Credits: Panel A: XMM-Newton EPIC (Guedel et al.),
Panel B: AAAS/Science
(ESA XMM-Newton and NASA Spitzer data)
An early present for astronomers, the cloud suggests that hot gas from many star-forming regions leaks into the interstellar medium.
The Orion nebula is the nearest dense star-forming region to Earth that contains stars much more massive than the Sun. XMM-Newton’s newly-discovered gas cloud is composed of winds blowing from these high-mass stars that are heated to millions of degrees as they slam into the surrounding gas.
“There is one star in particular that dominates the nebula,” says Manuel Güdel, Paul Scherrer Institut, Switzerland, who led the team that discovered the gas. The star in question is theta1 Orionis C, a giant star around 40 times mass of the Sun, with a surface temperature of 40,000°C. Güdel 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.
Credits: AAAS/Science (ESA XMM-Newton and NASA Spitzer data)
The high-temperature gas fills a region of the nebula that appears to be a huge cavity in optical and infrared images. 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,” says Güdel.
B: NASA/ Spitzer,
C: © Anglo-Australian Observatory/David Malin Images,
D: © Anglo-Australian Observatory/David Malin Images, VLA