HD 198357
Location of HD 198357 on the map (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Microscopium
Right ascension 20h 51m 00.75817s[1]
Declination −37° 54′ 47.9922″[1]
Apparent magnitude (V) 5.50±0.01[2]
Characteristics
Spectral type K3 III[3] or K3 II[4]
B−V color index +1.38[5]
Astrometry
Radial velocity (Rv)16.5±2.9[6] km/s
Proper motion (μ) RA: −7.436 mas/yr[1]
Dec.: −17.374 mas/yr[1]
Parallax (π)5.7348 ± 0.0797 mas[1]
Distance569 ± 8 ly
(174 ± 2 pc)
Absolute magnitude (MV)−0.75[7]
Details
Mass1.81±0.44[8] M☉
Radius37.8±1.9[9] R☉
Luminosity417+16
−15[1] L☉
Surface gravity (log g)1.06[10] cgs
Temperature4,318±51[11] K
Metallicity [Fe/H]−0.12[10] dex
Rotational velocity (v sin i)<1.0[12] km/s
Other designations
28 G. Microscopii[13], CD−38°14250, CPD−38°8121, GC 29053, HD 198357, HIP 102916, HR 7971, SAO 212488[14]
Database references
SIMBADdata

HD 198357 (HR 7971; 28 G. Microscopii) is a solitary star located in the southern constellation Microscopium. It is faintly visible to the naked eye as an orange-hued point of light with an apparent magnitude of 5.50.[2] Gaia DR3 parallax measurements imply a distance of 569 light-years[1] and the object is currently receding with a heliocentric radial velocity of 16.5 km/s.[6] At its current distance, HD 198357's brightness is diminished by 0.18 magnitudes due to interstellar extinction[15] and it has an absolute magnitude of −0.75.[7]

HD 198357 has a stellar classification of K3 III,[3] indicating that it is an evolved K-type giant star. David Stanley Evans gave a classification of K3 II, indicating a more evolved bright giant.[4] It has 1.81 times the mass of the Sun[8] but it has expanded to 37.8 times the radius of the Sun.[9] It radiates 417 times the luminosity of the Sun[1] from its photosphere at an effective temperature of 4,318 K.[11] HD 198357 is slightly metal deficient with an iron abundance three-quarters that of the Sun or [Fe/H] = −0.12[10] and it spins too slowly for its projected rotational velocity to be measured accurately.[12] HD 198357 has a peculiar velocity of 27.7+3.9
−4.1 km/s, indicating that it may be a runaway star (46% chance).[16]

References

  1. 1 2 3 4 5 6 7 8 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  2. 1 2 Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (March 2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27–L30. Bibcode:2000A&A...355L..27H. ISSN 0004-6361. S2CID 17128864.
  3. 1 2 Houk, N. (1982). Michigan Catalogue of Two-dimensional Spectral Types for the HD stars. Declinations −40° to −26°. Vol. 3. Bibcode:1982mcts.book.....H.
  4. 1 2 Evans, D. S. (1966). "Fundamental data for Southern stars (6th list)". Royal Greenwich Observatory Bulletins. 110: 185. Bibcode:1966RGOB..110..185E.
  5. ↑ Lake, R. (1965). "Photometric Magnitudes and Colours for Bright Southern Stars (Sixth List)". Monthly Notes of the Astronomical Society of South Africa. 24: 41. Bibcode:1965MNSSA..24...41L. ISSN 0024-8266.
  6. 1 2 Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35,495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. eISSN 1562-6873. ISSN 1063-7737. S2CID 119231169.
  7. 1 2 Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331–346. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. eISSN 1562-6873. ISSN 1063-7737. S2CID 119257644.
  8. 1 2 Hohle, M.M.; Neuhäuser, R.; Schutz, B.F. (April 2010). "Masses and luminosities of O- and B-type stars and red supergiants". Astronomische Nachrichten. 331 (4): 349–360. arXiv:1003.2335. Bibcode:2010AN....331..349H. doi:10.1002/asna.200911355. eISSN 1521-3994. ISSN 0004-6337. S2CID 111387483.
  9. 1 2 Kervella, P.; Thévenin, F.; Di Folco, E.; Ségransan, D. (October 2004). "The angular sizes of dwarf stars and subgiants". Astronomy & Astrophysics. 426 (1): 297–307. arXiv:astro-ph/0404180. Bibcode:2004A&A...426..297K. doi:10.1051/0004-6361:20035930. eISSN 1432-0746. ISSN 0004-6361.
  10. 1 2 3 Park, Sunkyung; Kang, Wonseok; Lee, Jeong-Eun; Lee, Sang-Gak (August 21, 2013). "Wilson-Bappu Effect: Extended to Surface Gravity". The Astronomical Journal. American Astronomical Society. 146 (4): 73. arXiv:1307.0592. Bibcode:2013AJ....146...73P. doi:10.1088/0004-6256/146/4/73. ISSN 0004-6256. S2CID 119187733.
  11. 1 2 Stassun, Keivan G.; et al. (9 September 2019). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal. 158 (4): 138. arXiv:1905.10694. Bibcode:2019AJ....158..138S. doi:10.3847/1538-3881/ab3467. eISSN 1538-3881. hdl:1721.1/124721. S2CID 166227927.
  12. 1 2 De Medeiros, J. R.; Alves, S.; Udry, S.; Andersen, J.; Nordström, B.; Mayor, M. (January 2014). "A catalog of rotational and radial velocities for evolved stars V: Southern stars *". Astronomy & Astrophysics. 561: A126. arXiv:1312.3474. Bibcode:2014A&A...561A.126D. doi:10.1051/0004-6361/201220762. eISSN 1432-0746. ISSN 0004-6361. S2CID 54046583.
  13. ↑ Gould, Benjamin Apthorp (1878). "Uranometria Argentina : brillantez y posicion de las estrellas fijas, hasta la septima magnitud, comprendidas dentro de cien grados del polo austral : con atlas". Resultados del Observatorio Nacional Argentino. 1. Bibcode:1879RNAO....1.....G.
  14. ↑ "HD 198357". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved August 6, 2023.
  15. ↑ Gontcharov, George A.; Mosenkov, Aleksandr V. (28 September 2017). "Verifying reddening and extinction for Gaia DR1 TGAS main sequence stars". Monthly Notices of the Royal Astronomical Society. 472 (4): 3805–3820. arXiv:1709.01160. Bibcode:2017MNRAS.472.3805G. doi:10.1093/mnras/stx2219. eISSN 1365-2966. ISSN 0035-8711. S2CID 118879856.
  16. ↑ Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (October 12, 2010). "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun". Monthly Notices of the Royal Astronomical Society. Oxford University Press (OUP). 410 (1): 190–200. arXiv:1007.4883. Bibcode:2011MNRAS.410..190T. doi:10.1111/j.1365-2966.2010.17434.x. ISSN 0035-8711. S2CID 118629873.
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