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Orion Nebula: January 15 - January 21, 2007.
We start the week with a celestial scenery alert just before dawn... Look for the Moon, Antares, Jupiter and Mars! The days ahead are filled with alternative catalog studies and meteor showers. So be sure to look skyward, because...
Here's what's up!
Monday, January 15 - If you’re up before dawn today, the Moon will be very near Antares, with an occultation in some areas (Check IOTA for details.) Jupiter will also be very near this pair, with Mars lower down in the eastern sky. With plenty of dark sky tonight, let's head around a fingerwidth northeast of Zeta Orionis and right on the celestial equator for a delightful bright nebula known as M78 (NGC 2068). This is both a binocular and small telescope Messier challenge object.
Often overlooked in favor of the Great Orion Nebula, this 8th magnitude diffuse area is easily captured under dark skies. Discovered by Méchain in 1789, M78 is part of the vast complex of nebulae and star birth that comprise the Orion region. Fueled by twin 10th magnitude stars, the nebula almost appears to binoculars to resemble a "double comet." Upon close scrutiny with a telescope, observers will note two lobes separated by a dark band of dust. Each lobe bears its own designation-NGC 2067 to the north and NGC 2064 to the south.
While studying, you will notice the entire area is surrounded by a region of absorption, making the borders appear almost starless. Filled with T Tauri-type stars and residing 1,600 light-years away, this reflection nebula is a cloud of interstellar dust which reflects the light of these young stars, the brightest of which is HD 38563A. In 1919, Vesto Slipher was the first to discover its reflective nature. As of 1999, seventeen Herbig-Haro objects are also associated with M78, and are believed to be jets of matter being expelled from newly forming stars.
Tuesday, January 16 - Wake up! Early this morning will be the peak of Delta Cancrid meteor shower. Yes, it's a pretty obscure one-no exciting parent Comet or disintegrating asteroid to blame it on-but since the Moon will only be a slim crescent, why not give it a go? The radiant will be just slightly west of the M44 "Beehive Cluster," making a worthy trip with binoculars. The Delta Cancrids are not exactly prolific-with a rate of only about 4 per hour-but they are very fast!
Tonight let's have a go at two Herschel 400 objects as we start about four fingerwidths southeast of Betelgeuse for NGC 2186. This large, loose open cluster is well suited to larger binoculars or small Telescopes and contains around 50 or so members that range in magnitude from 9 to 11. Look for many distinct pairings! NGC 2186 has been a study area for Astronomers and is known to contain circumstellar disks, which may be either newly-forming solar systems or just regenerated materials left over from formation.
The next hop is just northwest of apparent double Kappa Orionis. NGC 2194 is also a Herschel object and at magnitude 8.5 is well suited to smaller scopes. This rich galactic cluster can be well resolved in larger scopes and the similar magnitude members make it a delightful spray of stars.
Wednesday, January 17 - Tonight let's continue with our study of the Orion complex of nebulae associated with a molecular cloud. Known as LDN 1630 in Lynds' Catalogue of Dark Nebulae, it has many fine regions for study with a smaller scope under dark skies. Tonight return to M78 and let's look about one half degree northeast for the much fainter NGC 2071.
At its core is the smallest protoplanetary disc yet detected. Rotating around a young star, this "disc" could have the potential to form a solar system, and in size it is very similar to the orbit of Neptune. Located 1300 light-years away, it contains compact clusters of water molecules that allow researchers to study its motion through their radio emissions. Known as masers, these regions amplify radio emissions, and the entire area has been subject to jet activity. Although we cannot see the disc itself, you can detect a faint nebula associated with a 9th magnitude star in an average telescope. As with many types of objects, sometimes high magnification is not the answer. Try staying with minimal power to spot NGC 2071.
Now lace up your Nikes and let's head out to find "The Running Man"...
Located just a half a degree north of M43, this tripartite nebula consists of three separate areas of emission and reflection nebulae that seem to be visually connected. NGCs 1977, 1975 and 1973 would probably be pretty spectacular if they were a bit more distant from their grand neighbor! This whispery soft, conjoining nebula's fueling source is multiple star 42 Orionis. To the eye, a lovely triangle of bright nebulae with several enshrouded stars makes a wonderfully large region for exploration. Can you see the "Running Man" within?
Thursday, January 18 - If you are up before dawn, why not spend a moment or two looking at the sky? Just before dawn is your opportunity to spot the "New Moon in the Old Moon's Arms!"
Tonight let's do some study of open clusters that belong to different catalogs. The first three are known as "Dolidzes," and your marker star is Gamma Orionis.
The first is an easy hop of about one degree northeast of Gamma-Dolidze 21. Here we have what is considered a "poor" open cluster. Not because it isn't nice-but because it isn't populous. It is home to around 20 or so low wattage stars of mixed magnitude with no real asterism to make it special. The second is about one degree northwest of Gamma-Dolidze 17. The primary members of this bright group could easily be snatched with even small binoculars and would probably be prettier in that fashion. Five very prominent stars cluster together with some fainter members that are, again, poorly constructed. But it includes a couple of nice visual pairs. Low power is a bonus on this one to make it recognizable.
The last is about two degrees north of Gamma-Dolidze 19. Two well-spaced roughly 8th magnitude stars stand right out with a looping chain of far fainter stars between them and a couple of relatively bright members dotted around the edges. With the very faint stars added in, there are probably three dozen stars all told and this one is by far the largest concentration of this "Do" trio.
Now let's have a look at a deceptive open cluster located in Barnard's Loop around 2 degrees northeast of M78. While billed at a magnitude of roughly 8, NGC 2112 might be a binocular object, but it's a challenging one. This open cluster consists of around 50 or so stars of mixed magnitudes and only the brightest can be seen in small aperture. Add a little more size in equipment and you'll find a moderately concentrated, small cloud of stars that is fairly distinguishable against a stellar background.
Also known as Collinder 76, this unusual cluster resides in the galactic disc-an area of mostly very old, metal poor stars. It is believed that NGC 2112 is of a more intermediate age, based on recent photometric and spectroscopic data.
Friday, January 19 - Johann Bode was born today in 1747. He was the publicizer of the Titus-Bode law, a nearly geometric progression of the distances of the planets from the Sun. Also born today, but in 1851, was Jacobus Kapteyn. Kapteyn studied the distribution and motion of half a million stars and created the first modern model of the size and structure of the Milky Way Galaxy.
Are you ready for a New Moon challenge? Then take advantage of dark sky time to head to the eastern-most star in the belt-Zeta Orionis.
Alnitak resides at a distance of some 1600 light-years, but this 1.7 magnitude beauty contains many surprises-like being a triple system. Fine optics, high power and steady skies will be needed to reveal its members. About 15′ east and you will see that Alnitak also resides in a fantastic field of nebulosity which is illuminated by our tripartite star. NGC 2024 is an outstanding area of emission that holds a rough magnitude of 8-viewable in small scopes but requiring a dark sky. So what's so exciting about a fuzzy patch? Look again, for this beauty is known as the Flame Nebula.
Larger Telescopes will deeply appreciate this nebula's many dark lanes, bright filaments and unique shape. For the large scope, place Zeta out of the field of view to the north at high power and allow your eyes to re-adjust. When you look again, you will see a long, faded ribbon of nebulosity called IC 434 to the south of Zeta that stretches for over a degree. The eastern edge of the "ribbon" is very bright and mists away to the west, but look almost directly in the center for a small dark notch with two faint stars to the south. You have now located one of the most famous of the Barnard dark nebulae-B33.
B33 is also known as the Horsehead Nebula. It’s a very tough visual object-the classic chess piece shape is only seen in photographs-but those of you who have large aperture can see a dark "node" that is improved with a filter. B33 itself is nothing more than a small area cosmically (about 1 light-year in expanse) of obscuring dark dust, non-luminous gas, and dark matter-but what an incredible shape. If you do not succeed at first attempt? Do not give up. The "Horsehead" is one of the most challenging objects in the sky and has been observed with apertures as small as 150mm.
Saturday, January 20 - Simon Mayr was born today in 1573. Although Mayr's name is not usually recognized, we all recognize names that he's given. Mayr was also observing the moons of Jupiter at nearly the same time as Galileo and he was the one who assigned them the Greek names in use today. If you're up before dawn, look for Jupiter and see if you can spot Io, Ganymede, Callisto and Europa for yourself! While you're out, take a few minutes to watch the skies for the peak of the Coma Berenicid meteor shower. Although the activity for this one is fairly weak, with an average fall rate of about seven per hour, it still warrants study.
So what makes this particular shower of interest? Noted first in 1959, the stream was eventually tied in 1973 to another minor shower in the same orbit known as the December Leo Minorids. As we know, meteoroid streams are traditionally tied to the orbit of a comet, and in this case the Comet was unconfirmed! Observed in 1912 by B. Lowe, an Australian amateur astronomer, the Comet was officially designated as 1913I and was only seen four times before losing it to sunrise.
Using Lowe's observations, independent researchers computed the comet's orbit and it was basically forgotten about until 1954. At that time, Fred Whipple was studying meteoroid orbits and made the association between his photographic studies and the enigmatic Comet Lowe. By continuing to observe the annual shower, it was determined that the orbital period of the Comet was about 75 years, but the two major streams occurred about 27 and 157 years apart. Thanks to the uneven dispersion of material, it may be another decade before we see some real activity from this shower, but even one meteor can make your day!
And if you want to make your "night" an early one, why not trying looking for another odd meteor shower? Tonight will be the peak of the Delta Arietids! These unusual meteors also bear a resemblance to last week's Geminids, for the source of the stream appears to be a sun-grazing asteroid named Icarus. The hourly fall rate will be about 12 fast and bright "shooting stars." Be sure to watch early as the constellation of Aries will be in the best position for only a few hours after dark.
Sunday, January 21 - John Couch Adams was born today in 1792. Adams predicted the existence of Neptune. Also born today in 1908 was Bengt Stromgren-the developer of the theory of ionization nebulae (H II regions). Tonight after the "Old Moon in the New Moon's Arms" sets, we'll take a look at an ionization nebula as we return for an in-depth look at M42.
Known as the Great Orion Nebula, we've already learned where to find it-now let's learn what makes it up.
M42 is actually a great cloud of glowing gases whose size is beyond our comprehension. More than 20,000 times larger than our own solar system, its light is mainly fluorescent. For most people, the Great Orion Nebula will appear to have a slight greenish color-the result of doubly ionized oxygen. At the fueling heart of this immense region is an area known as the Trapezium, its four easily seen stars perhaps the most celebrated multiple system in the night sky. The Trapezium itself belongs to a faint cluster of stars which are now approaching the main sequence stage in an area known as the "Huygenian Region."
Buried in this cloud of mainly Hydrogen gas there are many star forming regions amidst the bright ribbons and curls. Appearing like "knots" in the structure, these are known as "Herbig-Haro objects" and are believed to be stars in their earliest states. There are also a great number of faint reddish stars and erratic variables-very young stars that may be of the accreting T Tauri type. Along with these are "flare stars" whose rapid variations mean that amateur Astronomers have a chance to witness new activity.
While you view M42, note that the region appears very turbulent. There is a very good reason. The Great Nebula’s many different areas move at different speeds both in recession and approach. The expansion rate at the outer edges of the nebula is an indication of radiation from the very youngest stars known. Although it may be as many as 23,000 years since the Trapezium brought it to "light," it is entirely possible that new stars are still forming in M42.
Written by Tammy Plotner
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