Omicron1 Eridani

For other stars with this Bayer designation, see Omicron Eridani.

Omicron¹ Eridani (ο¹ Eridani, abbreviated Omicron¹ Eri, ο¹ Eri), also named Beid /ˈbaɪd/,^[9][10] is a variable star in the constellation of Eridanus. With an average apparent visual magnitude of 4.04,^[3] it is visible to the naked eye on a clear, dark night. Based upon parallax measurements, it lies approximately 122 light-years from the Sun.

ο¹ Eridani

A light curve for Omicron1 Eridani, plotted from TESS data[1]
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Eridanus
Right ascension	04h 11m 51.93956s[2]
Declination	−06° 50′ 15.2864″[2]
Apparent magnitude (V)	4.04[3]
Characteristics
Spectral type	F0 III[4]
U−B color index	+0.10[3]
B−V color index	+0.32[3]
Variable type	δ Scuti[5]
Astrometry
Proper motion (μ)	RA: +10.76[2] mas/yr Dec.: +81.92[2] mas/yr
Parallax (π)	26.80 ± 0.32 mas[2]
Distance	122 ± 1 ly (37.3 ± 0.4 pc)
Absolute magnitude (MV)	+1.18[6]
Details
Mass	1.95[5] M☉
Radius	3.7±0.1[5] R☉
Luminosity	27[5] L☉
Surface gravity (log g)	3.39[4] cgs
Temperature	6,963[4] K
Metallicity [Fe/H]	−0.01[4] dex
Rotational velocity (v sin i)	108.1[7] km/s
Other designations
Beid, ο1 Eri, 38 Eri, BD−07°764, FK5 154, HD 26574, HIP 19587, HR 1298, SAO 131019[8]
Database references
SIMBAD	data

Nomenclature

ο¹ Eridani (Latinised to Omicron¹ Eridani) is the star's Bayer designation.

The system bears the traditional name Beid derived from the Arabic word بيض bayḍ meaning "eggs" (cf. neighboring Keid "(egg)shells"). In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)^[11] to catalogue and standardize proper names for stars. The WGSN approved the name Beid for this star on 12 September 2016 and it is now so included in the List of IAU-approved Star Names.^[10]

In Chinese, 九州殊口 (Jiǔ Zhōu Shū Kǒu), meaning Interpreters of Nine Dialects, refers to an asterism consisting of ο¹ Eridani, 39 Eridani, Xi Eridani, Nu Eridani, 56 Eridani and 55 Eridani.^[12] Consequently, the Chinese name for Omicron¹ Eridani itself is 九州殊口二 (Jiǔ Zhōu Shū Kǒu èr, English: the Second Star of Interpreters of Nine Dialects).^[13]

Properties

ο¹ Eridani is an evolved F-type giant star with a stellar classification of F0 III.^[4] It is a Delta Scuti variable star that undergoes non-radial pulsations,^[5] with a variation of just 0.03 magnitude over a period of 0.0747 days.^[14] The star is spinning rapidly with a projected rotational velocity of 108.1 km/s^[7] and a rotation period of less than around 1.9 days.^[5] This is creating an equatorial bulge that is 11% wider than the polar radius.^[15] Omicron¹ Eridani has nearly double the mass of the Sun, 3.7 times the Sun's radius, and shines with 27 times the solar luminosity^[5] from an outer atmosphere at an effective temperature of 6,963 K.^[4]

References

1. MAST: Barbara A. Mikulski Archive for Space Telescopes, Space Telescope Science Institute, retrieved 3 September 2022.
2. van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.
3. Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data, Bibcode:1986EgUBV........0M.
4. Gray, R. O.; et al. (July 2006), "Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample", The Astronomical Journal, 132 (1): 161–170, arXiv:astro-ph/0603770, Bibcode:2006AJ....132..161G, doi:10.1086/504637, S2CID 119476992.
5. Balona, Luis A. (October 2000), "The δ Scuti star 38 o¹ Eri", Monthly Notices of the Royal Astronomical Society, 318 (1): 289–293, Bibcode:2000MNRAS.318..289B, doi:10.1046/j.1365-8711.2000.03776.x.
6. Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
7. Schröder, C.; Reiners, Ansgar; Schmitt, Jürgen H. M. M. (January 2009), "Ca II HK emission in rapidly rotating stars. Evidence for an onset of the solar-type dynamo", Astronomy and Astrophysics, 493 (3): 1099–1107, Bibcode:2009A&A...493.1099S, doi:10.1051/0004-6361:200810377
8. "* omi01 Eri", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2016-10-11.
9. Davis, George A. (1944), "The pronunciations, derivations, and meanings of a selected list of star names", Popular Astronomy, 52: 8–30, Bibcode:1944PA.....52....8D.
10. Naming Stars, IAU.org, retrieved 16 December 2017.
11. IAU Division C Working Group on Star Names (WGSN), International Astronomical Union, retrieved 22 May 2016.
12. (in Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.
13. (in Chinese) 香港太空館 - 研究資源 - 亮星中英對照表 Archived 2010-08-11 at the Wayback Machine, Hong Kong Space Museum. Accessed on line November 23, 2010.
14. Rodríguez, E.; et al. (June 2000), "A revised catalogue of δ Sct stars", Astronomy and Astrophysics Supplement, 144 (3): 469–474, Bibcode:2000A&AS..144..469R, doi:10.1051/aas:2000221, hdl:10261/226673.
15. Van Belle, Gerard T. (2012), "Interferometric observations of rapidly rotating stars", The Astronomy and Astrophysics Review, 20 (1): 51, arXiv:1204.2572, Bibcode:2012A&ARv..20...51V, doi:10.1007/s00159-012-0051-2, S2CID 119273474.

External links

• Kaler, James B. (January 13, 2012), "Beid", Stars, University of Illinois, retrieved 2016-10-11.