The protagonists of this field are the stellar nursery NGC 7129 and the remote open cluster NGC 7142, the latter located almost twice the distance from Earth than NCG7129. Thinking to the depth dimension gives a sense of the majesty of this celestial landscape.
It is an RGB image: the red structures are not coming from H-alpha.
You can blink between the Zoom x 3 (Revision C) and the aligned 2004 Spitzer infrared image of NGC 7129 by opening the Revision C full page (*).
NGC 7129NGC 7129 is a reflection nebula located 3300 light years away in the constellation Cepheus. A young open cluster is responsible for illuminating the surrounding nebula. A recent survey indicates the cluster contains more than 130 stars less than 1 million years old. NGC 7129 is located just half a degree from nearby cluster NGC 7142.
The nebula is rosebud-shaped; the young stars have blown a large, oddly shaped bubble in the molecular cloud that once surrounded them at their birth. The rosy pink color comes from glowing dust grains on the surface of the bubble being heated by the intense light from the young stars within. The ultra-violet and visible light produced by the young stars is absorbed by the surrounding dust grains. They are heated by this process and release the energy at longer infrared wavelengths as photographed by the Spitzer Space Telescope (Revision D).
The much cooler molecular cloud outside the bubble is mostly invisible to Spitzer. However, three very young stars near the center of the nebula are sending jets of supersonic gas into the cloud. The collision of these jets heats carbon monoxide molecules in the nebula. This produces the complex nebulosity that appears like a stem of a rosebud.
NGC 7133NGC 7133, visible in the middle of the annotated version close to NGC 7129, is classified in Simbad as "Not an object (Error, Artifact)"
NGC 7142NGC 7142 is an open cluster about 6200 light-years away in the constellation Cepheus, and is thought to have the incredible age of 3-6 billion years.
Due to the observational difficulties NGC 7142 presents, it has been an infrequent topic of research. Current known studies include only work being done at the University of Kansas.
NGC 7142 is located near the reflection nebula NGC 7129, which is a first indication that the cluster may be obscured by an interstellar cloud.
Due to the uncertain amount of interstellar reddening, precise determination of age for this cluster has been especially difficult. Based on NGC 7142's color-magnitude diagram, it is believed that this cluster is close in age to the old open clusters M 67 and NGC 188 (although age determinations for these two clusters varies wildly in the literature). This makes it one of the oldest open clusters currently known.
Although thought to be an old cluster, NGC 7142 contains a surprisingly high number of blue stars. This runs contrary to the standard model of cluster evolution which predicts that old clusters should be devoid of such stars since bluer stars are more massive and thus evolve and die off faster, which should prevent them from still being present. Such stars are said to be blue stragglers in Globular Clusters and also here.
Note (*): To open the Revision C full page:
1. open the slideshow by clicking on Rev C.
2. Once in the slideshow on Rev C, click the top-left corner Icon
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