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We can actually do a quick calculation to prove to ourselves the answer to the question: How full is a globular cluster?Īssume all stars in the cluster are the size of the Sun, or roughly 700,000 km in radius. On average, the abundance of all elements heavier than helium is only 1-10% of the abundance of these same elements in the Sun and in the stars in open clusters. Again, this observation reveals another difference between these star clusters and open clusters. When we observe the stars in globular clusters spectroscopically, we can also measure the abundance of chemical elements in their atmospheres. There are several globular clusters visible near the Milky Way in the part of the sky you studied using the S tarry Night file on the last page however, there are many more distributed all over the sky. They do not seem to have any particular association with the band of light that we call the Milky Way. Also, unlike open clusters, we find globular clusters in every direction on the sky. ![]() ![]() Globular clusters are not found to contain any gas, nor are they, in general, associated with reflection or emission nebulae, like we see with open clusters. Thus, if the Sun were inside a globular cluster, we would see many thousands of stars in the sky many times brighter than the brightest stars we see in our night sky. NASA PICTURE OF THE DAY STAR CLUSTERS PCAs part of a research study in 1996 of the globular cluster M15, astronomers using the Hubble Space Telescope observed about 30,000 stars within 6.7 pc of the core of this globular cluster. If you were to draw this same sphere in the center of the globular cluster M13, it would contain approximately 10,000 stars. Thus, if we were able to draw a sphere around the Sun with a radius of 1.3 parsecs, it would only contain 2 stars: the Sun and Proxima Centauri. We have measured the distance to the nearest star to the Sun, Proxima Centauri, and it is 4.2 light-years, or about 1.3 parsecs. The density of stars inside a globular cluster is significantly higher than the density of stars around the Sun. “We (amateurs) can do more good work than the best professionals could do 30 years ago.Source: LEFT: Penn State Astronomy & Astrophysics, RIGHT: Astronomy Picture of the Day “To see a setup and how it operates is fascinating,” he said. Still, his passion for astrophotography remains strong. “Or it might stay in the basement,” he said. He is thinking of giving a few to a startup business he advises. When it was over, he had to remove his photographs from the walls and take them home.Ĭoles is not sure what he will do with the prints. On Friday, Coles was allowed to have a private event for roughly two dozen friends and relatives. So for 2½ years, only Fermilab employees could view the exhibit. But Wilson Hall - which used to host public lectures, concerts, film screenings and more - has not.Ĭourtesy of Eric ColesWhen Roses Aren't Red - APOD Februusing a red palette by Eric Coles of Glen Ellyn. The grounds and the Lederman Science Center have since reopened to the public. The laboratory was closed the next day because of the pandemic. NASA PICTURE OF THE DAY STAR CLUSTERS INSTALLWork to install the exhibit happened on March 20, 2020. The images Coles selected range in size from 10 by 12 inches to 30 by 40 inches. “Imaging the Cosmos: Astro Photography and Landscapes” had 34 metal prints from Coles and about 10 from Martin Murphy. The red one, left, is using RGB palette the other uses the Hubble pallette. Susan Coles displayed two of the Elephant's Trunk side by side to show how using different palettes changes the look of the images. That inspired Coles to approach the director of visual arts at Fermilab and ask if he could put on a show. He saw an astrophotography display in the gallery on the second floor of Wilson Hall. NASA has chosen his work 12 times for its Astronomy Picture of the Day.Ĭoles was a frequent visitor to Fermilab, attending lectures and other events every three to four weeks. Coles posts his images to, where he has 1,944 followers. ![]()
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