Tau5 Eridani

For other star systems with this Bayer designation, see Tau Eridani.
τ5 Eridani
Location of τ5 Eridani (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Eridanus
Right ascension 03h 33m 47.27613s[1]
Declination −21° 37′ 58.3830″[1]
Apparent magnitude (V) 4.26[2]
Characteristics
Spectral type B0 V + B9 V[3]
U−B color index 0.35[2]
B−V color index −0.09[2]
Astrometry
Proper motion (μ) RA: +44.94[1] mas/yr
Dec.: −28.16[1] mas/yr
Parallax (π)11.12 ± 0.21 mas[1]
Distance293 ± 6 ly
(90 ± 2 pc)
Absolute magnitude (MV)−0.51[4]
Orbit[5]
Period (P)6.2236 d
Eccentricity (e)0.2
Periastron epoch (T)2424446.548 JD
Argument of periastron (ω)
(secondary)		313°
Semi-amplitude (K1)
(primary)		107 km/s
Semi-amplitude (K2)
(secondary)		103 km/s
Details
τ5 Eri A
Mass3.30+0.24
−0.20[6] M☉
Radius3.2[3] R☉
Luminosity188[7] L☉
Surface gravity (log g)4.00±0.15[6] cgs
Temperature12,514±425[8] K
Rotational velocity (v sin i)55±8[3] km/s
Age157+23
−45[6] Myr
τ5 Eri B
Radius2.6[3] R☉
Rotational velocity (v sin i)50±8[3] km/s
Other designations
τ5 Eridani, τ5 Eri, 19 Eridani, BD-22° 628, HD 22203, HIP 16611, HR 1088, SAO 168634.[9]
Database references
SIMBADdata

Tau5 Eridani, Latinized from τ5 Eridani, is a binary star system in the constellation Eridanus. It is visible to the naked eye with a combined apparent visual magnitude of 4.26.[2] The distance to this system, as estimated using the parallax technique, is around 293 light years.[1]

Tau5 Eridani is a double-lined spectroscopic binary system.[10] The two stars orbit each other closely with a period of 6.2 days and an eccentricity of 0.2.[5] On average, the two stars are separated by around 0.183 AU.[3]

The primary component is a B-type main sequence star with a stellar classification of B0 V.[3] It is around 157 million years old and is spinning with a projected rotational velocity of 55 km/s.[3] The star has around 3.3[6] times the mass of the Sun and 3.2[3] times the Sun's radius. It radiates 188[7] times the solar luminosity from an outer atmosphere at an effective temperature of 12,514 K.[8]

The secondary component has a stellar classification of B9 V.[3] It is slightly smaller, with an estimated size equal to 2.6 times the radius of the Sun.[3]

Although τ5 Eridani has no bright visual companion stars, the galaxy IC 1953 is less than 10' away. It is one of the brighter members of a loose group of galaxies called the Eridanus Group scattered around the components of τ Eridani.

  1. ^ a b c d e f Cite error: The named reference vanLeeuwen2007 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference Mermilliod1986 was invoked but never defined (see the help page).
  3. ^ a b c d e f g h i j k Cite error: The named reference Howe2009 was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Pourbaix2004 was invoked but never defined (see the help page).
  6. ^ a b c d Cite error: The named reference Kraus2016 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference Mcdonald2012 was invoked but never defined (see the help page).
  8. ^ a b Cite error: The named reference David2015 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference vanRensbergen2006 was invoked but never defined (see the help page).