| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Sagittarius |
| Right ascension | 20h00m 20.249s[1] |
| Declination | −33° 42′ 12.42″[1] |
| Apparent magnitude (V) | 5.66[2] |
| Characteristics | |
| Spectral type | F8.5 V Fe−0.6 CH−0.5[3] |
| U−B color index | −0.04[2] |
| B−V color index | +0.498[4] |
| Astrometry | |
| Radial velocity (Rv) | −13.2[5] km/s |
| Proper motion (μ) | RA: +128.794 mas/yr[1] Dec.: −289.360 mas/yr[1] |
| Parallax (π) | 45.1537 ± 0.0551 mas[1] |
| Distance | 72.23 ± 0.09 ly (22.15 ± 0.03 pc) |
| Absolute magnitude (MV) | 4.06[6] |
| Details | |
| Surface gravity (log g) | 4.31[3] cgs |
| Temperature | 6,333[3] K |
| Metallicity [Fe/H] | −0.09[3] dex |
| Rotational velocity (v sin i) | 72.6[7] km/s |
| Age | 100 or 500[4] Myr |
| Other designations | |
262 G. Sgr[8], CD−34° 14082, GJ 773.4, 9679, HD 189245, HIP 98470, HR 7631, SAO 211724[9] | |
| Database references | |
| SIMBAD | data |
HD 189245 is the Henry Draper catalogue designation for a solitary[10] star in the southern constellationofSagittarius. It has an apparent visual magnitude of 5.66,[2] which means it is faintly visible to the naked eye. Parallax measurements from the Hipparcos satellite indicate a distance of 72 light years from the Sun.[1] It is drifting closer with a heliocentric radial velocity of −13 km/s.[5]
The stellar classification of this star is F8.5 V Fe−0.6 CH−0.5,[3] indicating that it is an F-type main sequence star with a spectrum that shows deficiencies in iron (Fe) and methylidyne (CH) in its outer atmosphere. It is a variable star with an active chromosphere and is a source of X-ray emission.[3][11] HD 189245 is spinning rapidly with a projected rotational velocity of 72.6[7] km/s. Gyrochronology indicates this is a young star with an estimated age of 500 million years. However, the amount of X-ray emission suggests an even younger star that is roughly 100 million years old.[4]
The velocity components of HD 189245 indicate that it is a likely member of the AB Doradus moving group of stars, which share a common motion through space. This group has an age of around 50 million years and is centered at a point 98 ly (30 pc) from the Sun.[12]
{{citation}}: CS1 maint: postscript (link)
