Upsilon1 Eridani

---

title: "Upsilon1 Eridani" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["k-type-giants", "horizontal-branch-stars", "eridanus-(constellation)", "bayer-objects", "durchmusterung-objects", "flamsteed-objects", "henry-draper-catalogue-objects", "hipparcos-objects", "bright-star-catalogue-objects"] description: "Red clump star in the constellation Eridanus" topic_path: "science/astronomy" source: "https://en.wikipedia.org/wiki/Upsilon1_Eridani" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Red clump star in the constellation Eridanus ::

| name= υ1 Eridani | image = |image=Eridanus constellation map.svg|alt=|float=center|width=250 |label=|position=right |mark=Red circle.svg|mark_width=10|mark_link=Upsilon1 Eridani |x=315|y=615 | caption = Location of υ1 Eridani (circled in red) | constell = Eridanus | epoch = J2000.0 (ICRS) | ra = | dec = | appmag_v = 4.51 | type = red clump | class = K0 III-IV | b-v = +0.98 | u-b = +0.70 | variable = | radial_v = | prop_mo_ra = −114.78 | prop_mo_dec = −271.79 | parallax = 25.67 | p_error = 0.24 | parallax_footnote = | absmag_v = 1.60 | mass = 1.54 | radius = 7.3 | luminosity = 24 | temperature = 4,941 | metal_fe = | gravity = 3.09 | rotational_velocity = 2.15 | age_myr = | names = υ1 Eridani, υ1 Eri, 50 Eridani, CD−30°1883, HD 29085, HIP 21248, HR 1453, SAO 169570 | Simbad = ups01+Eri Upsilon1 Eridani (υ1 Eri) is a single star in the constellation Eridanus. It has an apparent visual magnitude is 4.51, which is bright enough to be faintly visible to the naked eye on a clear, dark night. The distance to this star, as determined using the parallax method, is around 127 light years.

This is an evolved red clump giant star with a stellar classification of K0III-IV. The measured angular diameter, after correction for limb darkening, is . At an estimated distance of this star, this yields a physical size of about 7.3 times the radius of the Sun. It has 154% of the Sun's mass and radiates 24 times the solar luminosity from its outer atmosphere at an effective temperature of 4,941 K.

References

| title=Validation of the new Hipparcos reduction | last1=van Leeuwen | first1=F. | journal=Astronomy and Astrophysics | volume=474 | issue=2 | pages=653–664 | date=2007 | arxiv=0708.1752 | bibcode=2007A&A...474..653V | doi=10.1051/0004-6361:20078357 | s2cid=18759600 | postscript=. }}

| display-authors=1 | last1=Gray | first1=R. O. | last2=Corbally | first2=C. J. | last3=Garrison | first3=R. F. | last4=McFadden | first4=M. T. | last5=Bubar | first5=E. J. | last6=McGahee | first6=C. E. | last7=O'Donoghue | first7=A. A. | last8=Knox | first8=E. R. | title=Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample | journal=The Astronomical Journal | volume=132 | issue=1 | pages=161–170 | date=July 2006 | doi=10.1086/504637 | bibcode=2006AJ....132..161G | arxiv=astro-ph/0603770 | s2cid=119476992 | postscript=. }}

| last1=Luck | first1=R. Earle | last2=Heiter | first2=Ulrike | title=Giants in the Local Region | journal=The Astronomical Journal | volume=133 | issue=6 | pages=2464–2486 | date=June 2007 | doi=10.1086/513194 | bibcode=2007AJ....133.2464L | postscript=. | doi-access=free }}

| last1=Alves | first1=David R. | title=K-Band Calibration of the Red Clump Luminosity | journal=The Astrophysical Journal | volume=539 | issue=2 | pages=732–741 |date=August 2000 | doi=10.1086/309278 | bibcode=2000ApJ...539..732A | arxiv=astro-ph/0003329 | s2cid=16673121 | postscript=. }}

| display-authors=1 | last1=Richichi | first1=A. | last2=Percheron | first2=I. | last3=Khristoforova | first3=M. | title=CHARM2: An updated Catalog of High Angular Resolution Measurements | journal=Astronomy and Astrophysics | volume=431 | pages=773–777 |date=February 2005 | issue=2 | doi=10.1051/0004-6361:20042039 | bibcode=2005A&A...431..773R | postscript=. | doi-access=free }}

| first1=Kenneth R. | last1=Lang | title=Astrophysical formulae | volume=1 | series=Astronomy and astrophysics library | edition=3rd | publisher=Birkhäuser | date=2006 | isbn=3-540-29692-1 | url=https://books.google.com/books?id=OvTjLcQ4MCQC&pg=PA41 }}. The radius (R*) is given by: :\begin{align} 2\cdot R_* & = \frac{(39.0\cdot 1.74\cdot 10^{-3})\ \text{AU}}{0.0046491\ \text{AU}/R_{\bigodot}} \ & \approx 14.6\cdot R_{\bigodot} \end{align}

| 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=* ups01 Eri | access-date=2016-10-13 | postscript=. }}

References

1. (2007). "Precise radial velocities of giant stars. III. Spectroscopic stellar parameters". Astronomy and Astrophysics.

::callout[type=info title="Wikipedia Source"] This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page. ::