Phi Herculis

Phi Herculis

φ Herculis in optical light
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Hercules
Right ascension 16h 08m 46.17745s[1]
Declination +44° 56′ 05.6663″[1]
Apparent magnitude (V) 4.24[2]
Characteristics
Spectral type B9VspHgMn[3] + A8V[4]
U−B color index −0.23[2]
B−V color index −0.06[2]
Variable type α2 CVn?[5]
Astrometry
Radial velocity (Rv)−16.3±0.4[6] km/s
Proper motion (μ) RA: −26.63[1] mas/yr
Dec.: +36.76[1] mas/yr
Parallax (π)15.99 ± 0.45 mas[1]
Distance204 ± 6 ly
(63 ± 2 pc)
Absolute magnitude (MV)A: 0.100 ± 0.059
B: 2.670 ± 0.074[7]
Orbit[7]
Period (P)564.834±0.038 d
Semi-major axis (a)32.027±0.028 mas
Eccentricity (e)0.52614±0.00086
Inclination (i)9.1±0.4°
Longitude of the node (Ω)190.4±1.4°
Periastron epoch (T)2450121.43 ± 0.20 JD
Argument of periastron (ω)
(secondary)		350.3±1.4°
Semi-amplitude (K1)
(primary)		2.772±0.073 km/s
Semi-amplitude (K2)
(secondary)		8.1[4] km/s
Details
φ Her A
Mass3.05±0.24[7] M☉
Luminosity72[8] L☉
Surface gravity (log g)4.05±0.15[4] cgs
Temperature11,525±150[4] K
Metallicity [Fe/H]−0.03[7] dex
Rotational velocity (v sin i)8.0±1.0[4] km/s
Age210[7] Myr
φ Her B
Mass1.614±0.066[7] M☉
Surface gravity (log g)4.30±0.15[4] cgs
Temperature8,000±150[4] K
Rotational velocity (v sin i)50.0±3.0[4] km/s
Other designations
φ Her, 11 Her, BD+45°2376, FK5 601, HD 145389, HIP 79101, HR 6023, SAO 45911.[9]
Database references
SIMBADdata

Phi Herculis (φ Her) is a binary star[4] system in the northern constellation of Hercules. Based upon an annual parallax shift of 15.99 mas as seen from Earth,[1] it is located around 204 light years from the Sun. With a combined apparent visual magnitude of 4.24,[2] it is bright enough to be seen with the naked eye.

A light curve for Phi Herculis, assuming a 3.708 day period,[10] plotted from TESS data[11]

This is a single-lined spectroscopic binary star system with an orbital period of 564.8 days and an eccentricity of 0.526.[7] The primary, component A, is a B-type main sequence star with a stellar classification of B9VspHgMn.[3] It is a chemically peculiar star of the type called a mercury-manganese star.[4] The star is tentatively catalogued as an Alpha2 Canum Venaticorum variable, with brightness variations of just 0.01 magnitudes.[5][12]

The secondary, component B, was first separated via interferometry in 2004.[13] It is an A-type main sequence star of class A8V.[4] The magnitude difference between the two components is 2.64.[13]

  1. ^ a b c d e f Cite error: The named reference vanLeeuwen2007 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 Cite error: The named reference Abt1995 was invoked but never defined (see the help page).
  4. ^ a b c d e f g h i j k Cite error: The named reference Adelman2007 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference gcvs was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference deBruijne2012 was invoked but never defined (see the help page).
  7. ^ a b c d e f g Cite error: The named reference Torres2007 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference Mcdonald2012 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 Kochukhov was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference MAST was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Kazarovets1999 was invoked but never defined (see the help page).
  13. ^ a b Cite error: The named reference Zavala2004 was invoked but never defined (see the help page).