Mirfak
Alpha Per
Physical Properties
Position & Identifiers
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Multiple Star System
Eyepiece View
Sep: 164.0″ · PA: 198° · N up, E left
Resolved · Rayleigh: 2.3″ · Dawes: 1.9″ · Eff: 3.1″
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Stellar Lifecycle
Spectral Classification
Hertzsprung-Russell Diagram
Blackbody Spectrum
Stellar Absorption Spectrum
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Stellar Notes
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About Mirfak
Description
Mirfak (Alpha Persei) is the brightest star in the constellation Perseus at magnitude 1.79, located about 510 light-years from Earth. It is a yellow-white supergiant of spectral type F5Ib, about 8.5 times the mass of the Sun and roughly 5,000 times more luminous. Mirfak is the brightest member of the Alpha Persei Moving Cluster (Melotte 20), a nearby open cluster of young blue stars surrounding it.
Observing Tips
Mirfak is easy to find between Cassiopeia and the Pleiades. It lies at the heart of the Alpha Persei Cluster (Melotte 20), which is best appreciated through binoculars — dozens of blue-white stars cascade across a field of about 3 degrees, with the yellow-white Mirfak at the center creating a beautiful color contrast. This cluster is one of the finest binocular objects in the northern sky. The famous Double Cluster (NGC 869/884) lies about 8 degrees to the northeast. Best observed from October through March.
History
The name Mirfak comes from the Arabic 'Mirfaq al-Thurayya' meaning 'elbow of the Pleiades.' Perseus has been recognized as a constellation since ancient times, associated in Greek mythology with the hero who slew Medusa. Mirfak's membership in the Alpha Persei Cluster was established through proper motion studies in the 20th century.
Fun Facts
The Alpha Persei Cluster surrounding Mirfak is about 50-70 million years old and is one of the nearest open clusters to Earth. Despite being in the same cluster, Mirfak's yellow-white color stands out dramatically against its younger, bluer cluster mates. The cluster is slowly dispersing and will cease to exist as a recognizable group within a few hundred million years.