NGC 2362 (Tau Canis Majoris) Cluster – The Youngest Cluster in the Milky Way
NGC 2362 (Caldwell 64) is a visually stunning open cluster of around 60 stars spread across 6′ (9 light years) in the Canis Major constellation. The cluster is located on the outer edge of the Orion-Cygnus arm of the Milky Way Galaxy. It was discovered by Giovanni Batista Hodierna before 1654 and rediscovered by William Herschel in March 1785. Its brightest star at the centre of the cluster is Tau Canis Majoris (mag 4.4), and therefore it is sometimes called the Tau Canis Majoris Cluster. NGC 2362 has a distance of 5,100 light years and is a relatively young 4-5 million years in age. There have been numerous mistaken associations of nebulosity with this cluster and all modern researchers now agree that there is no native nebulosity. The cluster does however sit within a large bubble of HII gas associated with the Sharpless 310 nebula. The nebula may be a remnant of the clusters original nursery cloud which has otherwise been blown away by the stellar winds of the hot young stars.
The central Tau Canis Majoris star is actually a multiple star system in its own right, but the component stars cannot be resolved by smaller telescopes. The core is a close binary with two stars of equal magnitude (Rosat X-Ray satellite images).
Image taken on 1/10/2010 5.55 am New Mexico time on GRAS 3 (TAK TOA 150/FLI ML8300 one shot colour camera). RA: 07h 18m 42.1s DEC: -24° 57′ 00″ (J2000). 10 minute exposure @ 1 x 600 seconds.
Big Sunspot Group AR 1339
Sunspot group AR 1339 is an impressive sight right now and its high energy Delta class magnetic field has produced some spectacular M-Class flares over the last 24 hours. As it approaches the central meridian of the sun it is worth keeping a watch for X-Class flares from this region which may produce some impressive auroras down here on Earth. AR1339 appears at the top in the images with AR 1338 below. To the left three new active regions are just rounding the limb (AR’s 1340, 1341 & 1342). Images taken 11.21 – 11.46 UT using a DMK41 camera, CaK PST, Ha PST, CaK B1200 diagonal.
Berkeley 17 – The Oldest Open Cluster in the Milky Way
The Berkeley Open Cluster catalogue contains 104 clusters observed by astronomers at the University of California, Berkeley using the Palomar Observatory Sky Survey (POSS) plates. The catalogue was published in 1958 by Jiri Alter et al. The Berkeley clusters are a fascinating and challenging group to explore and contain some of the oldest and most distant open clusters in our galaxy. Over the next few weeks i’m going to introduce you to a few of these clusters with the help of some images taken using the GRAS remote telescopes in New Mexico.
Berkeley 17 (Be17) is found in the constellation Auriga and currently holds the title for the oldest open cluster in our galaxy. There is some dispute over the maximum age estimate depending on which astronomical paper you read, but the average figure is somewhere around 10.06 – 10.08 billion years old (a 2006 paper gives a date range of 8.5- 9 billion years, but does not rule out a greater age) . Be17 does have a rival for oldest open cluster, NGC 6791 in Lyra, but until a definitive date range is provided for the latter Be17 reigns supreme.
Like most of the Berkeley clusters Be17 is very faint with magnitudes of its estimated 400 member stars in the range 17.8 – 20.0. It appears as a slightly more dense clump in the centre of the photo below and is largely populated by old red stars of relatively high metallicity with no evidence of any blue stragglers which are more common in older globular clusters. Be17 is thought to inhabit the thin disk of our galaxy and therefore helps to date the formation of the thin disk as well as supplying an upper date limit for the formation of the thick disk and halo.
Imaged using GRAS 03 TAK TOA 150/FLI ML8300 one shot colour camera. 24th September 2011 09:11:37 UTC RA: 05h 20m 32.0s DEC: 30° 34′ 30″ (J2000) 20 minutes exposure @ 2 x 600 seconds.
The Sun – 15th October 2011 – Lots of surface activity
Lovely clear blue skies today, but with loads of atmospheric jitter so close up images of the activity were not possible. These Ha and CaK images were taken between 10.30 and 12.30 UT. There are seven active regions gliding over the surface of the sun with lots of nice spot, filament and pore detail. Active regions in the images include 1312, 1313, 1318 on the right and 1314, 1316, 1317, 1319 on the left.
M13 Globular Cluster in Hercules
Summer is traditionally the time for amateur astronomers to observe and image the globular clusters that inhabit the outer halo of our galaxy as the dense starfield and dust clouds in the galactic plane of the Milky Way do not obscure our view at this time. I left it quite late this year to take a look at the Northern Hemisphere’s finest globular cluster and chanced on it quite by accident while imaging some open clusters for a series of future blog posts.
M13 is the brightest globular in northern skies with a naked eye magnitude of 5.7 and is visible as a fuzzy star in dark skies free of light pollution. There are around 600,000 gravitationally bound stars around and within its tight core and it orbits the Milky Way every 500 million years on an elliptical path extending up to 80,000 light-years from the galactic centre at its furthest point of travel. Like all globulars it is an extremely old object and has a Universe defying estimated age of 14 billion years (the Universe is 13.75 billion years old). This age may ultimately be revised down but currently, along with some other stubborn globulars like NGC 5286 (15 – 17 billion years old), it refuses to conform to the accepted age range. The scatter of globulars around the halo of our galaxy effectively marks the former extent of the galaxy during its earliest stages of development and well before the recognizable spiral arms developed around the inner core. In common with other globulars the constituent stars are generally very old red giants nearing the end of their life and the metal content is typically low, but there are a number of bright blue stars called Blue Stragglers in the core which are much younger. Blue Stragglers are thought to form from collisions or mergers between the tightly packed stars in the core.
Imaged 8.57 pm 30/9/11 using GRAS G3 (Takahasi TOA 150 refractor/FLI ML8300 one shot color camera) in New Mexico. 20 minute exposure – 2 x 600 sec. RA: 16h 41m 42.0s DEC: 36° 28′ 01″ (J2000). Processed with Maxim DL5/Photoshop CS2.
The Sun 30-9-11 AR1302 & Filaments
There are currently five active regions forming a band of activity across the sun today including AR1301, 1302, 1305, 1306 and 1307. AR 1302 has given us some pretty impressive flares, but seems to be approaching the western limb in a rather subdued state. Although quiet AR1302 still harbors the magnetic strength to produce some X-Class flares and is still very dynamic visually with some impressive active region filaments arcing high above the main sunspots at its core. Images taken 12.10-12.55 UTC+1 with PST Ha, PST CaK, DMK41.
Ha Disk
CaK Disk
Close up of AR1302 and its arching filaments. AR 1305 to left
CaK of AR 1302 (right) and AR 1305 (left)
Ever seen the Zodiacal Light ?
No, me neither until this morning. I was reading Bob Kings excellent Astro Bob astronomical blog http://astrobob.areavoices.com/ and the entry for yesterday happened to discuss the autumn phenomena called the Zodiacal Light http://astrobob.areavoices.com/2011/09/28/comet-honda-visits-the-ghost-of-comets-past/ This faint, low, roughly triangular glow of light, best seen in the east just before morning twilight, represents the reflected light from cosmic dust which has gathered on the ecliptic plane. The ecliptic plane is slightly tilted upward at this time of year which makes it more visible, particularly when the moon is absent. This interplanetary dust lies in a lens shaped band centered around the sun and extending out beyond Earth’s orbit. The dust is commonly thought to derive from the trail of comets passing through the solar system. I had a look this morning and there was certainly a very faint and high glow extending up at least 45 degrees into the sky when looking east around 6-6.30 am. I didn’t have the DSLR with me at the time but later on I thought I would have a look at the fisheye weather cams for the GRAS telescope in New Mexico and sure enough a faint triangular glow in the east was clearly discernible. Take a look at the image below and if you can see a faint wedge of light shooting up above the pole at the bottom of the image toward the Milky Way – that is the Zodiacal Light !
Massive Sunspot AR11302
Sunspot AR11302 is a true behemoth at 150,000 km in length. It was crackling with B and C class flares today after calming down somewhat from its release of two X Class flares on the 22nd and 24th September. The spot is now facing Earth and if it releases any more high energy flares in the next couple of days we could see some spectacular aurorae down here around midnight in northern latitudes. Seeing conditions were extremely poor during imaging with a lot of atmospheric turbulence so these images don’t really do justice to the amount of finely structured features that were on view today.
80mm PST Mod Ha view:
CaK PST view:
80mm PST Mod Ha view with bright C Class flare activity in AR 11302:
The other Double Cluster – NGC 884 and NGC 957
Most people are familiar with the spectacular view of the main Double Cluster located in Perseus which consists of the bright open clusters NGC 884 and 869 lying some 7300 light years distant. This jewelled duo shining at magnitudes 6.1 and 5.3 are easily resolved in a moderate 3″ telescope, but binoculars will also provide a nice view and you can even see the cluster as a faint sparkling smudge of light with the naked eye on a clear night in a dark location. While images of this cluster can be found in every coffee table book and all over the web I thought it might be fun to try something a little different when I realised that the nearby NGC 957 would just fit into the view along with NGC 884, providing an alternate double cluster. For this image I used the GRAS20 Tak 106 FSQ in New Mexico which has a nice widefield view capable of comfortably framing both clusters. The image is a 600 sec unbinned one-shot colour exposure centred on RA: 02h 20m 59.0s DEC: 57° 09′ 30″ (J2000)
I wonder how many more images containing two or more open clusters found in our galaxy can actually be imaged in one frame ? Only one other springs immediately to mind for me and that is the M35/NGC 2158 combination in Gemini which I imaged back in 2008 with my Equinox ED80 and a Canon 350d DSLR (see below) . If you can think of any more do let me know via the blog !
NGC 957 (top left) and NGC 884 (right) :
Another double! M35 (bright blue stars) & NGC 2158 (tight yellowish white cluster bottom left):
Comet C/2009 P1 Garradd
I revisited Comet C/2009 P1 Garradd last night on its journey through the region between Aquila and Hercules courtesy of the GRAS G3 telescope (Takahashi TOA 150/SBIG ST 2000XCM) in New Mexico. This observatory has been plagued by cloud and rain for the last two weeks, but before the moon rose at 9.30 pm last night (NM time) the sky was gloriously clear so I took the opportunity to reserve some time on the one-shot colour camera. The image below is the result of just a 5 minute exposure and shows the coma and faint gas tail glowing the characteristic blue-green of cyanogens and diatomic carbon which are fluorescing in the sunlight. C/2009 P1 appears to be around magnitude 7.0 now and should continue to brighten slowly through to February 2012 when it will reach its peak magnitude of 6.0 and may become visible to the naked eye. The two bright stars on the right side of the image are HIP 91205 (top – mag 7.75) and HIP 91169 (bottom – mag 8.60). Image taken 17/9/2011 9.24pm (New Mexico time) RA: 18h 37m 13.0s DEC: 19° 52′ 17″ (J2000)
