Press Release

Orion Nebula

January 28, 1999

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Object Name: Orion Nebula
Telescope: Subaru Telescope / Cassegrain Focus
Instrument: CISCO
Filter: J (1.25 micron), K' (2.15 micron), H 2 -line (2.12 micron)
Color: Blue (J), Green (K'), Red (H 2 -line)
Date: UT 1999 Jan 14 (J), Jan 12 (K'), Jan 14 (H 2 -line narrow band filter)
Exposure: 68 sec (J), 338 sec (K'), 30 sec (H 2 -line)
Field of View: 4.1 arcmin by 4.8 arcmin
Orientation: North up, east left
Position: RA(J2000.0)=5h35m15s, DEC(J2000.0)=-5d23m29s

This is an infrared image of the the famous Orion nebula (Messier 42), located 1500 light years away. At the center of the image is the Trapezium, a group of four bright stars. Many stars seen around the Trapezium are young stars embedded in the Orion molecular cloud located behind the Orion nebula. Many of them are seen only at infrared wavelengths. Blue, faint, and diffuse emission extending over the entire region is due to hot gas ionized by strong ultraviolet radiation emitted by the Trapezium stars. The bright bar seen in the lower left part of the image is an ionization front.

Above the Trapezium, a butterfly-like red feature is seen in the image, containing the Kleinman-Low (KL) nebula which is deeply embedded in the Orion molecular cloud. At the center of the KL nebula is a star called IRc2, which is in the process of forming. This star is believed to be 30 times more massive than the Sun, and its activities are the cause of the big butterfly feature.

This false-color image was synthesized from three images taken with J (1.25 micron), K' (2.15 micron), and H 2 -line (2.12 micron, narrow band) filters, assigning blue for J, green for K', and red for H 2 -line images. Nine images of contiguous fields were obtained with CISCO, which has a 2 arcmin by 2 arcmin field of view, and were combined to make this image. Some ghost (false) images from very bright stars are seen.



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