Chi Herculis

Not to be confused with X Herculis.
Chi Herculis
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Hercules
Right ascension 15h 52m 40.54114s[1]
Declination +42° 27′ 05.4511″[1]
Apparent magnitude (V) 4.59[2]
Characteristics
Spectral type G0V Fe-0.8 CH-0.5[3]
U−B color index +0.01[2]
B−V color index +0.57[2]
Astrometry
Radial velocity (Rv)−56.09±0.10[4] km/s
Proper motion (μ) RA: +438.816[1] mas/yr
Dec.: +630.313[1] mas/yr
Parallax (π)63.1627 ± 0.1490 mas[5]
Distance51.6 ± 0.1 ly
(15.83 ± 0.04 pc)
Absolute magnitude (MV)+3.59[6]
Orbit[7]
Period (P)51.2865±0.4082 d
Semi-major axis (a)0.96±0.58″
Eccentricity (e)0.0000
Inclination (i)131.68±27.61°
Longitude of the node (Ω)51.69±37.96°
Periastron epoch (T)48349.0039±4.4425
Argument of periastron (ω)
(secondary)		0.00°
Details
Mass1.054+0.015
−0.054[8] M☉
Radius1.71+0.04
−0.05[8] R☉
Luminosity3.24[6] L☉
Surface gravity (log g)4.02+0.02
−0.03[8] cgs
Temperature5,837[3] K
Metallicity [Fe/H]−0.45[3] dex
Rotational velocity (v sin i)2.4[9] km/s
Age7.4[10] Gyr
Other designations
χ Her, 1 Her, BD+42° 2648, FK5 1166, GJ 602, HD 142373, HIP 77760, HR 5914, SAO 45772, WDS J16254+1402AB[11]
Database references
SIMBADdata

Chi Herculis, Latinized from χ Herculis, is a Sun-like[12] star in the northern constellation of Hercules. Based upon an annual parallax shift of 63.16 mas as seen from Earth, it is located 51.6 light years from the Sun. The star is faintly visible to the naked eye with an apparent visual magnitude of 4.59.[2] It has a relatively high proper motion, showing a transverse movement of 0.769 arc seconds per year[13] and is drifting closer to the Sun with a radial velocity of −56 km/s.[4]

This is a suspected binary star system for which orbital elements have been published, listing a circular orbit with period of 51.3 days.[7] However, sources do not confirm this and so the binarity remains in doubt.[14] The observable component is a G-type main sequence star with a stellar classification of G0V Fe-0.8 CH-0.5,[3] indicating abnormal deficiencies in iron and the CH molecule. The surface magnetic activity for this star is distinctly lower than the typical level for regular stars, and hence it is considered a good candidate for being in a Maunder minimum phase.[15]

Chi Herculis is an older star with an estimated age of 7.4 billion years and is spinning with a projected rotational velocity of 2.4.[9] It has a mass slightly higher than the Sun and 1.7 times the Sun's radius.[8] The star's photosphere is radiating 3.24[6] times the Sun's luminosity at an effective temperature of 5,837.[3] Chi Herculis has been examined for the presence of an infrared excess that could indicate an orbiting debris disk, but none was found.[12] The low metal content and a relatively high velocity of 80 kilometers per second suggest that the star is a visitor from another part of the Galaxy, and is just moving through the local neighborhood.[16]

  1. ^ a b c d Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference Mermilliod1986 was invoked but never defined (see the help page).
  3. ^ a b c d e Cite error: The named reference Gray2006 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference deBruijne2012 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference vanLeeuwen2007 was invoked but never defined (see the help page).
  6. ^ a b c Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference Hartkopf2006 was invoked but never defined (see the help page).
  8. ^ a b c d Cite error: The named reference Takeda2007 was invoked but never defined (see the help page).
  9. ^ a b Cite error: The named reference Fekel1997 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Casagrande2011 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  12. ^ a b Cite error: The named reference Maldonado2012 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference Lepine2005 was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference Rodriguez2015 was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference Hempelmann1996 was invoked but never defined (see the help page).
  16. ^ Kaler, Jim. "Chi Herculis". stars.astro.illinois.edu.