Posted on by Ian O'Neill

Coolest, Darkest Brown Dwarf Discovered

An artist impression of a brown dwarf (Hallinan et al., NRAO/AUI/NSF)

The coolest brown dwarf has been discovered, with a surface temperature of 623 Kelvin (that’s only 350 Celsius or 660 degrees Fahrenheit). Compare with the surface temperature of our Sun, a modest 6,000 Kelvin, you can see that this featherweight dwarf “star” is a little odd. As far as stars go, this one is pretty unspectacular, but it does hold a vast amount of interest. It may not be as sexy as a supernova or as exotic as a neutron star, the humble brown dwarf may provide the essential link between planets (specifically gas giants) and stars. They are effectively failed stars, and this new discovery demonstrates just how cold they can be…

Brown dwarfs are the link between massive planets and small stars. They have an upper limit of about 80 Jupiter masses, but are not massive enough to sustain nuclear fusion in their core. They do however experience convection from the interior to the surface. The confusion arises when trying to find the lower limit of brown dwarf size, at what mass does the gas giant planet start being a brown dwarf star? This grey area is thought to be characterized by an entirely new stellar type: Y-class dwarfs. Until now Y-class dwarfs have been very elusive and have only existed in theory.

A comparison of the size of Jupiter, a brown dwarf, a small star and the Sun (Gemini Observatory/Artwork by Jon Lomberg)

Astronomers using near-infrared and infrared instruments at the Canada France Hawaii and Gemini North telescopes and the European Southern Observatory in Chile have discovered a Y-class dwarf, bringing this strange failed star from theory and into reality. What’s more, it’s in our cosmic neighbourhood, only 40 light-years from Earth. This brown dwarf has been unglamorously named “CFBDS0059”, but I would have called it something like “The Dark Star” or “The Death Star”, as it is so dim and its surface temperature is approximately the same as the surface temperature of the planet Mercury (but much cooler than the surface temperature of Venus). As it is so cool, it isn’t very luminescent and only radiates in the near-infrared wavelengths (it’s not even as hot as a standard electric stove element), requiring specialist equipment to detect it. As it turns out, CFBDS0059 is small, only 15-30 times the mass of Jupiter, fulfilling the lower mass limit of brown dwarf stars and will be known as the first Y-class dwarf to be observed.

But what is the indicator that a Y-class brown dwarf has been observed? Using spectrometers, astronomers have been able to see the constituent compounds making up the brown dwarf’s atmosphere. Should ammonia be discovered, it’s a pretty sure sign that a Y-class dwarf has been found.

“We are starting to see a little hint of ammonia absorption.” Loic Albert (stellar researcher) of the Canada France Hawaii Telescope in Hawaii, commenting on CFBDS0059.

There are two other verified classes of dwarfs, L and T-class dwarfs. L-class dwarfs are hotter, with temperatures from 2200 to 3600°F and T-class dwarfs are cooler than 2190°F and methane-rich. CFBDS0059 is obviously much, much cooler, but researchers believe there may be still cooler dwarfs out there, possibly condensing any water vapour in their atmospheres to form clouds, setting Y-class dwarfs far from the characteristics of its L and T-class cousins. Should they get any colder, water will freeze into ice crystals, giving them more planetary than stellar characteristics.

Source: Discovery.com

Posted on by Fraser Cain

Milky Way’s Black Hole Gave Off a Burst 300 Years Ago

Sagittarius A*. Image credit: Chandra

Our Milky Way’s black hole is quiet – too quiet – some astronomers might say. But according to a team of Japanese astronomers, the supermassive black hole at the heart of our galaxy might be just as active as those in other galaxies, it’s just taking a little break. Their evidence? The echoes from a massive outburst that occurred 300 years ago.

The astronomers found evidence of the outburst using ESA’s XMM-Newton space telescope, as well as NASA and Japanese X-ray satellites. And it helps solve the mystery about why the Milky Way’s black hole is so quiet. Even though it contains 4 million times the mass of our Sun, it emits a fraction of the radiation coming from other galactic black holes.

“We have wondered why the Milky Way’s black hole appears to be a slumbering giant,” says team leader Tatsuya Inui of Kyoto University in Japan. “But now we realize that the black hole was far more active in the past. Perhaps it’s just resting after a major outburst.”

The team gathered their observations from 1994 to 2005. They watched how clouds of gas near the central black hole brightened and dimmed in X-ray light as pulses of radiation swept past. These are echoes, visible long after the black hole has gone quiet again.

One large gas cloud is known as Sagittarius B2, and it’s located 300 light-years away from the central black hole. In other words, radiation reflecting off of Sagittarius B2 must have come from the black hole 300 years previously.

By watching the region for more than 10 years, the astronomers were able to watch an event wash across the cloud. Approximately 300 years ago, the black hole unleashed a flare that made it a million times brighter than it is today.

It’s hard to explain how the black hole could vary in its radiation output so greatly. It’s possible that a supernova in the region plowed gas and dust into the vicinity of the black hole. This led to a temporary feeding frenzy that awoke the black hole and produced the great flare.

Original Source: ESA News Release

Posted on by Tammy Plotner

Binoculars for Astronomy

Astronomy is best when you get outside and look into the skies with your own eyes. And the best way to get started is with a set of binoculars for astronomy. They’re light, durable, easy to use, and allow you to see objects in the night sky that you just couldn’t see with your own eyes. There are so many kinds of binoculars out there, so we’ve put together this comprehensive guide to help you out.

Everyone should own a pair of binoculars. Whether you’re interested in practicing serious binocular astronomy or just want a casual cosmic close-up, these portable “twin telescopes” are both convenient and affordable. Learning more about how binoculars work and what type of binoculars work best for astronomy applications will make you much happier with your selection. The best thing to do is start by learning some binocular “basics”.

What are binoculars and how do they work?
Binoculars are both technical and simple at the same time. They consist of an objective lens (the large lens at the far end of the binocular), the ocular lens (the eyepiece) and a prism (a light reflecting, triangular sectioned block of glass with polished edges).

The prism folds the light path and allows the body to be far shorter than a telescope. It also flips the image around so it doesn’t look upside-down. The traditional Z-shaped porro prism design is well suited to astronomy and consists of two joined right-angled prisms which reflects the light path 3 times. The sleeker, straight barrelled roof prism models are more compact and far more technical. The light path is longer, folding 4 times and requires stringent manufacturing quality to equal the performance. These models are better suited to terrestrial subjects, and are strongly not recommended for astronomy use.

If you’re using binoculars for astronomy, go with a porro prism design.

Choosing the Lens Size
Every pair of binoculars will have a pair of numbers associated with it: the magnifying power times (X) the objective lens size. For example, a popular ratio is 7X35. For astronomical applications, these two numbers play an important role in determining the exit pupil – the amount of light the human eye can accept (5-7mm depending on age from older to younger). By dividing the objective lens (or aperture) size by the magnifying power you can determine a pair of binoculars exit pupil.

Like a telescope, the larger the aperture, the more light gathering power – increasing proportionately in bulk and weight. Stereoscopic views of the night sky through big binoculars is an incredible, dimensional experience and one quite worthy of a mount and tripod! As you journey through the binocular department, go armed with the knowledge of how to choose your binoculars lens size.

Why does the binocular lens size matter? Because binoculars truly are a twin set of refracting telescopes, the size of the objective (or primary) lens is referred to as the aperture. Just as with a telescope, the aperture is the light gathering source and this plays a key role in the applications binoculars are suited for. Theoretically, more aperture means brighter and better resolved images – yet the size and bulk increases proportionately. To be happiest with your choice, you must ask yourself what you’ll be viewing most often with your new binoculars. Let’s take a look at some general uses for astronomy binoculars by their aperture.

Different Sizes of Binoculars
Binoculars with a lens size of less that 30mm, such as 5X25 or 5X30, are small and very portable. The compact models can fit easily into a pocket or backpack and are very convenient for a quick look at well-lit situations. In this size range, low magnifications are necessary to keep the image bright.

Compact models are also great binoculars for very small children. If you’re interested in choosing binoculars for a child, any of these models are very acceptable – just keep in mind a few considerations. Children are naturally curious, so limiting them to only small binoculars may take away some of the joy of learning. After all, imagine the thrill of watching a raccoon in its natural habitat at sundown… Or following a comet! Choose binoculars for a child by the size they can handle, whether the model will fold correctly to fit their interpupilary size, and durability. Older children are quite capable of using adult-sized models and are naturals with tripod and monopod arrangements. For less than the price of most toys, you can put a set of quality optics into their hands and open the door to learning. Children as young as 3 or 4 years old can handle 5X30 models easily and enjoy wildlife and stargazing both!

Binocular aperture of up to 40mm is a great mid-range size that can be used by almost everyone for multiple applications. In this range, higher magnification becomes a little more practical. For those who enjoy stargazing, this is an entry level aperture that is very acceptable to study the Moon and brighter deep sky objects and they make wonderful binoculars for older children.

Binoculars up to 50-60mm in lens size are also considered mid-range, but far heavier. Again, increasing the objective lens size means brighter images in low light situations – but these models are a bit more bulky. They are very well suited to astronomy, but the larger models may require a support (tripod, monopod, car window mount) for extended viewing. Capable of much higher magnification, these larger binocular models will seriously help to pick up distant, dimmer subjects such as views of distant nebulae, galaxies and star clusters. The 50mm size is fantastic for older children who are ready for more expensive optics, but there are drawbacks.

The 50-60mm binoculars are pushing the maximum amount of weight that can be held comfortably by the user without assistance, but don’t rule them out. Available in a wide range of magnifications, these models are for serious study and will give crisp, bright images. Delicate star clusters, bright galaxies, the Moon and planets are easily distinguishable in this aperture size. These models make for great “leave in the car” telescopes so you always have optics at hand. For teens who are interested in astronomy, binoculars make an incredible “First Telescope”. Considering a model in this size will allow for most types of astronomical viewing and with care will last through a lifetime of use.

Binoculars any larger than 50-60mm are some serious aperture. These are the perfect size allowing for bright images at high magnification. For astronomy applications, binoculars with equations like 15X70 or 20X80 are definitely going to open a whole new vista to your observing nights. The wide field of view allows for a panoramic look at the heavens, including extended comet tails, large open clusters such as Collinder Objects, starry fields around galaxies, nebulae and more… If you have never experienced binocular astronomy, you’ll be thrilled at how easy objects are to locate and the speed and comfort at which you can observe. A whole new experience is waiting for you!

Binocular Magnification
When choosing binoculars for astronomy, just keep in mind that all binoculars are expressed in two equations – the magnifying power X the objective lens size. So far we have only looked at the objective lens size. Like a telescope, the larger the aperture, the more light gathering power – increasing proportionately in bulk and weight. Stereoscopic views of the night sky through big binoculars is an incredible, dimensional experience, but for astronomical applications we need these two numbers to play an important role in determining the exit pupil – the amount of light the human eye can accept. By dividing the objective lens (or aperture) size by the magnifying power you can determine a pair of binoculars exit pupil. Let’s take a look at why that’s important.

How do binoculars magnify? What’s the best magnification to use? What magnifying power do I choose for astronomy? Where do I learn about what magnifying power is best in binoculars? Because binoculars are a set of twin refracting telescopes meant to be used by both eyes simultaneously, we need to understand how our eyes function. All human eyes are unique, so we need to take a few things into consideration when looking at the astronomy binocular magnification equation.

By dividing the objective lens (or aperture) size by the magnifying power you can determine a pair of binoculars exit pupil and match it to your eyes. During the daylight, the human eye has about 2mm of exit pupil – which makes high magnification practical. In low light or stargazing, the exit pupil needs to be more around 5 to be usable.

While it would be tempting to use as much magnification as possible, all binoculars (and the human eye) have practical limits. You must consider eye relief – the amount of distance your eye must be away from the secondary lens to achieve focus. Many high “powered” binoculars do not have enough outward travel for eye glass wearers to come to focus without your glasses. Anything less than 9mm eye relief will make for some very uncomfortable viewing. If you wear eyeglasses to correct astigmatism, you may wish to leave your glasses on while using binoculars, so look for models which carry about 15mm eye relief.

Now, let’s talk about what you see! If you look through binoculars of two widely different magnifying powers at the same object, you’ll see you have the choice of a small, bright, crisp image or a big, blurry, dimmer image – but why? Binoculars can only gather a fixed amount of light determined by their aperture (lens size). When using high magnification, you’re only spreading the same light over a larger area and even the best binoculars can only deliver a certain amount of detail. Being able to steady the view also plays a critical role. At maximum magnification, any movement will be exaggerated in the viewing field. For example, seeing craters on the Moon is a tremendous experience – if only you could hold the view still long enough to identify which one it is! Magnification also decreases the amount of light that reaches the eye. For these reasons, we must consider the next step – choosing the binocular magnification – carefully.

Binoculars with 7X magnifying power or less, such as 7X35, not only delivers long eye relief, but also allows for variable eye relief that is customizable to the user’s own eyes and eyeglasses. Better models have a central focus mechanism with a right eye diopter control to correct for normal right/left eye vision imbalance. This magnification range is great for most astronomy applications. Low power means less “shake” is noticed. Binoculars with 8X or 9X magnification also offer long eye relief, and allows comfort for eyeglass wearers as well as those with uncorrected vision. With just a bit more magnification, they compliment astronomy. Binoculars 10 x 50 magnifying power are a category of their own. They are at the edge of multipurpose eye relief and magnifying power at this level is excellent across all subject matter. However, larger aperture is recommended for locating faint astronomy subjects.

Binoculars with 12-15X magnifying power offer almost telescopic views. In astronomy applications, aperture with high magnification is a must to deliver bright images. Some models are extremely well suited to binocular astronomy with a generous exit pupil and aperture combined. Binoculars with 16X magnification and higher are on the outside edge of high magnification at hand-held capabilities. They are truly designed exclusively as mounted astronomical binoculars. Most have excellent eye relief, but when combined with aperture size, a tripod or monopod is suggested for steady viewing. If you’re interested in varying the power, you might want to consider zoom binoculars. These allow for a variety of applications that aren’t dependent solely on a single feature. Models can range anywhere from as low as 5X magnification up to 30X, but always bear in mind the higher the magnification – the dimmer the image. Large aperture would make for great astronomy applications when a quick, more magnified view is desired without being chained to a tripod.

Other Binocular Features
The next thing to do is take a good look at the binoculars you are about to purchase. Check out the lenses in the light. Do you see blue, green, or red? Almost binoculars have anti-reflection coatings on their air to glass surfaces, but not all are created equal. Coatings on binocular lenses were meant to assist light transmission of the object you’re focusing on and cancelling ambient light. Simply “coated” in the description means they probably only have this special assistance on the first and last lens elements – the ones you’re looking at. The same can also be said of the term “multi-coated”, it’s probably just the exterior lens surface, but at least there’s more than one layer! “Fully coated” means all the air-to-glass surfaces are coated, which is better… and “fully multi-coated” is best. Keeping stray light from bouncing around and spoiling the light you want to see is very important, but beware ruby coated lenses… These were meant for bright daylight applications and will rob astronomical binoculars of the light they seek.

Last, but not least, is a scary word – collimation. Don’t be afraid of it. It only means the the optics and the mechanics are properly aligned. Most cheap binoculars suffer from poor collimation, but that doesn’t mean you can’t find an inexpensive pair of binoculars that are well collimated. How can you tell? Take a look through them with both eyes. If you can’t focus at long distance, short distance and a distance in-between, there is something wrong. If you can’t close either eye and come to focus with the other, there’s something wrong. Using poorly collimated binoculars for any length of time causes eye strain you won’t soon forget.

Price range for Astronomy Binoculars
So, how much? What does a good pair of binoculars for astronomy cost? First look for a quality manufacturer. Just because you’ve chosen a good name doesn’t mean you’re draining your pocket. Smaller astronomy binoculars of high quality are usually around or under $25. Mid-sized astronomy binoculars range from $50 to $75 as a rule. Large astronomy binoculars can run from a little over $100 to several hundred dollars. Of course, choosing a high-end pair of binoculars of any size will cost more, but with proper care they can be handed down through generations of users. Keep in mind little things that might be good for your applications, like rubber-coated binoculars for children who bang them around more, or fog-proof lenses if you live in a high humidity area. Cases, lens caps and neck straps are important, too.

Some Suggested Binoculars
The purpose of this guide was to help you understand how to choose the best binoculars for astronomy. But if you trust me, and just want some suggestions… here you go.

For all purpose astronomy binoculars, I’d recommend the Celestron Up-Close and Ultima Series as well as Meade Travel View. Nikkon and Bushnell binoculars in this size range are an investment, and best undertaken after you decide if binocular astronomy and this size is right for you. Amazon.com offers a wide range of these binoculars.

While so much information on binoculars may seem a little confusing at first, just a little study will take you on your way to discovering astronomy binoculars that are perfect for you!

Posted on by Tammy Plotner

Universe Today Exclusive – Cygnus Nova V2491 Revealed for Readers

Clouds got you down? No chance of seeing V2491 Cyg because of the weather? Are you sleeping when Cygnus is up? One of the most beautiful facets of having an astronomer around is being able to share information with other observatories around the world and put them to work. This time the job was handed to our friends in Australia who were able to produce for us an exclusive look at an elusive nova.

In trial test on image acquisition utilizing the combined resources of Macedon Ranges Observatory and its resident astronomers, they were able to nab the nova in less than 30 minutes from notice being given. The image was then processed, labeled and returned again halfway around the world within hours for UT readers to enjoy.

On 15 April 2008 from 10.50 to 11.40 UT, Joseph Brimacombe from Cairns, Queensland, Australia was busy employing remote technology located at 32 degrees 54 minutes North; 15 degrees 32 min West and recording the nova with an SBIG ST-L-1001 CCD camera. Coupled with a 20″ Ritchey-Chretien Optical System, 8 separate exposures of 5 minutes duration were taken in white light, and the results speak for themselves.

By comparing the zoom map of the area presented in the original Cygnus Nova Alert it’s easy to see the identifying line of three stars which helps orient the viewer to the general area. As predicted, Cygnus Nova V2491 easily stands out amongst the background stars.

Says Observatory Director, Burt Candusio: “The exercise was primarily designed to test the imaging and response capabilities of M.R.O resident astronomers. If another similar event presents itself, we would now be confident in our capabilities of imaging a target effectively and quickly from any part of the globe. A most pleasing outcome for all concerned and especially for Joseph Brimacombe.”

But the thrill was nothing compared to Joe’s own success: “Trapped under the mostly cloudy Cairns skies, I was remotely imaging the running chicken nebula (NGC 2944) at the Macedon Range Observatory and the Pinwheel galaxy (M101) at New Mexico Skies, when my good mate Bert Candusio notified me of a new nova (V2491) in Cygnus. At the time, it was 60 degrees below the horizon at the MRO, but 50 degrees above the horizon at NMS, so I slewed my 20 inch RCOS at NMS to the co-ordinates Bert had provided. There was just sufficient time before dawn to snap 8 x 5 min luminance frames of a dense star field. Both Bert and I were delighted to find the nova near the middle of the frame. We estimate the magnitude at around 10. The beauty of NGC 2944 and M101 was not a match for the excitement of imaging an acute stellar explosion for the first time!”

In the case of V2491 Cyg, the only thing better than having the stars up above is having friends down under. Our thanks go to our friends at Macedon Ranges Observatory!

Posted on by Nancy Atkinson

New Technique Can Estimate Size and Frequency of Meteorite Impacts

News today from the National Science Foundation will have an impact on how scientists are able to study…. well, impacts. A team of geologists has developed a new way of determining the size and frequency of meteorites that have collided with Earth in the past. By studying sediments found on the ocean floor and looking for isotopes of the rare element osmium, scientists can now figure out not only when a meteorite impact occurred in Earth’s history, but also the size of the meteorite. One of the most exciting benefits of this new technique is the potential for identifying previously unknown impacts.

When meteorites collide with Earth, they carry a different osmium isotope ratio than the levels normally seen throughout the oceans.

“The vaporization of meteorites carries a pulse of this rare element into the area where they landed,” says Rodey Batiza of the National Science Foundation, which funded the research. “The osmium mixes throughout the ocean quickly. Records of these impact-induced changes in ocean chemistry are then preserved in deep-sea sediments.”

François Paquay, a geologist at the University of Hawaii at Manoa analyzed samples from two sites where core samples of the ocean floor were taken, one near the equatorial Pacific and another located off of the tip of South Africa. He measured osmium isotope levels during the late Eocene period, a time during which large meteorite impacts are known to have occurred.

“The record in marine sediments allowed us to discover how osmium changes in the ocean during and after an impact,” says Paquay.

The scientists believe this new approach to estimating impact size will become an important complement to a more well-known method based on iridium.

Paquay’s team also used this method to make estimates of impact size at the Cretaceous-Tertiary (K-T) boundary 65 million years ago. Since the osmium carried by meteorites is dissolved in seawater, the geologists were able to use their method to estimate the size of the K-T meteorite as four to six kilometers in diameter. The meteorite was the trigger, scientists believe, for the mass extinction of dinosaurs and other life forms.

But Paquay doesn’t believe this method will work for events larger than the K-T impact. With such a large meteorite impact, the meteorite contribution of osmium to the oceans would overwhelm existing levels of the element, making it impossible to sort out the osmium’s origin.
But it will be interesting to follow this to see if new, unknown impacts in Earth’s history can be discovered.

Original News Source: Eureka Alert

Posted on by Nancy Atkinson

More Space News From Russia

When it rains space news from Russia, it pours. Not only did the news break today about the Russian Space Agency’s plans to send monkeys to Mars, but also, Russia wants to build an Earth-orbiting factory to build large, interplanetary ships that might be too large to launch from Earth. Additionally, Roscosmos, the Russian space agency said that beginning in 2010, they will likely terminate ferrying space tourists to the International Space Station.

According to the head of Roscosmos Anatoly Perminov, the space agency proposed building a manned assembly complex in Earth orbit and the Russian Security Council supported the idea in an April 11, 2008 meeting. No word on exactly when an orbiting spaceship assembly line would be constructed, but Perminov said it likely wouldn’t be built until after the ISS is completed, which they said would be about 2020. Also, no word if the interplanetary ships will be built for humans or monkeys.

As far as curtailing the program that brings space tourists to the ISS, the Perminov said the increase in crew size on the ISS from the current three members to six in 2009, and then the proposed retirement of the space shuttle in 2010, will put “growing pressure” on the Russian Soyuz spacecraft that carries crews and supplies to the space station. Perminov said they will no longer accept proposals from space tourists, adding that space tourism shouldn’t interfere with scientific research. Roscosmos teamed up with the company Space Adventures beginning in 2001 to bring tourists to the ISS, which seemed to be a fairly lucrative program for the cash-strapped Russian space agency. Existing contracts to bring tourists to the station will be fulfilled, Perminov said.

Dennis Tito became the first space tourist in 2001 when he paid $20 million to ride the Soyuz for a week-long stay on the ISS. The next (and sixth) tourist will be game developer Richard Garriott, scheduled for a Soyuz flight in October 2008.

Original News Source: Lenta Ru (translated)

Posted on by Tammy Plotner

Universe Today Astronomy Picture of the Week: NGC 3199 – The Interstellar Snow Plough

NGC 3199 - Credit: Ken Crawford

One thing is certain, Wolf-Rayet stars produce some interesting
science. In this week’s portrait we see a distorted bubble produced
by a moving star blowing a strong stellar wind into a surrounding
uniform interstellar medium – yet is isn’t uniform. What exactly is
going on here?

Hanging out some 11,736 light years away in the southern constellation
of Carina (RA 10:17:24.0 Dec -57:55:18), NGC 3199 is classed as a
diffuse nebula or supernova remnant. Discovered by John Herschel in
1834, it has been known throughout historic astronomy observations as
bright, large, crescent-shaped nebula with embedded stars, but modern
astronomy shows it as much more. It’s being pushed along by
Wolf-Rayet star 18.

Says Dr. Michael Corcoran: “Wolf-Rayet stars (named for their
discoverers) are very large, massive stars (stars which are about 20
times bigger than the sun) nearly at the end of their stellar lives.
As these stars age, material which the stars have cooked up in their
central nuclear furnaces (like carbon and oxygen) gradually reach the
surface of the star. When enough material reaches the surface, it
absorbs so much of the intense light from the star that an enormously
strong wind starts to blow from the star’s surface. This wind becomes
so thick that it totally obscures the star – so when we look at a
Wolf-Rayet star, we’re really just seeing this thick wind. The amount
of material which the wind carries away is very large – typically, a
mass equivalent to that of the entire earth is lost from the star each
year. The mass loss is so large that it significantly shortens the
star’s life, and as you can imagine has important effects on the space
surrounding the star too. We think that very massive stars become
Wolf-Rayet stars just before they explode as supernova (though no one
has yet seen such a star explode).

At magnitude 11, NGC 3199 is observable with larger amateur
telescopes, but the crescent shape is cause for study by some of the
finest research telescopes and astronomers in the world. Through
optical observations, the ring nebula and cavities around WF stars have
painted a history of mass loss in these highly evolved stellar
curiosities. By studying molecular gases associated with Wolf-Rayet
stars, it appears that some materials seem to be avoiding optical
emission.

In reading scientific reports submitted by A. P. Marston, molecular
gas has already been observed around Wolf-Rayet Star 18 – the first to
confirm the presence of HCN, HCO+, CN, and HNC and molecules. This
makes the Wolf-Rayet ring nebula NGC 3199 very unique and filled
associated molecular gas that took the form clumpy ejecta and
interstellar material. At one time, NGC 3199’s formation was believed
to be caused by bow shock, but current data now shows the associated
Wolf Rayet star is moving at a right angle to its enveloping
environment. Could this be an indication that something else is at
work here? Astronomers seem to think so.

According to their information, it is possible the northern area of
the optically bright nebula is being torn apart by a possible blowout
of Wolf Rayet wind. This, in turn, affects the surrounding ejecta and
could very well account for the observed velocity. By modeling
molecular abundances, the central Wolf Rayet star could be contributing a
portion of its material to this nebula as ejecta. Despite its still
unsolved mysteries, NGC 3199 is a stunning portrait. J.E. Dyson and
Ghanbari summed it up best when they described it as an “interstellar
snow plough”.

This week’s awesome astronomy picture is the work of Ken Crawford, taken at Macedon Ranges Observatory.

Says Ken: “This image was taken using an Apogee CCD Camera that uses primarily Narrow Band data which is color mapped mixed with RGB for natural star colors and back ground balancing. The bright blue area shows lots of OIII (ionized oxygen) signal which really shows the direction of the star movement well. The star is said to be moving at about 60 km/s through the interstellar gas.”

Posted on by Tammy Plotner

Cygnus Nova Alert!!

Supernova (Artist Rendering: Courtesy of NASA)

According to today’s April 11 IAU Circular 8934, issued by the Central Bureau for Astronomical Telegrams at the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts a 7th-magnitude nova was discovered on April 10, 2008, by Koichi Nishiyama and Fujio Kabashima in Japan. It’s time to observe!

NASA

The event is located in Cygnus, about one-third of the way from Albireo (β Cygni) to Sadr (γ Cygni) – RA 19 43 0 Dec +32 19. From early reports, it may still be continuing to brighten. Ernesto Guido and Giovanni Sostero of Remanzacco, Italy confirmed the discovery before the IAU announcement was made and estimated the nova’s magnitude at 7.5 at approximate 09:00:00 UT, 11 April 2008.

This image above is a map of Cygnus where the dimmest star shown is magnitude 7.5. The target area is circled. Binoculars and small telescopes are very capable of seeing this event! The zoomed map you see here is slightly larger than a binocular field of view and features the target area. The magnitudes are also set to 7.5. Should the event brighten, any stars you see that are in the target area brighter than what is shown will be the nova event.

If any updates or corrections occur, I will post them immediately. Clear skies and good luck!

Posted on by Nancy Atkinson

Phoenix Spacecraft Maneuvers for Mars Landing

Looking towards a May 25 landing for the Phoenix Mars Lander, the navigation team for mission adjusted the flight path for the spacecraft on April 10. “This is our first trajectory maneuver targeting a specific location in the northern polar region of Mars,” said Brian Portock, chief of the Phoenix navigation team at the Jet Propulsion Laboratory. The mission’s two prior trajectory maneuvers, made last August and October, put the spacecraft on target to just intersect with Mars. But this recent maneuver put it on course to land at a site called “Green Valley,” a broad, flat valley in Mars north polar region. NASA announced they have “conditionally” approved this site, but a final decision has yet to be made. And why, you ask, hasn’t a final decision been made on a landing site at this late date?

Phoenix mission managers are still looking for a safe, yet exciting place to land. The proposed landing area is an ellipse about 62 miles by about 12 miles (100 kilometers by 20 kilometers). In looking at high resolution images of this area, researchers have mapped more than five million rocks in and around that ellipse, each big enough to end the mission if hit by the spacecraft during landing. “The environmental risks at landing — rocks and slopes — represent the most significant threat to a successful mission. There’s always a chance that we’ll roll snake eyes, but we have identified an area that is very flat and relatively free of large boulders,” said JPL’s David Spencer, Phoenix deputy project manager and co-chair of the landing site working group.

MRO’s High Resolution Imaging Science Experiment (HiRISE) camera has taken more than three dozen images of the area. Analysis of those images prompted the Phoenix team to shift the center of the landing target 13 kilometers (8 miles) southeastward, away from slightly rockier patches to the northwest. Navigators used that new center for planning the recent trajectory correction maneuver.

“Our landing area has the largest concentration of ice on Mars outside of the polar caps. If you want to search for a habitable zone in the arctic permafrost, then this is the place to go,” said Peter Smith, principal investigator for the mission, at the University of Arizona , Tucson .

When Phoenix lands, it will dig to an ice-rich layer expected to lie within arm’s reach of the surface. It will analyze the water and soil for evidence about climate cycles and investigate whether the environment there has been favorable for microbial life.

The April 10 trajectory adjustment began by pivoting Phoenix 145 degrees to orient and then fire spacecraft thrusters for about 35 seconds, then pivoting Phoenix back to point its main antenna toward Earth. The mission has three more planned opportunities for maneuvers before May 25 to further refine the trajectory for a safe landing at the desired location.

In the final seven minutes of its flight on May 25, Phoenix must perform a challenging series of actions to safely decelerate from nearly 21,000 kilometers per hour (13,000 mph). The spacecraft will release a parachute and then use pulse thrusters at approximately 914 meters (3,000 feet) from the surface to slow to about 8 kilometers per hour (5 mph) and land on three legs.

For more information about Phoenix , visit NASA’s site, and ASU’s site

Posted on by Nancy Atkinson

Evidence of Asteroid Impact For Sodom and Gomorrah?

Cuneiform clay tablet. Image Credit: Bristol University

A Cuneiform clay tablet that has puzzled researchers for over 150 years is now believed to describe an asteroid impact in 3123 BC in Austria. Researchers believe the tablet, which seemingly describes a cataclysmic event, may account for the biblical tale of Sodom and Gomorrah. No mention of pillars of salt however, on the clay tablet.

Geologists discovered evidence of a giant landslide centered at Köfels, Austria back in the 19th century. At 500 meters thick and five kilometers in diameter, this landslide mystified researchers trying to figure out why such an event occurred. Some researchers thought the landslide may have been caused by a meteorite impact, because of the evidence of crushing pressures and explosions. But there was no crater, so it didn’t look as an impact site should, and the impact theory fell out of favor. But researchers knew this wasn’t just an ordinary landslide.

But new research brings the impact theory back into play. It centers on another 19th century mystery, a Cuneiform tablet in the British Museum, known as “the Planisphere”. It was found in the remains of the library in the Royal Place at Nineveh, and was made by an Assyrian scribe around 700 BC. It is an astronomical work with drawings of constellations and the text has known constellation names. The clay tablet has attracted a lot of attention but until now no one has come up with a convincing explanation as to what it is.

Alan Bond and Mark Hempsell from Bristol University used computer programs to simulate trajectories and reconstruct the night sky thousands of years ago to establish what the Planisphere tablet refers to. It is a copy of the night notebook of a Sumerian astronomer as he records the events in the sky before dawn on the 29 June 3123 BC (Julian calendar). Half the tablet records planet positions and cloud cover, but the other half of the tablet records an object large enough for its shape to be noted even though it is still in space. The astronomer made an accurate note of its trajectory relative to the stars, which to an error better than one degree is consistent with an impact at Köfels.

The observation suggests the asteroid is over a kilometer in diameter and the original orbit about the Sun was an Aten type, a class of asteroid that orbits close to the earth, that is resonant with the Earth’s orbit. This trajectory explains why there is no crater at Köfels. The incoming angle was very low (six degrees) and means the asteroid clipped a mountain near the town of Längenfeld, 11 kilometers from Köfels, and this caused the asteroid to explode before it reached its final impact point. As it travelled down the valley it became a fireball, about five kilometers in diameter (the size of the landslide). When it hit Köfels it created enormous pressures that pulverized the rock and caused the landslide but because it was no longer a solid object it did not create a classic impact crater.

Mark Hempsell, hinting at the possible fate of Sodom and Gomorrah, added, “Another conclusion can be made from the trajectory. The back plume from the explosion (the mushroom cloud) would be bent over the Mediterranean Sea re-entering the atmosphere over the Levant, Sinai, and Northern Egypt. The ground heating though very short would be enough to ignite any flammable material – including human hair and clothes. It is probable more people died under the plume than in the Alps due to the impact blast.”

This evidence seems to coincide with the biblical story of the legendary dens of vice (“Then the Lord rained down burning sulfur on Sodom and Gomorrah – from the Lord out of the heavens” – Genesis 19:24) but it’s never been categorically proven that the towns actually existed in their suspected location close to the Dead Sea. And the story of Lot’s wife turning into a pillar of salt for turning around to witness the mayhem is just biblical legend as well.

The full translation of the tablet together with the analysis supporting these conclusions can be found in the book, “A Sumerian Observation of the Kofels’ Impact Event” by Bond and Hempsell.

Original News Sources: Bristol University and The Register