‘Hidden Treasure’ Reveals Reflected Glory

Messier 78 is a fine example of a reflection nebula. The ultraviolet radiation from the stars that illuminate it is not intense enough to ionize the gas to make it glow — its dust particles simply reflect the starlight that falls on them. Despite this, Messier 78 can be observed easily with a small telescope because it is one of the brightest reflection nebulas in the sky. It lies about 1350 light-years away in the constellation of Orion and can be found northeast of the easternmost star of Orion's belt.

A new image of Messier 78 from the Max Planck Gesellschaft (MPG)/European Southern Observatory (ESO) 2.2-m telescope at the La Silla Observatory in Chile is based on data selected by Igor Chekalin in his winning entry to the “Hidden Treasures” competition. Chekalin, who lives in Russia, uncovered the raw data for this image of Messier 78 in ESO's archives. He processed the raw data with great skill, claiming first prize in the contest for his final image. ESO's team of in-house image-processing experts then independently processed the raw data at full resolution to produce the image shown here.

This new image of the reflection nebula Messier 78 was captured using the Wide Field Imager camera on the MPG/ESO 2.2-meter telescope at the La Silla Observatory, Chile. This color picture was created from many monochrome exposures taken through blue, yellow/green and red filters, supplemented by exposures through a filter that isolates light from glowing hydrogen gas. The total exposure times were 9, 9, 17.5 and 15.5 minutes per filter, respectively. (Image: ESO and Igor Chekalin)

The pale blue tint seen in the nebula is an accurate representation of its dominant color. Blue hues are commonly seen in reflection nebulas because of the way the starlight is scattered by the tiny dust particles that they contain: The shorter wavelength of blue light is scattered more efficiently than the longer wavelength red light.

This image contains many other striking features apart from the glowing nebula. A thick band of obscuring dust stretches across the image from the upper left to the lower right, blocking the light from background stars. In the bottom right corner, many curious pink structures are also visible, which are created by jets of material being ejected from stars that have recently formed and are still buried deep in dust clouds.

Two bright stars, HD 38563A and HD 38563B, are the main powerhouses behind Messier 78. However, the nebula is home to many more stars, including a collection of about 45 low mass, young stars (less than 10 million years old) in which the cores are still too cool for hydrogen fusion to start, known as T Tauri stars. Studying T Tauri stars is important for understanding the early stages of star formation and how planetary systems are created.

Remarkably, this complex of nebulas has also changed significantly in the last ten years. In February 2004, the experienced amateur observer Jay McNeil took an image of this region with a 75-mm telescope and was surprised to see a bright nebula — the prominent fan-shaped feature near the bottom of this picture — where nothing was seen on most earlier images. This object is now known as McNeil's Nebula, and it appears to be a highly variable reflection nebula around a young star.

This color picture was created from many monochrome exposures taken through blue, yellow/green and red filters, supplemented by exposures through an H-α filter that shows light from glowing hydrogen gas. The total exposure times were 9, 9, 17.5 and 15.5 minutes per filter, respectively.

For more information, visit: www.eso.org