 172044 is a triple star[11] system in the northern constellationofLyra. It has a blue-white hue and is visible to the naked eye with an apparent visual magnitude of 5.41.[2] The distance to the primary component is approximately 535 light years based on parallax.[1] It is drifting closer with a radial velocity of −32.5 km/s, and is predicted to come as near as 77.3 light-years to the Sun some 4.5 million years from now.[2]
The dual nature of the primary star, component A, was announced in 1973 by H. A. Abt and M. A. Snowden. It is a single-lined spectroscopic binary with a preliminary orbital period of 4.59 years and an eccentricity (ovalness) of 0.16.[7] The visible component is a B-type bright giant with a stellar classification of B8IIpHgMn,[4] where the suffix notation indicates it is a chemically peculiar mercury-manganese star.[9]
Component B is a magnitude 9.40 companion of an unknown spectral type.[12] It was first reported by F. G. W. Struve in 1830. As of 2016, it has an angular separationof7.2 arcseconds along a position angle of 204° from the brighter component.[3]
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