Caused by the vanes supporting the secondary mirror
............... f = 1200mm Newtonian ................... f = 400mm Canon lens ...............
This star cluster is called the Pleiades, or the Seven Sisters. Most people can make out up to 6 stars with the naked eye but binoculars reveal many more stars. Only by taking a photograph will you see the wispy dust clouds surrounding the stars.
The photo on the left, through a Newtonian telescope, has spikes due to the mirror supports. The photo on the right was just with a camera plus telephoto lens - no spikes.