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Phi Herculis

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]

References

  1. ^ a b c d e f van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.
  2. ^ a b c d Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data, SIMBAD, Bibcode:1986EgUBV........0M.
  3. ^ a b Abt, Helmut A.; Morrell, Nidia I. (1995), "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars", Astrophysical Journal Supplement, 99: 135, Bibcode:1995ApJS...99..135A, doi:10.1086/192182.
  4. ^ a b c d e f g h i j k Zavala, R. T.; et al. (February 2007), "The Mercury-Manganese Binary Star φ Herculis: Detection and Properties of the Secondary and Revision of the Elemental Abundances of the Primary", The Astrophysical Journal, 655 (2): 1046–1057, arXiv:astro-ph/0610811, Bibcode:2007ApJ...655.1046Z, doi:10.1086/510108, S2CID 118994617.
  5. ^ a b Samus', N. N.; Kazarovets, E. V.; Durlevich, O. V.; Kireeva, N. N.; Pastukhova, E. N. (2017), "General catalogue of variable stars: Version GCVS 5.1", Astronomy Reports, 61 (1): 80, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.
  6. ^ de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, S2CID 59451347, A61.
  7. ^ a b c d e f g Torres, Guillermo (June 2007), "Astrometric-Spectroscopic Determination of the Absolute Masses of the HgMn Binary Star φ Herculis", The Astronomical Journal, 133 (6): 2684–2695, arXiv:astro-ph/0703193, Bibcode:2007AJ....133.2684T, doi:10.1086/516756, S2CID 11625161.
  8. ^ McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x, S2CID 118665352.
  9. ^ "phi Her", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2017-04-05.
  10. ^ Kochukhov, O.; Khalack, V.; Kobzar, O.; Neiner, C.; Paunzen, E.; Labadie-Bartz, J.; David-Uraz, A. (October 2021), "TESS survey of rotational and pulsational variability of mercury–manganese stars", Monthly Notices of the Royal Astronomical Society, 506 (4): 5328–5344, arXiv:2107.09096, doi:10.1093/mnras/stab2107.
  11. ^ MAST: Barbara A. Mikulski Archive for Space Telescopes, Space Telescope Science Institute, retrieved 8 December 2021.
  12. ^ Kazarovets, E. V.; et al. (1999), "The 74th Special Name-list of Variable Stars", Information Bulletin on Variable Stars, 4659 (4659): 1, Bibcode:1999IBVS.4659....1K.
  13. ^ a b Zavala, R. T.; et al. (December 2004), "Detection of the Secondary of the HgMn star Phi Herculis with the Navy Prototype Optical Interferometer", Bulletin of the American Astronomical Society, 36: 1527, Bibcode:2004AAS...20510715Z.