Friday, January 6, 2012

Weekly SkyWatcher's Forecast - January 8-14, 2012

Written by Tammy Plotner

Sunday, January 8 - On this day in 1942 - precisely 300 years after the death of Galileo, Stephen Hawking was born. The British theoretical astrophysicist, despite his physical limitations, became one of the world's foremost leaders in cosmological theory and his book "A Brief History of Time" remains one of the best written on the subject. Also born on this day in 1587 was Johannes Fabricius, son of the discoverer of variable star Mira, David Fabricius. Like many father and son teams, the pair went on to study astronomy together, and some of their most frightening work dealt with viewing sunspots through an unfiltered telescope - a practice which eventually blinded Galileo!

To honor them both tonight, let's take a look at a variable star and a distant sun so large that astronomers have even observed a "hot spots" on the surface - Alpha Orionis - more commonly know as Betelgeuse. This star is so massive that if it were to replace our own Sun, it would fill our solar system out to the distance of the orbit of Jupiter, and so distant that resolving it would be like aiming a telescope at a car headlight from 9656 kilometers away. It is an irregularly pulsing, red supergiant that changes roughly every 5.7 years and can drop in intensity by as much as a magnitude. It is also well known that Betelgeuse is a multiple star system, with four companions ranging from 11th to 14th magnitude, but it is believed its variability is caused by internal changes rather than an eclipsing body. As you view this giant star tonight, keep in mind how much of its hydrogen has been expended and how many times it has expanded and contracted in the 425 years it took for this light to reach your eyes. When it finally does go supernova, it will be almost half a century before we know it!

Monday, January 9 - Today in 1839, Scottish astronomer Thomas Henderson was the first to measure the distance to a star while stationed at the Cape of Good Hope. Using geometrical parallax, Alpha Centauri became the first stellar standard other than our own Sun. Although Henderson began as a lawyer's clerk, his impressive list of 60,000 star positions led to his appointment as the first Astronomer Royal in Scotland.

Tonight is Full Moon and it goes by many different names. During the month of January it is called the Full Wolf Moon. Its name comes from the North American Indians who would hear the wolves howling in search of food in the cold, snow-covered and barren landscape. In Europe it was referred to as the Moon after Yule. And you’ll be no fool if you can’t take your eyes off Mars… Small wonder! Right now it’s tipping the magnitude scales at +0.0! While deep sky studies are out, we can take a look at Iota Orionis. Known to the Arabs as "the Bright One of the Sword," we know it as the southern-most star in its asterism's namesake. Iota is estimated to be around 2000 light-years away and is about 20,000 times brighter than our own Sun. In the small telescope you will find Iota to be an easy and charming triple star. The bluish B star is relatively close at 11" in separation, but a bright 6.9 in magnitude. Much more distant at 50" is the disparate, magnitude 11 reddish C star. Iota itself is a spectroscopic binary and you will note another "white" double (Struve 747) unrelated to Iota about 8' to the southwest.

Staying at high power, the reason I ask you to look here tonight is to conquer a Herschel 400 object and study a region of the sky that would be far more impressive if it weren't for its alluring neighbor. If you look closely, you will see that Iota is involved in a region of the emission nebula known as NGC 1980, along with a small open cluster known as H 31. To be sure, the area is vague, as are all low surface brightness nebulae, but do look to the east of Iota where a much brighter, roundish area makes an unmistakable appearance!

Tuesday, January 10 - Robert W. Wilson was born this day in 1936. Wilson is the co-discoverer, along with Arno Penzias, of the cosmic microwave background, and in 1978 he won the Physics Nobel Prize. While we're "listening in," on this day in 1946, the US Army's Signal Corps became the first to successfully bounce radar waves off the Moon. Although this might sound like a minor achievement, let's look just a bit further into what it really meant! Known as "Project Diana," scientists were hard at work to find a way to pierce the Earth's ionosphere with radio waves - a feat believed at that time to be impossible. Headed by Lt. Col. John DeWitt, and working with only a handful of full-time researchers, a modified SCR-271 bedspring radar antenna was set up in the northeast corner of Camp Evans. The power was cranked up and it was aimed at the rising Moon. A series of radar signals were broadcast, and in each case, the echo was picked up in exactly 2.5 seconds - the time it takes light to travel to the Moon and back. The significance of Project Diana cannot be overestimated. The discovery that the ionosphere could be pierced, and that communication was possible opened the way to space exploration. Although it would be another decade before the first satellites were launched into space, they were later followed by manned rockets. Project Diana paved the way for all those achievements.

Let's return again to Orion tonight before moonrise, but preferably with binoculars since we will be studying a very large region known as "Barnard's Loop." Extending in a massive area about the size of the "bow," you will find Barnard's photographic namesake to the eastern edge of Orion, where it extends almost half the size of the constellation between Alpha and Kappa. Because the Orion complex contains so many rapidly evolving stars, it stands to reason that a supernova should have occurred there at some time. "Barnard's Loop" is quite probably the shell leftover from such a cataclysmic event. If taken as a whole, it would encompass 10 degrees of sky! For the most past, the nebula itself is very vague, but the eastern arc (where we are observing tonight) is relatively well defined against the starry field. Although it is similar to the Cygnus Loop - the Veil Nebula - our Barnard Loop is far more ancient. If you have transparent, dark skies then return again when skies are darker and enjoy! You can trace several degrees of this ancient remnant using just binoculars.

Wednesday, January 11 - Tonight in 1787, Sir William Herschel discovered two of Uranus' multiple moons - Oberon and Titania. If you’d like to see Uranus for yourself, it can be found just southeast of the circlet of Pices (0h 3m 53s) not long after skydark. It can be captured with mid-sized binoculars, but even a small telescope will reveal its slightly greenish orb!

Our study for tonight is the "holy grail" of multiple star systems as we look into the fueling core of M42 - Theta Orionis (Right Ascension: 05 35.3 – Declination: -05 24). Are you ready to walk into "the Trap?" Even the smallest of telescopes can reveal the four bright stars that comprise the quadrangle at the heart of the Great Orion Nebula known as the "Trapezium." Both the beginner and the seasoned veteran know that there are actually eight stars in this region and the journey we are about to undertake requires both aperture and fine skies. What can you really see? All four primary stars are easy. A steady hand with binoculars and even the most modest of telescopes make this foursome an awesome sight... And they seem to be in a dark "notch" of their own, don't they? A mid-sized scope will reveal two additional 11th magnitude stars, but excellent skies could mean the even smaller aperture could detect them as "red" companions to the "blue/white" primary stars. The remaining two components average about magnitude 16, putting them within reach of large amateur scopes, but what would you see?

When I first began observing the Trapezium area with a 12.5" telescope, I was sure that I would never see the two faintest members of the group. I was new to challenging double stars and had never looked at a diagram. (To this day, I still prefer to observe and describe things first and confirm them later. Knowing in advance what you are "supposed" to see influences what you "can" see.) I had seen the fainter stars that appeared as doubles, along with a faint wink here and there as well as one to the outside that made the whole thing appear like a pentagon. Little did I realize I was seeing all eight members, and there seemed to be so much more just on the edge of my perception. Thus began my own personal quest to study the "Trapezium" on a more professional level, just like challenging galaxy studies.

Using the 31" reflector at Warren Rupp Observatory, it was time to "walk into the Trap" and to answer all my observing questions through visual confirmation. While at first glance with a small telescope, the background region in this area might appear a black void, it is not. The nebula continues here, but changes form. Instead of seeing "smoke-like" filaments, the region around the Trapezium is scalloped, like fish scales. You can never see this in a photograph! I realized immediately that both the G and H stars that I had always questioned were quite within range of my 12.5" as I recognized the pattern. Then a moment of perfect clarity came and the view literally exploded in dozens of stars buried within the field surrounding these eight known as the "Trapezium." Upon formal study, I found that there are around 300 such stars within 5' of the Theta Orionis complex that exceed magnitude 17. According to Strand, the expansion rate puts them at an approximate age of 30,000 years, making it the youngest star cluster known. Regardless of what size telescope you use, you owe it to yourself to take the time to power up on the "Trap." Since the time the area was revealed to my eyes in all its open glory, I have seen scallops in the nebula and both fainter members on nights with exceptional seeing in much smaller telescopes. No matter how many stars you are able to resolve out of this region, you are looking into the very beginnings of starbirth...

Thursday, January 12 - Today in 1830 celebrates the founding of what - in 1831 - would become the Royal Astronomical Society. The RAS was conceived by John Herschel, Charles Babbage, James South, and several others. The RAS has published its Monthly Notices continuously since 1831. Believed to have been born today in 1907 was Sergei Pavlovich Korolev. While few people recognize Korolev's name, he was a Soviet rocket engineer whose contributions to the science made him as important to the Russian space program as Robert Goddard was to that of the United States. His developments led to Sputnik, Vostok, Voskhod, and eventually the Soyuz programs.

Tonight our study region is to the northeast of the Great Orion Nebula (M42) and has a designation of its own - M43 (Right Ascension: 5 : 35.6 - Declination: -05 : 16). Discovered by De Mairan in the latter half of the 18th century, this emission nebula appears to be separate from M42, but the division known as "the Fish Mouth" is actually caused by dark gas and dust within the nebula itself. At the heart of it is 7th magnitude "Bond's Star" - and wouldn't 007 be proud? This unusually bright OB star is creating a matter-bound Stromgren sphere! Translated loosely, this star is actually ionizing the gas near it, making an orb-shaped area of glowing hydrogen gas. Its size is governed by the density of both the gas and dust that surround Bond's Star. This "exciting" star of our show is more properly known as Nu Orionis and near it resides in a dense concentration of neutral material known as the "Orion Ridge." It is this combination of dust - mixed with gases - that make for a well balanced area of star formation. And besides... It's just cool!

If you’d like to take another look at something cool, turn your head and telescope towards Leo to examine Mars. Tonight the planet reaches the apparent diameter of 10” and simply commands attention. Be sure to look for its polar caps and dark markings.

Friday, January 13 - Got a wide field eyepiece? Then tonight is your chance to pick off both an inner planet and a way outer planet in the same field of view! After sky dark, set your sights on Venus and you’ll find Neptune less than a degree away to the north!

Tonight let's return to Orion's sword to have a look for something you might have missed. Starting with M42 and M43, be sure to log these two Messier catalog studies for your binocular or small telescope records, but have a much closer look about one degree north. NGC 1981 (Right Ascension: 5 : 35.2 - Declination: -04 : 26) is a 4th magnitude open cluster that looks like a stellar member of the Orion group to the unaided eye. In small binoculars, it is easily resolved into around a dozen members with its brightest star weighing in at around magnitude 6. In the small telescope, as many as twenty individual members are resolved in chains and small groups. The region of NGC 1981 has been studied for rotational movement in the Orion arm of our galaxy and it was found that the stars in this cluster are actually rotating around our galactic center faster than the stars in the Perseus arm. Well suited to even urban skies, NGC 1981 is also an Astronomical League Binocular Deep Sky object that you will very much enjoy. For larger telescopes looking for a real challenge, double star Struve 750 is part of this entertaining and easy galactic cluster!

Saturday, January 14 - Tonight it's big scope challenge time as we take on two Hershel 400 objects. Let's start with NGC 2202 (Right Ascension: 6 : 16.9 - Declination: +05 : 59) located about two fingerwidths southeast of Lambda Orionis, directly in line with Betelgeuse. This 12.9 magnitude planetary nebula isn't for everybody and one of the reasons the Herschel studies are what they are is because it is challenging. Appearing like a stellar point, H 34 is not particularly bright, but will take on the form of a slightly fuzzy and slightly green planetary nebula at high power. Be sure to look at a detailed chart carefully if you are using a smaller scope to correctly identify this object. It wouldn't be a challenge if it were easy!

The next is more readily achievable in smaller scopes and more easily found by heading north of Beta Eridani about two fingerwidths. The molecular cloud of reflection nebulae known as NGC 1788 (Right Ascension: 5 : 06.9 - Declination: -03 : 2) is roughly 1 to 3,000 light-years away and shows more as a faint, squarish nebulosity with embedded stars. Best at low power or with rich field scopes, this small glowing patch is sure to please!

If you’ve been following Mars, then take note of its position later tonight. The red planet is about to go slide into the constellation of Virgo!

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