Italian astro photographer showed us amazingly successful new image of the nebula “Helmet Thor” stars, related to a class of Wolf – Rayet stars. Emission nebula “Helmet Thor” and is known under two other symbols: NGC 2359 and LBN 1041. It was opened by the famous English astronomer William Herschel, German-born (William Herschel) in winter, January 31, 1785.
Nebula “Thor Helmet” is located at a distance of 15,000 light-years from Earth in the southern constellation of the “Big Dog”. Across this emission nebula is about 30 light-years. The title of this nebula is consistent with its form: the nebula looks like a mythical hero helmet. Almost in the center of the nebula “Helmet Thor” is a star belonging to the class of stars “Wolf – Rayet star.” This class of stars, which are characterized by very high temperature and luminosity. Star Wolf – Rayet stars are different from other hot stars in the presence of a wide spectrum of the emission bands of hydrogen, helium, and oxygen, carbon, nitrogen, in various degrees of ionization (NIII – NV, CIII – CIV, OIII – OV). Class name stars associated with the names of French astronomers S. Wolf and J. Rice, first drew attention to the features in their spectra in 1867.
Star Wolf – Rayet stars are divided into two sequences: nitrogen (WN) and carbon (WC). In the spectra of stars of the first sequence in the main line contains nitrogen, and in the spectra of the second – the line of carbon and oxygen. In the spectra of stars of both sequences are present line of helium and hydrogen, but hydrogen lines are weak and the estimates of the relative chemical composition consistently show that the hydrogen atoms in the atmospheres of Wolf – Rayet star is several times smaller than the helium atoms.
In the Milky Way galaxy known to date, only about 230 of Wolf – Rayet star, the luminosity with an average of 4,000 times the luminosity of the sun. With about 100 stars of this type are found in the Large Magellanic Cloud, and only 12 in the Small – Milky Way satellites