Globular Clusters

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.

G1_Web_23Oct2003.jpg (43957 bytes) 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 centre.  Full resolution image (700Kb)
M2_190717_Web.jpg (266960 bytes) 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 centre. Full Resolution Image (7Mb). Smaller High Res Image (1.5Mb)
M3_030514_Web.jpg (383188 bytes) 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 in Spain on 3rd May, 2014 using the Planewave scope and QSI camera.  It is an LRGB of 13:8:8:8 minutes.  Full Resolution Image (9.1Mb).   Smaller High Res Image (1.9Mb)
M4_160617_Web.jpg (293820 bytes) 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 (5.6Mb)Smaller High Res Image (1.2Mb)
M5_150602.jpg (249583 bytes) 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
M9_150602.jpg (298903 bytes) 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
M10_150602.jpg (247921 bytes) 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
M12_150602.jpg (280979 bytes) 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
M13_200806_Web.jpg (123682 bytes) 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
M13_170815_Web.jpg (248552 bytes) Another image of Messier 13 taken on 17th August 2015 using the 12.5 inch Planewave scope and QSI 683 camera.  This is an LRGB of 50 minutes luminance and 40 minutes for the colours.  Full Resolution Image (4.8Mb)Smaller High Res Image (1Mb)
M14_150602.jpg (270527 bytes) 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
M15_161014_Web.jpg (278532 bytes) Messier 15  A shot of this excellent globular cluster, taken through our Planewave telescope and using the QSI 683 camera.  This is an LRGB of 17:12:12:12 minutes.  M15 was first seen by Messier in 1764, it lies 30,600 light years away and has a diameter of about 130 light years.  Full Resolution Image (7.4Mb). Smaller High Res Image (1.4Mb)
M19_170617_Web.jpg (408441 bytes) 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.  Full Resolution Image (7.1Mb).    Smaller High Res Image (1.6Mb).
M22_180814_Web.jpg (393618 bytes) Messier 22  in the constellation of Sagittarius was the first globular cluster to be seen as such - i.e. a ball of stars.  The famous "Omega Centauri" was catalogued in 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 (4.4Mb). Smaller High Res Image (1.3Mb)
M28_210617_Web.jpg (503865 bytes) Messier 28  a globular cluster in Sagittarius.  The cluster 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 20:15:15:15 minutes, taken in Spain on 21st June, 2017.  Full Resolution Image (5.7Mb)Smaller High Res Image (1.6Mb)
M30_19Dec2001.jpg (37014 bytes) 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
M53_040602.jpg (169759 bytes) 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.
M54_210617_Web.jpg (373236 bytes) 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 neighbours, 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 20:15:15:15 minutes taken in Spain on 21stt June, 2017. Full Resolution Image (6.9Mb)Smaller High Res Image (1.7Mb)
M55_171001.jpg (279799 bytes) 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
M56_18Nov2001.jpg (62983 bytes) 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
M62_15June2002.jpg (180371 bytes) 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
M68_280303.jpg (231047 bytes) 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.
M69_130613_Web.jpg (437203 bytes) Messier 69  in Sagittarius.  A smaller globular cluster, 28,000 light years from us and about 55 light years in diameter.  It is one of the metal-richest globulars and it's stars show a relatively high abundance of elements heavier than Helium, confirming that the cluster formed at early cosmic times when the universe contained less heavier elements. This image was taken on 13th June, 2013 using the Planewave telescope and QSI 683 camera. It is an LRGB of 20:15:15:15 minutes. Full Resolution Image (9Mb)Smaller High Res (2Mb)
M70_140613_Web.jpg (403646 bytes) 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 was taken on 13th June, 2013 using the Planewave telescope and QSI 683 camera. It is an LRGB of 20:15:15:15 minutes.  Full Resolution Image (8.5Mb).  Smaller High Res (1.8Mb).
M71_20Dec2001.jpg (156006 bytes) 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
M72_151002.jpg (235146 bytes) 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.
M79_301206_Web.jpg (162281 bytes) 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
M80_15June2002.jpg (119546 bytes) 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
M92_13Aug2001.jpg (52003 bytes) 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
M107_220517_Web.jpg (555243 bytes) Messier 107 in the constellation of Ophiuchus is a very nice globular cluster at a distance of about 20,000 light years. It shines at a visual magnitude of 8.1.  Full Resolution Image (3Mb)
NGC1851_27Dec2000.jpg (43564 bytes) 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
NGC2419_22Dec2000.jpg (13660 bytes) 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

N5139_220409_Web.jpg (250022 bytes)

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 (20:15:15:15 mins) was taken with the Takahashi FSQ scope and ST8 camera.  Omega Centauri contains about a million stars and is 15,600 light years distant.  Full resolution image (1Mb)
NGC6934_27Dec2000.jpg (8700 bytes) 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
Palomar_4_230409_Web.jpg (448917 bytes) Palomar 4 in Ursa Major (also known as "Serpens Dwarf") .  The second most remote globular cluster in our galaxy.  Rarely imaged and partially obscured by dust from our own galaxy.  Imaged on 23rd April, 2009 at the Observatorio de La Divisa in Spain, this is an LRGB of 20  minutes for each component using the C14 at f/7 and ST10-XME camera.  Full Resolution Image (2.3Mb)

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