Upsilon4 Eridani
Star in the constellation Eridanus
title: "Upsilon4 Eridani" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["eridanus-(constellation)", "b-type-main-sequence-stars", "bayer-objects", "flamsteed-objects", "henry-draper-catalogue-objects", "hipparcos-objects", "bright-star-catalogue-objects", "spectroscopic-binaries", "durchmusterung-objects"] description: "Star in the constellation Eridanus" topic_path: "science/astronomy" source: "https://en.wikipedia.org/wiki/Upsilon4_Eridani" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0
::summary Star in the constellation Eridanus ::
| name = Upsilon4 Eridani |image={{Location mark |image=Caelum constellation map.png|alt=|float=center|width=260 |label=|position=right |mark=Red circle.svg|mark_width=10 |x=730|y=300 | epoch = J2000.0 | equinox = J2000.0 (ICRS) | constell = Eridanus | ra = | dec = | appmag_v = 3.56 | class = B8V + B9.5V | u-b = −0.36 | b-v = −0.12 | r-i = | radial_v = +17.6 | prop_mo_ra = +62.52 | prop_mo_dec = −7.24 | parallax = 18.33 | p_error = 0.15 | parallax_footnote = | absmag_v= −0.20 | reference = | axis_unitless = | period_unitless = | eccentricity = 0 | periastron = 2454407.7214 ± 0.002 JD | inclination = | k1 = | k2 = | source = | component1 = υ4 Eri A | mass = | radius = | luminosity = | temperature = | gravity = | metal_fe = | rotational_velocity = 19 | age_myr = 146 | component2 = υ4 Eri B | mass2 = | radius2 = | luminosity2 = | temperature2 = 12,250 | gravity2 = | names=υ4 Eri, 41 Eridani, CD−34°1614, HD 27376, HIP 20042, HR 1347, SAO 194902 | Simbad = ups04+Eri 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. Based upon parallax measurements, the pair are located around 54.6 pc from the Sun.
This is a double-lined spectroscopic binary star system, 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. Both stars show HgMn peculiarities in their spectrum, and their properties are nearly identical. The spin rate of the two stars is synchronized to their orbital period. It is possible that a nearby K-type star is also related.
References
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| doi=10.1117/12.2231859 | bibcode=2016SPIE.9907E..0QH | s2cid=125160002 | chapter=The orbit of the mercury-manganese binary 41 Eridani | title=Optical and Infrared Interferometry and Imaging V | date=2016 | editor-last1=Malbet | editor-last2=Creech-Eakman | editor-last3=Tuthill | editor-first1=Fabien | editor-first2=Michelle J. | editor-first3=Peter G. | last1=Hummel | first1=Christian A. | last2=Schöller | first2=Markus | last3=Duvert | first3=Gilles | last4=Le Bouquin | first4=Jean-Baptiste | last5=Hubrig | first5=Swetlana |series=Proceedings of SPIE | volume=9907 | pages=99070Q | arxiv=1703.07668 }}
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| last1=Mermilliod | first1=J.-C. | title=Compilation of Eggen's UBV data, transformed to UBV (unpublished) | journal=Catalogue of Eggen's UBV Data | publisher=SIMBAD | date=1986 | bibcode=1986EgUBV........0M | postscript=. }}
| title=* ups04 Eri -- Spectroscopic binary | access-date=2016-10-13 | postscript=. }}
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