AAO image reference AATCCD 17. « Previous || Next »
Top left is NE. Image width is about 7 arc min
Image and text © 1999-2002, Australian Astronomical Observatory, Photograph by S. Lee, C. Tinney and D. Malin.
This image is only available as a digital file
In a modest telescope M78 looks like a faint comet, exactly the kind of object Messier intended to include in his catalog to avoid confusion with the real thing. The same telescope will also reveal two stars of similar apparent brightness (about 10th magnitude) embedded in the nebula. It is light from these stars reflected by dust grains that is responsible for the nebulosity, and a look at our color picture shows that the whole field is shrouded in dust.
M78 is thus a reflection nebula, one of the brightest in the sky. But the conjunction of the two obvious stars and dust is not an accident. They are the brightest members of a small cluster of stars forming inside the dusty cloud. These are mostly invisible at optical wavelengths but some signs of them are evident in the two small, reddish nebulae towards the lower center and extreme lower left (SW) of the frame. These are Herbig-Haro objects, rapidly-moving jets ejected at an early stage in the formation of stars. Where such jets emerge from the dense dust they advertise recent star formation.
Entry from NGC 2000.0 (R.W. Sinnott, Ed.) © Sky Publishing Corporation, 1988:
NGC 2068 Nb 05 46.7 +00 03 s Ori8. 8.B, L, wisp, gmbN, 3 st inv, r; = M78For details of object position and photographic exposure, search technical table by AAT reference number.
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