Astronomy:HD 198357

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Short description: K-type giant in the constellation Microscopium
HD 198357
Microscopium constellation map.svg
Red circle.svg
Location of HD 198357 on the map (circled)
Observation data
Epoch J2000.0   Equinox (celestial coordinates)
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[1] mas/yr
Dec.: −17.374[1] mas/yr
Parallax (π)5.7348 ± 0.0797[1] mas
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
CD−38°14250, CPD−38°8121, GC 29053, HD 198357, HIP 102916, HR 7971, SAO 212488[13]
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[14] 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).[15]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  2. ↑ 2.0 2.1 Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P. et al. (March 2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics 355: L27–L30. ISSN 0004-6361. Bibcode: 2000A&A...355L..27H. 
  3. ↑ 3.0 3.1 Houk, N. (1982). Michigan Catalogue of Two-dimensional Spectral Types for the HD stars. Declinations −40° to −26°. 3. Bibcode: 1982mcts.book.....H. 
  4. ↑ 4.0 4.1 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. ISSN 0024-8266. Bibcode: 1965MNSSA..24...41L. 
  6. ↑ 6.0 6.1 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. doi:10.1134/S1063773706110065. ISSN 1063-7737. Bibcode: 2006AstL...32..759G. 
  7. ↑ 7.0 7.1 Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331–346. doi:10.1134/S1063773712050015. ISSN 1063-7737. Bibcode: 2012AstL...38..331A. 
  8. ↑ 8.0 8.1 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. doi:10.1002/asna.200911355. ISSN 0004-6337. Bibcode: 2010AN....331..349H. 
  9. ↑ 9.0 9.1 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. doi:10.1051/0004-6361:20035930. ISSN 0004-6361. Bibcode: 2004A&A...426..297K. 
  10. ↑ 10.0 10.1 10.2 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. doi:10.1088/0004-6256/146/4/73. ISSN 0004-6256. Bibcode: 2013AJ....146...73P. 
  11. ↑ 11.0 11.1 Stassun, Keivan G. et al. (9 September 2019). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal 158 (4): 138. doi:10.3847/1538-3881/ab3467. Bibcode: 2019AJ....158..138S. 
  12. ↑ 12.0 12.1 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. doi:10.1051/0004-6361/201220762. ISSN 0004-6361. Bibcode: 2014A&A...561A.126D. 
  13. ↑ "HD 198357". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+198357. 
  14. ↑ 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. doi:10.1093/mnras/stx2219. ISSN 0035-8711. Bibcode: 2017MNRAS.472.3805G. 
  15. ↑ 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. doi:10.1111/j.1365-2966.2010.17434.x. ISSN 0035-8711. Bibcode: 2011MNRAS.410..190T. 
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