Why is the Horsehead Nebula surrounded by a bubble? Although hard to make out, the famous Horsehead Nebula is the slight dark indentation in the bright streak just to the right of the image center. Glowing like an emission nebula, the origin of the bubble, known as Barnard's Loop, is currently unknown. Progenitor hypotheses include the winds from bright Orion stars and the supernovas of stars long gone. Barnard's Loop is too faint to be identified with the unaided eye. The nebula was discovered only in 1895 by E. E. Barnard on long duration film exposures. The above image was taken through RGB filters and improved by data coming from hydrogen filtered light to bring out detail. To the left of the Horsehead Nebula, visible as a small dark indentation, is the photogenic Flame Nebula while close to the right upper corner is shining the famous M42 nebula (text adapted from APOD). Mosaic of two frames collecting a total of 16 hours of light Pentax 67 EDIF 300mm f/4 - FLI Proline 16803 - Ha (240m) R (180m) G (320m) B (240m) - Warrumbungle Observatory, Coonabarabran, NSW, Australia
A variety of stars and nebulae can be found towards the constellation of Sagittarius. Dense fields of stars laced with dark lanes of dust crowd this region only a few degrees from the center of our Galaxy. Prominent nebulae include the red Lagoon Nebula (M8) in the center and the multicolored Trifid Nebula (M20) in the upper right. Another one, NGC 6559, is at the left of M8, separated from the larger nebula by a dark dust lane. All three are stellar nurseries about five thousand light-years or so distant. In this digital composition, the dominant red color of the emission nebulae is due to glowing hydrogen gas energized by the radiation of hot, young stars. The contrasting blue hues, most striking in the Trifid as well as NGC 6559, are due to dust reflected starlight. The bright HII region left of the Trifid is Sh-34 while the one closest to the bottom right corner is Sh-22. Also visible over Sh-34 the rainbow trace left by an asteroid. Almost at the center of this image is the open cluster M21 (text adapted from APOD). Pentax 67 EDIF 300mm f/4 - FLI Proline 16803 - Ha (120m) R (40m) G (40m) B (40m) - Warrumbungle Observatory, Coonabarabran, NSW, Australia
A jewel of the southern sky, the Great Carina Nebula, aka NGC 3372, spans over 300 light-years. Near the upper right of this expansive skyscape, it is much larger than the more northerly Orion Nebula. In fact, the Carina Nebula is one of our galaxy's largest star-forming regions and home to young, extremely massive stars, including the still enigmatic variable Eta Carinae, a star with well over 100 times the mass of the Sun. Nebulae near the center of the 12 degree wide field include NGC 3576 and NGC 3603. Near center at the top of the frame is open star cluster NGC 3532, the Firefly Pary Cluster. More compact, NGC 3766, the Pearl Cluster, can be spotted at the left. Anchoring the lower left of the cosmic canvas is another large star-forming region, IC 2948/2944 with embedded star cluster Collinder 249. That region is popularly known as the Running Chicken Nebula. (text adapted from APOD). 24 hours of total exposures went into this 4 panels mosaic covering about 140 square degrees of sky. Pentax 67 EDIF 300mm f/4 - FLI Proline 16803 - Ha (480m) OIII (480) R (160m) G (160m) B (160m) - Warrumbungle Observatory, Coonabarabran, NSW, Australia
