X-ray & Infrared Images of Flame Nebula
Astronomers have studied two star clusters to gain insight on how clusters of stars like our Sun form. These images show one of the clusters, NGC 2024 (located in the center of the Flame Nebula), in X-rays from Chandra and infrared data from Spitzer Space Telescope. A study of NGC 2024 and the Orion Nebula Cluster suggest that the stars on the outskirts of these clusters are older than those in the central regions. This is different from what the simplest idea of star formation predicts, where stars are born first in the center of a collapsing cloud of gas and dust when the density is large enough.
(Credit: X-ray: NASA/CXC/PSU/K.Getman, E.Feigelson, M.Kuhn & the MYStIX team; Infrared:NASA/JPL-Caltech)

Optical Image of the Flame Nebula
An optical image, from the Digitized Sky Survey, of a large field centered on the Flame Nebula. A comparison with the composite image from Chandra and Spitzer - shown as an overlay - demonstrates how powerful X-ray and infrared images are for studying star forming regions. The central cluster of stars, NGC 2024, is clearly observed in the X-ray and optical images but is not visible in the optical image.
(Credit: DSS)