Alpha Persei Cluster

Alpha Persei moving clusterAlpha PerseiCollinder 39Melotte 20
The Alpha Persei Cluster, also known as Melotte 20 or Collinder 39, is an open cluster in the constellation of Perseus.wikipedia
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Open cluster

open star clusterstar clusteropen clusters
The Alpha Persei Cluster, also known as Melotte 20 or Collinder 39, is an open cluster in the constellation of Perseus.
A number of open clusters, such as the Pleiades, Hyades or the Alpha Persei Cluster are visible with the naked eye.

Perseus (constellation)

PerseusPerseus constellationPer
The Alpha Persei Cluster, also known as Melotte 20 or Collinder 39, is an open cluster in the constellation of Perseus.
It and many of the surrounding stars are members of an open cluster known as the Alpha Persei Cluster.

Alpha Persei

α PerMirfakα Persei
The most luminous member is the ~2nd magnitude white-yellow supergiant Mirfak, also known as Alpha Persei.
Alpha Persei lies in the midst of a cluster of stars named as the eponymous Alpha Persei Cluster, or Melotte 20, which is easily visible in binoculars and includes many of the fainter stars in the constellation.

Psi Persei

ψ PerPsiψ Persei
Bright members also include Delta, Sigma, Psi, 29, 30, 34 and 48 Persei.
This star may be a member of the Alpha Persei Cluster, although its proper motion is high compared to other members.

Delta Persei

δ Perδ PerseiDelta
Bright members also include Delta, Sigma, Psi, 29, 30, 34 and 48 Persei.
Finally, this star may be a member of the Melotte 20 open cluster, which would make it the second-brightest member after Mirfak.

31 Persei

31 Per31
It is a likely member of the Alpha Persei Cluster.

29 Persei

29 Per29
This object is a member of the Alpha Persei Cluster.

30 Persei

30 Per30
It is a member of the Perseus OB3 association, which includes the Alpha Persei Cluster.

HD 21071

V576 PerV576 Persei
It is a member of the young Alpha Persei cluster, Melotte 20, and moving is closer to the Earth with a heliocentric radial velocity of −1.5 km/s.

34 Persei

Constellation

constellationsEuropean constellationModern constellation
The Alpha Persei Cluster, also known as Melotte 20 or Collinder 39, is an open cluster in the constellation of Perseus.

Stellar classification

spectral typeK-typeG-type
To the naked eye, the cluster consists of several blue spectral type B type stars.

Sigma Persei

σ PerSigmaσ Persei
Bright members also include Delta, Sigma, Psi, 29, 30, 34 and 48 Persei.

Hipparcos

HIPHipparcos CatalogueHipparcos satellite
The Hipparcos satellite and infrared color-magnitude diagram fitting have been used to establish a distance to the cluster of ~172 pc.

Hertzsprung–Russell diagram

Hertzsprung-Russell diagramHR diagramcolor-magnitude diagram
The Hipparcos satellite and infrared color-magnitude diagram fitting have been used to establish a distance to the cluster of ~172 pc.

Cosmic distance ladder

standard candlestandard candlesdistance
The distance established via the independent analyses agree, thereby making the cluster an important rung on the cosmic distance ladder.

Stellar kinematics

runaway starspace velocitymoving group

Epsilon Cassiopeiae

ε Casε Cassiopeiaeε Cas
This group may be kinematically associated with the alpha Persei Cluster, indicating that the Cas-Tau group, including Epsilon Cassiopeiae, may have been separated from the cluster through tidal interactions.