Category: Deepsky TOP 100
Sunday, November 13, 2005
Deepsky Top-100 (17): M 36, the Butterlfy Cluster
Towards the end of the year, Auriga climbs higher and higher in the night sky, and within its borders lie three of my favourite open clusters, M 36, M 37 and M 38. All three open clusters will be included in my Deepsky Top 100, but I will start with M 36, which I observed and sketched this week (8 November 2005).
Le Gentil discovered M 36 in 1749, while he was working as an assistant of Jaques Cassini at the Paris Observatory. Messier observed M 36 on 2 September 1764. It lies in Auriga, near the galactic anticenter, at a distance of 4100 light years. When you look in this direction (Auriga), you look away from the galactic centre, towards the nearest stretch of our galaxy's rim.
Click to enlarge (image from SkyTools 2 by CapellaSoft)
M 36 has a diameter of 12' and a visual brightness of magnitude 6. Its brightest star is a magnitude 8.86 B2 main sequence star. M 36 can be found roughly halfway between M 37 and M 38, about 8 degrees tot the east of Iota Aurigae. When the seeing in my backyard is "moderate" (mag. 4.7 visual) I can see M 36, M 37 and M 38 in my 8x50 finder scope as three faint patches of light.
As it is with many star clusters, most people "see" some kind of pattern in these objects. Some observers report that M 36 looks like a crab, others see a crooked Y, X or a big cross. I want to add one to the list. To me, at first glance, M 36 looks like a butterfly when looking through my 8-inch f/10 Klevtzov using a Televue 32mm plossl (field of view about 48' magnification 62x). Using a 20mm eyepiece, magnification 100x, I counted about 40 stars, ranging from magnitude 8 to 12.5. There are several arcs and small groups (2 or 3) of stars visible. I did not detect any form of nebulosity or background haze from unresolved stars. But when I increased the magnification, more (fainter) stars became visible. The sketch below should give you an idea. Anyway, let me know what you "see" when you go out and observe this beautiful open cluster.
This sketch was made on 8 November 2005, from 22.30 UT till 23.15 UT. The instrument used was the TAL 200K, a Vixen Lanthanum 20mm, magnification 100x and field of view approx. 30'. North is up and west is to the left.
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Math on 11/13 at 10:17 AM |
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Wednesday, July 27, 2005
Deepsky Top-100 (16): Beautiful Albireo
In my list of favourite deepsky objects for suburban backyards you will find only a few galaxies. Because of the severe light pollution these delicate structures with low surface brightness visually loose almost all detail or, even worse, aren't visible at all through my 8-inch telescope. I compensate this by adding some beautiful stars, double stars and multiple stars to my Deepsky Top-100.
My all time favourite double star is Beta Cygni, better known as Albireo. I have been observing Albireo for more than
25 years using a wide variety of telescopes and binoculars. For me personally this wonderful double hasn't lost much of its charm. I find Albireo at its best through my 4-inch refractor at a low magnification (30x): a superb golden-blue pair of stars against a more or less black background, a true celestial gem.
The name Albireo, seems to be the result of a mis-translation of the term Ab Ireo from the 1515 edition of Ptolemy's Almagest (star catalogue). According to R.H. Allen (Star Names, their lore and meaning) the original Arabian name of Albireo was Al Minar al Dajajah, the hen's beak. Deneb, marking the tail of the Swan, comes from Al Dhanab al Dajajah, the hen's tail. Gamma Cygni or Sadr, right at the heart of the Swan comes from Al Sadr al Dajajah, meaning the hen's breast.
Albireo is very easy to locate (see map below). First look for the constellation Cygnus, the Swan. In light-polluted suburban areas you will be able to identify the Swan as a large cross in the sky, with the bright white Deneb (Alpha Cygni) at the tail of the Swan and Albireo (Beta Cygni) at the swan's head.
Albireo consists of 2 components, a bright magnitude 3.1 orange class K giant star (like Arcturus) which is fusing helium into carbon and a magnitude 5.1 blue-white class B-dwarf that transforms hydrogen into helium (like our own Sun). The brighter A component has a luminosity of more than 700 Suns, while the dimmer B component is a 100 times the (visual) solar luminosity. The stars are separated by 34". The position angle of the B component is 54°. Albireo is probably a true physical double star, although hard evidence of orbital motion has not yet been detected. Recent measurements place them at a distance of almost 400 light years. According to these same measurements, the distance between the two stars is about 9 light years. However, the uncertainty of the distance of each of the components is about 25 light years.
So go out and observe Albireo! For me personally, nothing beats the "live" view of a beautiful double star. There is no sketch or image that comes even near to what you see through the eyepiece.
Clear Skies!
Click to enlarge (Image from Skytools 2 by CapellaSoft)
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Posted by
Math on 07/27 at 01:17 PM |
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Monday, March 28, 2005
Deepsky Top-100 (15): Stargate, Jaws and M 104
I just added a wonderful trio of deepsky objects to my Deepsky TOP 100, Stargate, Jaws and M 104.
Stargate and Jaws are two asterisms from Phil Harrington’s book “The Deepsky, an introduction”. They will help you to locating M 104, a bright galaxy near the Corvus-Virgo border. All three objects are very easy to locate and recognize, even from a suburban backyard. I found them with my 8-inch in a heavily light polluted southern sky. My advice, get out and hunt them down!
Follow this link to read the full story..........
Posted by
Math on 03/28 at 09:03 AM |
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Wednesday, November 10, 2004
Deepsky Top-100 (14): NGC 457, The ET Cluster
When you scan Cassiopeia and its neighbouring constellations with binoculars, the star fields in Cassiopeia seem to be much richer than in Perseus and Cepheus. The reason for this is that in the Perseus and Cepheus Milky Way, large nearby dust clouds of our own spiral arm (the Orion arm) block the view, while in the Cassiopeia Milky Way there are no dust clouds to .........follow this link to read the full story.
Posted by
Math on 11/10 at 04:01 AM |
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Tuesday, July 20, 2004
Deepsky Top-100 (13): M 57, the Ring Nebula
Centred between the constellations of Hercules and Cygnus lies a small constellation with a very distinctive star pattern, Lyra (the lyre). Four stars form the main “body” of the Lyre: Beta, Gamma, Delta and Zeta Lyrae. Together they make a kind parallelogram. At the northwestern corner of this parallelogram a triangle of follow this link to read the full story........
Posted by
Math on 07/20 at 01:51 PM |
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Tuesday, June 01, 2004
Deepsky Top-100 (12): M 13, the Great Globular Cluster in Hercules
Edmond Halley discovered M 13 in 1714. It is one of the finest globular clusters of the northern celestial hemisphere you can observe from your own backyard. M13 has a visual diameter of 14’ and a visual magnitude of 5.7. The cluster lies at a ..... follow this link to read the full story.
Posted by
Math on 06/01 at 11:09 AM |
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Monday, May 10, 2004
Deepsky Top-100 (11): Y Canum Venaticorum or La Superba
In Canes Venatici, the hunting dogs, you can find a beautiful red star, Y Canum Venaticorum, or “La Superba”. Y CVn is a carbon star. Most of these class C stars are evolved cooling giants with a large abundance of carbon dust in their outer shells. The apparent red color of carbon stars is caused by the carbon molecules (Carbon Monoxyide, Cyanogen, etc) in the outside layers of........ follow this link to read the full story
Posted by
Math on 05/10 at 06:35 AM |
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Sunday, April 18, 2004
Deepsky Top-100 (10): M 81 and M 82
Spring is a great time for observing galaxies, but you have to go to a dark sky site, to really find and enjoy them. There are however a few galaxies that can be seen from my light-polluted, suburban backyard. M 81 and M 82 in Ursa Major are..........follow this link to the deepsky section and read the full story.
Posted by
Math on 04/18 at 02:14 PM |
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