All good things come in three. Thus, we have a look at an image of the IC5146 Cluster this week – 3 weeks of images in a row, back to light curves next week. There are (obviously 🙂 ) several young variable sources in the field, and some of which have been discussed in the past (week 76, week 130, week 142, week 157).
The image above shows two versions of the cluster. Both are taken in the V, R, and I-band filters. On the left is a ‘zoomed’ in version obtained with the 1m telescopes of the LCO network. Each colour frame is exposed for 3x60s. On the right is the larger scale area visible in the images from the 0.4m telescopes of the LCO. For this, each colour frame has been exposed for 3x120s. The green colour of the nebulosity is due to emission from atomic hydrogen. It emits a red emission line (in the R-band). But since we assigned the R-band to the green colour channel, it looks green 🙂 . This has to be done as we need to assign the colours to the red, green, and blue channels in order of wavelength.
We can see in the left image that the cluster is surrounded by dark patches of gas and dust. These are the regions where less stars are visible just outside the green nebulosity. On the larger scale image, we can see that this is actually just the end of a long dark filament of material. It extends all the way from the cluster to the top right of the image. There is no obvious star formation (yet) visible in the rest of the filament, but maybe in a few 100,000 or a million years star formation will occur in other places along it. Most likely in the densest and darkest patch to the very top right. While we aim to keep HOYS running in the long term, there are no promises of a light curve of the week feature when these stars have started to form 😉 .