NGC 7789 is a large open cluster in the constellation of Cassiopeia. NGC 7789 was first observed on October 30, 1783 by astronomer Caroline Herschel and the cluster is also known as “Caroline’s Rose” because of its appearance in small telescopes. NGC 7789 is 8,000 light years distant and is believed to be approximately 50 light years across.
Astronomers believe that the NGC 7789 open cluster is about 1.6 billion years old. At this age, some of the stars seen in this image have exhausted their hydrogen fuel in their cores and have evolved into red giants. You can follow this link to more information about red giant stars –> https://www.space.com/22471-red-giant-stars.html
This image was taken with a Takahashi FSQ-106EDX IV telescope with a ZWO ASI1600MM-Cooled camera through Baader 36mm filters mounted in a ZWO EFW2 filter wheel. The total exposure time for this image was 4.2 hours with 21 subexposures of 240 seconds each for each of the color channels. The subexposures were calibrated, aligned and stacked in PixInsight. PixInsight’s LocalNormalization tool and DrizzleIntegration tool were utilized in the image integration steps. PixInsight post processing included MultiscaleLinearTransform, HistogramTransformation and ColorSaturation.
The image below is a high resolution crop which shows the several red giants in the cluster. Click on the image to get a higher resolution view.
The full frame wide field is shown below. Click on the image for a larger version. Click here to see a full resolution version on my Astrobin page.