Eta Persei (η Persei, abbreviated Eta Per, η Per), is a red supergiant in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The first constellati ...

Perseus In Greek mythology, Perseus (, ; Greek language, Greek: Περσεύς, Romanization of Greek, translit. Perseús) is the legendary founder of the Perseid dynasty. He was, alongside Cadmus and Bellerophon, the greatest Greek hero and slayer of ...

Parallax Parallax is a displacement or difference in the apparent position of an object viewed along two different sightline, lines of sight and is measured by the angle or half-angle of inclination between those two lines. Due to perspective (graphica ...

measurements by the

Gaia In Greek mythology, Gaia (; , a poetic form of ('), meaning 'land' or 'earth'),, , . also spelled Gaea (), is the personification of Earth. Gaia is the ancestral mother—sometimes parthenogenic—of all life. She is the mother of Uranus (S ...

spacecraft imply that it is 1,000 is

light-year A light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by the International Astr ...

s away from

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

. At such distance,

interstellar dust Cosmic dustalso called extraterrestrial dust, space dust, or star dustis dust that occurs in outer space or has fallen onto Earth. Most cosmic dust particles measure between a few molecules and , such as micrometeoroids (30 μm). Cosmic dust can ...

diminishes its apparent brightness by 0.47 magnitudes. The two components of Eta Persei itself are designated Eta Persei A (officially named Miram , a recent name for the system) and B.

Nomenclature

''η Persei'' ( Latinised to ''Eta Persei'') is the binary star's

Bayer designation A Bayer designation is a stellar designation in which a specific star is identified by a Greek alphabet, Greek or Latin letter followed by the genitive case, genitive form of its parent constellation's Latin name. The original list of Bayer design ...

. 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 The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...

(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 The International Astronomical Union (IAU) established a Working Group on Star Names (WGSN) in May 2016 to catalog and standardize proper names for stars for the international astronomical community. It operates under Division C – Education ...

(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, (), meaning '' Celestial Boat'', refers to an asterism consisting of Eta Persei, Gamma Persei, Alpha Persei, Psi Persei, Delta Persei,

48 Persei 48 Persei (also known as c Persei, 48 Per, HR 1273, HIP 19343, or ) is a Be star in the constellation Perseus, approximately the 500th brightest of the visible stars in apparent magnitude. It is "well known for its complex spectrum and ...

Mu Persei Mu Persei, Romanization of Greek, Latinised from μ Persei, is a binary star system in the Northern celestial hemisphere, northern constellation of Perseus (constellation), Perseus. It is visible to the naked eye as a point of ...

and

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. Consequently, the Chinese name for Eta Persei itself is (, .)

Properties

The primary star (η Persei A) has a

spectral classification ''Spectral'' is a 2016 Hungarian-American military science fiction action film co-written and directed by Nic Mathieu. Written with Ian Fried & George Nolfi, the film stars James Badge Dale as DARPA research scientist Mark Clyne, with Max M ...

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 Luminosity is an absolute measure of radiated electromagnetic radiation, electromagnetic energy per unit time, and is synonymous with the radiant power emitted by a light-emitting object. In astronomy, luminosity is the total amount of electroma ...

. Its surface has an

effective temperature The effective temperature of a body such as a star or planet is the temperature of a black body that would emit the same total amount of electromagnetic radiation. Effective temperature is often used as an estimate of a body's surface temperature ...

of , which is cooler than the Sun and gives it an orange hue, typical of

K-type star In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the ...

s. 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

{{DEFAULTSORT:Eta Persei Persei, Eta Perseus (constellation) K-type supergiants Miram 0834 017506 Persei, 15 Durchmusterung objects 013268 Double stars