A beautiful section of the northern sky, where the brilliant star δCas or “Ruchbah” stands sentinel, watching carefully over two small star clusters, NGC457 and NGC581.  Swimming in the sea of stars is the planetary nebula, Sh2-188, affectionately called “The Shrimp” or “The Dolphin” nebula.

Ruchbah, a magnificent binary star with an apparent magnitude of 2.74, shown brilliantly on this humid February night sky, its soft, bluish glow easily visible in this image.  Scientific literature reports that it is old (600 million years), has exhausted the hydrogen in its core, and is estimated to be 4% beyond the end of its main sequence lifetime  It has evolved into a giant star with a radius of about 3.9 times that of the Sun.  That is not  nearly as big as the trio of yellow and orange stars nearby, but it still burns bright and hot and dominates this region.

My favorite wide field image of this region, which captures the entire Cassiopeia constellation, was taken by photographer @Toshiya Arai  using a Zeiss 135mm lens.  Mr. Arai’s astrophotography skills are superb (both technical and aesthetic) and I am delighted he shares his work on Astrobin.  My image shown above would cover the lower left corner of his image

I hope you are doing well, enjoying this summer, and experiencing clearer skies than we are in central Pennsylvania (still plenty of smoke and haze from wildfires). ✨🔭

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Notable objects in this image (annoted in image B; closeups shown below):

NGC435.  A lovely open star cluster, whose asterism can be interpreted as an owl, kachina doll. dragonfly, or to some, the extra-terrestrial science fiction character “ET.”   It is the brightest open star cluster in this region of Cassiopeia and in my humble opinion one of the most beautiful in the northern sky.  Two bright stars (visible on the left) Phi Cassiopeiae (magnitude 5) and HD 7902 (magnitude 7) form the eyes of the owl or kachina doll, which in this image is leaning heavily to the left, almost on its side.  The next brightest star is the red supergiant variable star V466 Cassiopeiae.  I hope to spend more time on NGC435 this summer.  With a brightness of +6.5, this star cluster is is not visible to my naked eye, but I could easy to see with binoculars this night.



δCas.  Described earlier, this magnificent star “Ruchbah” (pronounced rùk’  bũ) is an abbreviation of the phrase “the knee of the one sits on the throne,” referring to Queen Cassiopeia, known as “the sitting queen.”

Stars HIP 7617 (HD 9900), HIP 7251(HD 9352), and χCas (HIP 7294/HD 9408).  These three luminous giants are ancient stars in our Milky Way galaxy.  All are visible to the naked eye and were very impressive in binoculars the night I imaged this region.  HD9900 is a very bright G-type star (mag. 5.5) with a distinct yellow color.   It is estimated to be around 10 billion years old and its size is 81 times larger than our sun.  Wow!  HD9352 is a also very luminous double K-type star (mag 5.65) with an orange to red color.  Its lifespan is estimated to be between 15 to 45 billion years and its size is 130 times larger than our sun.  χCas is the brightest of this stellar trio (mag. 4.65), a K-type star with a bright orange color.  Its lifespan is estimated to be between 15 to 45 billion years and its size is around 11 times larger than our sun. The most recent figures from the 2007 Hipparcos data report that χCas is 208 light years away from Earth.

I read an article published by three Russian astronomers (Chupina, et. al., 2006) who used these three stars and over 100 other stars to calculate the proper motions, radial velocities and  directions of their spatial motion.  Their findings helped advance our understanding of the stellar (corona) structures in the Ursa Major region and shed light (pun intended) on the complex kinematic inhomogeneities among stars in our galaxy. [N. V. Chupina, V. G. Reva, and S. V. Vereshchagin, 2006.  Kinematic structure of the corona of the Ursa Major flow found using proper motions and radial velocities of single stars, [i]Journal of Astronomy and Astrophysics, v. 451, pgs. 909–916.  DOI: 10.1051/0004-6361:20054009].  Fascinating stuff, but a lot of the details in the article were above my head!

Sh2-188.The little "shrimp nebula" (Sharpless 188), a planetary nebula,  is clearly visible in the upper left side of the photograph.  If you zoom in, you can see why it’s been given that crustacean moniker.   I also see how to others, its appears like a dolphin, leaping in the sea of stars (nose down and tail up in this photo).  No matter how it appears, the interesting thing is that the expanding gas from this planetary nebula is colliding with ambient gas in the interstellar medium. The nebula is nearly circular in shape but is much brighter to the southeast (upper left side in this image) because the central star is moving rapidly in that direction.  I would like to 



NGC581.  This small cluster was discovered in 1781 by Charles Messier's friend and collaborator Pierre Méchain, hence it also cataloged as M31.  I could easily see it with my binoculars this night.  The age of the M103 cluster is estimated to be 25 million years old and it is located between 8,000 to 9,500 light-years away from Earth.   There are about 40 certain-member stars in this cluster, two of which have magnitudes 10.5 (upper left), and a 10.8 red giant (center).The brightest star, visible in the lower right (within the circle) is Struve 131,  is actually not a member of the M103 cluster.   It is in the foreground (much closer to Earth) and located only a few hundred light-years away from us.  Though not visible in this image from a 248mm telescope, Struve 131 is a double, possibly a triple star.