Are you hungry for knowledge? Well, if you’ve got a filet mignon appetite and a hamburger budget, then get in line as the National Academies Press is offering free PDF downloads of more than 4,000 titles from its exhaustive library.
The mission of the National Academies Press (NAP) – publisher for the National Academy of Sciences, National Academy of Engineering, Institute of Medicine, and National Research Council – is to distribute the institutions’ content as widely as possible while maintaining its financial security. The project began in 1994 when the NAP began delivering content to developing countries, and even then 65% of the files were free.
“Our business model has evolved so that it is now financially viable to put this content out to the entire world for free,” said Barbara Kline Pope, executive director for the National Academies Press. “This is a wonderful opportunity to make a positive impact by more effectively sharing our knowledge and analyses.”
Just a quick browse through the titles shows such a wealth of information that one could spend hours choosing alone! You’ll find Agriculture, Earth Sciences, Forensics, Biology, Computers, Education, Health, Industry, Math, and yes… Space and Aeronautics, just to name a few. Based on the performance of NAP’s current free PDFs, projections suggest this change will enhance distribution of PDF reports from about 700,000 downloads per year to more than 3 million by 2013.
Where do you get ’em? Just head toward the NAP Website and have fun!
A very small part of the raw LOFAR image of the field centered on the bright quasar 3C196. It shows tens of discrete sources, the faintest having a flux density of only a few mJy at 150 MHz.The image has an angular resolution of 8 arcseconds. The image still needs to be deconvolved. The data was processed by Dr. Panos Labropoulos on the EoR-cluster at the University of Groningen.
[/caption]
The International LOFAR telescope is a Pan-European collaborative project led by ASTRON Netherlands Institute for Radio Astronomy. The radio telescope integrates thousands of simple dipole receivers with effective digital signal processing and high-performance computing. LOFAR can rapidly take in wide areas of the sky, aiming in multiple directions simultaneously. It also utilizes unexplored low frequencies, around around 150 MHz, which allows astronomers new insights. What has LOFAR done so far? Try capturing faint radio sources never revealed before.
An international team led by astronomers at ASTRON and the Kapteyn Institute of the University of Groningen have used the LOFAR telescope, designed and constructed by ASTRON, to make the deepest wide-field images of the sky to date. At the conference, the trouble of dealing with foreground noise was the topic – foreground noise that makes it nearly impossible to get a good radio view of the distant Universe. What researchers are looking for is the Epoch of Reionization (EoR) – a time which is postulated to have occurred in the period between about 400 and 800 million years after the Big Bang. Says the team, “During the EoR the neutral hydrogen was slowly disappearing, probably as a result of the strong ‘ionizing’ power of the first stars and quasars. Detecting the EoR is one of the hottest projects in astronomy today.”
Detecting a signal from a 13.8 billion year old event would be akin to the Holy Grail of radio astronomy, but the team of astronomers based at ASTRON and the Kapteyn Institute of the University of Groningen, headed by Prof. Ger de Bruyn, Dr. Michiel Brentjens, Prof. Leon Koopmans and Prof. Saleem Zaroubi, are willing to sift through the noise to diclose new findings. The LOFAR data images were obtained in a 6-hour synthesis on the night of 29/30 January 2011 and the evening of 1 April 2011 using 18 core stations and 7 remote stations. Signals were recorded with the High Band Antennas blanketing the frequency range from 115 – 163 MHz and then further refined.
One of the fields covered by the radio imaging is centered at the celestial North Pole since it is available year round from LOFAR’s central position. The second field is dedicated to bright, compact quasar 3C196 in the constellation of Lynx. The high resolution images already match – or even surpass – the best published images taken with the Giant Meter Wavelength Radio telescope (GMRT) in India. The images reveal a significant number of both very bright and very faint sources, spanning a so-called dynamic range of more than 200,000:1 in brightness between sources.
“This is an important record for the time being for LOFAR. The image quality, however, is still not perfect and significant improvements can be expected in the months ahead using improved knowledge of the effects of the LOFAR station beams.” says the team. “Continued efforts are also needed to improve the software to deal with imaging artifacts and the ionosphere. These two fields and several others will be observed for about 100 nights to conclusively detect signals from the EoR.”
Science becomes art! A unique and stunning compilation of images of the Saturn system from the Cassini mission. Created by Chris Abbas of Digital Kitchen, he says “The footage in this little film was captured by the hardworking men and women at NASA with the Cassini Imaging Science System. If you’re interested in learning more about Cassini and the on-going Cassini Solstice Mission, check it out at NASA’s Cassini website.”
NGC 6791 - The full Hubble Advanced Camera for Surveys field (top right) is full of stars estimated to be 8 billion years old. Bottom right: The blue circles identify hotter dwarfs that are 4 billion years old. The red circles identify cooler dwarfs that are 6 billion years old. - Credit: NASA, ESA, and L. Bedin (STScI)
[/caption]
Almost a century ago, astronomers Shapley and Melotte began classifying star clusters. This rough, initial go-around took in the apparent number of stars and the compactness of the field – along with color. By 1927, these “classes” were again divided to include both open and globular clusters. But there are some that simply defy definition.
According to Johns Hopkins astronomer Imants Platais, there is one case which has puzzled astronomers for decades: a well-known, seemingly open star cluster in the constellation of Lyra, named NGC 6791.
“This cluster is about twice the age of the sun and is unusually metal rich (at least twice the Sun’s metallicity),” said Platais, of the Henry A. Rowland Department of Physics and Astronomy’s Center for Astrophysical Sciences. “A couple of decades ago, it was also found that NGC 6791 contains a handful of very hot but somewhat dim stars, called hot subdwarfs. The presence of such stars in an open cluster is rare, though not unique.”
Why are these hot subdwarfs an anomaly? The facts about star clusters as we know them are that globular clusters are notoriously metal poor, while open clusters are metal rich. “The massive stars that create much of the metals live for only a short time, and when they die, they spit out or eject the metals they have created.” says the team. “The expelled metals become part of the raw material out of which the next stars are formed. Thus, there is a relationship between the age of a star and how much metal it contains: old stars have a lower metallicity than do younger ones. Less massive stars live longer than higher mass stars, so low mass stars from early generations still survive today and are studied extensively.”
A team led by Platais and Kyle Cudworth from The University of Chicago’s Yerkes Observatory set out to solve the mystery of NGC 6791 by taking a census of its stars. Their findings revealed several luminous stars in the horizontal branch of the HR diagram… Stars that would normally be found in globular clusters. The hot subdwarfs were confirmed to be genuine cluster members, but they now “appear to be simply the bluest horizontal branch stars”. What’s wrong with this picture? NGC 6791 contains simultaneously both red and very blue horizontal branch stars – making it both old and metal rich. Quite simply put, studying star clusters is key to understanding stellar evolution – unless the cluster starts breaking the rules.
“Star clusters are the building blocks of galaxies and we believe that all stars, including our own sun, are born in clusters. NGC 6791 is a real oddball among about 2,000 known open and globular star clusters in the Milky Way and as such provides a new challenge and a new opportunity, to our understanding of how stars form and evolve,” said Platais, who presented this work last week at the 218th meeting of the American Astronomical Society in Boston.
So… what about star clusters in other galaxies? Three hybrids have been discovered (2005) in the Andromeda Galaxy – M31WFS C1, M31WFS C2, and M31WFS C3. They have the same basic population and metallicity of a globular cluster, but they’re expanded hundreds of light years across and are equally less dense. Are they extended? Or perhaps a dwarf spheroidal galaxy? They don’t exist (as far as we know) in the Milky Way, but there’s always a possibility these hybrid clusters may call other galaxies home.
Hi everyone, if you look over on the right-hand side of the page I’ve added the new Google +1 button to every page on the site. Now you can click that button to endorse pages on the site that you enjoyed. An obvious place to click that button is on the Universe Today homepage. 🙂
If you’re wondering what the +1 button is, here’s what Google has to say. +1 is shorthand for “this is pretty cool” or “you should check this out.” Let visitors recommend your pages right in Google search results and help your site stand out. Here’s more info on the +1.
NGC 3603 - Credit: NASA, ESA, R. O'Connell (University of Virginia), F. Paresce (National Institute for Astrophysics, Bologna, Italy), E. Young (Universities Space Research Association/Ames Research Center), the WFC3 Science Oversight Committee, and the Hubble Heritage Team (STScI/AURA)
[/caption]
Hovering about the galactic plane and locked in the embrace of a spiral galaxy’s arms, open star clusters usually contain up to a few hundred members and generally span around thirty light years across. Most are young, up to a few tens of millions of years old – with a few rare exceptions as old as a few billion years. We understand that over time the members of a galactic cluster slowly drift apart to form loose associations. But what we don’t understand is exactly how their stars formed.
“The net effect of this is that their stars eventually become redistributed throughout the Galaxy,” said Nathan Leigh, a PhD student at McMaster University and lead author for a study being presented this week at the CASCA 2011 meeting in Ontario, Canada. “This is how we think most of the stars in the Milky Way came to be found in their currently observed locations.”
One of the reasons we’re not able to probe deeply into the construction and evolution of galactic clusters is because they are typically hidden by a dense veil of gas and dust. Beautiful to look at… But nearly impossible to cut through in visible light. This means we can’t directly observe the process of starbirth. To help understand this process, astronomers have combined their observations of star clusters so old they date back to the beginning of the Universe itself . And, thanks to modern computing, they are also able to generate state-of-the-art simulations for stellar evolution.
“Unfortunately, most star clusters take so long to dissolve that we cannot actually see it happening. But we now understand how this process occurs, and we can look for its signatures by examining the current appearances of clusters,” said Nathan Leigh. “We have gone about this by matching up the clusters we make with our simulations to the ones we actually observe. This tells us about the conditions at the time of their formation.”
These simulations have given Leigh and collaborators the stimulus they needed to re-trace the histories of real star clusters, giving us new clues about formation. To complete their studies, they relied upon highly sophisticated observations recently taken with the Hubble Space Telescope.
“Remarkably, we are finding that all star clusters more or less share a common history, extending all the way back to their births,” said Leigh. “This came as a big surprise to us since it suggests that the problem could be much simpler than we originally thought. Our understanding of not only how stars form, but also the history of our Galaxy, just took a much bigger step forward than we were expecting.”
Space Shuttle Endeavour landed safely at the Kennedy Space Center on June 1, 2011 at 2:35 a.m. EDT. During the 16 day STS-134 mission, Endeavour delivered the $2 Billion Alpha Magnetic Spectrometer to the International Space Station and journeyed more than sixteen million miles. Endeavour was towed back to the Orbiter Processing Facility in preparation for display at her new retirement home at the California Science Center. Credit: Ken Kremer
[/caption]
KENNEDY SPACE CENTER – Space Shuttle Endeavour and her six man crew landed safely today at the Kennedy Space Center in Florida at 2:35 a.m. EDT following a 16 day journey of more than sixteen million miles.
The STS-134 mission marked the end of Endeavour’s space exploration career. It was the 25th and last space mission by NASA’s youngest orbiter. Altogether, Endeavour has logged 299 days in space, orbited Earth 4,671 times and traveled 122,883,151 miles.
The crew was led by Shuttle Commander Mark Kelly. Also aboard were Pilot Greg H. Johnson and Mission Specialists Mike Fincke, Drew Feustel, Greg Chamitoff and the European Space Agency’s Roberto Vittori. Vittori is the last non NASA astronaut to fly on a shuttle mission.
The night landing capped a highly productive flight highlighted by the delivery of the $2 Billion Alpha Magnetic Spectrometer (AMS) to the International Space Station. AMS is a cosmic ray detector that seeks to unveil the invisible universe and search for evidence of dark matter, strange matter and antimatter.
5 of 6 crew members of STS-134 mission of Space Shuttle Endeavour at post landing press briefing. Credit: Ken Kremer
“What a great ending to this really wonderful mission,” said Bill Gerstenmaier, associate administrator for Space Operation at a briefing today for reporters “They’re getting great data from their instrument on board the space station. It couldn’t have gone any better for this mission.”
Mike Leinbach, the Space Shuttle Launch Director, said, “It’s been a great morning at the Kennedy Space Center. Commander Kelly and his crew are in great spirits.”
During the flight, Mike Fincke established a new record of 382 days for time a U.S. astronaut has spent in space. He broke the record on May 27, his 377th day on May 27, by surpassing previous record holder Peggy Whitson.
STS-134 was the 134th space shuttle mission and the 36th shuttle mission dedicated to ISS assembly and maintenance.
“You know, the space shuttle is an amazing vehicle, to fly through the atmosphere, hit it at Mach 25, steer through the atmosphere like an airplane, land on a runway, it is really, really an incredible ship,” said Kelly.
“On behalf of my entire crew, I want to thank every person who’s worked to get this mission going and every person who’s worked on Endeavour. It’s sad to see her land for the last time, but she really has a great legacy.”
After the landing at the Shuttle Landing Facility (SLF) , Endeavour was towed back into the Orbiter Processing Facility (OPF) where she will be cleaned and “safed” in preparation for her final resting place – Retirement and public display at the California Science Center in Los Angelos, California.
With the successful conclusion of Endeavour’s mission, the stage is now set for blastoff of the STS-135 mission on July 8, the very final flight of the three decade long shuttle Era.
“We’ve had a lot going on here,” said Mike Moses, space shuttle launch integration manager, “Being able to send Atlantis out to the pad and then go out and land Endeavour was really a combination I never expected to have.
It’s been a heck of a month in the last 4 hours !”
Shuttle Endeavour Landing Photos by Mike Deep for Universe Today
STS-134 Space Shuttle Commander Mark Kelly. Credit: Ken Kremer STS-134 Endeavour Post Landing Press Briefing.
Bill Gerstenmaier, NASA Associate Administrator for Space Operations, Mike Moses, Space Shuttle launch integration manager at NASA KSC, Mike Leinbach, Space Shuttle Launch Director at NASA KSC, laud the hard work and dedication of everyone working on the Space Shuttle program. Credit: Ken Kremer
Read my related stories about the STS-134 mission here:
As a part of NASA’s ongoing Year of the Solar System – which is actually a single Martian year long, or 23 months – the excitement of planetary exploration is being brought to people around the world through a enthusiastic science outreach program called From Earth to the Solar System (FETTSS). A continuation of the well-received International Year of Astronomy 2009 From Earth to the Universe program, FETTSS provides over 90 beautiful high-resolution images of fascinating locations around our solar system; from the ice geysers of Enceladus to the plasma arcs of solar prominences, the cold dunes of Mars to the hot springs of Yellowstone, the FETTSS collection showcases many wonders of many worlds – and helps bring them within view of as many people as possible.
The images are displayed in public locations, hosted by organizations that raise all the necessary funding to have them printed and installed. The FETTSS site exists to provide the high-resolution print images as well as offer guidance as to how to best plan, market and set up an installation.
What’s wonderful about From Earth to the Solar System – as well as its predecessor From Earth to the Universe – is how it brings the fascination of science and astronomy to people who may not have previously given it much thought. By presenting large-format images with descriptive captions in common places – such as in an airport or outside in a public park – FETTSS hosts are actively capturing the interest of viewers and engaging them in astronomy – many undoubtedly for the first time.
People around the world are being connected with the most recent work of scientists and researchers in a way that’s attractive, informative and yet accessible. This is the key to any successful outreach program.
The images are at once artistic and informative, weaving together themes in astrobiology, planetary science, and astronomy. Including contributions from backyard astronomers, large telescopes in space, and even point-and-shoot cameras of field researchers, the collection represents the current state of exploration as seen through the eyes of the scientific community.
Currently an exhibit is just wrapping up in Corpus Christi, Texas, at the Museum of Science and History and was very well-received by both people and the press! The next scheduled event will take place in June at the National Air and Space Museum in Washington, DC.
A FETTU outdoor installation in Geneva
FETTSS looks to build on the success of the 2009 FETTU program.
“We are hoping to replicate some of FETTU’s success and bring a measure of sustainability to the FETTU concept. ‘From Earth to the Solar System’ is taking a similar grassroots-type of approach to exhibit creation, and will hopefully help remove the barrier to ‘seeking science out’ for some visitors and help make setting up an exhibit more efficient for organizers,” said Kimberly Kowal Arcand, Media Production Coordinator for the Harvard-Smithsonian Center for Astrophysics and FETTSS principal investigator.
“With FETTU – and what we hope to find with FETTSS – there was a wonderful response from both visitors and organizers,” said Arcand. “We found, unexpectedly, a sort of emotional and personal connection to the images in the FETTU project and I’m interested to see if we find that again with FETTSS. I was personally overwhelmed with the response to FETTU… it was the most inspiring thing I have ever worked on!”
Already, exhibitors worldwide have expressed interest in hosting FETTSS installations… from Argentina, Serbia, China, Colombia, Canada, UK, Ireland, Egypt, Spain, Armenia, as well as from numerous locations in the US – many of whom had previously hosted FETTU events.
So with such a great program and strong response, the question remains: what’s next?
“From Earth to the Sun? From Earth to the Galaxies?” suggested Arcand.
With all that’s being discovered, whatever it is it’s sure to be another success!
For more information about FETTSS or to host an FETTSS event in your area, visit the main site here.
M1-67 is the youngest wind-nebula around a Wolf-Rayet star, called WR124, in our Galaxy. Credit: ESO
[/caption]
In 1867, astronomers using the 40 cm Foucault telescope at the Paris Observatory, discovered three stars in the constellation Cygnus (now designated HD191765, HD192103 and HD192641), that displayed broad emission bands on an otherwise continuous spectrum. The astronomers’ names were Charles Wolf and Georges Rayet, and thus this category of stars became named Wolf–Rayet (WR) stars. Now using the Canadian MOST microsatellite, a team of researchers from the Universite de Montreal and the Centre de Recherche en Astrophysique du Quebec have made a stunning observation. They probed into the depth of the atmospheric eclipses in the Wolf-Rayet star, CV Serpentis, and observed a never before seen change of mass-loss rate.
Thanks to the service of MOST – Canada’s first space telescope and its high precision photometry – the team has observed significant changes in the depth of the atmospheric eclipses in the 30-day binary WR+O system. The equipment is aboard a suitcase-sized microsatellite (65 x 65 x 30 cm) which was launched in 2003 from a former ICBM in northern Russia. It is on a low-Earth polar orbit and has long outlived its original estimated life expectancy, offering Canadian astronomers almost eight years (and still counting) of ultra-high quality space-based data. Now this data gives us a huge insight into the heart of Wolf-Rayet stars.
Intrinsically luminous, WR stars can be massive or mid-sized, but the most interesting stage is arguably the last 10% in the lifetime of the star, when hydrogen fuel is used up and the star survives by much hotter He-burning. Towards the end of this phase, the copious supply of carbon atoms head for the stellar surface and are ejected in the form of stellar winds. WR stars in this stage are known as WC stars… and their production of carbon dust is one of the greatest mysteries of the Cosmos. These amorphous dust grains range in size from a few to millions of atoms and astronomers hypothesize their formation may requires high pressure and less than high temperatures.
“One key case is undoubtedly the sporadic dust-producing WC star in CV Ser. MOST was recently used to monitor CV Ser twice (2009 and 2010), revealing remarkable changes in the depths of the atmospheric eclipse that occurs every time the hot companion’s light is absorbed as it passes through the inner dense WC wind.” says the researchers. “The remarkable, unprecedented 70% change in the WC mass-loss rate might be connected to dust formation.”
And all thanks to the MOST tiny little satellite imaginable…
Original Story Source: AstroNews and excerpt from Wikipedia.
Artist's Conception of a Neutron Star Courtesy of NASA
[/caption]
They came into existence violently… Born at the death of a massive star. They are composed almost entirely of neutrons, barren of electrical charge and with a slightly larger mass than protons. They are quantum degenerates with an average density typically more than one billion tons per teaspoonful – a state which can never be created here on Earth. And they are absolutely perfect for study of how matter and exotic particles behave under extreme conditions. We welcome the extreme neutron star…
In 1934 Walter Baade and Fritz Zwicky proposed the existence of the neutron star, only a year after the discovery of the neutron by Sir James Chadwick. But it took another 30 years before the first neutron star was actually observed. Up until now, neutron stars have had their mass accurately measured to about 1.4 times that of Sol. Now a group of astronomers using the Green Bank Radio Telescope found a neutron star that has a mass of nearly twice that of the Sun. How can they make estimates so precise? Because the extreme neutron star in question is actually a pulsar – PSR J1614-2230. With heartbeat-like precision, PSR J1614-2230 sends out a radio signal each time it spins on its axis at 317 times per second.
According to the team; “What makes this discovery so remarkable is that the existence of a very massive neutron star allows astrophysicists to rule out a wide variety of theoretical models that claim that the neutron star could be composed of exotic subatomic particles such as hyperons or condensates of kaons.”
The presence of this extreme star poses new questions about its origin… and its nearby white dwarf companion. Did it become so extreme from pulling material from its binary neighbor – or did it simply become that way through natural causes? According to Professor Lorne Nelson (Bishop’s University) and his colleagues at MIT, Oxford, and UCSB, the neutron star was likely spun up to become a fast-rotating (millisecond) pulsar as a result of the neutron star having cannibalized its stellar companion many millions of years ago, leaving behind a dead core composed mostly of carbon and oxygen. According to Nelson, “Although it is common to find a high fraction of stars in binary systems, it is rare for them to be close enough so that one star can strip off mass from its companion star. But when this happens, it is spectacular.”
Through the use of theoretical models, the team hopes to gain insight as to how binary systems evolve over the entire lifetime of the Universe. With today’s extreme super-computing powers, Nelson and his team members were able to calculate the evolution of more than 40,000 plausible starting cases for the binary and determine which ones were relevant. As they describe at this week’s CASCA meeting in Ontario, Canada, they found many instances where the neutron star could evolve higher in mass at the expense of its companion, but as Nelson says, “It isn’t easy for Nature to make such high-mass neutron stars, and this probably explains why they are so rare.”
