Theta Eridani

Theta Eridani
Location of θ Eridani (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Eridanus
θ1 Eri
Right ascension 02h 58m 15.6764s[1]
Declination −40° 18′ 16.839″[1]
Apparent magnitude (V) 3.18[2]
θ2 Eri
Right ascension 02h 58m 16.4037s[3]
Declination −40° 18′ 16.906″[3]
Apparent magnitude (V) 4.11[2]
Characteristics
θ1 Eri
Spectral type A3IV-V[4]
U−B color index +0.14[5]
B−V color index +0.128±0.012[6]
θ2 Eri
Spectral type A1V[4]
B−V color index +0.08[5]
Variable type suspected[7]
Astrometry
θ1 Eri
Radial velocity (Rv)+11.9±2.6[6] km/s
Proper motion (μ) RA: −57.132[1] mas/yr
Dec.: +23.058[1] mas/yr
Parallax (π)19.9047 ± 0.2062 mas[1]
Distance164 ± 2 ly
(50.2 ± 0.5 pc)
θ2 Eri
Proper motion (μ) RA: −50.502[3] mas/yr
Dec.: +16.613[3] mas/yr
Parallax (π)19.5270 ± 0.1372 mas[3]
Distance167 ± 1 ly
(51.2 ± 0.4 pc)
Absolute magnitude (MV)−0.59 (combined)[6]
Details
θ1 Eri
Mass2.6[8] M☉
Radius4.85[a] R☉
Luminosity96[8] L☉
Temperature8,200[8] K
Rotational velocity (v sin i)65.1[9] km/s
θ2 Eri
Mass1.95[10] M☉
Radius2.7[11] R☉
Luminosity37[11] L☉
Surface gravity (log g)3.83[10] cgs
Temperature8,293[10] K
Metallicity [Fe/H]−0.197[10] dex
Rotational velocity (v sin i)102.5[12] km/s
Other designations
Theta Eri, θ Eri, CD−40° 771, HIP 13847, SAO 216113, CCDM J02583-4018, WDS 02583-4018
θ1 Eri: Acamar, HD 18622, HR 897
θ2 Eri: HD 18623, HR 898
Database references
SIMBADθ1 Eri
θ2 Eri

Theta Eridani, Latinized from θ Eridani, is a binary system in the constellation of Eridanus with a combined apparent magnitude of 2.88.[6] Its two components are designated θ1 Eridani, formally named Acamar /ˈækəmɑːr/ (the traditional name of the system),[13][14] and θ2 Eridani. The system's distance from the Sun based on parallax measurements is approximately 165 light-years.

  1. ^ a b c d e Cite error: The named reference edr3a was invoked but never defined (see the help page).
  2. ^ a b Cite error: The named reference tycho2 was invoked but never defined (see the help page).
  3. ^ a b c d e Cite error: The named reference edr3b was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Gray_et_al_2006 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference VizieR was invoked but never defined (see the help page).
  6. ^ a b c d Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
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  8. ^ a b c d Cite error: The named reference kaler was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference ammler2012 was invoked but never defined (see the help page).
  10. ^ a b c d Cite error: The named reference starhorse was invoked but never defined (see the help page).
  11. ^ a b Cite error: The named reference ticv8 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference diaz2011 was invoked but never defined (see the help page).
  13. ^ Rumrill, H. B. (June 1936). "Star Name Pronunciation". Publications of the Astronomical Society of the Pacific. 48 (283). San Francisco, California: 139. Bibcode:1936PASP...48..139R. doi:10.1086/124681. S2CID 120743052.
  14. ^ "IAU Catalog of Star Names". Retrieved 28 July 2016.


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