Upsilon4 Eridani

For other star systems with this Bayer designation, see Upsilon Eridani.
Upsilon4 Eridani
Location of Upsilon4 in Eridanus (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Eridanus
Right ascension 04h 17m 53.66241s[1]
Declination −33° 47′ 54.0569″[1]
Apparent magnitude (V) 3.56[2]
Characteristics
Spectral type B8V + B9.5V[3]
U−B color index −0.36[2]
B−V color index −0.12[2]
Astrometry
Radial velocity (Rv)+17.6[4] km/s
Proper motion (μ) RA: +62.52[1] mas/yr
Dec.: −7.24[1] mas/yr
Parallax (π)18.33 ± 0.15 mas[1]
Distance178 ± 1 ly
(54.6 ± 0.4 pc)
Absolute magnitude (MV)−0.20[5]
Orbit[6]
Period (P)5.0103250±0.0000008 d
Semi-major axis (a)1.902±0.006 mas
Eccentricity (e)0
Inclination (i)146.2±0.1°
Periastron epoch (T)2454407.7214 ± 0.002 JD
Semi-amplitude (K1)
(primary)		62.68±0.17[7] km/s
Semi-amplitude (K2)
(secondary)		64.70±0.15[7] km/s
Details[6]
υ4 Eri A
Mass3.17±0.07 M☉
Radius2.32±0.18 R☉
Luminosity100.6±4.3 L☉
Surface gravity (log g)4.21±0.07 cgs
Temperature12,930±440[8] K
Rotational velocity (v sin i)19[8] km/s
Age146[8] Myr
υ4 Eri B
Mass3.07±0.07 M☉
Radius2.32±0.18 R☉
Luminosity87.4±3.3 L☉
Surface gravity (log g)4.21±0.07 cgs
Temperature12,250 K
Other designations
υ4 Eri, 41 Eridani, CD−34° 1614, HD 27376, HIP 20042, HR 1347, SAO 194902.[9]
Database references
SIMBADdata

Upsilon4 Eridani is a close binary star system in the constellation Eridanus. It is visible to the naked eye with an apparent visual magnitude of 3.56.[2] Based upon parallax measurements, the pair are located around 54.6 parsecs (178 ly) from the Sun.[1]

This is a double-lined spectroscopic binary star system,[10] which means that the Doppler-shifted spectral lines of both components can be distinguished. The pair have a circular orbit with a period of five days. The system is composed of two B-type main-sequence stars: one has a stellar classification of B8V and the other B9.5V.[3] Both stars show HgMn peculiarities in their spectrum,[7] and their properties are nearly identical.[6] The spin rate of the two stars is synchronized to their orbital period.[6] It is possible that a nearby K-type star is also related.[3]

  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 Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference rgcrv was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Hubrig2001 was invoked but never defined (see the help page).
  6. ^ a b c d Cite error: The named reference Hummel2017 was invoked but never defined (see the help page).
  7. ^ a b c Cite error: The named reference Hubrig2012 was invoked but never defined (see the help page).
  8. ^ a b c 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 chini2012 was invoked but never defined (see the help page).