As you can tell by the name, the Cepheus Flare is located in the constellation Cepheus. If you expected it to be in a different constellation, like Ophiuchus, you're thinking too hard about the object. If you thought I might joke about the Cepheus Flare being in the constellation Ophiuchus, well, you're wrong. I was originally going to joke about it being in the constellation Leo instead.
Anyway, the term "flare" might be slightly misleading. This isn't a short, brief flash of light. Well, actually, a few brief flashes of light were involved in the formation of the Cepheus Flare, but those flashes of light don't have anything to do with the name, and I'll get to them later. Anyway, the Cepheus Flare actually contains a lot of clouds of interstellar gas and dust located at distances between 1076 and 1200 light years (330 to 368 pc) [1], and most of these clouds appears somewhat dark, at least in the visible part of the electromagnetic spectrum. This complex of interstellar gas and dust spans a region of somewhere between 10 to 20 degrees on the sky [2]. For context, the part of the sky that is visible above the horizon at any time is 180 degrees from one horizon through the zenith to the other horizon, so the Cepheus Flare would occupy up to 1/9 of that distance.
The Cepheus Flare received its name because it extends upwards or "flares" outwards from the plane of the galaxy. The object was actually given this name by Edwin Hubble in a paper in 1934 where he was performing an analysis of the locations of all of the galaxies (or, as he called them, "extra-galactic nebulae") in the sky [2]. Hubble had ascertained that it was virtually impossible to see galaxies in the plane of the Milky Way because they were obscured by clouds within our galaxy (although he did not seem to know or at least he did not explictly state that those gas clouds contained interstellar dust, which is what is responsible for obscuring those galaxies) [2]. Hubble also identified some regions outside the plane of our galaxy where other galaxies were also obscured, and he called these regions "flares". The Cepheus Flare is one of these regions [2].
Although Edwin Hubble did a lot of groundbreaking work, our understanding of how the universe works has advanced significantly since he published his 1934 paper. Most notably, we have been able to observe the Cepheus Flare across the entire electromagnetic spectrum, and this has revealed the detailed structure of the object. As I mentioned before, the Cepheus Flare is made up of interstellar gas and dust. The gas was only imaged at radio wavelengths for the first time in 1967 [3]. While its presence of dust could be inferred by how it absorbs light from behind the Cepheus Flare, it was only imaged at infrared wavelengths in the 1980s by the Infrared Astronomical Satellite. These and subsequent observations have shown that the Cepheus Flare can be divided into five smaller clouds, four of which have names starting with L that I'm not going to read out because they will just sound like random numbers [4]. The fifth cloud is associated with the nebula NGC 7023, which is a location where light from a bright blue star in front of the cloud is reflecting off the interstellar dust behind it [4].
Aside from this interstellar gas and dust, the Cepheus Flare is also known to be a location where stars are forming [4]. In fact, the various clouds within the Cepheus Flare are at the stage where the gas has gravitationally collapsed to form objects called dense cores that are really just cold, compressed balls of gas and dust that are on the threshold of beginning to form into individual stars. Moreover, a few of these objects in the Cepheus Flare have collapsed inwards even more to form what could be described as protostars because the objects have begun to emit light although fusion is not yet taking place within the centers of the objects. Given the abundance of dense cores and protostars within the Cepheus Flare, it has been a popular place for astronomers to observe how this phase of star formation is taking place.
However, what I personally find really exciting about the Cepheus Flare is that it is an example of how several supernova explosions within our galaxy can trigger the formation of stars. At first, this might not sound intuitive, because explosions in space are supposed to destroy things. Just look at, for example, what happened in the J. J. Abrams version of Star Trek [5]. However, most planets and stars in the viscinity of supernovae are unlikely to be destroyed by the explosions [6], but supernova explosions will ionize and blow away the surrounding interstellar gas. This stops the formation of stars near the supernovae, which actually makes sense, but gas on the outside of the shockwaves created by the supernvoae will be compressed, and when interstellar gas get compressed, it forms stars.
This is the process that we are seeing taking place in the Cepheus Flare [7]. At several different times millions of years in the past, supernovae would have formed in the center of the object, pushing the gas outwards to form bubble-like structures of compressed gas [7]. NGC 7023 and the various other gas clouds with names beginning with L have formed on the outside of these bubbles, and stars are now forming within those clouds. I primarily study interstellar dust and star formation in other galaxies, and this is something I have seen happening in other galaxies. I find it really exciting to actually know about an example in our galaxy where this is happening , and I hope to see more science results come out about the stars forming in this region as well as more models describing the details of how supernova explosions shaped the Cepheus Flare.