Globular Clusters
Globular clusters usually require a larger telescope and higher magnification to observe to best effect, although the larger and closer ones can be spectacular in small instruments.
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Globular Clusters |
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Globular clusters are the most amazing
objects. Huge balls
of stars, they are particularly interesting for astronomers because all the stars in the ball formed at
the same time and so a close study of the different stars in a cluster can
tell us a lot about how stars of different initial mass age at different
rates. Globular clusters are not formed within the galaxy structure,
but usually large numbers of them form a halo around the main galactic
structure. Our Milky Way galaxy has more than a hundred of these
objects, of varying sizes, and several examples of them are displayed below.
Globular clusters usually require a larger telescope and higher magnification to observe to best effect, although the larger and closer ones can be spectacular in small instruments. |
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G1 in Andromeda. To show that globular clusters are not limited to our galaxy, this 30 minute image through the C-14 telescope is of the globular cluster known simply as G1. The interesting thing about this cluster is that it is associated with the 2.5 million light years distant galaxy, Messier 31, and so is the most distant globular cluster we have imaged in our equipment. G1 is the fuzzy three pointed object to the upper left of the bright triangle of stars just above center. Full resolution image (700Kb) |
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Messier 2 this time in our Milky Way galaxy, is a fine globular cluster in the constellation of Aquarius. It was discovered in 1746 by Maroldi. and was added to Messier's catalogue in 1760. M2 is about 36,800 light years away from us and has a well compressed, intense core. In spite of the intensity of the core, many stars can be resolved and there are several star chains radiating outwards from the center |
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Messier 3 A very pretty globular cluster in Canes Venatici. This cluster does not have the grandeur of M13, but we think it is more delicate. This image was taken at the George Observatory, Houston, Texas on 5th August, 2001 using the FSQ-106 at F8. It is a 20 minute image (20 x 1minute exposures stacked) |
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Messier 4 in Scorpius, was not discovered by Messier at all, but by a Monsieur de Cheseaux in 1746. It is surprisingly disappointing in my opinion, being fairly dim, even though it is only 6,500 light years distant. A possible reason for this is the abundance of older, yellow and red stars in this cluster, reducing its intrinsic luminosity. Full Resolution Image (2.1Mb) |
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Messier 5 one of my favourite globular clusters. M5 is a splendid cluster, almost as bright and interesting as the famous M13 and it looks really spectacular in our C-14 under moderately dark skies |
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Messier 9 in the constellation of Ophiuchus is actually the first of the five discovered by Messier in this part of the sky. It is about 19,000 light years distant, and so this makes it quite faint compared with other clusters visible in this region |
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Messier 10 discovered by Messier on May 29th, 1764, a day before finding M12. M10 is is the nearest of the globular clusters in Ophiuchus and is about 15,000 light years away |
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Messier 12 was discovered the day after M10. This is one of eight globular clusters in Ophiuchus which Messier entered into his catalogue. This one is about 19,500 light years distant |
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Messier 13 The great "Globular Cluster" in Hercules. 25,000 light years distant, and containing 500,000 stars, this jewel of the northern skies was imaged at our Spanish observatory on 20th August, 2006 using our Takahashi FSQ-106 refractor working at f/8 and the ST-8E camera. There is a full resolution image here |
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Messier 14 was discovered on 1st June, 1764 - a busy year for our old French friend. In fact he discovered five globular clusters between 28th May and 5th June of that year. This one is about 33,000 light years away and is the furthest away of the Ophiuchus clusters. M14 is a very large and bright cluster, with a diameter in excess of 110 light years |
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Messier 15 A shot of this excellent globular cluster, taken through our FSQ-106 telescope at f/5. The exposures are 20 seconds each in white light. M15 has a very bright core and it is hard to stop it "burning out". M15 was first seen by Messier in 1764, it lies 30,600 light years away and has a diameter of about 130 light years |
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Messier 19 was discovered on 5th June, 1764 - the last of the five to be found. It is about 28,000 light years away and is a really pretty object, with a lot of associated stars and star chains surrounding it |
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Messier 22 in the constellation of Sagittarius was the first globular cluster to be seen as such - i.e. a ball of stars. The great and famous "Omega Centauri" was catalogued as far back as the 2nd century A.D., but only as a star. At a distance of 10,000 light years, M22 is one of the nearest globulars, with an absolute magnitude of -8.5, a luminosity of 210,000 suns, and a diameter of 70 light years. Full Resolution Image (1Mb) |
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....And another shot of this beautiful cluster, taken this time with the Takahashi refractor at f/8. The rather wider perspective gives the cluster a different appearance. There is a full resolution image here (1.4Mb) |
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Messier 28 a globular cluster in Sagittarius. We usually start an evenings work by shooting one of the many globular clusters in Sagittarius if it's in the sky. M28 was actually spotted by Mr. Messier on July 27, 1764 as "a nebula containing no star" but of course we now know different! About 19,000 light years away, this image is an LRGB of 20:5:5:5 minutes at f/8 |
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Messier 30 in Capricornus is a fairly small but bright globular cluster, discovered by Charles Messier in August 1764. The stars in the cluster are well resolved and there is an extensive halo, with chains of stars extending outwards. M30 is at a distance of 26,700 light years |
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Messier 53 in Coma Berenices is another very nice globular cluster. It is one of the more outlying clusters, being approximately 60,000 light years from the galactic centre. It is also about the same distance from our solar system. This is a 10 minute luminance with the C14. |
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Messier 54 in Sagittarius was discovered in July 1778 by Messier himself. It is about 68,000 light years away and therefore twice as bright as its immediate neighbors, M69 and M70. It is much above average in luminosity for a globular cluster, with a brilliance equivalent to 480,000 suns. This image is an LRGB of 20:5:5:5 minutes taken at f/8 |
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Messier 55 yet another of those "early evening" globular clusters in Sagittarius. M55 is one of the more spectacular, with hundreds of stars visible in telescopes with only moderate power. With a diameter of 15 arc minutes it is quite large and we liked it so much we imaged it twice (by mistake of course!). This is an LRGB of 20:5:5:5 minutes at f/8 |
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Messier 56 is a small globular cluster in the constellation of Lyra. Discovered by Messier on 19th January, 1779, the same night he discovered the "comet of 1779", M56 lies 31,000 light years away from us. This image, which has been left in monochrome, shows well resolved stars in the core of the cluster |
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Messier 62 draws us back to Ophiuchus. Mr. Messier missed this one during his earlier discoveries in this constellation and it was not catalogued until 7th June, 1771, a full seven years after he found M9 and the rest. That would explain the out-of-sequence number, which is very odd when you're Messier hunting. M62 is 20,500 light years distant and quite bright, which makes me wonder why he missed it first time around |
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Messier 68 in Hydra is very low in the sky for northern observers. It was discovered by Charles Messier himself in 1780 and is 33,000 light years from Earth. This is a 20 minute luminance in the C14. |
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Messier 69 in Sagittarius. A smaller globular cluster, 28,000 light years from us and about 55 light years in diameter. Stellar concentration is average for a globular cluster and it is one of the metal-richest globulars. Its stars show a relatively high abundance of elements heavier than Helium, but the value is still significantly lower than that for stars like our Sun, confirming that the cluster formed at early cosmic times when the universe contained less heavier elements. This image, taken at f/8 is an LRGB of 20:5:5:5 minutes |
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Messier 70 also in Sagittarius. Alongside M69 in the sky, M70 is about the same size (7.8 arc minutes in diameter) and slightly further away at 29,400 light years. The core is extremely dense, and the cluster has undergone core collapse at some point, in common with about 29 of the 147 known Milky Way globulars. This cluster became famous in 1995 when Hale and Bopp were observing M70 when they spotted the comet. This image taken with the C14 at f/7 is a 16 minute luminance. Full Resolution Image (0.8Mb) |
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Messier 71 in Sagitta is a globular cluster about which there has been some argument. It lacks the central compression and other features of a "normal" globular, but recent studies have detected globular characteristics. It is relatively young for a globular, at 9-10 billion years, and altogether is a bit of an enigma. 12,000 light years distant and with a luminosity of only 13,200 suns, it is rather disappointing for an object of this type |
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Messier 72 in Aquarius is one of the smaller and fainter globular clusters in Messier's list. It is 53,000 light years away and is a considerable distance beyond the galactic centre. This is a 15 minute luminance image with the C14 telescope. |
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Messier 79 Another globular cluster, this one in Lepus, just beneath Orion. M79 was also discovered by Mechain, in October 1790 and it's distance from Earth is about 41,000 light years. It has a large, dense core but the cluster is quite well resolved. This image is an LRGB compilation of 5 minute images (30:30:30:30). Full Resolution Image (0.8Mb). Thanks to Dennis Borgman and Tracy Knauss, here is a Labelled Image |
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Messier 80 is in the constellation of Scorpius and was discovered by Messier on 4th January, 1781. In doing this he beat his rival, Mechain by three weeks. M80 is about 28,000 light years away from us, which puts it about four times more distant than M4 |
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Messier 92 in the constellation of Hercules. This beautiful globular cluster is so often overlooked because there are few pointer stars in that area of the sky to help you to find it. Actually, it isn't that difficult, and M92 is a very compact, round object as the image shows. The camera was 2x2 binned for this image - 20 white, 5 each of the colors, with an exposure time of 20 seconds |
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NGC 1851 Another challenge! This lovely globular cluster is in the constellation of Columba, below Lepus and Canis Major, but we got it. This cluster shines at magnitude 7.2, has a dense, bright unresolvable core, surrounded by fainter and looser concentric rings of stars |
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NGC 2419 At magnitude 10.3, located in Lynx, near Auriga, this little cluster is known as the "Intergalactic Wanderer" because it is 300,000 light years from our Galaxy's center and has a true space velocity which is greater than that needed to escape from our Galaxy at its location. There are no other globulars near it, and astronomers assume that the Milky Way has lost its grip on this little fellow |
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NGC 5139 (Omega Centauri) The largest and brightest globular cluster in the sky is a southern skies object, but it is visible during late Spring and Summer months from lower latitudes of the continental USA. This LRGB (1:1:1:2) image has components which are approximately 4 minutes total exposure using a series of eight 30 second exposures. Omega Centauri contains about a million stars and is 15,600 light years distant |
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NGC 5139. Our latest effort at this beautiful, but difficult globular, low in the southern sky. This is an LRGB of 10:10:10:10 minutes with the Takahashi FSQ at f/5 and the SBIG ST8-XE camera, taken in Spain on 17th June 2008. Full resolution image (1.3Mb) |
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NGC 6934 a very small globular cluster, at least as it appears from Earth. This little fellow is in Delphinus and shines only at magnitude 8.7. It is very hard to resolve into stars in our 14" telescope, but this CCD image just manages to do so. It is only 3 minutes of arc in diameter |