Tuesday, September 16, 2014

The Tulip Nebula (Sharpless 101)

The Tulip Nebula is an emission nebula in a distance of 6,000 light years from earth in the constellation Cygnus.
(click on image for full resolution)

The image consists of 130min Ha, 300min OIII and 250min SII.

The nebula gets excited by the young, energetic star HDE 227018 at the center of the nebula near the arc. HDE 227018 moves very fast through the nebula (almost certainly it was not created within the nebula). The arc is probably bow shock, indicating in which way HDE 227018 moves.

Another interesting object in the nebula is a star to the right of the nebula: Cygnus X-1. In 1964 during a rocket flight, it was identified as a very strong x-ray emitter. After more analysis, researchers identified it as a binary system where the second star is invisible. From the movement of the visible star, the mass of the invisible partner was determined to be between 20 and 35 solar masses. Since the largest possible mass of a neutron star can not exceed three solar masses, the compact object was suspected to be a black hole. In 1974, Stephen Hawking and Kip Thorne had a wager - with Stephen Hawking betting it is not a black hole. He conceded the bet in 1990 after additional observational data strengthened that case. And if Stephen Hawking concedes, there aren't any doubts left. And with that, Cygnus X-1 became one of the first confirmed black holes.

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