Star Clusters – Page 44 – Astronomy Sketch of the Day

Halo Wanderer

Globular Cluster, M62
Sketch and Details by Frank McCabe

Globular Cluster M-62 (NGC 6266)

In the halo of the Milky Way our home galaxy there are about 160 or so globular clusters orbiting the galactic center. Like life forms they are mostly alike but each is uniquely different in size, shape, density, chemistry, and the like. At 22,500 light years (l.y.) from us this globular is only 6100 l.y. from the galactic center. This cluster is also known to be distorted in shape from spherical due to tidal forces acting upon it by the galactic center. More than 200 RR Lyrae variable stars reside in this globular, a much higher number than most and in the spring of 2002 Chandra X-ray Observatory discovered a rich population of close X-ray emitting binary stars in this globular. M-62 is located on the Ophiuchus side of the constellation border with Scorpius. From my location near Chicago it never rises higher than 19° above the southern horizon. But even on an average night it is an impressive sight in a moderate telescope. This globular cluster was discovered by Charles Messier 237 years ago last month.

Other Features for M-62

R.A.17hrs. 1 min.; Dec. -30°7 min. Epoch 2000
Average distance between stars 0.25 l.y.
Diameter 100 l.y. across 14 arc minutes
Visual magnitude 6.5

Sketching:

9”x11” white sketching paper; 6B, 4B, HB graphite pencils and a blending stump;

Scanned and inverted; brightness of some stars adjusted with MS Paint.

Scope: 10” f/5.7 Dobsonian: 24 mm widefield eyepiece 60x and 12 mm eyepiece 121x

Date and Time: 7-2-2008, 4:00-4:40 UT

Seeing: Pickering 6/10

Transparency: Below average 2/5

NELM: 4.4

Frank McCabe

Coathanger for the Cloak of Night

The Coathanger Asterism, Collinder 399
Sketch and Details by Rony De Laet

Binocular Icon 21 : The Coathanger.

One of the highlights of a summer binocular tour of the heavens is Collinder 399. It is a loose group of stars, which is visible to the naked eye. The first written observations of this cluster go back to AD 946, when the Persian astronomer Al Sufi described Cr 399 as a little cloud. Cr 399 can be found between Cygnus and Aquila, a mere 5° west of Sagitta. From my backyard, I can detect a trio of stars in a little fuzzy spot. With a pair of binoculars, the cluster shows a real coathanger! Point the bino’s at Albireo and draw a line to Anser (Alpha Vulpeculae). Continue in the same direction until Answer nears the northern border of the field of view. Cr 399 should appear at the southern edge of the field stop of the binoculars. The Coathanger is an amazing sight, even under light polluted skies. The cluster consists of 10 bright stars. Six of them form the 1.4° long bar of the hanger, in a perfect east to west orientation. Cr 399 is believed to be a chance alignment and not a true cluster.

Site : Bekkevoort, Belgium
Date : June 10, 2008
Time : around 00.30UT
Binoculars : Bresser 8×56
FOV: 5.9°
Filter : none
Mount : Trico Machine Sky Window
Seeing : 2,5/5
Transp. : 3.5/5
Nelm : around 5.3
Sketch Orientation : N up, W right.
Digital sketch made with Photo Paint, based on a raw pencil sketch.

Above the Great Sand Sea of Namibia

47 Tucanae
Sketch and Details by Dave Riddle

It has been said that if we used all our senses to the fullest, we would stand in a constant state of amazement. Perhaps a telescope is merely a way to extend one of our senses — the gift of eyesight. I have come to appreciate how fortunate I have been to fulfill a few of childhood dreams. When the opportunity arose back in 2004 to visit Africa and take a five day road trip from Johannesburg, South Africa to the Great Sand Sea of Namibia, I jumped at the chance. I would spend eight weeks at the Sossusvlei Mountain Lodge under what must be some of the darkest skies found on our planet. The chance for daylight sightseeing combined with exploring the night skies of the southern hemisphere proved too much to resist…I’ll argue that the celestial wonders visible through a telescope are just as impressive as some of the other natural wonders seen along the way — the Augrabies Falls of S. Africa, the herds of elephants or the remarkable sand dunes of Sossusvlei. Submitted is a Photoshop rendering of 47 Tucanae, arguably the finest globular the heavens can offer. I used a 12″ Schmidt-Cassegrain at 250X to make the original graphite pencil and ink.

Dave Riddle

A Surprising GC

M92, a surprising globular cluster in Hercules
Sketch and Details by Jeremy Perez

I didn’t realize how nice this globular cluster would look. It stood up well to magnification, with stars resolving across the face of the cluster. It appeared noticeably elliptical in its outer reaches, pointing southwest to northeast. The core was soft but robust. It seemed that the core’s brightness was harder along the north side, and faded more softly to the south. I would estimate its dimensions at 6′ x 4′. Also, the core seemed to reside closer to the south-southeast side of the overall body of the cluster. A bright yellow star hung about 6′ to the east of the core. Overall, the cluster gave the offhand appearance of an elliptical galaxy.

Factoids:
M92 is a globular cluster about 26,000 light years away in the constellation Hercules. It is a bit more distant than it’s brighter, neighboring cluster M13. An age estimate of 16 billion years is being re-evaluated based on new distance scale information for the universe from the Hipparcos satellite, and so may be a bit younger. Its 14′ extension yields a diameter of 109 light years, and may have a mass of about 330,000 solar masses. It is approaching us at 112 km/sec. The precession of Earth’s axis will cause M92 to become our “North Cluster” or “Polarissima Borealis” in about 14,000 years, as it was previously, about 12,000 years ago.

Subject M56 (NGC 6341)
Classification Globular Cluster (Class IV)
Position* Hercules [RA: 17:17.1 / Dec: +43:08]
Size* 14.0′
Brightness* 6.4
Date/Time June 30, 2005 – 11:00 PM
(July, 2005 – 06:00 UT)
Observing Loc. Flagstaff, AZ – Home
Instrument Orion SVP 6LT Reflector (150 mm dia./1200 mm F/L)
Eyepieces/Mag. 10 mm (120X)
Conditions Clear, breezy, 68�F
Seeing 5-6/10
Transparency Mag 5.8 NELM
Sources SEDS
*Based on published data.

Arrowhead, Butterfly or Starfish?

M93, an open cluster in the constellation Puppis
Sketch and Details by Jeremy Perez

This is a triangular arrow shaped cluster with its tip pointing southwest. This southwest tip hosts one orange and one yellow star. In the center lies a trapezium-like arrangement of stars. The main body appears to be 16′ in diameter. The brightest neighboring star lies 30′ to the southeast.

Factoids:
M93 lies 3600 light years away and its 80 or so member stars span 20-25 light years across. Its brightest stars are B9 Blue Giants, and its age is estimated at 100 million years. While its stars form a triangular shape, Kenneth Glyn Jones found it to look like a butterfly, while Admiral Smyth found it more like a starfish. It was one of the last deep sky objects discovered by Charles Messier personally and was cataloged in 1781.

Subject M93 (NGC 2447)
Classification Open Cluster
Position* Puppis [RA: 07:44.6 / Dec: -23:52
Size* 22′
Brightness* 6.0
Date/Time February 4, 2005 – 9:15 PM
(February 5, 2005 – 04:15 UT)
Observing Loc. Flagstaff, AZ – Home
Instrument Orion SVP 6LT Reflector (150 mm dia./1200 mm F/L)
Eyepieces/Mag. 32 mm (37X)
Conditions Clear, 29�F
Seeing 2/10
Transparency Mag 5.0
Sources SEDS
*Based on published data.

Flocking to Scutum

M11
Sketch and Details by Kiminori Ikebe

M11(NGC 6705) Sct open cluster
Difficulty level 1

Date of observation: 1999/10/06 20:23
Observing site: Makinoto
Transparency/seeing/sky darkness: 3/5/3
Instruments: 32cm Dobsonian with XL14 at 110x
Width of field: 0.6 degree
This is a fine and bright cluster containing many stars. At 110x it is highly concentrated but almost completely resolved. There is a 7.8-magnitude star near the center. It is very conspicuous. There are two faint stars nearby. It is a fine sight with an equal double on the south side, which is as bright as the star near the center. The distribution of the resolved stars is quite uneven. The general shape of the cluster is that of a diamond and a beautiful chain of stars is seen in the southeast outlying area. Dark areas and dense patches of stars are intermingled. There are scattered outliers northeast of the cluster. They seem to be members of the cluster.

M13 by way of Binoculars

M13
Sketch and Details by Rony De Laet

The Great Globular in Hercules.

One of the finest globular clusters for northern hemisphere observers is undoubtedly M13 in Hercules. With a magnitude of 5.8, the cluster is a naked eye object under mag 6 skies. The cluster is also an easy to find object, even for novice observers. Just draw a line from Eta Herculis to Zeta Herculis and you’ll bump into M13. Just put Eta at the northern edge of the field of view, and M13 will appear centered in your view. Under dark skies, the Globular can be seen without optical aid as a tiny smudge of light.

While many globulars have a star like core, M13 appeared to me with a granular core. Its halo is very large compared to other globulars. I could detect a mag 10 star at the western border of the halo. The bright star at the top of the sketch is Eta Herculis.

With M13 riding high in the sky, try to compare it with other globulars like M3, M5, M10 and M12. At first, these globulars may all look alike. But with patience, each globular will show slightly different features!

Site : Bischofshofen, Austria
Date : May 3, 2008
Time : around 22.30UT
Binoculars : Bresser 8×56
FOV: 5.9°
Filter : none
Mount : Trico Machine Sky Window
Seeing : 3/5
Transp. : 4/5
Nelm : 6.0
Sketch Orientation : N up, W right.
Digital sketch made with Photo Paint, based on a raw pencil sketch.

The Sparkling Heart of Canis Major

M41
Sketch and Details by Wade V. Corbei

I was able to observe M41 (NGC 2287) on Jan. 18th (early 19th), the ONLY day so far this month that has allowed for any sort of observing.

I was actually quite surprised at this OC that contained quite a few star-chains that only brought more interest, complexity and beauty to this jewel of the night-sky residing within Canis Major. I was fortunate in that my one night of observing was extremely clear and steady, allowing for some great observing of many of the fainter stars within this region.

This sketch, like all others, started out with a plain ol’ mechanical pencil, a #2 pencil & paper (my sketch book). The original sketch was then scanned into and digitized in PhotoShop CS3.

According to my observing notes, I spent a total of 1-hour & 10-minutes at the EP sketching and observing this OC. The longer I gazed at this OC, more star-chains and fainter stars seemed to slowly emrge from the inky darkness. I do rememebr having to stretch a bit after observing and sketching this one.

Majestic Swarm

NGC 5139 (Omega Centauri)
Sketch and Details by Dave Riddle

My attempt to sketch Omega Centauri caused me to recall the trials faced by Frederick Catherwood, the famed British illustrator, while he tried to capture the Mayan “idols” found in Central America during the early 1800s. As recounted in C. W. Ceram’s “Gods, Graves, and Scholars”, Catherwood faced the daunting task of reproducing forms that were utterly different from any any thing he had experienced before and “for a time his crayon simply would not function.”

I spent an hour or so studying NGC 5139 before starting my sketch. Using a 12″ Schmidt-Cassegrain at 100X, prominent stars chains, clumps of stars and mysterious dark voids made their appearance. At first glance, Omega had appeared as a rather structureless oblate globe of stars.

My original graphite pencil and ink drawing was made on the evening of April 18, 2005 with rather poor seeing conditions and a waxing gibbous moon over the desert of Namibia. The submitted drawing is a Photoshop interpretation of the sketch.

Dave Riddle

Bisected Globular

M4
Sketch by Michael Vlasov

M4 lies about 7,200 light years away, and is one of the closest globular clusters. It displays a bar-like structure that runs through its center. The bar consists of 11th magnitude stars, is 2.5′ long and runs at a position angle of 12°. The cluster is obscured by interstellar matter, and so is dimmed greatly. Deep photography reveals a diameter of 36, equating to 75 light years, whereas its visual diameter has been estimated at 14′. At Class IX, it is one of the most open of globular clusters, with a half-mass radius of 3.65′ or 8 light years.

M4 was discovered by De Chéseaux in 1745-46 and subsequently catalogued by Messier in 1764 who resolved it into stars. It was the only one he could resolve, calling it a “cluster of very small stars”, and so was the first globular ever resolved into stars.

Source: SEDS.