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NGC 7762 & NGC 884
Ian Fleming & Evan Kroon

NGC 7662 NGC 884
NGC 7762 - Ian Fleming NGC 884- Evan Kroon

NGC 7762 and NGC 884 are both open star clusters. Open star cluster are cluster that have few stars with low mass making them disperse easily. Open star clusters are generally younger star clusters. The stars in open star cluster generally share a mutual gravitational attraction. But this attraction can be broken up by other cluster or clouds of gas.

NGC 7762 is a fairly young open cluster containing several hot blue stars. On November 23, 1788, NGC 7762 was discovered by William Herschel and was later determined to be apart of the constellation Cepheus found in the northern sky. This open star cluster coveres a distance of approximately 15 to 20 arcmin. In the image above, there is a small amount of reddish-brown clouds scattered throughout the star cluster. The reason for this unique coloring is a result of the location of NGC 7762 just outside the large nebula Cederblad 214, which tends to emit gas clouds through the overall view of NGC 7762.

NGC 884 is an open star cluster located in the Perseus constellation. It was discover by Hipparchas some time between 190- 120 b.c. NGC 884 is part of a double cluster along with NGC 869. NGC 884 and NGC 869 are unique in that they are only a few hundred light years apart. The two star cluster can be seen with the naked eye if observed from a dark loaction. NGC 884 is thought to be more than 7000 light years away from earth.This open cluster isapproximately 30 arcmin in distance.

NGC 7762 and NGC 884 can both be found in the northern hemisphere and in constellations that have names originating from mythological kings. Light from both star clusters come from the stars in the clusters, and in NGC 7762 the light also comes from the dust and gas surrounding the cluster as well. Though the overall ages of the star clusters are vastly different, there are numerous young stars in both clusters. This helps explain the color scheme of each cluster, in which both contain young stars that are blue and white.

NGC 7762 and NGC 884 are both open star clusters. NGC 884 is thought to be about two times larger than NGC 7762. NGC 884 may also be older than NGC 7762 this can be deduced from the presence of reddish stars found in NGC 884. Stars give off different wavelengths based on their energy. Red wavelength signal less energy, Most of a stars life is spent in "main sequence", which basically means that it is undergoing nuclear reactions in the burning of hydrogen. When it runs out of hydrogen to burn, the star becomes unbalanced, meaning its size and temperature will change. As the temperature decreases the star will become red.NGC 884 is estimated to be around 12.5 million years old, while NGC 7762 is 1.8 G years old which actually makes it older than NGC 884. Our deduction of age based on color is wrong.

References:

Arnette, Bill. "Helix Nebula." Nine Planets. <http://astro.nineplanets.org/twn/n7293x.html>.

Frommert, Hartmut. "NGC 7293." Students for the Exploration and Development of Space. <http://spider.seds.org/ngc/ngc.cgi?7293>

Open Cluster NGC 7762 (2016). In DSO Browser. Retrieved December 1, 2016, from https://dso-browser.com/deep-sky/8978/ngc-7762/open-cluster

Patat, F., & Carraro, G. (1995, December). NGC 7762: A forgotten moderate age open cluster. In The SAO/NASA Astrophysics Data System. Retrieved December 6, 2016, from http://adsabs.harvard.edu/abs/1995A%26AS.114.281P

Rothstein, D. (2015, June/July). What can we learn from the color of a star? (Intermediate). Retrieved November 21, 2016, from http://curious.astro.cornell.edu/physics/82-the-universe/stars-and-star-clusters/measuring-the-stars/389-what-can-we-learn-from-the-color-of-a-star-intermediate

Wikipedia, "NGC 884".

Wikipedia, "NGC 7762".

Object NGC 7762 NGC 884
Right Ascension (J2000) 23:50:2 2 : 22.4
Declination (J2000) +68:01:48.008 +57 : 07
Filters used B (Blue), R (Red), V (Green) B (Blue), , R (Red), V (Green)
Exposure time per filter B,10 (3x200 sec) V, and R 5 (3 x 100s) B,10 (3x200 sec) V, and R 5 (3 x 100s)
Image dimension 1091x595 pixels; 23.63x12.87 arcminutes 901x980 pixels; 23.66x15.95 arcminutes
Date/time observed October 07, 2016, 10:28 UT October 07, 2016, 10:28 UT

 

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