The Seven Sisters, also called the Pleiades or M45, is an open star cluster located about 400 light years away towards the constellation Taurus. It is about 13 light years across and is one of the brightest and closest star clusters to us.
The cluster contains over 3000 stars, most of which are considered middle aged. Surrounding the brighter stars are reflection nebulae, gas and dust reflecting the light from the stars. Also buried in the cluster are faint, low mass brown dwarf stars.
This image shows a dark interstellar cloud ravaged by the passage of Merope, one of the brightest stars in the Pleiades star cluster. Just as a torch beam bounces off the wall of a cave, the star is reflecting light from the surface of pitch-black clouds of cold gas laced with dust. As the nebula approaches Merope, the strong starlight shining on the dust decelerates the dust particles. The nebula is drifting through the cluster at a relative speed of roughly 11 kilometres per second.
The Hubble Space Telescope has caught the eerie, wispy tendrils of a dark interstellar cloud being destroyed by the passage of one of the brightest stars in the Pleiades star cluster. Like a flashlight beam shining off the wall of a cave, the star is reflecting light off the surface of pitch black clouds of cold gas laced with dust. These are called reflection nebulae.
Perhaps the most famous star cluster on the sky, the Pleiades can be seen without binoculars from even the depths of a light-polluted city. Also known as the Seven Sisters and M45, the Pleiades is one of the brightest and closest open clusters. The Pleiades contains over 3000 stars, is about 400 light years away, and only 13 light years across. Quite evident in the above photograph are the blue reflection nebulae that surround the brighter cluster stars. Low mass, faint, brown dwarfs have also been found in the Pleiades.
The Pleiades open cluster, or Messier 45. A collection of Hot, Blue Stars that formed together from the same nebula.
At 444 lightyears away, t’s one of the closest clusters to our Solar System and is just visible to the Naked Eye on most nights in Northern-Hemisphere Winter, making it an easy target for any Northern-Hemisphere Astronomer.