Eta Persei

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Star system in the constellation Perseus

title: "Eta Persei" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["bayer-objects", "perseus-(constellation)", "k-type-supergiants", "stars-with-proper-names", "bright-star-catalogue-objects", "henry-draper-catalogue-objects", "flamsteed-objects", "durchmusterung-objects", "hipparcos-objects", "double-stars"] description: "Star system in the constellation Perseus" topic_path: "science/astronomy" source: "https://en.wikipedia.org/wiki/Eta_Persei" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Star system in the constellation Perseus ::

| name=η Persei | image= |image=Perseus constellation map.svg |float=center |alt= |label= |position=right |width=260 |mark=Red circle.svg |mark_width=10 |mark_link=η Persei |x=674|y=242 |caption=Location of η Per (circled) | epoch = J2000 | ra = | dec = | appmag_v = 3.79 | constell = Perseus | class = K3 Ib | b-v = +1.69 | u-b = +1.90 | variable = |type=Red supergiant}} | radial_v = | prop_mo_ra = +16.346 | prop_mo_dec = −13.518 | pm_footnote = | parallax = 3.2657 | p_error = 0.1873 | parallax_footnote = | absmag_v = −4.29 | mass = | radius = | luminosity = | luminosity_bolometric = | temperature = | metal_fe = | gravity = 0.26 | rotational_velocity = 5.8 | age_myr = | names=Miram, η Persei, η Per, Eta Per, 15 Persei, BD+55 714, CCDM J02506+5553A, FK5 99, GC 3390, HD 17506, HIP 13268, HR 834, IDS 02434+5529 A, PPM 28039, SAO 23655, WDS J02507+5554A | Simbad=Eta+Persei

Eta Persei (η Persei, abbreviated Eta Per, η Per), is a red supergiant in the constellation of Perseus. Parallax measurements by the Gaia spacecraft imply that it is 1,000 is light-years away from Earth. At such distance, interstellar dust diminishes its apparent brightness by 0.47magnitudes.

The two components of Eta Persei itself are designated Eta Persei A (officially named Miram , a recent name for the system) and B.

Nomenclature

::figure[src="https://upload.wikimedia.org/wikipedia/commons/b/be/Eta_Persei.jpg" caption="η Persei in optical light"] ::

η Persei (Latinised to Eta Persei) is the binary star's Bayer designation. The designations of its two components as Eta Persei A and B derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).

Eta Persei mysteriously gained the named Miram in the 20th Century, though no source is known. In 2016, the IAU organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems. It approved the name Miram for the component Eta Persei A on 5 September 2017 and it is now so included in the List of IAU-approved Star Names.

This star, together with Delta Persei, Psi Persei, Sigma Persei, Alpha Persei and Gamma Persei has been called the Segment of Perseus.

In Chinese, 天船 (Tiān Chuán), meaning Celestial Boat, refers to an asterism consisting of Eta Persei, Gamma Persei, Alpha Persei, Psi Persei, Delta Persei, 48 Persei, Mu Persei and HD 27084. Consequently, the Chinese name for Eta Persei itself is 天船一 (Tiān Chuán yī, .)

Properties

The primary star (η Persei A) has a spectral classification of K3Ib, meaning that it is a lower luminosity red supergiant star. It has expanded to 170 times the Sun's size and currently is emitting 7,500 times its luminosity. Its surface has an effective temperature of , which is cooler than the Sun and gives it an orange hue, typical of K-type stars.

Multiple star catalogues list a number of companions to Eta Persei, but it is unclear if any are physically related. The brightest close companion is 8th-magnitude HD 237009 away, with 9th-magnitude HD 17456 away. Of the six companions listed in the Washington Double Star Catalogue, only HD 237009 has a similar parallax to Eta Persei.

References

{{cite Gaia DR3. 454491450699845248
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(2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues.
(2002). "A catalog of rotational and radial velocities for evolved stars. II. Ib supergiant stars". Astronomy and Astrophysics.
{{cite Gaia DR3. 454491381981202944
(2009). "Comparing the Ca ii H and K Emission Lines in Red Giant Stars". Publications of the Astronomical Society of the Pacific.
(2023-12-01). "33 New Stellar Angular Diameters from the NPOI, and Nearly 180 NPOI Diameters as an Ensemble". The Astronomical Journal.
"Naming Stars". IAU.org.
(2010). "On the naming convention used for multiple star systems and extrasolar planets".
Kaler, Jim. "Eta Persei".
"IAU Working Group on Star Names (WGSN)".
"WG Triennial Report (2015-2018) - Star Names".
Allen, R. H.. (1963). "Star Names: Their Lore and Meaning". Dover Publications Inc.
(6 March 2024). "The Colour of Stars".
(2005). "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters". Astronomy and Astrophysics.
{{in lang. zh [http://aeea.nmns.edu.tw/2006/0607/ap060711.html AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 11 日] {{Webarchive. link. (2012-02-04)

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