‘Santa Claus’ gas cloud in our galaxy excites astronomers

December 1st, 2007 - 1:28 pm ICT by admin  

Paris , Dec 1: European Space Agency’s (ESA) XMM-Newton X-ray observatory has discovered a huge cloud of high-temperature gas shaped somewhat like the silhouette of Santa Claus, in the Orion constellation in our galaxy.
Found in a nearby star forming region, the newly-discovered gas cloud is composed of winds blowing from high-mass stars that are heated to millions of degrees as they slam into the surrounding gas.
The origin of the gas cloud is a result of winds blowing from one particular star in the Orion Nebula.
“There is one star in particular that dominates the nebula,” says Manuel Gsuedel, Paul Scherrer Institut, Switzerland, who led the team that discovered the gas.
The star in question is theta-1 Orionis C, a giant star around 40 times mass of the Sun, with a surface temperature of 40,000 degree Celsius. Guedel and his colleagues think that the violent collision between the wind from this star and the surrounding dense gas is largely responsible for the newly-discovered hot gas cloud.
The new observations, taken with XMM-Newton’s European Photon Imaging Camera (EPIC) camera, suggest that astronomers are seeing only a particular portion of the gas. The X-rays from this portion escape absorption by patches of cold gas covering much of the front of the Orion nebula.
The surrounding pattern of absorbing clouds gives the detected gas its Santa Claus shape, with his prominent hat outlined by the northern gas bubble. In its entirety, the hot gas probably fills the whole nebula.
The team discovered it whilst conducting a survey of the young stars in the region. In the background of many of those images was a faint glow of X-rays. “The diffuse signal came up time and time again. Finally, we realized that it was something real,” said Gsuedel.
The presence of the hot gas in a fairly common nebula like Orion is surprising.
Although theory has predicted such hot gas clouds, previous observations suggested that a large number of massive stars shedding winds, or supernova explosions are required. These are found in some regions of vigorous high-mass star formation, which are scattered only rarely throughout the galaxy. The new observations show that much smaller collections of high mass stars can produce hot gas as well.
The team now plans to obtain new observations to determine how the gas flows out of the Orion nebula. In particular, they want to see whether it connects with a giant bubble created by supernova explosions from previous generations of massive stars. (ANI)

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