Tau4 Eridani

For other star systems with this Bayer designation, see Tau Eridani.
τ4 Eridani
Location of τ4 Eridani (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Eridanus
Right ascension 03h 19m 31.0006s [1]
Declination −21° 45′ 28.315″ [1]
Apparent magnitude (V) 3.65[2]
Characteristics
Evolutionary stage asymptotic giant branch[3]
Spectral type M3/4 III[4]
U−B color index +1.79[2]
B−V color index +1.61[2]
Variable type Lb[5]
Astrometry
Radial velocity (Rv)+41.7±0.7[6] km/s
Proper motion (μ) RA: +52.774 mas/yr[1]
Dec.: +32.718 mas/yr[1]
Parallax (π)10.6153 ± 0.3213 mas[1]
Distance307 ± 9 ly
(94 ± 3 pc)
Absolute magnitude (MV)−0.79[7]
Details
Mass1.73±0.3[8] M☉
Radius103[9] R☉
Luminosity1,537[10] L☉
Surface gravity (log g)0.91[11] cgs
Temperature3,652[9] K
Other designations
τ4 Eridani, τ4 Eri, 16 Eridani, BD-22° 584, HD 20720, HIP 15474, HR 1003, SAO 168460.[12]
Database references
SIMBADdata

Tau4 Eridani (τ4 Eridani, τ4 Eri) is a binary star system in the constellation Eridanus. It is visible to the naked eye with an apparent visual magnitude of 3.65.[2] The distance to this star can be estimated using the parallax method, which yields a value of roughly 300 light years. [1]

A visual band light curve for Tau4 Eridani, plotted from data published by Tabur et al. (2009)[13]

This is an evolved red giant star currently on the asymptotic giant branch[3] with a stellar classification of M3/4 III.[4] It is a slow irregular variable star of type Lb, undergoing changes in magnitude over the range 3.57−3.72[5] with a periodicity of 23.8 d.[13] The measured angular diameter of Tau4 Eridani is 10.58±1.00 mas.[14] At its estimated distance, this yields a physical size of about 106 times the radius of the Sun.[15] It shines with 1,537[10] times the luminosity of the Sun from an outer atmosphere at an effective temperature of 3,650 K.[9]

This is most likely a binary star system.[16] The companion is a magnitude 9.5 star at an angular separation of 5.7″ along a position angle of 291°, as of 2013.[17]

  1. ^ 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.
  2. ^ a b c d Cite error: The named reference Mermilliod1986 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference Lebzelter2008 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference houk1988 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Ruban2006 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference Gontcharov2006 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Cardini2005 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference halabi was invoked but never defined (see the help page).
  9. ^ a b c Cite error: The named reference wood was invoked but never defined (see the help page).
  10. ^ a b Cite error: The named reference Mcdonald2012 was invoked but never defined (see the help page).
  11. ^ Ayres, Thomas (2023-05-01), "In the Trenches of the Solar-Stellar Connection. VII. Wilson-Bappu 2022", The Astrophysical Journal Supplement Series, 266 (1): 6, Bibcode:2023ApJS..266....6A, doi:10.3847/1538-4365/acb535, ISSN 0067-0049 Tau4 Eridani database entry at VizieR.
  12. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  13. ^ a b Cite error: The named reference Tabur2009 was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference Richichi2005 was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference lang2006 was invoked but never defined (see the help page).
  16. ^ Cite error: The named reference mnras389_2_869 was invoked but never defined (see the help page).
  17. ^ Cite error: The named reference WDSC2014 was invoked but never defined (see the help page).