Alpha Persei
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| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Perseus |
| Right ascension | 03h 24m 19.4s |
| Declination | +49° 51′ 40″ |
| Apparent magnitude (V) | 1.79 |
| Characteristics | |
| Spectral type | F5 Ib[1] |
| U−B color index | 0.37 |
| B−V color index | 0.48 |
| Astrometry | |
| Radial velocity (Rv) | -2 km/s |
| Proper motion (μ) | RA: 24.11 mas/yr Dec.: -26.01 mas/yr |
| Parallax (π) | 5.51 ± 0.66 mas |
| Distance | approx. 590 ly (approx. 180 pc) |
| Details | |
| Mass | 7.3 ± 0.3[1] M☉ |
| Radius | 60 ± 7[2] R☉ |
| Surface gravity (log g) | 1.90 ± 0.04[1] |
| Temperature | 6,350 ± 100[1] K |
| Age | 4.1 × 107 years[1] years |
| Other designations | |
Alpha Persei (α Per) is the brightest star in the constellation of Perseus, just outshining the constellation's best known star Algol. It also bears the traditional names Mirfak and Algenib. A yellow-white supergiant, it lies around 590 light years from Earth and is a member of a cluster of stars known as the Alpha Persei Cluster.
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[edit] Physical properties
Its luminosity is 5,000 times and its diameter 62 times that of our Sun. It has a similar spectrum to Procyon, though the latter star is much less luminous. This difference is highlighted in their spectral designation under the Yerkes spectral classification, published in 1943, where stars are ranked on luminosity as well as spectral typing. Procyon is thus F5 IV.[3] Since 1943, the spectrum of Alpha Persei has served as one of the stable anchor points by which other stars are classified.[4]
It lies in the middle of a cluster of stars known as the Alpha Persei Cluster, or Melotte 20, which is easily visible in binoculars and includes many of the fainter stars of Perseus.
In the Hertzsprung–Russell Diagram, Mirfak lies very close to the region in which Cepheid variables are found. It is thus useful in the study of these stars, which are extremely important standard candles.
[edit] Visibility
A fairly bright star of the second magnitude, Mirfak is circumpolar when viewed from the latitude of New York.[5]
[edit] Etymology and cultural significance
The names Mirfak and Algenib are Arabic in origin. The former, meaning 'Elbow' and also written Mirphak, Marfak or Mirzac, comes from the Arabic Mirfaq al-Thurayya, while Algenib, also spelt Algeneb, Elgenab, Gęnib, Chenib or Alchemb, is derived from الجنب al-janb, or الجانب al-jānib, 'the flank' or 'side'.[5] Gamma Pegasi also bears the name Algenib.
It forms part of Tien Yuen, the Heavenly Enclosure, in traditional Chinese astronomy. It is known as 天船三 (Mandarin: tiān chuán sān), the Third Star of the Celestial Boat.[5]
Hinali'i is the name of the star in Native Hawaiian astronomy. The name of the star is meant to commemorate a great tsunami and mark the beginning of the migration of Maui. According to some Hawaiian folklore, Hinali'i is the point of separation between the earth and the sky that happened during the creation of the Milky Way.[6]
[edit] Footnotes
- ^ a b c d e Lyubimkov, Leonid S. et al. (February 2010), "Accurate fundamental parameters for A-, F- and G-type Supergiants in the solar neighbourhood", Monthly Notices of the Royal Astronomical Society 402 (2): 1369–1379, Bibcode 2010MNRAS.402.1369L, doi:10.1111/j.1365-2966.2009.15979.x
- ^ Nordgren, Tyler E. et al. (December 1999), "Stellar Angular Diameters of Late-Type Giants and Supergiants Measured with the Navy Prototype Optical Interferometer", The Astronomical Journal 118 (6): 3032-3038, Bibcode 1999AJ....118.3032N, doi:10.1086/301114
- ^ Ramanamurthy G (2007). Biographical Dictionary of Great Astronomers. Sura Books. p. 167. ISBN 817478697X.
- ^ Garrison, R. F. (December 1993), "Anchor Points for the MK System of Spectral Classification", Bulletin of the American Astronomical Society 25: 1319, Bibcode 1993AAS...183.1710G, http://www.astro.utoronto.ca/~garrison/mkstds.html, retrieved 2012-02-04
- ^ a b c Allen, Richard Hinckley (1963). Star Names: Their Lore and Meaning (revised edition). Dover. pp. 332–33. ISBN 0-486-21079-0.
- ^ Malama Maunakea Astronomy
[edit] External links
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