M 78

Diffuse Nebula M78 (NGC 2068), a reflection nebula,

Orion complex, a large cloud of gas and

dust centered on the Orion Nebula

M42/M43, and is about 1,600

light years distant. It is the brightest portion of a vast dust cloud which

includes NGC 2071 (northeast, lower right in our image), NGC 2067 (close

northwest), and very faint NGC 2064 (southwest), all visible in our image.

M78 shines in the reflected light of bright blue (early B-type) stars,

among them the brightest, HD 38563 at apparent magnitude 10.

At its distance, M78 measures almost 4 light years in extension.

In and near this nebula, 45 low mass stars with hydrogene emission lines,

irregular variables similar to the star T Tauri, were detected.

Stars of this type are main sequence stars which vary in brightness

(by about 3 magnitudes) and spectral type (which is about F or G, and similar

to the chromosphere of our sun), are 4 to 5 times brighter than their spectral

type would suggest, and associated with nebulosity which may be bright or dark.

Probably these are very young stars which are still in their formation process.

Visually, M78 resembles a faint comet. The other nebulae in this field require

a very dark sky and are much more difficult than M78.