98 Herculis

98 Herculis is a single[6] star located approximately 590[1] light years from the Sun in the northern constellation Hercules. It is visible to the naked eye as a dim, red-hued point of light with an apparent visual magnitude of 4.96.[2] The brightness of the star is diminished by an extinction of 0.19 due to interstellar dust.[7] The star is moving closer to the Earth with a heliocentric radial velocity of −19 km/s.[2]

98 Herculis
Observation data
Epoch J2000      Equinox J2000
Constellation Hercules
Right ascension 18h 06m 01.90000s[1]
Declination +22° 13′ 07.9396″[1]
Apparent magnitude (V) 4.96[2]
Characteristics
Spectral type M3-SIII[3] or M3IIIBa0.2[4]
B−V color index 1.656±0.062[2]
Astrometry
Radial velocity (Rv)−19.48±0.21[2] km/s
Proper motion (μ) RA: −12.028[1] mas/yr
Dec.: −6.067[1] mas/yr
Parallax (π)5.5201 ± 0.1610[1] mas
Distance590 ± 20 ly
(181 ± 5 pc)
Absolute magnitude (MV)−1.78[2]
Details
Radius85.39+10.72
−8.50[1] R☉
Luminosity1,329.7±44.7[1] L☉
Temperature3,772+203
−217[1] K
Other designations
98 Her, NSV 10208, BD+22° 3273, HD 165625, HIP 88657, HR 6765, SAO 85725[5]
Database references
SIMBADdata

This is an aging red giant star on the asymptotic giant branch[8] with a stellar classification of M3-SIII,[3] where the suffix notation indicating this is an S-type star. It is a mild barium star with an intensity class of 0.2,[9][4] and is a suspected variable star, although Percy and Shepherd (1992) were unable to confirm this.[10] With the hydrogen at its core exhausted, the star has expanded to around 85[1] times the Sun's radius. It is radiating 1,330[1] times the luminosity of the Sun from its swollen photosphere at an effective temperature of 3,772 K.[1]

References
  1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
  3. Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series, 71: 245, Bibcode:1989ApJS...71..245K, doi:10.1086/191373.
  4. Lu, Phillip K. (1991), "Taxonomy of barium stars", Astronomical Journal, 101: 2229, Bibcode:1991AJ....101.2229L, doi:10.1086/115845.
  5. "98 Her". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-06-17.
  6. Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
  7. Famaey, B.; et al. (January 2005), "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters", Astronomy and Astrophysics, 430 (1): 165–186, arXiv:astro-ph/0409579, Bibcode:2005A&A...430..165F, doi:10.1051/0004-6361:20041272, S2CID 17804304.
  8. Eggen, Olin J. (July 1992), "Asymptotic giant branch stars near the sun", Astronomical Journal, 104 (1): 275–313, Bibcode:1992AJ....104..275E, doi:10.1086/116239.
  9. Gomez, A. E.; et al. (1997), "Absolute magnitudes and kinematics of barium stars", Astronomy and Astrophysics, 319: 881, Bibcode:1997A&A...319..881G.
  10. Percy, J. R.; Shepherd, C. W. (October 1992), "A Photometric Survey of Small-Amplitude Red Variables", Information Bulletin on Variable Stars, 3792: 1, Bibcode:1992IBVS.3792....1P.
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