HD 194783

HD 194783
Location of HD 194783 on the map (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Microscopium
Right ascension 20h 28m 46.74360s[1]
Declination −35° 35′ 45.1068″[1]
Apparent magnitude (V) 6.08±0.01[2]
Characteristics
Spectral type B8 II/III[3] or B9pHgMn[4]
B−V color index −0.11[5]
Astrometry
Radial velocity (Rv)−9.7±1.2[6] km/s
Proper motion (μ) RA: +2.959 mas/yr[1]
Dec.: −21.638 mas/yr[1]
Parallax (π)4.3936 ± 0.0714 mas[1]
Distance740 ± 10 ly
(228 ± 4 pc)
Absolute magnitude (MV)−0.59[7] or −1.10[8]
Details
Mass4.03±0.05[1] M☉
Radius4.19±0.21[9] R☉
Luminosity390±12[1] L☉
Surface gravity (log g)3.75[10] cgs
Temperature14,028[8] K
Metallicity [Fe/H]−0.20[10] dex
Rotation6 d[11]
Rotational velocity (v sin i)≤30[11] km/s
Age70[8] Myr
Other designations
2 G. Microscopii[12], CD−36°14166, CPD−36°9170, FK5 3637, GC 28464, HD 194783, HIP 101017, HR 7817, SAO 212160, TIC 34864575[13]
Database references
SIMBADdata

HD 194783 (HR 7817; 2 G. Microscopii) is a solitary star located in the southern constellation Microscopium near the border with Sagittarius. It is barely visible to the naked eye as a bluish-white-hued point of light with an apparent magnitude of 6.08.[2] The object is located relatively far at a distance of 740 light-years based on Gaia DR3 parallax measurements,[1] but it is drifting closer with a heliocentric radial velocity of −9.7 km/s.[6] At its current distance, HD 194783's brightness is diminished by an interstellar extinction of 0.31 magnitudes[14] and it has an absolute magnitude of either −0.59 or −1.10,[7][8] depending on the source.

HD 194783 has a stellar classification of B8 II/III,[3] indicating that it is an evolved B-type star with the blended luminosity class of a bright giant and a lower luminosity giant star. It has also been given a class of B9pHgMn,[4] indicating that it is a chemically peculiar mercury-manganese star. It has 4.03 times the mass of the Sun[1] and a slightly enlarged radius 4.19 times that of the Sun's.[9] It radiates 390 times the luminosity of the Sun[1] from its photosphere at an effective temperature of 14,028 K.[8] The heavy metal (iron) to hydrogen ratio–what astronomers dub as the star's metallicity–is 63% that of the Sun's.[10] HD 194783 is estimated to be approximately 70 million years old.[8]

In 1989, HD 194783 was reported to be a spectrum variable with a period of 6 days. The projected rotational velocity of the star is not known, but it is said to be no higher than 30 km/s.[11] HD 194783 was also observed to have a relatively weak magnetic field of about −43 gauss.[15]

  1. ^ a b c d e f g h i Cite error: The named reference GaiaDR3 was invoked but never defined (see the help page).
  2. ^ a b Cite error: The named reference Tycho2000 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference Houk1982 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Andersen1977 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Corben1971 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference Gontcharov2006 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  8. ^ a b c d e f Cite error: The named reference Westin1985 was invoked but never defined (see the help page).
  9. ^ a b Cite error: The named reference Kervella2004 was invoked but never defined (see the help page).
  10. ^ a b c Cite error: The named reference Anders2022 was invoked but never defined (see the help page).
  11. ^ a b c Cite error: The named reference Rajamohan1989 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Gould1879 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference Gontcharov2017 was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference Hubrig2006 was invoked but never defined (see the help page).