by Josh Lake, science faculty –
This winter, Pomfret astronomy students have been learning to use the powerful telescope and camera housed in our observatory. They’ve taken pictures of star clusters and nebulae, and they recently captured one of the most famous clouds of hydrogen in the night sky: The Orion Nebula, M42. This is one of the few clouds of gas and dust that is visible with binoculars (and even the naked eye under clear dark skies). It can be found underneath the famous 3 belt stars of Orion in the southern winter sky:
When seen with binoculars, the nebula looks like a fuzzy white patch. The human eye’s cones, which are sensitive in red, green, and blue wavelengths of light, cannot see colors that faint. Only the rods allow us to see the object, as they are far more sensitive light detectors but cannot perceive color.
Enter the camera and telescope! Using a CCD camera that is much like the one in your cell phone (only far bigger and more sensitive), students recorded a ‘stack’ of images in three filters and combined them to create a full color image of the beautiful nebula. Jon Pate ’12 processed one of the best this year:
This is as close as we can get to a ‘real color’ image — the red color is really what glowing ionized hydrogen looks like, but this image has far greater contrast than the human eye would normally allow.
Students also exposed a set of frames in narrowband filters, looking at only three specific element transitions: hydrogen alpha, oxygen III, and sulphur II. Given this data, with each frame just a black and white image, students had to choose which colors to map to and which features to reveal.
Below, you can see the processing choices that each student made. Some of them preferred to enhance the dusty regions surrounding the stellar nursery; others increased the contrast to reveal the structure in the core. Some wanted to make the background black, while others brought out the faint filaments in the supposedly empty space. Each one provides a unique look at the Orion Nebula and its features, and all of them have a certain beauty. Which one is your favorite?
Stay tuned for updates from the observatory as students tackle their first image of a galaxy.