Welcome to another Messier Monday. In our ongoing tribute to the great Tammy Plotner, we bring you another item from the Messier Catalog!
In the 18th century, while searching the night sky for comets, French astronomer Charles Messier kept noting the presence of fixed, diffuse objects in the night sky. In time, he would come to compile a list of approximately 100 of these objects, with the purpose of making sure that astronomers did not mistake them for comets. However, this list – known as the Messier Catalog – would go on to serve a more important function, acting as a milestone in the history of the study of Deep Sky Objects.
However, not all objects in the catalog were first discovered by Charles Messier himself. Some, like the Lagoon Nebula, were observed sooner, owing to the fact that they are visible to the naked eye. This interstellar cloud, which is located in the Sagittarius constellation, has been known of since the late 17th century, and is one of only two star-forming nebulae that is visible to the naked eye from mid-northern latitudes.
Wow, is this gorgeous or what?! Argentinean astronomers Julia Arias and Rodolfo Barbá used the Gemini South telescope in Chile to obtain this stunning new image, allowing us to dive right into part of the Lagoon Nebula (M8). This region of the Lagoon is sometimes called the “Southern Cliff” because it resembles a sharp drop-off. Beyond the cliff, light from a spattering of young background stars in the upper left of the image shines through the cloudscape.
The Lagoon nebula is located near the constellation Sagittarius in the southern Milky Way. Viewed through large amateur telescopes, it appears as a pale ghostly glow with a touch of pink. In this image, the astronomers used special filters to reveal characteristics of the gas clouds. The reds, blues and greens represent each of three data sets results in a very strong color differentiation. And so, this isn’t what the Lagoon Nebula would actually look like were we to travel there and take a look with our own eyes. Two narrow-band optical filters sensitive to hydrogen (red) and ionized sulfur (green) emission, and another that transmits far red light (blue). And so, for example, light from the far-red end of the spectrum, beyond what the eye can see, appears blue in this image.
Arias and Barbá obtained the imaging data to explore the evolutionary relationship between the newborn stars and what are known as Herbig-Haro (HH) objects. HH objects form when young stars eject large amounts of fast-moving gas as they grow. This gas plows into the surrounding nebula, producing bright shock fronts that glow as the gas is heated by friction and surrounding gas is excited by the high-energy radiation of nearby hot stars. The researchers found a dozen of these HH objects in the image, spanning sizes that range from a few thousand astronomical units (about a trillion kilometers) to 1.4 parsecs (4.6 light-years), i.e. a little greater than the distance from the Sun to its nearest neighbor Proxima Centauri.