HD 175640
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| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aquila[1] |
| Right ascension | 18h 56m 22.660s[2] |
| Declination | −01° 47′ 59.50″[2] |
| Apparent magnitude (V) | 6.20[1] |
| Characteristics | |
| Spectral type | B9 IIIp(HgMnEu st, CaMg wk)[3] B9 V[4] |
| B−V color index | −0.046±0.005[1] |
| Variable type | Stable[4] |
| Astrometry | |
| Radial velocity (Rv) | −26±4[1] km/s |
| Proper motion (μ) | RA: −2.811 mas/yr Dec.: −19.318 mas/yr |
| Parallax (π) | 6.3201±0.0448 mas[2] |
| Distance | 516 ± 4 ly (158 ± 1 pc) |
| Absolute magnitude (MV) | 0.22[1] |
| Details | |
| Mass | 3.12±0.1[4] M☉ |
| Radius | 2.66±0.28[4] R☉ |
| Luminosity | 94.56[1] L☉ |
| Surface gravity (log g) | 4.03[5] cgs |
| Temperature | 12324±9[5] K |
| Metallicity [Fe/H] | 0.18±0.04[1] dex |
| Rotational velocity (v sin i) | 1.6±0.3[6] km/s |
| Other designations | |
| BD−01°3602, FK5 3510, GC 25995, HD 175640, HIP 92963, HR 7143, SAO 142825[7] | |
| Database references | |
| SIMBAD | data |
HD 175640 is a star in the equatorial constellation of Aquila. It has an apparent visual magnitude of 6.20,[1] which is bright enough to be visible to the naked eye under suitable seeing conditions. The star is located at a distance of approximately 516 light years as determined through parallax measurements.[2] At that distance, the star's color is modified by an extinction of 0.36 magnitude due to interstellar dust.[8] It is drifting closer with a heliocentric radial velocity of roughly −26 km/s.[1]
This is classified as a mercury-manganese star, which is a late B-type chemically peculiar star of type CP3. A distinctive feature of this class of stars is an apparent extreme overabundance of the elements mercury and manganese.[9] It has a low longitudinal magnetic field strength of −0.6±2.2 G.[6] This is a particularly stable star, showing no signs of pulsation.[4] As with other HgMn stars, it is spinning slowly, showing a projected rotational velocity of 1.6 km/s.[6]
In 2007, some evidence was found that this may be a single-lined spectroscopic binary star system. In particular, shifts in radial velocity were observed in the range of 7 to −7 km/s.[10]
