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HD 194937

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HD 194937
Location of HD 194937 on the map (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Delphinus
Right ascension 20h 28m 07.53959s[1]
Declination +08° 26′ 14.8132″[1]
Apparent magnitude (V) 6.23±0.01[2]
Characteristics
Spectral type G9 III[3]
U−B color index +0.92[4]
B−V color index +1.08[4]
Astrometry
Radial velocity (Rv)−10.8±0.3[5] km/s
Proper motion (μ) RA: +40.673 mas/yr[1]
Dec.: +16.897 mas/yr[1]
Parallax (π)8.874 ± 0.0216 mas[1]
Distance367.5 ± 0.9 ly
(112.7 ± 0.3 pc)
Details
Mass1.51[6] M☉
Radius9.68±0.49[7] R☉
Luminosity52.6±0.2[1] L☉
Surface gravity (log g)2.67±0.02[8] cgs
Temperature4,786[9] K
Metallicity [Fe/H]−0.03[9] dex
Rotational velocity (v sin i)1.8[9] km/s
Age2.88[6] Gyr
Other designations
7 G. Delphini[10], AG+08°2789, BD+07°4477, FK5 3638, GC 28466, HD 194937, HIP 100953, HR 7820, SAO 125841[11]
Database references
SIMBADdata

HD 194937 (HR 7820; 7 G. Delphini) is a star located in the equatorial constellation Delphinus, the dolphin. It has an apparent magnitude of 6.23,[2] making it barely visible to the naked eye even under ideal conditions. Gaia DR3 parallax measurements imply a distance of 367.5 light years[1] and it is currently drifting closer with a heliocentric radial velocity of −10.8 km/s.[5] At its current distance, HD 194937's brightness is diminished by an interstellar extinction of 0.24 magnitudes.[12]

HD 194937 has a stellar classification of G9 III,[3] indicating that it is an evolved G-type giant star that has ceased hydrogen fusion at its core and left the main sequence. The object has 1.51 times the mass of the Sun but at the age of 2.88 billion years,[6] it has expanded to 9.68 times the radius of the Sun.[7] It radiates 52.6 times the Sun's luminosity[1] from its enlarged photosphere at an effective temperature of 4,786 K,[9] giving the star an orange hue when it is viewed in the night sky. HD 194937 is slightly metal deficient with an iron abundance 93.3% of the Sun's and it spins slowly with a projected rotational velocity of 1.8 km/s.[9]

References

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  1. ^ a b c d e f g 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. ^ a b 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. ^ a b Halliday, Ian (September 1955). "Luminosity Function and Space Motions of G8-K1 Stars Derived from Spectroscopic Parallaxes". The Astrophysical Journal. 122: 222. Bibcode:1955ApJ...122..222H. doi:10.1086/146080. ISSN 0004-637X. S2CID 119640884.
  4. ^ a b Johnson, H. L.; Mitchell, R. I.; Iriarte, B.; Wisniewski, W. Z. (1966). "UBVRIJKL Photometry of the Bright Stars". Communications of the Lunar and Planetary Laboratory. 4: 99–110. Bibcode:1966CoLPL...4...99J.
  5. ^ a b 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.
  6. ^ a b c Dotter, Aaron; Chaboyer, Brian; Jevremović, Darko; Kostov, Veselin; Baron, E.; Ferguson, Jason W. (September 2008). "The Dartmouth Stellar Evolution Database". The Astrophysical Journal Supplement Series. 178 (1): 89–101. arXiv:0804.4473. Bibcode:2008ApJS..178...89D. doi:10.1086/589654. eISSN 1538-4365. ISSN 0067-0049. S2CID 119290835.
  7. ^ a b Kervella, P.; Thévenin, F.; Di Folco, E.; Ségransan, D. (April 8, 2004). "The angular sizes of dwarf stars and subgiants: Surface brightness relations calibrated by interferometry". 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. S2CID 6077801.
  8. ^ Luck, R. Earle; Heiter, Ulrike (2007). "Giants in the Local Region". The Astronomical Journal. 133 (6): 2464–2486. Bibcode:2007AJ....133.2464L. doi:10.1086/513194. ISSN 0004-6256. S2CID 121584418. Retrieved January 4, 2025.
  9. ^ a b c d e Takeda, Yoichi; Tajitsu, Akito (August 1, 2017). "On the observational characteristics of lithium-enhanced giant stars in comparison with normal red giants" (PDF). Publications of the Astronomical Society of Japan. 69 (4). arXiv:1706.02273. Bibcode:2017PASJ...69...74T. doi:10.1093/pasj/psx057. ISSN 0004-6264. S2CID 119451146. Retrieved January 4, 2025.
  10. ^ 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.
  11. ^ "HD 194937". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved January 3, 2024.
  12. ^ 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.
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