FK Comae Berenices

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Template:Short description

FK Comae Berenices
File:FKComLightCurve.png
Light curves for FK Comae Berenices. The main plot shows the short term variability plotted from TESS data;[1] the inset, adapted from Panov and Dimitrov (2007),[2] shows the long term variability.
Observation data
Epoch J2000      Equinox J2000
Constellation Coma Berenices
Right ascension Template:RA[3]
Declination Template:DEC[3]
Apparent magnitude (V) 8.14 – 8.33[4]
Characteristics
Spectral type G4 III[5]
Variable type FK Com[4]
Astrometry
Radial velocity (Rv)Script error: No such module "val".[5] km/s
Proper motion (μ) RA: −51.969[3] mas/yr
Dec.: −22.262[3] mas/yr
Parallax (π)4.6102±0.0446 mas[3]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)1.2[6]
Details
Mass1.1[7] Template:Solar mass
Radius6.99[3] Template:Solar radius
Luminosity26.8[3] Template:Solar luminosity
Surface gravity (log g)2.359[8] cgs
Temperature4,966[3] K
Metallicity [Fe/H]−0.89[7] dex
Rotation2.4 days[9]
Rotational velocity (v sin i)160[10] km/s
Metallicity [Fe/H]{{{metal_fe2}}} dex
Other designations
Template:Odlist[11]
Database references
SIMBADdata

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FK Comae Berenices is a variable star that varies in apparent magnitude between 8.14 and 8.33 over a period of 2.4 days. In 1966, Pavel Fedorovich Chugainov discovered that the star, then called HD 117555, varied in brightness.[12] It was given its variable star designation, FK Comae Berenices, in 1968.[13] It is the prototype for the FK Comae Berenices (FK Com) class of variable stars. The variability of FK Com stars may be caused by large, cool spots on the rotating surfaces of the stars. This star is thought to be the result of a recent binary merger, resulting in a high rate of both spin and magnetic activity.

The spectral class of FK Comae Berenices is G4 III, although it is considered unusual in having very broad absorption lines as well as some emission lines. The broadened spectral lines are due to rapid rotation.[10]

The rotation rate of FK Comae Berenices is unusually fast for a cool giant star. It is speculated that this is due to the merger of a contact binary pair of stars into a single star. The rotation produces extremely strong magnetic fields which are expected to brake the star to a slower rotation rate. Analysis of variability due to star spots on the surface show that the star rotates at different speeds at different latitudes.[9]

FK Comae Berenices is listed as a companion to the slightly brighter HD 117567. The two are not thought to be physically associated, with HD 117567 being a much closer F2 main sequence star.[14]

References

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  3. ↑ a b c d e f g h Template:Cite Gaia DR2
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  5. ↑ a b Script error: No such module "citation/CS1".
  6. ↑ Script error: No such module "citation/CS1".
  7. ↑ a b Script error: No such module "citation/CS1".
  8. ↑ Script error: No such module "citation/CS1".
  9. ↑ a b Script error: No such module "citation/CS1".
  10. ↑ a b Script error: No such module "citation/CS1".
  11. ↑ Template:Cite simbad
  12. ↑ Script error: No such module "Citation/CS1".
  13. ↑ Script error: No such module "Citation/CS1".
  14. ↑ Script error: No such module "citation/CS1".

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External links

Template:Stars of Coma Berenices

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