HD 189245

HD 189245
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Sagittarius
Right ascension 20h 00m 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]
Distance72.23 ± 0.09 ly
(22.15 ± 0.03 pc)
Absolute magnitude (MV)4.06[6]
Details
Surface gravity (log g)4.31[3] cgs
Temperature6,333[3] K
Metallicity [Fe/H]−0.09[3] dex
Rotational velocity (v sin i)72.6[7] km/s
Age100 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
SIMBADdata

HD 189245 is the Henry Draper catalogue designation for a solitary[10] star in the southern constellation of Sagittarius. 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]

  1. ^ a b c d e Cite error: The named reference GaiaEDR3 was invoked but never defined (see the help page).
  2. ^ a b c Cite error: The named reference mnrassa31_7 was invoked but never defined (see the help page).
  3. ^ a b c d e f Cite error: The named reference aj132_1_161 was invoked but never defined (see the help page).
  4. ^ a b c Cite error: The named reference aj143_6_135 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Nordström2004 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference Reiners2006 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference aaa493_3_1099 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference ua1879 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference mnras389_2_869 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Jeffries1993 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Nakajima2012 was invoked but never defined (see the help page).