HD 198404

HD 198404 (HR 7975) is a star in the equatorial constellation Delphinus. It has an apparent magnitude of 6.19,^[2] allowing it to be faintly seen with the naked eye. Parallax measurements place the object at a distance of 395 light years^[1] and it is approaching the Solar System with a heliocentric radial velocity of −21.6 km/s.^[5]

HD 198404

Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Delphinus
Right ascension	20h 49m 59.0925s[1]
Declination	+05° 32′ 40.5081″[1]
Apparent magnitude (V)	6.19±0.01[2]
Characteristics
Spectral type	K0[3]
U−B color index	+0.79[4]
B−V color index	+0.98[4]
Astrometry
Radial velocity (Rv)	−21.63±0.31[5] km/s
Proper motion (μ)	RA: +43.408 mas/yr[1] Dec.: −0.174 mas/yr[1]
Parallax (π)	8.2537 ± 0.1261 mas[1]
Distance	395 ± 6 ly (121 ± 2 pc)
Absolute magnitude (MV)	+0.7[6]
Details
Mass	3.12[7] M☉
Radius	10.54[8] R☉
Luminosity	56.3[9] L☉
Surface gravity (log g)	2.8[7] cgs
Temperature	4,809[10] K
Metallicity [Fe/H]	+0.17[7] dex
Other designations
21 G. Delphini, AG+05°3046, BD+05°4626, GC 29044, HD 198404, HIP 102833, HR 7975, SAO 126267, WDS J20500+0533A[11][12]
Database references
SIMBAD	data

HD 198404 has a simple stellar classification of K0,^[3] indicating that it is a K-type star. Its enlarged diameter of 10.54 R_☉^[8] and its low surface gravity^[7] suggest that it has evolved away from the main sequence to become a giant star.^[7] HD 198404 has 3.12 times the mass of the Sun^[7] and radiates at 56 times the luminosity of the Sun^[9] from its photosphere at an effective temperature of 4,809 K,^[10] giving it a yellowish orange hue. The star is metal enriched, having an iron abundance 48% greater than that of the Sun.^[7]

HD 198404 has an optical companion located 78.2″ away along a position angle of 127° (as of 2014).^[13]

References

1. Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
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.
3. Cannon, Annie Jump; Pickering, Edward Charles (1923). "The Henry Draper catalogue : 19h and 20h". Annals of Harvard College Observatory. 98: 1. Bibcode:1923AnHar..98....1C.
4. Cousins, A. W. J. (16 November 1964). "Photometric Data for Stars in the Equatorial Zone (Seventh List)". Monthly Notes of the Astronomical Society of South Africa. 23: 175. Bibcode:1964MNSSA..23..175C. ISSN 0024-8266.
5. Famaey, B.; Jorissen, A.; Luri, X.; Mayor, M.; Udry, S.; Dejonghe, H.; Turon, C. (January 2005). "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters". Astronomy and Astrophysics. 430: 165. arXiv:astro-ph/0409579. Bibcode:2005A&A...430..165F. doi:10.1051/0004-6361:20041272. S2CID 17804304.
6. 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. ISSN 1063-7737. S2CID 119257644.
7. Liu, Y. J.; Tan, K. F.; Wang, L.; Zhao, G.; Sato, Bun'ei; Takeda, Y.; Li, H. N. (31 March 2014). "The Lithium Abundances of a Large Sample of Red Giants". The Astrophysical Journal. 785 (2): 94. arXiv:1404.1687. Bibcode:2014ApJ...785...94L. doi:10.1088/0004-637X/785/2/94. eISSN 1538-4357. ISSN 0004-637X.
8. Kervella, Pierre; Arenou, Frédéric; Thévenin, Frédéric (2022). "Stellar and substellar companions from Gaia EDR3". Astronomy & Astrophysics. 657: A7. arXiv:2109.10912. Bibcode:2022A&A...657A...7K. doi:10.1051/0004-6361/202142146. eISSN 1432-0746. ISSN 0004-6361.
9. McDonald, I.; Zijlstra, A. A.; Boyer, M. L. (21 November 2012). "Fundamental parameters and infrared excesses of Hipparcos stars: Parameters and IR excesses from Hipparcos". Monthly Notices of the Royal Astronomical Society. 427 (1): 343–357. arXiv:1208.2037. Bibcode:2012MNRAS.427..343M. doi:10.1111/j.1365-2966.2012.21873.x. ISSN 0035-8711.
10. Anders, F.; et al. (August 2019). "Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18". Astronomy & Astrophysics. 628: A94. arXiv:1904.11302. Bibcode:2019A&A...628A..94A. doi:10.1051/0004-6361/201935765. ISSN 0004-6361.
11. "HR 7975". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved June 21, 2022.
12. 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.
13. Mason, Brian D.; Wycoff, Gary L.; Hartkopf, William I.; Douglass, Geoffrey G.; Worley, Charles E. (December 2001). "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog". The Astronomical Journal. 122 (6): 3466–3471. Bibcode:2001AJ....122.3466M. doi:10.1086/323920. ISSN 0004-6256.