Messier 78 (NGC 2068), a bright reflection nebula in Orion

Messier 78 (NGC 2068), a bright reflection nebula in Orion

This new image (released May 2, 2012) of the region surrounding Messier 78 shows clouds of cosmic dust threaded through the nebula like a string of pearls. It reveals the submillimetre-wavelength radiation from dust grains in space, showing that dust can be dazzling. Dust is important to astronomers as dense clouds of gas and dust are the birthplaces of new stars.

In the centre of the image is Messier 78. When seen in visible light we see the pale blue glow of starlight reflected from clouds of dust. The APEX observations are overlaid on the visible-light image in orange. Sensitive to longer wavelengths, they reveal the gentle glow of dense cold clumps of dust, some of which are even colder than -250ºC. In visible light, this dust is dark and obscuring, which is why telescopes such as APEX are so important for studying the dusty clouds in which stars are born.

One filament seen by APEX appears in visible light as a dark lane of dust cutting across Messier 78. This tells us that the dense dust lies in front of the reflection nebula, blocking its bluish light. Another prominent region of glowing dust seen by APEX overlaps with the visible light from Messier 78 at its lower edge. The lack of a corresponding dark dust lane in the visible light image tells us that this dense region of dust must lie behind the reflection nebula.

Observations of the gas in these clouds reveal gas flowing at high velocity out of some of the dense clumps. These outflows are ejected from young stars while the star is still forming from the surrounding cloud. Their presence is therefore evidence that these clumps are actively forming stars.

At the top of the image is another reflection nebula, NGC 2071. While the lower regions in this image contain only low-mass young stars, NGC 2071 contains a more massive young star (HDE 290861) with an estimated mass five times that of the Sun, located in the brightest peak.

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