HD 170657

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HD 170657
Observation data
Epoch J2000      Equinox J2000
Constellation Sagittarius
Right ascension 18h 31m 18.9597s[1]
Declination –18° 54′ 31.722″[1]
Apparent magnitude (V) 6.82
Characteristics
Spectral type K2V[2]
U−B color index +0.56[3]
B−V color index +0.87[3]
Variable type Suspected[4]
Astrometry
Radial velocity (Rv) –35[5] km/s
Proper motion (μ) RA: –140.14[1] mas/yr
Dec.: –194.60[1] mas/yr
Parallax (π) 75.71 ± 0.89[1] mas
Distance 43.1 ± 0.5 ly
(13.2 ± 0.2 pc)
Details
Mass 0.79 ± 0.11[6] M☉
Surface gravity (log g) 4.61[6] cgs
Temperature 5,156[6][7] K
Rotational velocity (v sin i) 1.5[6] km/s
Age 1.6–6.1[7] Gyr
Other designations
GJ 716, BD-18 4986, HD 170657, LTT 7358, SAO 161557, HIP 90790.[8]

HD 170657 is a star in the constellation Sagittarius. It is located at a distance of about 43 light years. It has 0.79 solar masses and is a suspected variable star that varies in apparent magnitude from 6.82−6.88.[4]

When observed with the Spitzer Space Telescope, this star did not display an excess emission of infrared radiation, which may otherwise indicate the presence of an orbiting debris disk.[7] The space velocity components of this star are (U, V, W) = (–41, –26, +6) km/s.[9]

Sources give contradictory measurements for the abundance of elements in this star. Lawler et al. (2009) lists an iron abundance of [Fe/H] = 0.27 dex,[7] while Valenti et al. (2005) has an iron abundance of [Fe/H] = –0.15.[6]

References

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