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HD 204018
location of HD 204018 (circled)
Observation data
Epoch J2000.0      Equinox ICRS
Constellation Microscopium[1]
A
Right ascension 21h 27m 01.62303s[2]
Declination −42° 32′ 52.5560″[2]
Apparent magnitude (V) 5.58±0.01[3]
B
Right ascension 21h 27m 01.75500s[4]
Declination −42° 32′ 55.0458″[4]
Apparent magnitude (V) 8.09±0.01[3]
Characteristics
A
Evolutionary stage subgiant[5]
Spectral type kA4 hF0 V mF6[6]
U−B color index +0.15[7]
B−V color index +0.39[7]
B
Evolutionary stage main sequence[8]
Spectral type F8 V[9]
U−B color index +0.06[9]
B−V color index +0.55[9]
Astrometry
Radial velocity (Rv)18.3±2.8[10] km/s
A
Proper motion (μ) RA: −48.257 mas/yr[2]
Dec.: +13.160 mas/yr[2]
Parallax (π)18.489±0.0498 mas[2]
Distance176.4 ± 0.5 ly
(54.1 ± 0.1 pc)
Absolute magnitude (MV)+1.74[11]
B
Proper motion (μ) RA: −53.002 mas/yr[4]
Dec.: +15.410 mas/yr[4]
Parallax (π)18.5325±0.0349 mas[4]
Distance176.0 ± 0.3 ly
(54.0 ± 0.1 pc)
Absolute magnitude (MV)+4.00[9]
Details
A
Mass1.73[2] M☉
Radius1.09[8] R☉
Luminosity12.8[2] L☉
Surface gravity (log g)3.86±0.08[12] cgs
Temperature6,778[13] K
Rotational velocity (v sin i)85[14] km/s
Age1.36±0.19[2] Gyr
B
Mass1.02[15] M☉
Radius1.09±0.21[16] R☉
Luminosity1.29[8] L☉
Surface gravity (log g)4.29[15] cgs
Temperature6,235±115[17] K
Metallicity [Fe/H]−0.11[18] dex
Rotational velocity (v sin i)72.8[19] km/s
Age3.46[18] Gyr
Other designations
69 G. Microscopii[20], CD−43°14539, CPD−43°9451, GC 30021, HD 204018, HIP 105913, HR 8202, SAO 230692, WDS J21270-4233AB[21]
Database references
SIMBADThe system
A
B

HD 204018, also designated as HR 8202, is a visual binary located in the southern constellation of Microscopium. The primary has an apparent magnitude of 5.58,[3] making it faintly visible to the naked eye under ideal conditions. The companion has an apparent magnitude of 8.09.[3] The system is located relatively close at a distance of 176 light years based on Gaia DR3 parallax measurements[2][4] but is receding with a heliocentric radial velocity of 18.3 km/s.[10] At its current distance, HD 204018's combined brightness is diminished by 0.13 magnitudes due to interstellar dust.[22]

HD 204018A is an Am star with a stellar classification of kA4hF0 VmF6,[6] indicating that it has the calcium K-line of an A4 star, the hydrogen lines of a F0 main-sequence star and the metallic lines of a F6 star. It has 1.73 imes the mass of the Sun[2] and 2.42 times the Sun's radius.[2] It radiates 12.8 times the luminosity of the Sun[2] from its photosphere at an effective temperature of 6,778 K,[13] giving it a yellowish-white hue. At an age of 1.5 billion years, HD 2014018A is estimated to be on the subgiant branch.[5] An alternate model places it on the main sequence at an age of 1,35 billion years.[2] The object spins at a moderate speed with a projected rotational velocity of 85 km/s.[14]

The companion is an F8 main sequence star[9] located 2+1⁄2" away along a position angle of 151°.[23] It has an angular diameter of 0.186±0.035 arcseconds,[17] which yields a radius of 1.09 R☉ at its estimated distance.[16] It has 102% times the mass of the Sun[15] and an effective temperature of 6,235 K.[17] HD 204018B is estimated to be 3.46 billion years old and is slightly metal deficient.[18]

There is a magnitude 12 co-moving companion located 295.3" away from the system along a position angle of 75°.[23] It is a red dwarf with an estimated spectral class of K6 and any orbit would take over a million years.[24]

References

[edit]
  1. ^ Roman, Nancy G. (1987). "Identification of a constellation from a position". Publications of the Astronomical Society of the Pacific. 99 (617): 695. Bibcode:1987PASP...99..695R. doi:10.1086/132034. Constellation record for this object at VizieR.
  2. ^ a b c d e f g h i j k l 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.
  3. ^ a b c d Fabricius, C.; Høg, E.; Makarov, V. V.; Mason, B. D.; Wycoff, G. L.; Urban, S. E. (March 2002). "The Tycho double star catalogue". Astronomy & Astrophysics. 384 (1): 180–189. Bibcode:2002A&A...384..180F. doi:10.1051/0004-6361:20011822. eISSN 1432-0746. ISSN 0004-6361.
  4. ^ a b c d e 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.
  5. ^ a b Corbally, C. J. (December 1984). "Close visual binaries. III - Parameters and evolutionary status". The Astronomical Journal. 89: 1887. Bibcode:1984AJ.....89.1887C. doi:10.1086/113700. ISSN 0004-6256.
  6. ^ a b Abt, Helmut A.; Morrell, Nidia I. (July 1995). "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars". The Astrophysical Journal Supplement Series. 99: 135. Bibcode:1995ApJS...99..135A. doi:10.1086/192182. ISSN 0067-0049.
  7. ^ a b Feinstein, A. (April 1967). "Multicolor UBVRI observations of metallic-line stars". Publications of the Astronomical Society of the Pacific. 79: 184. Bibcode:1967PASP...79..184F. doi:10.1086/128464. eISSN 1538-3873. ISSN 0004-6280.
  8. ^ a b c Hardegree-Ullman, Kevin K.; Apai, Dániel; Bergsten, Galen J.; Pascucci, Ilaria; López-Morales, Mercedes (2023). "Bioverse: A Comprehensive Assessment of the Capabilities of Extremely Large Telescopes to Probe Earth-like O2 Levels in Nearby Transiting Habitable-zone Exoplanets". The Astronomical Journal. 165 (6): 267. arXiv:2304.12490. Bibcode:2023AJ....165..267H. doi:10.3847/1538-3881/acd1ec.
  9. ^ a b c d e Corbally, C. J. (August 1984). "Close visual binaries. I - MK classifications". The Astrophysical Journal Supplement Series. 55: 657. Bibcode:1984ApJS...55..657C. doi:10.1086/190973. eISSN 1538-4365. ISSN 0067-0049.
  10. ^ 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.
  11. ^ 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.
  12. ^ 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.
  13. ^ a b Schofield, Mathew; et al. (14 March 2019). "The Asteroseismic Target List for Solar-like Oscillators Observed in 2 minute Cadence with the Transiting Exoplanet Survey Satellite". The Astrophysical Journal Supplement Series. 241 (1): 12. arXiv:1901.10148. Bibcode:2019ApJS..241...12S. doi:10.3847/1538-4365/ab04f5. eISSN 1538-4365.
  14. ^ a b Huang, Su-Shu (September 1953). "A Statistical Study of the Rotation of the Stars". The Astrophysical Journal. 118: 285. Bibcode:1953ApJ...118..285H. doi:10.1086/145751. eISSN 1538-4357. ISSN 0004-637X.
  15. ^ a b c Anders, F.; et al. (February 2022). "Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia EDR3 stars brighter than G = 18.5". Astronomy & Astrophysics. 658: A91. arXiv:2111.01860. Bibcode:2022A&A...658A..91A. doi:10.1051/0004-6361/202142369. eISSN 1432-0746. ISSN 0004-6361.
  16. ^ a b Lang, Kenneth R. (2006). Astrophysical formulae. Astronomy and astrophysics library. Vol. 1 (3 ed.). Birkhäuser. ISBN 3-540-29692-1.. The radius (R*) is given by:
  17. ^ a b c Stevens, Daniel J.; Stassun, Keivan G.; Gaudi, B. Scott (29 November 2017). "Empirical Bolometric Fluxes and Angular Diameters of 1.6 Million Tycho-2 Stars and Radii of 350,000 Stars with Gaia DR1 Parallaxes". The Astronomical Journal. 154 (6): 259. arXiv:1708.05025. Bibcode:2017AJ....154..259S. doi:10.3847/1538-3881/aa957b. eISSN 1538-3881. S2CID 119191064.
  18. ^ a b c Gontcharov, G. A. (December 2012). "Dependence of kinematics on the age of stars in the solar neighborhood". Astronomy Letters. 38 (12): 771–782. arXiv:1606.08814. Bibcode:2012AstL...38..771G. doi:10.1134/S1063773712120031. eISSN 1562-6873. ISSN 1063-7737.
  19. ^ Balona, L. A. (2019). "Evidence for spots on hot stars suggests major revision of stellar physics". Monthly Notices of the Royal Astronomical Society. 490 (2): 2112. arXiv:1910.01584. Bibcode:2019MNRAS.490.2112B. doi:10.1093/mnras/stz2808.
  20. ^ 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.
  21. ^ "HR 8202". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 21 December 2022.
  22. ^ 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.
  23. ^ a b 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.
  24. ^ Tokovinin, Andrei (23 February 2018). "The Updated Multiple Star Catalog". The Astrophysical Journal Supplement Series. 235 (1): 6. arXiv:1712.04750. Bibcode:2018ApJS..235....6T. doi:10.3847/1538-4365/aaa1a5. eISSN 1538-4365.