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Messier 45, the closest Messier object, is an open cluster in the constellation Taurus. Its stars seem to be surrounded by a dust cloud that reflects the blue light of the brightest B stars present in the cluster. This reflection nebula, however, does not belong to the cluster, as their velocities and direction of movement are different. The dust cloud is closer to us and the stars’ blue light just happens to be dispersed by the dust before it reaches us. This nebulosity was not discovered until 1859 and given the catalog number of NGC 1435 (Merope Nebula). The cluster is about 100 million years old and the star formation ended about 80 million years ago. This is the reason that explains that there are no O-Type stars in the cluster, because all of the original ones must have gone supernova long ago.
This image is a two panel mosaic, showing a fragment of the larger cluster. It was taken with broad band filters (LRGB) and a third panel had to be added (taking the central region) in order to reduce the internal reflections in the telescope, due to the extreme brightness of the stars.
Additional Information
Object
Name(s): Messier 45. The Pleiades Cluster. The Seven Sisters. Subaru (Japanese)
Type: Open Cluster with non-related Reflection Nebula
RA: 03h 46m 59s
Dec: +24º 06’ 52”
Constellation: Taurus
Size (arcmin): 120×120 arc min
Magnitude: +1.5
Distance: 444 ly
Image
Date: 2019-12-23 to 2021-02-08
Location: Curiosity2 Observatory, New Mexico Skies, Mayhill, NM, USA
Size (arcmin): 54×31 arcmin
Telescope: 24” (61 cm) f/6.5 Reflector
Camera: FLI PL16803 (4096x4096pix)
Guiding: Astrodon MonsterMOAG off-axis guider
Total exposure: 32 h 15 m (L: 13 h; RGB: 19h 15m)
Processing: CCDStack, Photoshop CC 2021