Blog Entries:
|
Pages: 1 2 3 4 5 ... 84 Next >>
|
Displaying 1 - 10 of 833 matches.
|
The BIG Project commences… 
08/29/2008 15:10 GMT
[-] Not an auspicious start to the biggest project we’ve carried out to date….. I’m currently sitting in Bristol Airport while the aircraft I was destined to fly in was snapped up by another flight (to Mahon) whose passengers had been waiting here since 3am! The Mahon aircraft was grounded so they took ours! We have to wait for the Mahon flight to return to Bristol before we can leave which is estimated at 2145hrs!
Late arrivals are always a problem as the car rental places sometimes close by midnight. Thankfully they leave the room key in a pigeon hole at the Residencia.
All for now as I packed my laptop power adapter to keep my hand luggage weight down! Oh for a solar powered laptop!
Paul
The BIG Project commences… - http://www.chileastro.com/?p=279
[+] Not an auspicious start to the biggest project we’ve carried out to date….. I’m currently sitting in Bristol Airport while the aircraft I was destined to fly in was snapped up by another flight (to Mahon) whose passengers had been waiting here since 3am! The Mahon aircraft was grou ... more [158845]
Chile Astronomical Observatory - http://www.chileastro.com/
[ More results from Chile Astronomical Observatory ]
|
Integral locates origin of high-energy emission from Crab Nebula
08/29/2008 10:17 GMT
[-]  Thanks to data from ESA’s Integral gamma-ray observatory, scientists have been able to locate where particles in the vicinity of the rotating neutron-star in the Crab Nebula are accelerated to immense energies.
The discovery, resulting from more than 600 individual observations of the nebula, put in place another piece of the puzzle in understanding how neutron stars work.
Rotating neutron-stars, or pulsars, are known to accelerate particles to enormous energies, typically one hundred times more than the most powerful accelerators on Earth, but scientists are still uncertain exactly how these systems work and where the particles are accelerated.
A step forward in this understanding is now accomplished thanks to a team of researchers from the UK and Italy, led by Professor Tony Dean of the University of Southampton, who studied high-energy polarised light emitted by the Crab Nebula – one of the most dramatic sights in deep space.
The Crab Nebula is the result of a supernova explosion which was seen from Earth on 4 July 1054. The explosion left behind a pulsar with a nebula of radiating particles around it. The pulsar contains the mass of the Sun squeezed into a volume of about 10 km radius, rotating very fast – about 30 times a second – thereby generating very powerful magnetic fields and accelerating particles. A highly collimated jet, aligned with the spin axis of the pulsar and a bright radiating ‘donut’ structure (or torus) around the pulsar itself, are also seen.
So, the Crab is known to accelerate electrons - and possibly other particles - to extremely high speed, and so produces high energy radiation. But where exactly are these particles accelerated?
Looking into the heart of the pulsar with Integral’s spectrometer (SPI), the researchers made a detailed study to assess the polarization – or the alignment - of the waves of high-energy radiation originating from the Crab.
They saw that this polarised radiation is highly aligned with the rotation axis of the pulsar. So they concluded that a significant portion of the electrons generating the high-energy radiation must originate from a highly-organised structure located very close to the pulsar, very likely directly from the jets themselves. The discovery allows the researchers to discard other theories that locate the origin of this radiation further away from the pulsar.
Professor Tony Dean of the University’s School of Physics and Astronomy commented that the discovery of such alignment – also matching with the polarisation observed in the visible band - is truly remarkable. “The findings have clear implications on many aspects of high energy accelerators such as the Crab,” he added.
"The detection of polarised radiation in space is very complicated and rare, as it requires dedicated instrumentation and an in-depth analysis of very complex data”, said Chris Winkler, Integral Project Scientist at ESA. “Integral’s ability to detect polarised gamma-radiation and, as a consequence, to obtain important results like this one, confirms it once more as a world-class observatory.”
Notes for editors:
The results are published in the 29 August issue of the scientific journal Science, in a paper titled ‘Polarized gamma-ray emission from the Crab’, by: A. J. Dean, D.J. Clark, V.A.McBride, A.J.Bird, A.B.Hill and S.E.Shaw (University of Southampton’s School of Physics and Astronomy); J.B. Stephen and L. Bassani (INAF-IASF, Bologna); and A. Bazzano and P. Ubertini (INAF-IASF, Roma).
Integral locates origin of high-energy emission from Crab Nebula - http://cmarchesin.blogspot.com/2008/08/integral-locates-origin-of-high-energy.html
[+] Thanks to data from ESA’s Integral gamma-ray observatory, scientists have been able to locate where particles in the vicinity of the rotating neutron-star in the Crab Nebula are accelerated to immense energies.The discovery, resulting from more than 600 individual observations of the nebula, put i ... more [158653]
astronomy cmarchesin - http://cmarchesin.blogspot.com/
[ More results from astronomy cmarchesin ]
|
How does my galaxy grow?
08/29/2008 09:58 GMT
[-]  Assembling the Most Massive Galaxies in the UniverseAstronomers have caught multiple massive galaxies in the act of merging about 4 billion years ago. This discovery, made possible by combining the power of the best ground- and space-based telescopes, uniquely supports the favoured theory of how galaxies form.
How do galaxies form? The most widely accepted answer to this fundamental question is the model of 'hierarchical formation', a step-wise process in which small galaxies merge to build larger ones. One can think of the galaxies forming in a similar way to how streams merge to form rivers, and how these rivers, in turn, merge to form an even larger river. This theoretical model predicts that massive galaxies grow through many merging events in their lifetime. But when did their cosmological growth spurts finish? When did the most massive galaxies get most of their mass?
To answer these questions, astronomers study massive galaxies in clusters, the cosmological equivalent of cities filled with galaxies. "Whether the brightest galaxies in clusters grew substantially in the last few billion years is intensely debated. Our observations show that in this time, these galaxies have increased their mass by 50%," says Kim-Vy Tran from the University of Zürich, Switzerland, who led the research.
The astronomers made use of a large ensemble of telescopes and instruments, including ESO's Very Large Telescope (VLT) and the Hubble Space Telescope, to study in great detail galaxies located 4 billion light-years away. These galaxies lie in an extraordinary system made of four galaxy groups that will assemble into a cluster.
In particular, the team took images with VIMOS and spectra with FORS2, both instruments on the VLT. From these and other observations, the astronomers could identify a total of 198 galaxies belonging to these four groups.
The brightest galaxies in each group contain between 100 and 1000 billion of stars, a property that makes them comparable to the most massive galaxies belonging to clusters.
"Most surprising is that in three of the four groups, the brightest galaxy also has a bright companion galaxy. These galaxy pairs are merging systems," says Tran.
The brightest galaxy in each group can be ordered in a time sequence that shows how luminous galaxies continue to grow by merging until recently, that is, in the last 5 billion years. It appears that due to the most recent episode of this 'galactic cannibalism', the brightest galaxies became at least 50% more massive.
This discovery provides unique and powerful validation of hierarchical formation as manifested in both galaxy and cluster assembly.
"The stars in these galaxies are already old and so we must conclude that the recent merging did not produce a new generation of stars," concludes Tran. "Most of the stars in these galaxies were born at least 7 billion years ago."
The team is composed of Kim-Vy H. Tran (Institute for Theoretical Physics, University of Zürich, Switzerland), John Moustakas (New York University, USA), Anthony H. Gonzalez and Stefan J. Kautsch (University of Florida, Gainesville, USA), and Lei Bai and Dennis Zaritsky (Steward Observatory, University of Arizona, USA). The results presented here are published in the Astrophysical Journal Letters: "The Late Stellar Assembly Of Massive Cluster Galaxies Via Major Merging", by Tran et al.
Science Contact:
Kim-Vy Tran
Institute for Theoretical Physics
University of Zürich, Switzerland
Phone: +41 44 635 5820
E-mail: vy (at) physik.unizh.ch How does my galaxy grow? - http://cmarchesin.blogspot.com/2008/08/how-does-my-galaxy-grow.html
[+] Assembling the Most Massive Galaxies in the UniverseAstronomers have caught multiple massive galaxies in the act of merging about 4 billion years ago. This discovery, made possible by combining the power of the best ground- and space-based telescopes, uniquely supports the favoured theory of how gal ... more [158654]
astronomy cmarchesin - http://cmarchesin.blogspot.com/
[ More results from astronomy cmarchesin ]
|
More DMK 41AU02.AS First Light Images — The Sun
08/29/2008 05:10 GMT
[-] Over at the Sunnymeade Astro Blog, Mark Walters has posted a detailed account of his first experiences, using a new DMK 41AU02.AS. He writes:
The DMK 41AU02.AS USB camera arrived yesterday. At 1280×960 resolution this should theoretically be able to display the whole disk in IC Capture and allow single videos of the surface and proms to be taken which can be combined without having to laboriously stitch panes together. First light today proved that this is indeed the case. It was great being able to see the whole disk on the screen. Until I zoomed out I was scrolling a lot to see which edge was passing out of frame view first, but zooming out made this easy to judge so that the disk could be centred on the chip for best overall focus.
Having found the optimum settings for prom and surface capture I saved these configurations specifically for the DMK41 as the DMK21 configurations cannot be used and result in an error. A video of 2000 frames produces a file size of 2.28 GB in just over two minutes at the 1/15 sec max capture rate. In Registax 4 I came up against the problem that Registax will only recognise AVI files up to 1GB in size which equals 869 frames. Beyond that Registax throws up a read failure message and the aligning procedure fails. So until registax 5 comes out I may be limited to videos of 869 frames, which isn’t too bad, but I would prefer to be able to stack at least 1000 to reduce noise in the final image. K3CCD Tools may be the answer to my problem but an early attempt to stack in that resulted in confusion - I need to read the manual !
The whole disk view does seem to show up the shortcomings of the PST now though. It appears my PST may be slightly astigmatic with focus better on one half of the sun than the other. This is really obvious now whereas with the smaller DMK21 each pane was capable of being sharpened so that the overall view looked more consistent. Sharpening the whole DMK shots does look OK though and the inconsistent focus may even be due to the chip not being square to the objective in the holder - need to check that!
Today was not exactly the sunny, blue-sky day that was promised by the weather forecasters! We actually got 1 hour of patchy clear sky then thick cloud the rest of the day and rain in the evening. I captured these images at 9.16 UT. Not much to see in terms of proms, but the active region is a little larger and there were some small filaments around. Overall i’m pleased with the speed at which I can create a high resolution full disk now and will be even happier when Registax 5 comes along !
Below are three photos which he uses to illustrate the text (click to zoom):
Mark, I can only commend you for these great first light photo!
Keep up the good work and send us some more of your great work! 
More DMK 41AU02.AS First Light Images — The Sun - http://www.astronomycamerasblog.com/2008/08/29/more-dmk-41au02as-first-light-images-the-sun/
[+] Over at the Sunnymeade Astro Blog, Mark Walters has posted a detailed account of his first experiences, using a new DMK 41AU02.AS. He writes:
The DMK 41AU02.AS USB camera arrived yesterday. At 1280×960 resolution this should theoretically be able to display the whole disk in IC Capture and allo ... more [158564]
Astronomy Cameras Blog / Official Blog to The Imaging Source Astronomy Cameras - http://www.astronomycamerasblog.com/
[ More results from Astronomy Cameras Blog / Official Blog to The Imaging Source Astronomy Cameras ]
|
New Dark Matter Clues
08/28/2008 23:05 GMT
[-]  Credit: NASA, ESA, CXC, M. Bradac (University of California, Santa Barbara), and S. Allen (Stanford University) Here’s the latest from Hubble and Chandra, it’s a colloboration. It’s an amazingly deep image, even beyond showing another example showing dark and ordinary matter can be separated by a collision. Click the image and have a look and see how many galaxies you can see.
The Hubblesite press release:
A powerful collision of galaxy clusters has been captured by NASA’s Hubble Space Telescope and Chandra X-ray Observatory. The observations of the cluster known as MACS J0025.4-1222 indicate that a titanic collision has separated the dark from ordinary matter and provide an independent confirmation of a similar effect detected previously in a target dubbed the Bullet Cluster. These new results show that the Bullet Cluster is not an anomalous case.
The picture aside, the data show two distinct peaks in the total mass distribution and both are offset from the main baryonic component among other things. If you would like to read the Draft paper by Bradac et al., click here to get the pdf from Hubblesite.
Credit: NASA, ESA, CXC, M. Bradac (University of California, Santa Barbara), and S. Allen (Stanford University)
New Dark Matter Clues - http://tomsastroblog.com/?p=1832
[+] Credit: NASA, ESA, CXC, M. Bradac (University of California, Santa Barbara), and S. Allen (Stanford University)
Here’s the latest from Hubble and Chandra, it’s a colloboration. It’s an amazingly deep image, even beyond showing another example showing dark and ordinary matter can ... more [158392]
Tom’s Astronomy Blog - http://www.tomsastroblog.com/
[ More results from Tom’s Astronomy Blog ]
|
submitted!
08/28/2008 22:23 GMT
[-] Visualize me doing that NFL-style end-zone post-touchdown dance. The faint-source proper motion paper is submitted to The Astronomical Journal and to the arXiv, where it will appear in the next day or two. Lang, Jester, and Rix all did some last-minute pulling together to get that done. Thanks, team! Now, does anyone want to follow up our brown dwarfs with infrared spectroscopy? submitted! - http://hoggresearch.blogspot.com/2008/08/submitted.html
[+] Visualize me doing that NFL-style end-zone post-touchdown dance. The faint-source proper motion paper is submitted to The Astronomical Journal and to the arXiv, where it will appear in the next day or two. Lang, Jester, and Rix all did some last-minute pulling together to get that done. Thanks, t ... more [158389]
Hogg's Research - http://hoggresearch.blogspot.com/
[ More results from Hogg's Research ]
|
Mars VMC and Celestia
08/28/2008 21:54 GMT
[-]   If you haven't checked out the Celestia Scripts at in the ESA VMC archive, then do so now. Each image archive comes with a Celestia Script to help you orient yourself with respect to Mars. The scripts do require Celestia 1.5 or better to run (they crashed my old Celestia 1.4.1), and DON'T rename the .celx extension to .cel. If you do that the script won't run (yes, I'm an idiot, yes, I should read instructions first). The scripts are somewhat slow, it takes a minute for the script to load and run on my system. You will need a map of Mars (like Google Mars) to get more feature names. At the top (west) of the image is the Tharsis region, and the mountain visible is Arisa mons, Vallis Marinensis is lost in the glare of the limb. The big bright patch at the bottom is the crater Argyre, with Galle crater at the bottom. I still don't know the big crater in the middles name yet. Check out my images on the ESA VMC webcam site! While you are there, check out the images from Riding with Robots. Mars VMC and Celestia - http://astroblogger.blogspot.com/2008/08/mars-vmc-and-celestia.html
[+] If you haven't checked out the Celestia Scripts at in the ESA VMC archive, then do so now.Each image archive comes with a Celestia Script to help you orient yourself with respect to Mars. The scripts do require Celestia 1.5 or better to run (they crashed my old Celestia 1.4.1), and DON'T rename the ... more [158393]
Astroblog - http://astroblogger.blogspot.com/
[ More results from Astroblog ]
|
|
Pages: 1 2 3 4 5 ... 84 Next >>
|
Displaying 1 - 10 of 833 matches.
|
|
|
[English]
> home
> add a blog
> browse blogs
> browse blog entries
> report abuse
More blog channels:
Astronomy Blogs
Beer Blogs
Celebrity Blogs
Coffee Blogs
Cooking Blogs
Poker Blogs
Tea Blogs
Wine Blogs
|
