M45 - Pleiades
Messier 45 or M45 is an open cluster in the constellation Taurus. It has an apparent visual magnitude of 1.6 and its angular diameter is 110 arc-minutes. M45 lies at an estimated distance of 440 light years. The Equinox 2000 coordinates are RA= 3h 47m, Dec= +24° 07´ which makes M45 best seen during the winter. The Messier Winter Star Chart shows the position of all Messier objects visible during that season. As one of the more famous objects in the Messier Catalog, it is commonly known as the Pleiades or Seven Sisters.
The image above shows the uncropped view of M45 through the Takahashi E-180 Astrograph (North is up). A 2x enlargement of this image appears to the right. The a higher magnification view of this open cluster, see M45 (ASA N12) .
M45 is one of the most famous night sky asterisms and is known as the Pleiades, the Seven Sisters and Subaru. The cluster is composed of extremely hot and luminous blue stars. The faint reflection nebula visible around the brightest stars is an unrelated dust cloud that the cluster is currently passing through. Gravitational interactions with other stars in the galactic neighborhood will eventualy disperse the custer about 250 million years in the future.
This open cluster has been known since antiquity and is easily visible to the naked eye. According to Kharchenko et al. (2005), the distance of M45 is 425 light years and its diameter is 15 light years. It contains 332 stars and its estimated age is 100 million years.
Messier's Description of M45
March 4, 1769
`A cluster of stars, known by the name of the Pleiades. The position reported is that of the star Alcyone.'
- Object: M45
- Other Names: Pleiades, Seven Sisters, Subaru
- Object Type: open cluster
- Object Data: Apparent Magnitude = 1.6, Angular Size = 110 arc-minutes
- Object Position (Equinox 2000): RA= 3h 47m, Dec= +24° 07´, Constellation = Taurus
- Date/Time: 2011 Jan 27 at 03:43 UTC
- Location: Bifrost Astronomical Observatory, Portal, AZ
- Mount: Astro-Physics 1200GTO
- Telescope: Takahashi Epsilon 180 Hyperbolic Astrograph
- Camera: Canon EOS 550D (Rebel T2i) (modified with a Baader UV/IR filter)
- Field of View: 1.70° x 2.56° at 1.7 arc-sec/pixel (web version: 10.0 arc-sec/pixel)
- Exposure: x 300s, f/2.8, ISO 800
- File Name: M45-01w.jpg
- Processing (Adobe Camera Raw): Graduated Filter, Vignetting Correction, Noise Reduction, White Balance, Curves
- Processing (Photoshop CS5): Average Images, Curves, Noise Reduction
- Original Image Size: 3454 × 5179 pixels (17.9 MP); 11.5" x 17.3" @ 300 dpi
- Rights: Copyright 2011 by Fred Espenak. All Rights Reserved. See: Image Licensing.