Astronomers' Capture Hercules Star Cluster

The hundreds of thousands of stars that make the mighty Hercules globular cluster shine bright in this astronomers' photo.

Astrophotography team Bob and Janice Fera took this image in May 18 and 20, 2012 from Eagle Ridge Observatory in Foresthill, Calif.

Also known as M13, this cluster has more than 100,000 stars that shine from about 25,000 light-years away. The brightest stars  are packed tightly at the core and sometimes slam into each other creating new stars called “blue stragglers.”

These blue stars shine a bluish-white because their core temperatures are extremely hot. Bright red stars found within the cluster are cooler because they are older stars that have expanded in size. These stars are often called ancient red giants.

The Feras used an Officina Stellare RC-360AST 14" f/8 Ritchey Chretien Cassegrain telescope with two-element field flattener to observe the M13 cluster. An Apogee Alta U16M CCD camera with Astrodon filters was used to capture the image.

When Galaxies Collide: Linked Arms

The two galaxies seen here, NGC 6050 and IC 1179, are located about 450 million light-years away in the constellation Hercules.

The spiral bodies are seen crashing together, with an enormous eddy of stars seeming to form between their conjoined arms.

This object is part of the Hercules Galaxy Cluster, itself located within the Great Wall of superclusters, the largest known structure in the universe.

Image: NASA, ESA, the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration and K. Noll (STScI)

Messier 13: The Great Globular Cluster in Hercules

In 1716, English astronomer Edmond Halley noted, "This is but a little Patch, but it shews itself to the naked Eye, when the Sky is serene and the Moon absent."

Of course, M13 is now modestly recognized as the Great Globular Cluster in Hercules, one of the brightest globular star clusters in the northern sky. Telescopic views reveal the spectacular cluster's hundreds of thousands of stars.

At a distance of 25,000 light-years, the cluster stars crowd into a region 150 light-years in diameter, but approaching the cluster core upwards of 100 stars could be contained in a cube just 3 light-years on a side. For comparison, the closest star to the Sun is over 4 light-years away.

Along with the cluster's dense core, the outer reaches of M13 are highlighted in this sharp colour image. The cluster's evolved red and blue giant stars show up in yellowish and blue tints.