HD 175740
Star in the constellation Lyra
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HD 175740 is a single[8] star in the northern constellation of Lyra.[1] This object has an orange hue and is dimly visible to the naked eye with an apparent visual magnitude of 5.46.[1] It is located at a distance of approximately 266 light years from the Sun based on parallax,[2] and has an absolute magnitude of 0.89.[1] The star is drifting closer with a radial velocity of −9.5 km/s, and is predicted to come as close as 31.7 light-years in around 8 million years.[4]
 | |
| Observation data Epoch J2000.0 Equinox ICRS | |
|---|---|
| Constellation | Lyra[1] |
| Right ascension | 18h 54m 52.17758s[2] |
| Declination | +41° 36′ 09.7934″[2] |
| Apparent magnitude (V) | 5.46[1] |
| Characteristics | |
| Spectral type | K0III[3] |
| B−V color index | 1.034±0.004[1] |
| Astrometry | |
| Radial velocity (Rv) | −9.52±0.13[4] km/s |
| Proper motion (μ) | RA: −2.059[2] mas/yr Dec.: −2.234[2] mas/yr |
| Parallax (π) | 12.2448±0.0874 mas[2] |
| Distance | 266 ± 2 ly (81.7 ± 0.6 pc) |
| Absolute magnitude (MV) | 0.89[1] |
| Details | |
| Mass | 1.39[5] or 2.795[4] M☉ |
| Radius | 10.17+0.35 −0.73[2] R☉ |
| Luminosity | 49.90±0.45[2] L☉ |
| Surface gravity (log g) | 2.8[6] cgs |
| Temperature | 4,811+181 −81[2] K |
| Metallicity [Fe/H] | −0.01±0.06[1] dex |
| Rotational velocity (v sin i) | 4.0[6] km/s |
| Age | 4.78[5] Gyr |
| Other designations | |
| BD+41°3177, GC 25972, HD 175740, HIP 92831, HR 7146, SAO 47909, WDS J18549+4136A[7] | |
| Database references | |
| SIMBAD | data |
This is an aging giant star with a stellar classification of K0III,[3] having evolved off the main sequence after the supply of hydrogen at its core was exhausted. It is an estimated 4.78[5] billion years old with 1.39[5] times the mass of the Sun, although Bailer-Jones et al. (2018) give a higher estimate of 2.8[4] times the Sun's mass. The elemental composition of this star has made it the first giant to be a candidate solar sibling, suggesting it may have been born in the same star cluster as the Sun.[9] It has expanded to ten[2] times the girth of the Sun and is radiating 50[2] times the Sun's luminosity from its photosphere at an effective temperature of 4,811 K.[2]
HD 175740 has a magnitude 12.6 visual companion, located at an angular separation of 8.4″ along a position angle (PA) of 300°, as of 2013. A magnitude 11.5 companion lies at a separation of 24.1″ along a PA of 39°, as of 2014. Both were discovered by American astronomer G. W. Hough in 1887.[10]