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Stars with planet forming disks.
If you're a newly forming star system, there's no better place to be than a stellar nursery. All those raw elements make the perfect building blocks of stars and planets. The problem is that super hot giant stars can release great torrents of radiation, blasting away newly forming planets.
In a new study gathered using NASA's Spitzer Space Telescope, Astronomers have started to map out these danger zones around the super hot stars. If you're a cooler star with newly forming planets, you need to be at least 1.6 light-years away. Since the stars are moving around in a stellar nebula, a newly forming system needs to keep this distance at all times. If it strays into one of these danger zones, its new planets will literally be boiled away into interstellar space.
These massive stars are known as type O-stars. They live fast and die young, reaching a mass dozens of time greater than our Sun, and only lasting for a few million years at the most. But during that short life, they can cause quite a lot damage. Astronomers used Spitzer to measure the number of stars with planet forming disks. As the stars got closer to the O-stars, the percentage that had disks dropped dramatically.
Astronomers think that our Sun started out in a similarly dangerous environment, but was able to successfully navigate through the minefield of O-stars until it could reach its current, more spacious home.
Matter Should Dominate the Universe Forever
Thanks to Einstein, we know that matter and energy are just different versions of one another. E=mc2 tells you how much energy you'd get if you converted mass into energy. Don't try, it's hard. Physicists were concerned that all matter in the universe would eventually decay into radiation after trillions and trillions of years of time.
But the impact of dark energy, a mysterious force accelerating the expansion of the universe, might change those predictions for the fate of matter. Physicists Lawrence Krauss and Robert Scherrer recently published a paper in the journal Physical Review D that predicts that the ratio between matter and radiation should remain roughly the same as Dark energy continues to spread the universe apart.
Right now we can see most of the universe, but as it continues to expand, distant objects will appear to be moving away from us faster than the speed of light, and will disappear from view. In 10 trillion years from now, only our local cluster of galaxies will be visible. Krauss and Scherrer have calculated that new radiation created from decaying matter will be diluted as soon as it's created, thanks to dark energy.
As particles decay into radiation, the Dark energy will increase the separation between photons, decreasing their energy and density in the universe. The clumps of matter that remain will still dominate.
Original Source: http://www.vanderbilt.edu/news/releases/2007/4/25/cosmologically-speaking-diamonds-may-actually-be-forever
Earth-Sized Planet Discovered in the Habitable Zone
Great big Jupiter-like planets are one thing, but the Holy Grail of extrasolar planetary discover is going to be another Earth - complete with life. We're not there yet, but Astronomers announced the next best thing yesterday: a roughly Earth-mass planet orbiting within the habitable zone of its parent star. In other words, liquid water could exist on this rocky planet.
The host star is called Gliese 581, and it's one of the 100 closest star to us, located only 20.5 light years away in the constellation Libra. Unlike our Sun, it's a Red Dwarf star, emitting much less light and energy. This brings its habitable zone in close and tight to the star. For a planet to be orbiting its parent star within this habitable zone, it's got to have a really tight orbit.
And this is how the planet was discovered. It was made by measuring the star's radial velocity, where the planet's gravity tugs its parent star back and forth (aka, the Wobble Method). Astronomers can measure this velocity with tremendous precision to determine the planet's mass and orbital period. And the tool for the job is the European Southern Observatory's HARPS (High Accuracy Radial Velocity for Planetary Searcher) spectrograph connected to the 3.6-m telescope at La Silla, Chile.
The planet is 'Earth-like', but it wouldn't seem much like home. It's 50% larger than the Earth, and has about 5 times our planet's mass. It also completes an orbit every 13 days - it's 14 times closer to its star than the Earth is to the Sun. Since it's in the habitable zone, there would very likely be liquid water on its surface.
Unfortunately, the radial method only tells Astronomers what the planet's mass and orbital distance are. They're not directly observing it. So there's no way to know if there is actually water on the surface, or even oxygen in the atmosphere that would indicate the presence of life. But future missions, like Darwin, will certainly put it in the cross hairs to get a better look for life.
The discovering team think that turning up an Earth-sized planet around a Red Dwarf star is now just a matter of time.
Original Source: http://www.eso.org/outreach/press-rel/pr-2007/pr-22-07.html
What's Up this Week: April 23 - April 29, 2007
Monday, April 23 - Pioneer quantum physicist Max Planck was born on this day in 1858. In 1900, Max developed the Planck equation to explain the shape of blackbody spectra (a function of temperature and wavelength of emission). A 'blackbody' is any object that absorbs all incident radiation - regardless of wavelength. For example, heated metal has blackbody properties because the energy it radiates is thermal. The blackbody spectrum's shape remains constant, and the peak and height of an emitter can be measured against it - be it cosmic background radiation or our own bodies.
Now, let's put this knowledge into action. stars themselves approximate blackbody radiators, because their temperature directly controls the color we see. A prime example of a 'hot' star is Alpha Virginis, better known as Spica. Compare its color to the cooler Arcturus... What colors do you see? There are other astronomical delights that radiate like blackbodies over some or all parts of the spectrum as well. You can observe a prime example in a nebula such as M42, in Orion. By examining the radio portion of the spectrum, we find the temperature properly matches that of electrons involved in the process of fluorescence. Much like a common household fixture, this process is what produces the visible light we can see.
Tonight's outstanding lunar feature will be crater Maurolycus just southwest of the three rings of Theophilus, Cyrillus and Catharina. This lunar club challenge spans 114 kilometers and goes below the lunar surface by 4730 meters. Be sure to look for Gemma Frisius just to its north.
Tuesday, April 24 - Today in 1970, China launched its first satellite. Named Shi Jian 1, it was a successful technological and research craft. This achievement made China the fifth country to send a vessel into space.
Before we explore space, let's have a look at the Moon tonight as challenge craters Cassini and Cassini A now come into view just south of the black slash of the Alpine Valley. The major crater spans 57 kilometers and reaches a floor depth of 1240 meters. The challenge is to also spot the central crater A, which is only 17 kilometers wide, yet drops down another 2830 meters below the surface.
Now let's have a look at 140 light-year distant Epsilon Hydrae - the northernmost star in the small circlet east of Procyon. While it and Rho will make a beautiful visual double for binoculars, Epsilon itself is a multiple system. Its A and B components are a tough split for any scope, but the 8th magnitude C star is easier. The D component is a dwarf star.
Wednesday, April 25 - Today marks the 15th anniversary of the deployment of Hubble Space Telescope. While everyone in the astronomical community is well aware of what this magnificent telescope 'sees,' did you know that you can see it with just your eyes? The HST is a satellite that can be tracked and observed. Visit heavens-above.com and enter your location. This page will provide you with a list of visible passes for your area. Although you can't see details of the scope itself, it's great fun to track with binoculars or see the Sun glinting off its surface in a scope.
Keep a watch on the skies tonight as the Mu Virginid meteor shower reaches its peak at 7 to 10 per hour. With dark skies tonight, you still might catch one of these medium speed meteors radiating from a point near the constellation of Libra.
Tonight look for Saturn one degree south of the Moon. This could be an occultation, so check IOTA information! As we look at the lunar surface, the terminator is silently moving west revealing old craters in a new light. Let's have a look:
(1) Sinus Asperitatis, (2) Theophilus, (3) Cyrillus, (4) Catharina, (5) Rupes Altai, (6) Piccolomini, (7) Sacrobosco, (8) Abulfeda, (9) Almanon, (10) Taylor, (11) Abenezra, (12) Apianus, (13) Playfair, (14) Aliacensis, (15) Werner, (16) Blanchinus, (17) Lacaille, (18) Walter, (19) Regiomontanus, (20) Purbach, (21) Thebit, (22) Arzachel, (23) Alphonsus, (24) Ptolemaeus, (25) Albategnius.
Thursday, April 26 - On this date in 1920, the Shapely-Curtis debate raged in Washington on the nature of and distance to spiral nebulae. Shapely claimed they were part of one huge Galaxy to which we all belonged, while Curtis maintained they were distant galaxies of their own. Thirteen years later on the same date, Arno Penzias was born. He went on to become a Nobel Prize winner for his part in the Discovery of the cosmic microwave background radiation, through searching for the source of the 'noise' coming from a simple horn antenna. His Discovery helped further our understanding of cosmology in ways that Shapely and Curtis could have never dreamed of.
Tonight Regulus is less than a degree away from the waxing gibbous Moon. Check IOTA! On the lunar surface, we can enjoy a strange, thin feature. If you used last night's map, you're well acquainted with this area! Look toward the lunar south where you will note the prominent rings of craters Ptolemaeus, Alphonsus, Arzachel, Purbach, and Walter descending from north to south. Just west of them, you'll see the emerging Mare Nubium. Between Purbach and Walter you will see the small, bright ring of Thebit with a crater caught on its edge. Look further west and you will see a long, thin, dark feature cutting across the mare. Its name? Rupes Recta - better known as The Straight Wall, or sometimes Rima Birt. It is one of the steepest known lunar slopes rising around 366 meters from the surface at a 41 degree angle.
Be sure to mark your lunar challenge notes and we'll visit this feature again!
Friday, April 27 - Tonight we'll use what we learned last month to locate another unusual feature - Montes Recti or the 'Straight Range.' You'll find this curiosity tucked between Plato and Sinus Iridum on the north shore of Mare Imbrium.
To binoculars or small scopes at low power, this isolated strip of mountains will appear as a white line drawn across the grey mare. It is believed this feature may be all that is left of a crater wall from the Imbrium impact. It runs for a distance of around 90 kilometers, and is approximately 15 kilometers wide. The Straight Range and some of its peaks reach up to 2072 meters! Although this doesn't sound particularly impressive, that's over twice as tall as the Vosges Mountains in central western Europe, and on the average very comparable to the Appalachian Mountains in the eastern United States.
Now have a look at 27 Hydrae about a fingerwidth southwest of Alpha. It's an easy double for any equipment with its slightly yellow 5th magnitude primary and distant, white, 7th magnitude secondary. Although it is wide, the pair is a true binary system.
Saturday, April 28 - Today was a very busy day in astronomy history. Newton published his Principia in 1686 on April 28. In 1774, Francis Baily was born. He went on to revise star catalogs and explain the phenomenon at the beginning and ending of a total solar eclipse which we know as 'Baily's Beads.' 1900 saw the birth of Jan Hendrick Oort, who quantified the Milky Way's rotation characteristics and envisioned the vast, spherical area of comets outside our solar system that we now call the Oort Cloud. Last, but not least, was the birth of Bart Jan Bok in 1906 who studied the structure and dynamics of the Milky Way.
Tonight you are on your own without a map. Lunar features are easy when you become acquainted with them! Return to the Moon and explore with binoculars or telescopes the area to the south around another easy and delightful lunar feature, the crater Gassendi. At around 110 kilometers in diameter and 2010 meters deep, this ancient crater contains a triple mountain peak in its center. As one of the most 'perfect circles' on the Moon, the south wall of Gassendi has been eroded by lava flows over a 48 kilometer expanse and offers a great amount of detail to telescopic observers on its ridge- and rille-covered floor.
For those observing with binoculars? Gassendi's bright ring stands on the north shore of Mare Humorum...an area about the size of the state of Arkansas!
For SkyWatchers, no equipment is necessary to enjoy the Alpha Bootid meteor shower - despite the Moon. Pull up a comfortable seat and face orange Arcturus as it climbs the sky in the east. These slow meteors have a fall rate of 6 to 10 per hour and leave very fine trails, making an evening of quiet contemplation most enjoyable.
Sunday, April 29 - If you're up before dawn and would like to catch Uranus in binoculars, you'll find it less than a degree north of Mars!
Return to the Moon tonight to have a look on the terminator near the southern cusp for two outstanding features. The easiest is crater Schickard - a class V mountain-walled plain that spans 227 kilometers. Named for German Astronomer Wilhelm Schickard, this beautiful old crater with the subtle interior details has another crater caught on its northern wall named Lehmann.
Look further south for one of the Moon's most incredible features - Wargentin. Among the many strange things on the lunar surface, Wargentin is unique. Once upon a time, it was a very normal crater and had been that way for hundreds of millions of years - then it happened. Either a fissure opened in its interior, or the meteoric impact that formed it caused molten lava to begin to rise. Oddly enough, Wargentin's walls were without large enough breaks to allow the lava to escape and it continued to fill the crater to the rim. Often referred to as 'the Cheese,' enjoy Wargentin tonight for its unusual appearance and be sure to note Nasmyth and Phocylides as well!
While we're out, have a look at R Hydrae about a fingerwidth east of Gamma - which is a little more than fistwidth south of Spica. R is a beautiful, red, long-term variable first observed by Hevelius in 1662. Located about 325 light-years from us, it's approaching - but not that fast. Be sure to look for a visual companion star as well!
Book Review: Brave New Universe
A steady progression of space borne and Earth-based telescopes bring long ago, far away events into our common perspective. We take these images, massage and arrange the hard won data, and, develop new interpretations of our existence and surroundings. Paul Halpern and Paul Wesson in their book Brave New universe – Illuminating the Darkest Secrets of the Cosmos lay bare recent theories and postulations resulting from this. As they show, new information, when added to the mix, can as easily validate as confuse current prognoses.
Knowledge of our Cosmos in Greek times was little more than a concept of crystalline shells rotating about the central Earth orb. For these same Greeks, time was forever and beginnings were maybe 10,00 years previous and no ending was in sight. Today, we have a Big Bang beginning, consider negative times that might have come beforehand, and worry about big crunches or big freezes. As well, in wondering about the spatial dimensions, we've progressed past spheres and now contemplate universes that pop into and out of existence. Further, where people once only imagined three spatial and one temporal axis, we're migrating into other realms, such as the branes with 11 surfaces. These ideas on space and time and the materials within are the elements of cosmology.
Halpern and Wesson's book is cosmological. In it, there's some history of astronomy, backgrounders in physics and a slight tinge of philosophy. But such is the state of cosmology; it's much more than one simple subject. In accordance with this, the authors give the reader an abundance of historical background and current activity within this area of study. In a roughly chronological, historical order, they rebuild our database of knowledge. But, where a database is well ordered and linked, this book has a tendency to meander off to subjects, as the authors' inclination or whim suggests. This is the danger with books on cosmology; the authors try to cover too much ground. Here, as the paragraphs and chapters get ever more detailed, the authors provide lots regarding the skies above but fail to present a cohesive rationale. Thus, their approach to illuminating secrets serves to weaken the idea of cosmology as a field of study rather than fill the reader with an understanding of its riches.
With the authors using this approach, they've erred. They've written a book about cosmology. But given the depth and breadth of their discussion, only other accomplished Cosmologists will benefit from reading it. Yet, expectedly, most other Cosmologists will be well initiated into the subject material. Hence, it's a challenge identifying an appropriate audience for the book. Those who would benefit the most would be advanced undergraduates who have the basic understanding and skill but aren't sure about their next direction of study.
With this consideration, there's reason for the book seeming like a series of lectures or notes bound together. Each selection is well researched, supported with accreditation and written clearly. In an effort to avoid using equations, the authors talk the reader through some very simple algebra. However, this is another indication of confusion, as a few simple equations could have easily shown the intentions of a few paragraphs. In a further attempt to simplify the subject, the authors use many analogies. Some aid, some confuse. In consequence, this book, though current and accurate, is difficult to apply or find focus. Rather, from this book, the reader will get the impression that cosmology is an odd collection of strict math, conceptual physics, free wheeling philosophy and other advanced study areas. It's an effort to read. There is some reward to the reading but it doesn't come easily.
Cosmology is the answer to our questions about time and space. Better equipment and greater effort lifts our knowledge well past the bounds of what our eye can see. Paul Halpern and Paul Wesson in their book Brave New Universe – Illuminating the Darkest Secrets of the Cosmos take the reader to extremes. They show how far out our thinking keeps going in our quest for a greater understanding of our whereabouts.
The Sun, In Thrilling 3-D
NASA's newest solar observatories have released their first images of the Sun, and they're great. Of course, to really enjoy the pictures, you'll need 3-D glasses.
The observatories are the twin Solar Terrestrial Relations Observatory (STEREO) satellites, which were launched on October 25th, 2006. They both orbit the Sun at the same distance as the Earth, but one has moved ahead of us in orbit, while the other has fallen behind. And between the two spacecraft, it's like looking at the Sun with binoculars (a bad idea, don't do it, unless you're a properly shielded spacecraft).
To properly enjoy this image, you're really going to need a pair of 3-D glasses. If you don't have any yet, you can usually get them from a toy store, or inside a children's book with 3-D images. They're the glasses with blue and red eyes. NASA has a link to some sources of glasses you can buy here.
A 3-dimensional view of the Sun is very important, as it allows scientists to get a sense of perspective. As coronal mass ejections are generated on the surface of the Sun, they'll be able to better predict the exact direction the spray of material will go. We'll get much more accurate space weather forecasts for when material is expected to reach the Earth.
Original Source: http://www.nasa.gov/mission_pages/stereo/news/stereo3D_press.html
Expedition 14 Returns to Earth
The two crewmembers of Expedition 14 returned to Earth on Saturday, with astro-tourist Charles Simonyi along for the ride. Commander Mike Lopez-Alegria and Flight Engineer Mikhail Tyurin had been aboard the International Space Station since September 20th, while Simonyi arrived on April 7th. Their Soyuz TMA-9 capsule touched down in the Central Asian steppes of Kazakhstan at 1231 GMT (8:31 am EDT).
The mission saw several records. Mike Lopez-Alegria set a new US record for the longest single spaceflight, reaching 215-days in space during Expedition 14. And billionaire Charles Simonyi was in space for 14 days - the longest flight for a paying tourist.
The landing itself was pushed back a day because heavy rains made the landing site difficult to land at. It was eventually moved to another site, drier and further south.
Original Source: http://www.nasa.gov/mission_pages/station/expeditions/expedition14/exp14_undocking.html
Hubble's Detailed Photograph of the Carina Nebula
It's hard to believe, but the Hubble Space Telescope has been churning out Discovery after Discovery for 17 years now. To celebrate the anniversary, NASA and ESA released a high-resolution image taken by Hubble of the Carina Nebula. And what a photograph!
The Carina Nebula is located 7,500 light-years away in the southern constellation Carina. Inside are many many stars in various stages of birth and death, including more than a dozen which are 50 to 100 times the mass of the Sun. One of the brightest is Eta Carina, in the far-left of the image, which should explode as a supernova within thousands of years. Take a good look, this is similar to an environment that our solar system might have emerged from billions of years ago.
The full image was stitched together from several photographs taken by Hubble, covering a region of space 50 light-years on a side. And it's really really big: 29,566 x 14,321 pixels. Here's a http://hubblesite.org/newscenter/archive/releases/2007/16/image/a/warn/ link to a page with the biggest downloads, including a 200 MB JPEG.
I really can't do it more justice, I'm too distracted starting at the picture to write any more, but Phil Plait (aka the Bad Astronomer) did a http://www.badastronomy.com/bablog/2007/04/24/hubbles-17th-chaos-birth-and-near-death/.
Original Source: http://www.spacetelescope.org/news/html/heic0707.html
Black Holes Could Provide the Seeds of Life
You've heard it all before. black holes pull with a gravity so strong that nothing, not even light, can escape. You would think that black holes are the place where everything goes to die, but it might be possible that black holes are the source of life as well.
Astronomers now suspect that there's a supermassive black hole lurking at the heart of most galaxies in the universe. These black monsters do crush any matter that falls in, but they're surrounded by a Halo of other material waiting to fall in - like water backing up in a drain. This backup releases a tremendous amount of energy. And so, some material can get so hot and energetic that it escapes the clutches of the black hole.
Supermassive black holes are known to produce powerful hot winds that stream across the galaxy, and this gas might be very special. A recent calculation by researchers from the Harvard-Smithsonian Center for Astrophysics calculated that 2-5% of this material is ejected in this way. carbon and oxygen atoms are propelled out at high speeds - as fast as 6.5 million km per hour (4 million miles an hour).
And so, star-forming nebulae comprised of mostly Hydrogen and helium could receive a spray of heavier oxygen and carbon atoms from a supermassive black hole, thousands of light-years away. These atoms make up the basic building blocks of all life here on Earth.
Original Source: http://cfa-www.harvard.edu/press/2007/pr200709.html
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