The Hercules Cluster is one of the best known, and as you would expect, one of the most beautiful clusters to be seen in a small telescope. Also known as M13 this is a rich globular cluster with several hundred thousand stars it lies about 25,000 light years away in the constellation Hercules.
The cluster is always worth stopping by, whatever size telescope you are using. If I am using a larger ‘scope I might try to locate the small galaxy NGC6207 located about ½° to the northeast (upper left). If I am using an even larger ‘scope like my 18″ I can also try for the challenging IC4617 that lies halfway between NGC6207 and the cluster.
The image here is a luminance image only, taken through a filter that blocks IR and allows the remainder of the visible spectrum through to the detector. To get allow capture of the fainter stars while not overexposing the core a range of exposures from 10 seconds to five minutes were combined to create the image seen here…
As I get back into astrophotography I am starting to conquer the little issues that make huge differences in the results.
I did get a nice session in last week, with several targets imaged. I am still struggling with processing LRGB color data and have some learning ahead of me. In the meantime the monochrome luminance images look pretty good.
I had hoped to get some more telescope time in tonight, the weather decided otherwise. May as well process photos while I listen to rain on the roof.
Using a new age-dating method and the W. M. Keck Observatory on Maunakea, an international team of astronomers have determined that ancient star clusters formed in two distinct epochs – the first 12.5 billion years ago and the second 11.5 billion years ago. These results are being published in Monthly Notices of the Royal Astronomical Society.
Although the clusters are almost as old as the Universe itself, these age measurements show the star clusters – called globular clusters – are actually slightly younger than previously thought.
“We now think that globular clusters formed alongside galaxies rather than significantly before them,” research team leader, Professor Duncan Forbes of Swinburne University of Technology said.
The new estimates of the star cluster average ages were made possible using data obtained from the SAGES Legacy Unifying Globulars and GalaxieS (SLUGGS) survey, which was carried out on Keck Observatory’s 10-meter, Keck II telescope. Observations were carried out over years using the powerful DEIMOS multi-object spectrograph fitted on Keck II, which is capable of obtaining spectra of one hundred globular clusters in a single exposure.
DEIMOS breaks the visible wavelengths of objects into spectra, which the team used to reverse-engineer the ages of the globular clusters by comparing the chemical composition of the globular clusters with the chemical composition of the Universe as it changes with time.
A seasonally appropriate astrophoto, NGC2264, also known as the Christmas Tree Cluster. It does have the outline of a tree decorated with stars in place of ornaments. This was shot on the evening of the 23rd from the driveway.
Keeping the exposures short I concentrated on the stars rather than the nebula that fills the region. I am working on the appearance of my stars, attempting to improve my technique. Not sure if I have succeeded here, they are better. I used some Photoshop tricks to preserve the color of the stars in working on the image. Better, but not quite up the the standard I aspire to.
There seem to be a few deep sky objects that are appropriate for the season. The Rosette Nebula makes a nice wreath, the Christmas Tree, etc. The folks at WISE published a nice infrared image of Barnard 3 that also looks like a wreath. Long winter nights are an excellent time to consider the night sky. Not much else to do, I am on call for the weekend, thus staying home. It is new moon and the recent storms have departed allowing dark skies. May as well take a few more astrophotos.
In the fable of the town and country mice, the country mouse visits his city-dwelling cousin to discover a world of opulence. In the early cosmos, billions of years ago, galaxies resided in the equivalent of urban or country environments. Those that dwelled in crowded areas called clusters also experienced a kind of opulence, with lots of cold gas, or fuel, for making stars.
Today, however, these galactic metropolises are ghost towns, populated by galaxies that can no longer form stars. How did they get this way and when did the fall of galactic cities occur?
A new study from NASA’s Spitzer Space Telescope finds evidence that these urban galaxies, or those that grew up in clusters, dramatically ceased their star-making ways about 9 billion years ago (our universe is 13.8 billion years old). These galactic metropolises either consumed or lost their fuel. Galaxies in the countryside, by contrast, are still actively forming stars.
“We know the cluster galaxies we see around us today are basically dead, but how did they get that way?” wondered Mark Brodwin of the University of Missouri-Kansas City, lead author of this paper, published in the Astrophysical Journal. “In this study, we addressed this question by observing the last major growth spurt of galaxy clusters, which happened billions of years ago.”