HD 194937

Last updated
HD 194937
Delphinus constellation map.svg
Red circle.svg
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]
Distance 367.5 ± 0.9  ly
(112.7 ± 0.3  pc)
Details
Mass 1.51 [6]   M☉
Radius 9.68±0.49 [7]   R☉
Luminosity 52.6±0.2 [1]   L☉
Surface gravity (log g)2.67±0.02 [8]   cgs
Temperature 4,786 [9]   K
Metallicity [Fe/H]−0.03 [9]   dex
Rotational velocity (v sin i)1.8 [9]  km/s
Age 2.88 [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
SIMBAD data

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]

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References

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  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 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. 1 2 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. 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.
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  7. 1 2 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. 1 2 3 4 5 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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