Alpha Persei Cluster

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Alpha Persei Cluster
Melotte 20.jpg
Observation data (2000.0 epoch)
Right ascension 03h 26m 42.0s [1]
Declination +48° 48′ 00″ [1]
Distance 570  ly [1] (175  pc [1] )
Apparent magnitude  (V)1.2
Apparent dimensions (V)6.1° [1]
Physical characteristics
Estimated age50–70 Mya [2] [3]
Other designationsPer OB3, [4] Cr 39, Mel 20, OCl 392.0 [5]
Associations
Constellation Perseus
See also: Open cluster, List of open clusters

The Alpha Persei Cluster, also known as Melotte 20 or Collinder 39, is an open cluster of stars in the northern constellation of Perseus. To the naked eye, the cluster consists of several blue-hued spectral type B stars. The most luminous member is the ~2nd magnitude yellow supergiant Mirfak, also known as Alpha Persei. Bright members also include Delta, Sigma, Psi, 29, 30, 34, and 48 Persei. The Hipparcos satellite and infrared color-magnitude diagram fitting have been used to establish a distance to the cluster of ~560 light-years (172  pc ). [6] [7] The distance established via the independent analyses agree, thereby making the cluster an important rung on the cosmic distance ladder. As seen from the Earth, the extinction of the cluster due to interstellar dust is around 0.30. [8]

Contents

The cluster is centered to the northeast of Alpha Persei. [8] It has a core radius of 11.4 ± 1.4 ly, a half-mass radius of 18 ly, [8] and a tidal radius of 70.6 ± 8.5 ly, [1] with 517 members being identified within the latter. [8] The cluster shows solid evidence of having undergone mass segregation, with the mean stellar mass decreasing toward the edge. [9] The age of this cluster is about 50–70 million years. [2] [3] Cluster member stars show a near-solar metallicity, meaning the abundance of elements with atomic numbers higher than 2 are similar to those in the Sun. [8] The cluster shows evidence of tidal tails, which are most likely of galactic origin. [10]

The cluster field displays evidence of a much larger, background star stream. This feature is quite a bit older than the cluster, with an estimated age of 5 ± 1 Gyr. The center of the stream lies 290 ly from the cluster and it has an overall thickness of 590 ly along the line of sight. This is most likely the remains of an old, massive cluster that now has a combined mass of ~6000  M☉ . [10]

Members

The following prominent stars are considered members of the cluster with high likelihood:

Designation Spectral
type 		Visual
magnitude
α Per (33 Per) [11] F5Ib1.81
δ Per (39 Per)B5III3.01
ε Per (45 Per)B1V2.88
ψ Per [11] B5Ve4.31
HD 21278 [12] [13] B5V4.99
31 Per [11] B5V5.05
29 Per [11] [13] B3V5.16
30 Per [13] B8V5.49
34 Per B3V4.67
48 Per B3Ve4.03
HD 21699 B8 III5.49
HD 21071 [13] B7V6.09

See also

Related Research Articles

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<span class="mw-page-title-main">Alpha Persei</span> Brightest star in the constellation Perseus

Alpha Persei, formally named Mirfak, is the brightest star in the northern constellation of Perseus, outshining the constellation's best-known star, Algol. Alpha Persei has an apparent visual magnitude of 1.8, and is a circumpolar star when viewed from mid-northern latitudes.

<span class="mw-page-title-main">Coma Star Cluster</span> Open cluster in the constellation Coma Berenices

The Coma Star Cluster is a nearby open cluster located in the constellation Coma Berenices. The cluster contains about 40 brighter stars with a common proper motion. The brighter stars of the cluster make out a distinctive "V" shape as seen when Coma Berenices is rising. The cluster used to represent the tail of Leo. However, in around 240 BC, Ptolemy III renamed it for the Egyptian queen Berenice's legendary sacrifice of her hair.

<span class="mw-page-title-main">Zeta Persei</span> Star in the constellation Perseus

Zeta Persei is a star in the northern constellation of Perseus. With an apparent visual magnitude of 2.9, it can be readily seen with the naked eye. Parallax measurements place it at a distance of about 846 light-years from Earth, though measuremets of its Ca II lines place it at 1,300 light-years.

17 Vulpeculae is a single, blue-white hued star in the northern constellation of Vulpecula. The distance to this star can be estimated from its annual parallax shift of 6.8168±0.1430, which yields a separation of roughly 480 light years. It is moving nearer with a heliocentric radial velocity of −8 km/s, and will make its closest approach in around 6.1 million years at a distance of about 419 ly (128.36 pc). The star is faintly visible to the naked eye with an apparent visual magnitude of 5.08.

<span class="mw-page-title-main">S Persei</span> Red supergiant or hypergiant variable star in the constellation Perseus

S Persei is a red supergiant or hypergiant located near the Double Cluster in Perseus, north of the cluster NGC 869. It is a member of the Perseus OB1 association and one of the largest known stars. If placed in the Solar System, its photosphere would engulf the orbit of Jupiter. It is also a semiregular variable, a star whose variations are less regular than those of Mira variables.

<span class="mw-page-title-main">Psi Persei</span> Star in the constellation Perseus

Psi Persei is a single Be star in the northern constellation of Perseus. It has an apparent visual magnitude of about 4.2, so it is visible to the naked eye at night under suitably dark skies. Based on parallax measurements, it is located at a distance of roughly 580 light-years from the Earth.

<span class="mw-page-title-main">34 Persei</span> Binary star system in the constellation Perseus

34 Persei is a binary star system in the northern constellation of Perseus. It is visible to the naked eye as a faint, blue-white hued point of light with a combined apparent visual magnitude of 4.67. The system is located approximately 540 light years away from the Sun based on parallax, but it is drifting closer with a radial velocity of −3.5 km/s. It is a likely member of the Alpha Persei Cluster.

<span class="mw-page-title-main">HD 21278</span> Binary star system in the constellation Perseus

HD 21278 is a binary star system in the constellation Perseus, located within the 60±7 million year old Alpha Persei Cluster. It has a blue-white hue and is visible to the naked eye with a combined apparent visual magnitude of 4.99. The system is located at a distance of approximately 580 light years from the Sun based on parallax, and it is drifting further away with a radial velocity of +1.20 km/s.

30 Persei is a binary star system in the northern constellation Perseus. It is faintly visible to the naked eye with an apparent visual magnitude of 5.49. Based upon an annual parallax shift of 4.46±0.39 mas, is located roughly 730 light years from the Sun. It is a member of the Perseus OB3 association, which includes the Alpha Persei Cluster.

<span class="mw-page-title-main">29 Persei</span> Star in the constellation Perseus

29 Persei is a single star in the northern constellation of Perseus, located approximately 640 light years away from the Sun based on parallax. It is visible to the naked eye as faint, blue-white hued star with an apparent visual magnitude of 5.16. This object is a member of the Alpha Persei Cluster.

114 Tauri, or o Tauri, is a single, blue-white hued star in the zodiac constellation of Taurus. It is a faint star but visible to the naked eye with an apparent visual magnitude of 4.88. The distance to this star, as determined from its annual parallax shift of 5.22±0.21 mas, is roughly 620 light years. It is moving further from the Sun with a heliocentric radial velocity of 16.5 km/s, having come as close as 240 ly (75 pc) some 9.6 million years ago. It is a member of the Cas-Tau OB association of co-moving stars, and has a peculiar velocity of 8.3 km/s.

<span class="mw-page-title-main">7 Persei</span> Star in the constellation Perseus

7 Persei is a star in the constellation Perseus, located 774 light years away from the Sun. While the star bears the Bayer designation Chi Persei, it is not to be confused with the entire cluster NGC 884, commonly referred to as Chi Persei. It is faintly visible to the naked eye as a dim, yellow-hued star with an apparent visual magnitude of 5.99. This object is moving closer to the Earth with a heliocentric radial velocity of −12.5 km/s.

<span class="mw-page-title-main">9 Persei</span> Blue supergiant star in the constellation Perseus

9 Persei is a single variable star in the northern constellation Perseus, located around 4,300 light years away from the Sun. It has the Bayer designation i Persei; 9 Persei is the Flamsteed designation. This body is visible to the naked eye as a faint, white-hued star with an apparent visual magnitude of about 5.2. It is moving closer to the Sun with a heliocentric radial velocity of −15.2 km/s. The star is a member of the Perseus OB1 association of co-moving stars.

57 Persei, or m Persei, is a suspected triple star system in the northern constellation of Perseus. It is at the lower limit of visibility to the naked eye, having a combined apparent visual magnitude of 6.08. The annual parallax shift of 16.4 mas provides a distance measure of 199 light years. 57 Persei is moving closer to the Sun with a radial velocity of about −23 km/s and will make perihelion in around 2.6 million years at a distance of roughly 22 ly (6.6 pc).

<span class="mw-page-title-main">42 Persei</span> Binary star system in the constellation Perseus

42 Persei is a binary star system in the northern constellation of Perseus. It has the Bayer designation n Persei, while 42 Persei is the Flamsteed designation. The system is visible to the naked eye as a dim, white-hued point of light with an apparent visual magnitude of 5.11. It is located around 93 parsecs (302 ly) distant from the Sun, but is drifting closer with a radial velocity of −12.4 km/s.

<span class="mw-page-title-main">31 Persei</span> Star in the constellation Perseus

31 Persei is a single star in the northern constellation of Perseus. It is visible to the naked eye as a dim, blue-white hued point of light with an apparent visual magnitude of 5.05. This star is located around 172 parsecs (560 ly) away from the Sun, and it is drifting closer with a radial velocity of −1.6 km/s. It is likely a member of the Alpha Persei Cluster.

3 Persei is a single, orange-hued star in the northern constellation of Perseus. It is dimly visible to the naked eye under good viewing conditions, having an apparent visual magnitude of 5.70 The star is located around 79 parsecs (257 ly) distant, based upon an annual parallax shift of 12.7 mas.

<span class="mw-page-title-main">HD 21071</span> Star in the constellation Perseus

HD 21071 is a blue-white hued variable star in the northern constellation of Perseus. Also known as V576 Persei, it is a sixth magnitude star that is dimly visible to the naked eye under good viewing conditions, having an apparent visual magnitude of 6.09. The brightness of the star varies with a multiperiodic cycle. The distance to HD 21071, as determined from an annual parallax shift of 6.1 mas, is 535 light years. 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.

References

  1. 1 2 3 4 5 6 Kharchenko, N. V.; et al. (2013), "Global survey of star clusters in the Milky Way. II. The catalogue of basic parameters", Astronomy and Astrophysics, 558: 8, arXiv: 1308.5822 , Bibcode:2013A&A...558A..53K, doi:10.1051/0004-6361/201322302, S2CID   118548517, A53.
  2. 1 2 Prosser, Charles F.; et al. (October 1996). "ROSAT Pointed Observations of the Alpha Persei Cluster". Astronomical Journal. 112: 1570. Bibcode:1996AJ....112.1570P. doi: 10.1086/118124 .
  3. 1 2 Paunzen, E.; Mermilliod, J.-C. "WEBDA: Alpha Persei". Universität Wien. Retrieved 2020-10-17.
  4. ↑ Coyne, G. V.; et al. (March 1979), "Wavelength dependence of polarization. XXXIII - The Alpha Persei star cluster", Astronomical Journal, 84: 356–369, Bibcode:1979AJ.....84..356C, doi: 10.1086/112431
  5. ↑ "Cl Melotte 20". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2020-10-17.{{cite web}}: CS1 maint: postscript (link)
  6. ↑ van Leeuwen, F. (2009). "Parallaxes and proper motions for 20 open clusters as based on the new Hipparcos catalogue". Astronomy & Astrophysics. 497 (1): 209–242. arXiv: 0902.1039 . Bibcode:2009A&A...497..209V. doi:10.1051/0004-6361/200811382. S2CID   16420237.
  7. ↑ Majaess, D.; et al. (2011). "Deep Infrared ZAMS Fits to Benchmark Open Clusters Hosting delta Scuti Stars". Journal of the American Association of Variable Star Observers. 39 (2): 219. arXiv: 1102.1705 . Bibcode:2011JAVSO..39..219M.
  8. 1 2 3 4 5 Lodieu, N.; et al. (August 2019). "A 5D view of the α Per, Pleiades, and Praesepe clusters". Astronomy & Astrophysics. 628: 26. arXiv: 1906.03924 . Bibcode:2019A&A...628A..66L. doi:10.1051/0004-6361/201935533. S2CID   182952614. A66.
  9. ↑ Sheikhi, Najmeh; et al. (March 2016). "The binary fraction and mass segregation in Alpha Persei open cluster". Monthly Notices of the Royal Astronomical Society. 457 (1): 1028–1036. arXiv: 1601.02186 . Bibcode:2016MNRAS.457.1028S. doi: 10.1093/mnras/stw059 .
  10. 1 2 Nikiforova, Victoria V.; et al. (September 2020). "The Relation of the Alpha Persei Star Cluster with the Nearby Stellar Stream". The Astronomical Journal. 160 (3): 11. arXiv: 2007.11211 . Bibcode:2020AJ....160..142N. doi: 10.3847/1538-3881/aba753 . S2CID   220686998. 142.
  11. 1 2 3 4 Zuckerman, B.; et al. (June 2012). "Stellar Membership and Dusty Debris Disks in the α Persei Cluster". The Astrophysical Journal. 752 (1): 12. arXiv: 1204.3950 . Bibcode:2012ApJ...752...58Z. doi:10.1088/0004-637X/752/1/58. S2CID   119207634. 58.
  12. ↑ Morrell, Nidia; Abt, Helmut A. (July 10, 1992), "Spectroscopic binaries in the Alpha Persei cluster", Astrophysical Journal, Part 1, 393 (2): 666–673, Bibcode:1992ApJ...393..666M, doi:10.1086/171534.
  13. 1 2 3 4 Hoogerwerf, Ronnie (March 2000), "OB association members in the ACT and TRC catalogues", Monthly Notices of the Royal Astronomical Society, 313 (1): 43–65, Bibcode:2000MNRAS.313...43H, doi: 10.1046/j.1365-8711.2000.03192.x
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