HD 204018

HD 204018
location of HD 204018 (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Microscopium
A
Right ascension 21h 27m 01.62303s[1]
Declination −42° 32′ 52.5560″[1]
Apparent magnitude (V) 5.58±0.01[2]
B
Right ascension 21h 27m 01.75500s[3]
Declination −42° 32′ 55.0458″[3]
Apparent magnitude (V) 8.09±0.01[2]
Characteristics
A
Evolutionary stage subgiant[4]
Spectral type kA4 hF0 V mF6[5]
U−B color index +0.15[6]
B−V color index +0.39[6]
B
Spectral type F8 V[7]
U−B color index +0.06[7]
B−V color index +0.55[7]
Astrometry
Radial velocity (Rv)18.3±2.8[8] km/s
A
Proper motion (μ) RA: −48.257 mas/yr[1]
Dec.: +13.160 mas/yr[1]
Parallax (π)18.489 ± 0.0498 mas[1]
Distance176.4 ± 0.5 ly
(54.1 ± 0.1 pc)
Absolute magnitude (MV)+1.74[9]
B
Proper motion (μ) RA: −53.002 mas/yr[3]
Dec.: +15.410 mas/yr[3]
Parallax (π)18.5325 ± 0.0349 mas[3]
Distance176.0 ± 0.3 ly
(54.0 ± 0.1 pc)
Absolute magnitude (MV)+4.00[7]
Details
A
Mass1.65±0.11[10] M☉
Radius2.55±0.13[11] R☉
Luminosity15±1.2[12] L☉
Surface gravity (log g)3.86±0.08[13] cgs
Temperature6,778[14] K
Rotational velocity (v sin i)85[15] km/s
Age1.36±0.19[1] Gyr
B
Mass1.02[16] M☉
Radius1.09±0.21[17] R☉
Surface gravity (log g)4.29[16] cgs
Temperature6,235±115[18] K
Metallicity [Fe/H]−0.11[19] dex
Age3.46[19] 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 Microscopium. The primary has an apparent magnitude of 5.58,[2] making it faintly visible to the naked eye under ideal conditions. The companion has an apparent magnitude of 8.09.[2] The system is located relatively close at a distance of 176 light years based on Gaia DR3 parallax measurements[1][3] but is receding with a heliocentric radial velocity of 18.3 km/s.[8] 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,[5] 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 1.65 times the mass of the Sun[10] and 2.55 times the Sun's radius.[11] It radiates 15 times the luminosity of the Sun[12] from its photosphere at an effective temperature of 6,778 K,[14] giving it a yellowish-white hue. At an age of 1.5 billion years, HD 2014018A is estimated to be on the subgiant branch.[4] An alternate model places it on the main sequence at an age of 1,35 billion years.[1] The object spins at a moderate speed with a projected rotational velocity of 85 km/s.[15]

The companion is an F8 main sequence star[7] located 2+1⁄2" away along a position angle of 151°.[23] It has an angular diameter of 0.186±0.035 arcseconds,[18] which yields a radius of 1.09 R☉ at its estimated distance.[17] It has 102% times the mass of the Sun[16] and an effective temperature of 6,235 K.[18] HD 204018B is estimated to be 3.46 billion years old and is slightly metal deficient.[19]

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]

  1. ^ a b c d e f g Cite error: The named reference GaiaDR3A was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference Fabricius2002 was invoked but never defined (see the help page).
  3. ^ a b c d e Cite error: The named reference GAiaDR3B was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Corbally19842 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Abt1995 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference Feinstein1967 was invoked but never defined (see the help page).
  7. ^ a b c d e Cite error: The named reference Corbally1984 was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference Gontcharov2006 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  10. ^ a b Cite error: The named reference AP1999 was invoked but never defined (see the help page).
  11. ^ a b Cite error: The named reference Kervella2004 was invoked but never defined (see the help page).
  12. ^ a b Cite error: The named reference Chanlder2016 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference Stassun2019 was invoked but never defined (see the help page).
  14. ^ a b Cite error: The named reference Schofield2019 was invoked but never defined (see the help page).
  15. ^ a b Cite error: The named reference Huang1953 was invoked but never defined (see the help page).
  16. ^ a b c Cite error: The named reference Anders2022 was invoked but never defined (see the help page).
  17. ^ a b Cite error: The named reference Lang2006 was invoked but never defined (see the help page).
  18. ^ a b c Cite error: The named reference Stevens2017 was invoked but never defined (see the help page).
  19. ^ a b c Cite error: The named reference Gontcharov2012 was invoked but never defined (see the help page).
  20. ^ Cite error: The named reference Gould1879 was invoked but never defined (see the help page).
  21. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  22. ^ Cite error: The named reference Gontcharov2017 was invoked but never defined (see the help page).
  23. ^ a b Cite error: The named reference Mason2001 was invoked but never defined (see the help page).
  24. ^ Cite error: The named reference msc was invoked but never defined (see the help page).