This image is the result of a one night, first-light project using the Optolong L-eXtreme filter. The target was the small and rather faint object, S142, (known to some as the Wizard Nebula or the Flying Horse (Pegasus) Nebula) located in Cepheus.

It is not, of course, the nebula that is interesting to me, but the cause of the nebula, and that would be the small, young open cluster NGC7380. Class O and B stars of this cluster are part of the larger Cep OB1 Stellar Association. If you are not familiar with Stellar Associations, check out my four-part series on the Cep OB2 Association. You can find Part I here.

NGC 7380 is a young cluster, with age estimates ranging from 4 to 11 million years old. Personally--not that I'm an expert--the nature of the stars and the surrounding HII emissions would suggest a younger cluster. In particular, there are a large number of pre main sequence (very, very young) stars. These PMS stars are intrinsically interesting because they are so rare; stars spend little time of their lives in this stage, suggesting an even younger cluster.

The area around the HII emissions is just showing signs of ionization by nearby OB stars. The characteristic ridges and knots of dust and gas in the nebula are the evidence of that. Incidentally, it is a beautiful nebula. Longer FL is necessary to really bring out the stunning detail. Try it! Research has shown that while all of the OB stars in the vicinity contribute some to the ionization of the gas in the region, there are two star performers in this drama: DH Cep (HD 215835) and, to a lesser extent HE 215806.

Of the two, DH Cep is the more powerful and more interesting object. DH Cep is a spectroscopic binary of two massive, nearly identical O stars (Classes O5.5V + O6V). Spectroscopic binaries seem to rarely occur as "identical twins", making this pair a unique object of study. Although it (the binary system) may not look like much in the image, this is a powerful object. The stellar wind's shockwave is already evident--the crumpled ridges show where the shockwave is meeting the resistance of hidden stars and protostars. DH Cep is made all the more interesting by the fact that it also emits x-rays and that the couple is extremely young--no more than two million years old. From a cosmic perspective, these are truly newborns and they are only now unleashing their power!

The second major influence on the nebula is the older Class B0Ib star HD 215806. As a Class B star, the ionizing influence would not expected to be much, but HD 215086 is just barely Class B. The thinning gas immediately to its front (to the left of the star in the image) shows its ionizing power and that it is already contributing to the shape of the nebula.

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As I said earlier, this was the first time I'd used the L-eXtreme filter. It did quite a bit of damage to the stars, but some repair was possible in post. The effectiveness of the filter with HII and OIII emissions, though, is undeniably profound. To my mind, this is a great outcome for only four hours of integration and minimal post processing effort. I can see why the filter is so popular.

I hope you enjoyed the read and the image. As always, I appreciate you taking the time to stop and have a look. I may add one or two more images to this study of Cep OB1; there is at least one more good Sharpless object that falls in the OB1 region, and quite a few beautiful and massive Class O monsters!