210318 - M13 "Great" globular cluster of Hercules
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ASTRO:
type=globular star cluster mag=5.8 const=Hercules dist=22.2 k ly; size=168 ly other=estimated to contain >300 k stars IMAGE: location=EB Driveway BrtlCls=5 exposure=DSLR OSC; 20x180s (1.0h), ISO1600 EQUIPMENT: camera=Nikon D90 (mod) optics=ES102 w1.0x fltnr, F=714mm, f/7 filter=Optolog L-Pro LPS mount=Celestron AVX guiding=Orion 60x240mm, ZWO ASi224MC SOFTWARE: acquisition=Stellarium, APT, PHD2, processing=DSS, PhotoshopCC, LrC |
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Messier 13 or M13, also designated NGC 6205 and sometimes called the Great Globular Cluster in Hercules is a globular cluster of several hundred thousand stars in the constellation of Hercules. Single stars in this globular cluster were first resolved in 1779 by William Herschel.
About one third of the way from Vega to Arcturus, four bright stars in Hercules form the keystone-shaped asterism, the broad torso of the hero. M13 can be seen in this asterism 2⁄3 of the way north from stars Zeta to Eta Herculis. Although only telescopes with great light-gathering capability can fully resolve the stars of the cluster, M13 may be visible to the naked eye as a "fuzzy ball" depending on circumstances. With a low-power telescope, M13 looks like a fuzzy patch or snowball. The cluster is circumpolar, and therefore visible throughout the year from latitudes greater than 36 degrees north, with the longest visibility during Northern Hemisphere spring and summer.
About 145 light-years in diameter, M13 is composed of several hundred thousand stars, the brightest of which is a red giant, the variable star V11, also known as V1554 Herculis, with an apparent visual magnitude of appx 12. Classified as a Cepheid variable, V11 has a visual magnitude of 11.95 and lies appx 25,100 light years from Earth.
The Hercules Globular Cluster contains the estimated mass of about 1/2 million solar masses. It is located appx 22,200 light-years away from Earth. It is one of 147 known GC's that orbit the center of the Milky Way. (Sometimes referred to as, "The Sentinels of the Galaxy" by the scientific community, there may be more that have not yet been discovered.) Typical of most CG's in the Milky Way, M13 is extremely old, with an estimated age of 11.7 B years, making it almost as old (at 14.5 B yrs) as the universe itself.
Messier 13 is a class 5 globular cluster, which means its central concentration of stars is higher than some other GC's, but not as high as others. ...It has an "intermediate" concentration. But still, its central region is densely packed, with up to a hundred stars populating a cube only 3 light years on a side. To illustrate, our closest neighbor, Alpha Centauri, the nearest star system to Earth, is just over 4 light years away. So stars in M13’s core region are about 500 times more concentrated than those in our immediate interstellar neighborhood. They are so close together that they sometimes collide and produce new stars. The resulting newly formed, young stars, so-called "blue stragglers", are particularly interesting to astro-scientists.
The Hercules Globular Cluster was the target of a 1974 effort to send an extra-terrestrial radio message, beamed from the Arecibo Observatory in Puerto Rico, which contained information about the human race, Earth’s location and other data. The message was sent from the Arecibo extra large radio telescope array in the direction of M13 as a way of potentially contacting extraterrestrial civilizations. However, due to astrophysical characteristics of M13 that are better understood today, the message will never reach its intended target. It will arrive at the past position of M13 in about 25,000 years, but the cluster will no longer be there at that point in time; it will have already "moved-on" in its orbital path around the center of the Milky Way.
About one third of the way from Vega to Arcturus, four bright stars in Hercules form the keystone-shaped asterism, the broad torso of the hero. M13 can be seen in this asterism 2⁄3 of the way north from stars Zeta to Eta Herculis. Although only telescopes with great light-gathering capability can fully resolve the stars of the cluster, M13 may be visible to the naked eye as a "fuzzy ball" depending on circumstances. With a low-power telescope, M13 looks like a fuzzy patch or snowball. The cluster is circumpolar, and therefore visible throughout the year from latitudes greater than 36 degrees north, with the longest visibility during Northern Hemisphere spring and summer.
About 145 light-years in diameter, M13 is composed of several hundred thousand stars, the brightest of which is a red giant, the variable star V11, also known as V1554 Herculis, with an apparent visual magnitude of appx 12. Classified as a Cepheid variable, V11 has a visual magnitude of 11.95 and lies appx 25,100 light years from Earth.
The Hercules Globular Cluster contains the estimated mass of about 1/2 million solar masses. It is located appx 22,200 light-years away from Earth. It is one of 147 known GC's that orbit the center of the Milky Way. (Sometimes referred to as, "The Sentinels of the Galaxy" by the scientific community, there may be more that have not yet been discovered.) Typical of most CG's in the Milky Way, M13 is extremely old, with an estimated age of 11.7 B years, making it almost as old (at 14.5 B yrs) as the universe itself.
Messier 13 is a class 5 globular cluster, which means its central concentration of stars is higher than some other GC's, but not as high as others. ...It has an "intermediate" concentration. But still, its central region is densely packed, with up to a hundred stars populating a cube only 3 light years on a side. To illustrate, our closest neighbor, Alpha Centauri, the nearest star system to Earth, is just over 4 light years away. So stars in M13’s core region are about 500 times more concentrated than those in our immediate interstellar neighborhood. They are so close together that they sometimes collide and produce new stars. The resulting newly formed, young stars, so-called "blue stragglers", are particularly interesting to astro-scientists.
The Hercules Globular Cluster was the target of a 1974 effort to send an extra-terrestrial radio message, beamed from the Arecibo Observatory in Puerto Rico, which contained information about the human race, Earth’s location and other data. The message was sent from the Arecibo extra large radio telescope array in the direction of M13 as a way of potentially contacting extraterrestrial civilizations. However, due to astrophysical characteristics of M13 that are better understood today, the message will never reach its intended target. It will arrive at the past position of M13 in about 25,000 years, but the cluster will no longer be there at that point in time; it will have already "moved-on" in its orbital path around the center of the Milky Way.