42 Herculis

42 Herculis

42 Herculis in optical light
Observation data
Epoch J2000      Equinox J2000
Constellation Hercules
Right ascension 16h 38m 44.84465s[1]
Declination +48° 55′ 42.0160″[1]
Apparent magnitude (V) 4.86[2]
Characteristics
Evolutionary stage asymptotic giant branch[3]
Spectral type M2.5III[3]
B−V color index 1.562±0.011[2]
Astrometry
Radial velocity (Rv)−55.74±0.33[2] km/s
Proper motion (μ) RA: −47.768[1] mas/yr
Dec.: +27.349[1] mas/yr
Parallax (π)7.2737 ± 0.1764 mas[1]
Distance450 ± 10 ly
(137 ± 3 pc)
Absolute magnitude (MV)−0.65[2]
Details
Radius63.81+5.20
−7.75[1] R☉
Luminosity733.6±20.5[1] L☉
Surface gravity (log g)1.50[4] cgs
Temperature3,760.5+251.5
−144.5[1] K
Other designations
42 Her, NSV 7896, BD+49°2531, FK5 1434, HD 150450, HIP 81497, HR 6200, SAO 46210, WDS J16387+4856[5]
Database references
SIMBADdata

42 Herculis is a single[6] star located around 450[1] light years away from the Sun in the northern constellation of Hercules.[5] It is visible to the naked eye as a faint, red-hued star with an apparent visual magnitude of 4.86.[2] The star is moving closer to the Earth with a heliocentric radial velocity of −56 km/s.[2]

This is an aging red giant star on the asymptotic giant branch with a stellar classification of M2.5III.[3] It has been catalogued as a suspected variable star,[5] although a 1992 photometric survey found the brightness to be constant.[7] Having exhausted the supply of hydrogen at its core, the star has expanded to 64 times the Sun's radius. It is radiating 734 times the luminosity of the Sun from its swollen photosphere at an effective temperature of 3761 K.[1]

There is an unknown source of X-ray and far ultraviolet emission originating from a location offset by more than one arcsecond from the star.[8] This may indicate there is an undetected main sequence companion.[4]

  1. ^ a b c d e f g h i j Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  2. ^ a b c d e f Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  3. ^ a b c Cite error: The named reference Eggen1992 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference ortiz2016 was invoked but never defined (see the help page).
  5. ^ a b c Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Percy1992 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference Famaey2009 was invoked but never defined (see the help page).