Space and astronomy news
An intersection of two of my favorite entities (Minute Physics and Neil deGrasse Tyson) now covers a topic that has been on my mind lately: does the Universe — and therefore humanity — have a purpose?
deGrasse Tyson was asked by the Templeton Foundation to answer this question and poses here that if there is a purpose, the cosmic environment has a strange way of showing it.
What do you think?
The folks over at PHD Comics have put together a new video in their Two-Minute Thesis series, this one featuring Ph.D candidate Or Graur of the University of Tel Aviv and the American Museum of Natural History discussing the secret lives — and deaths — of astronomers’ “standard candles” of universal distance, Type Ia supernovae.
Judging distances across intergalactic space isn’t easy, so in order to figure out how far away galaxies are astronomers have learned to use the light from Type Ia supernovae, which flare up with the brilliance of 5 billion Suns… and rather precisely so.
Type Ia supernovae are thought to be created from a pairing of two stars: one super-dense white dwarf which draws in material from a binary companion until a critical mass — about 40% more mass than the Sun – is reached. The overpacked white dwarf suddenly undergoes a rapid series of thermonuclear reactions and explodes in an incredibly bright outburst of material and energy.
But exactly what sorts of stellar pairs lead to Type Ia supernovae and how frequently they occur aren’t known, and that’s what Ph.D candidate Or Graur is aiming to learn more about.
Read more: A New Species of Type Ia Supernova?
“We don’t really know what kind of star it is that leads to these explosions, which is kind of embarrassing,” says Graur. “The companion star could be a regular star like our Sun, a red giant or supergiant, or another white dwarf.”
Because stars age at certain rates, by looking deeper into space with the Hubble and Subaru telescopes Graur hopes to determine how often and when in the Universe’s history Type Ia supernovae occur, and thus figure out what types of stars are most likely responsible.
“My rate measurements favor a second white dwarf as the binary companion,” Graur says, “but the issue is far from settled.”
Watch the video for the full story, and visit PHD TV and PHD Comics for more great science illustrations.
Video: PHDComics. Animation: Jorge Cham. Series Producer: Meg Rosenburg. Inset image: merging white dwarfs causing a Type Ia supernova. (NASA/CXC/M Weiss)
The well-known star-forming region of the Orion Nebula. Credit: Canada-France-Hawaii Telescope / Coelum (J.-C. Cuillandre & G. Anselmi)
Precise distances are difficult to gauge in space, especially within the relatively local regions of the Galaxy. Stars which appear close together in the night sky may actually be separated by many hundreds or thousands of light-years, and since there’s only a limited amount of space here on Earth with which to determine distances using parallax, astronomers have to come up with other ways to figure out how far objects are, and what exactly is in front of or “behind” what.
Recently, astronomers using the 340-megapixel MegaCam on the Canada-France-Hawaii Telescope (CFHT) observed the star-forming region of the famous Orion nebula — located only about 1,500 light-years away — and determined that two massive groupings of the nebula’s stars are actually located in front of the cluster as completely separate structures… a finding that may ultimately force astronomers to rethink how the many benchmark stars located there had formed.
Although the Orion nebula is easily visible with the naked eye (as the hazy center “star” in Orion’s three-star sword, hanging perpendicular below his belt) its true nebulous nature wasn’t identified until 1610. As a vast and active star-forming region of bright dust and gas located a mere 1,500 light-years distant, the various stars within the Orion Nebula Cluster (ONC) has given astronomers invaluable benchmarks for research on many aspects of star formation.
[Read more: Astrophoto – Orion’s Bloody Massacre]
Now, CFHT observations of the Orion nebula conducted by Dr. Hervé Bouy of the European Space Astronomy Centre (ESAC) and Centre for Astrobiology (CSIC) and Dr. João Alves of the Institut für Astronomie (University of Vienna) have shown that a massive cluster of stars known as NGC 1980 is actually in front of the nebula, and is an older group of approximately 2,000 stars that is separate from the stars found within the ONC… as well as more massive than once thought.
“It is hard to see how these new observations fit into any existing theoretical model of cluster formation, and that is exciting because it suggests we might be missing something fundamental.”
– Dr. João Alves, Institut für Astronomie, University of Vienna
In addition their observations with CFHT — which were combined with previous observations with ESA’s Herschel and XMM-Newton and NASA’s Spitzer and WISE — have led to the discovery of another smaller cluster, L1641W.
According to the team’s paper, “We find that there is a rich stellar population in front of the Orion A cloud, from B-stars to M-stars, with a distinct 1) spatial distribution; 2) luminosity function; and 3) velocity dispersion from the reddened population inside the Orion A cloud. The spatial distribution of this population peaks strongly around NGC 1980 (iota Ori) and is, in all likelihood, the extended stellar content of this poorly studied cluster.”
The findings show that what has been known as Orion Nebula Cluster is actually a combination of older and newer groups of stars, possibly calling for a “revision of most of the observables in the benchmark ONC region (e.g., ages, age spread, cluster size, mass function, disk frequency, etc.)”
[Read more: Astronomers See Stars Changing Right Before Their Eyes in Orion Nebula]
“We must untangle these two mixed populations, star by star, if we are to understand the region, and star formation in clusters, and even the early stages of planet formation,” according to co-author Dr. Hervé Bouy.
The team’s article “Orion Revisited” was published in the November 2012 Astronomy & Astrophysics journal. Read the CFHT press release here.
The Canada-France-Hawaii Telescope’s Mauna Kea summit dome in September 2009. Credit: CFHT/Jean-Charles Cuillandre
Inset image: Orion nebula seen in optical – where the molecular cloud is invisible – and infrared, which shows the cloud. Any star detected in the optical in the line of sight over the region highlighted in the right panel must therefore be located in the foreground of the molecular cloud. Credit: J. Alves & H. Bouy.
An “bridge” of hot gas stretches between galaxy clusters Abell 401 and Abell 399
It may not be good practice to burn bridges but this is one super-heated bridge that astronomers were happy to find: an enormous swath of hot gas connecting two galaxy clusters 10 million light-years apart, and nearly a billion light-years away.
Using ESA’s Planck space telescope, astronomers have identified leftover light from the Big Bang interacting with a filament of hot gas stretching between Abell 401 and Abell 399, two galactic clusters each containing hundreds of individual galaxies.
Launched in May 2009, Planck is designed to study the Cosmic Microwave Background (CMB) — the leftover light from the Big Bang. When this radiation interacts with large-scale cosmic structures, like the hot gas bridging clusters of galaxies, its energy is modified in a specific way. This is referred to as the Sunyaev–Zel’dovich Effect (SZE), and Planck is specifically attuned to finding it.
This, however, is Planck’s first discovery of inter-cluster gas found using the SZ technique.
The temperature of the gas is estimated to be around 80 million degrees C, similar to the temperature of the gas found within the clusters themselves. It’s thought that the gas may be a combination of cosmic web filaments left over from the early Universe mixed with gas from the clusters.
The image above shows the clusters Abell 401 and Abell 399 as seen at optical wavelengths with ground-based telescopes overlaid with the SZE from Planck. The entire bridge spans a distance about the size of two full Moons in the sky.
Read more on ESA’s news page here.
Top image: Sunyaev–Zel’dovich effect: ESA Planck Collaboration; optical image: STScI Digitized Sky Survey. Inset image: Artist’s impression of Planck against the CMB. (ESA and the HFI Consortium, IRAS)
When introducing his book “About Time: Cosmology and Culture at the Twilight of the Big Bang,” author Adam Frank tells us that he is setting out to “unfold the grandest conception of the universe we human beings have been able to imagine and explore. At the same time embracing our most intimate and most personal experience of the world — the very frame of human life.”
“This book is about time, both cosmic and human.”
For those interested in the complex journey of humanity through the cosmos, Frank does not fail in his quest to unravel the unique web of ‘time’ into a thread of understandable science. That is, if you can take a partially solved puzzle and write a book that connects the proverbial dots of known science and cultural anthropology with the partially understood theories of cosmology and related sciences.
Mission accomplished by Frank.
Upon first receiving this book, I was hopeful that Frank would present the material of thousands of years of science in a unique and interesting way; setting his writing apart from the hundreds of other astronomy books I’ve read. Frank, being a seasoned writer and astrophysics professor, did not disappoint. Frank takes you on a conversational journey, filled with real life examples, both personal and historical, to share his view of some of the most multifarious ideas being considered in our galaxy today.
The first few chapters are a review of compound science related to our galaxy, but Frank quickly dives into a discussion of how culture has been affected by the world around it. From there Frank draws a picture from intricate ideas and theories of how society fits in the larger puzzle of cosmology. All while focusing on the measurement of time.
If you are looking to take your perspective of cosmology to a new and deeper level, allow Adam Frank to steal some of your time and read his book “About Time”. Frank will surely have you viewing your society, history, and clock in a whole new perspective. Not to mention putting you on the forefront of scientific theories and cultural progress being considered in the world of cosmology.
Adam Frank is Professor of Astrophysics at the University of Rochester and a regular contributor to Discover and Astronomy magazines, and is the co-founder of National Public Radio’s popular 13:7 Cosmos & Culture blog. He won an American Astronomical Society Prize for his scientific writing. His first book was The Constant Fire: Beyond the Science vs. Religion Debate.
This plot shows the locations of 150 blazars (green dots) used in the a new by the Fermi Gamma-Ray Telescope. Credit: NASA/DOE/Fermi LAT Collaboration
All the light that has been produced by every star that has ever existed is still out there, but “seeing” it and measuring it precisely is extremely difficult. Now, astronomers using data from NASA’s Fermi Gamma-ray Space Telescope were able to look at distant blazars to help measure the background light from all the stars that are shining now and ever were. This enabled the most accurate measurement of starlight throughout the universe, which in turn helps establish limits on the total number of stars that have ever shone.
“The optical and ultraviolet light from stars continues to travel throughout the universe even after the stars cease to shine, and this creates a fossil radiation field we can explore using gamma rays from distant sources,” said lead scientist Marco Ajello from the Kavli Institute for Particle Astrophysics and Cosmology at Stanford University in California and the Space Sciences Laboratory at the University of California at Berkeley.
Their results also provide a stellar density in the cosmos of about 1.4 stars per 100 billion cubic light-years, which means the average distance between stars in the universe is about 4,150 light-years.
The total sum of starlight in the cosmos is called the extragalactic background light (EBL), and Ajello and his team investigated the EBL by studying gamma rays from 150 blazars, which are among the most energetic phenomena in the universe. They are galaxies powered by extremely energetic black holes: they have energies greater than 3 billion electron volts (GeV), or more than a billion times the energy of visible light.
The astronomers used four years of Fermi data on gamma rays with energies above 10 billion electron volts (GeV), and the Fermi Large Area Telescope (LAT) instrument is the first to detect more than 500 sources in this energy range.
To gamma rays, the EBL functions as a kind of cosmic fog, but Fermi measured the amount of gamma-ray absorption in blazar spectra produced by ultraviolet and visible starlight at three different epochs in the history of the universe.
Fermi measured the amount of gamma-ray absorption in blazar spectra produced by ultraviolet and visible starlight at three different epochs in the history of the universe. (Credit: NASA’s Goddard Space Flight Center)
“With more than a thousand detected so far, blazars are the most common sources detected by Fermi, but gamma rays at these energies are few and far between, which is why it took four years of data to make this analysis,” said team member Justin Finke, an astrophysicist at the Naval Research Laboratory in Washington.
Gamma rays produced in blazar jets travel across billions of light-years to Earth. During their journey, the gamma rays pass through an increasing fog of visible and ultraviolet light emitted by stars that formed throughout the history of the universe.
Occasionally, a gamma ray collides with starlight and transforms into a pair of particles — an electron and its antimatter counterpart, a positron. Once this occurs, the gamma ray light is lost. In effect, the process dampens the gamma ray signal in much the same way as fog dims a distant lighthouse.
From studies of nearby blazars, scientists have determined how many gamma rays should be emitted at different energies. More distant blazars show fewer gamma rays at higher energies — especially above 25 GeV — thanks to absorption by the cosmic fog.
The researchers then determined the average gamma-ray attenuation across three distance ranges: The closest group was from when the universe was 11.2 years old, a middle group of when the Universe was 8.6 billion years old, and the farthest group from when the Universe was 4.1 billion years old.
This animation tracks several gamma rays through space and time, from their emission in the jet of a distant blazar to their arrival in Fermi’s Large Area Telescope (LAT). During their journey, the number of randomly moving ultraviolet and optical photons (blue) increases as more and more stars are born in the universe. Eventually, one of the gamma rays encounters a photon of starlight and the gamma ray transforms into an electron and a positron. The remaining gamma-ray photons arrive at Fermi, interact with tungsten plates in the LAT, and produce the electrons and positrons whose paths through the detector allows astronomers to backtrack the gamma rays to their source.
From this measurement, the scientists were able to estimate the fog’s thickness.
“These results give you both an upper and lower limit on the amount of light in the Universe and the amount of stars that have formed,” said Finke during a press briefing today. “Previous estimates have only been an upper limit.”
And the upper and lower limits are very close to each other, said Volker Bromm, an astronomer at the University of Texas, Austin, who commented on the findings. “The Fermi result opens up the exciting possibility of constraining the earliest period of cosmic star formation, thus setting the stage for NASA’s James Webb Space Telescope,” he said. “In simple terms, Fermi is providing us with a shadow image of the first stars, whereas Webb will directly detect them.”
Measuring the extragalactic background light was one of the primary mission goals for Fermi, and Ajello said the findings are crucial for helping to answer a number of big questions in cosmology.
A paper describing the findings was published Thursday on Science Express.
Source: NASA
From the initial expansion of the Big Bang to the birth of the Moon, from the timid scampering of the first mammals to the rise — and fall — of countless civilizations, this fascinating new video by melodysheep (aka John D. Boswell) takes us on a breathless 90-second tour through human history — starting from the literal beginnings of space and time itself. It’s as imaginative and powerful as the most gripping Hollywood trailer… and it’s even inspired by a true story: ours.
Enjoy!
(Video by melodysheep, creator of the Symphony of Science series.)
Frame from a simulation of the merger of two black holes and the resulting emission of gravitational radiation (NASA/C. Henze)
The short answer? You get one super-SUPERmassive black hole. The longer answer?
Well, watch the video below for an idea.
This animation, created with supercomputers at the University of Colorado, Boulder, show for the first time what happens to the magnetized gas clouds that surround supermassive black holes when two of them collide.
The simulation shows the magnetic fields intensifying as they contort and twist turbulently, at one point forming a towering vortex that extends high above the center of the accretion disk.
This funnel-like structure may be partly responsible for the jets that are sometimes seen erupting from actively feeding supermassive black holes.
The simulation was created to study what sort of “flash” might be made by the merging of such incredibly massive objects, so that astronomers hunting for evidence of gravitational waves — a phenomenon first proposed by Einstein in 1916 — will be able to better identify their potential source.
Read: Effects of Einstein’s Elusive Gravity Waves Observed
Gravitational waves are often described as “ripples” in the fabric of space-time, infinitesimal perturbations created by supermassive, rapidly rotating objects like orbiting black holes. Detecting them directly has proven to be a challenge but researchers expect that the technology will be available within several years’ time, and knowing how to spot colliding black holes will be the first step in identifying any gravitational waves that result from the impact.
In fact, it’s the gravitational waves that rob energy from the black holes’ orbits, causing them to spiral into each other in the first place.
“The black holes orbit each other and lose orbital energy by emitting strong gravitational waves, and this causes their orbits to shrink. The black holes spiral toward each other and eventually merge,” said astrophysicist John Baker, a research team member from NASA’s Goddard Space Flight Center. “We need gravitational waves to confirm that a black hole merger has occurred, but if we can understand the electromagnetic signatures from mergers well enough, perhaps we can search for candidate events even before we have a space-based gravitational wave observatory.”
The video below shows the expanding gravitational wave structure that would be expected to result from such a merger:
If ground-based telescopes can pinpoint the radio and x-ray flash created by the mergers, future space telescopes — like ESA’s eLISA/NGO — can then be used to try and detect the waves.
Read more on the NASA Goddard new release here.
First animation credit: NASA’s Goddard Space Flight Center/P. Cowperthwaite, Univ. of Maryland. Second animation: NASA/C. Henze.
The Minute Physics folks have created another great video, this time explaining why the sky is dark at night. Although at first glance it seems like an easy question to answer, throw in Olbers’ Paradox (the light from an infinite amount of stars should make the night sky completely bright) and it really is quite a complicated matter. In fact, it takes the Minute Physics teams nearly four minutes to explain it all!
Caption: Fully integrated Gaia payload module with nearly all of the multilayer insulation fabric installed. Credit: Astrium SAS
Earlier this month ESA’s Gaia mission passed vital tests to ensure it can withstand the extreme temperatures of space. This week in the Astrium cleanroom at Intespace in Toulouse, France, had it’s payload module integrated, ready for further testing before it finally launches next year. This is a good opportunity to get to know the nuts and bolts of this exciting mission that will survey a billion stars in the Milky Way and create a 3D map to reveal its composition, formation and evolution.
Gaia will be operating at a distance of 1.5 million km from Earth (at L2 Lagrangian point, which keeps pace with Earth as we orbit the Sun) and at a temperature of -110°C. It will monitor each of its target stars about 70 times over a five-year period, repeatedly measuring the positions, to an accuracy of 24 microarcseconds, of all objects down to magnitude 20 (about 400,000 times fainter than can be seen with the naked eye) This will provide detailed maps of each star’s motion, to reveal their origins and evolution, as well as the physical properties of each star, including luminosity, temperature, gravity and composition.
The service module houses the electronics for the science instruments and the spacecraft resources, such as thermal control, propulsion, communication, and attitude and orbit control. During the 19-day tests earlier this month, Gaia endured the thermal balance and thermal-vacuum cycle tests, held under vacuum conditions and subjected to a range of temperatures. Temperatures inside Gaia during the test period were recorded between -20°C and +70°C.
“The thermal tests went very well; all measurements were close to predictions and the spacecraft proved to be robust with stable behavior,” reports Gaia Project Manager Giuseppe Sarri.
For the next two months the same thermal tests will be carried out on Gaia’s payload module, which contains the scientific instruments. The module is covered in multilayer insulation fabric to protect the spacecraft’s optics and mirrors from the cold of space, called the ‘thermal tent.’
Gaia contains two optical telescopes that can precisely determine the location of stars and analyze their spectra. The largest mirror in each telescope is 1.45 m by 0.5 m. The Focal Plane Assembly features three different zones associated with the science instruments: Astro, the astrometric instrument that detects and pinpoints celestial objects; the Blue and Red Photometers (BP/RP), that determines stellar properties like temperature, mass, age, elemental composition; and the Radial-Velocity Spectrometer (RVS),that measures the velocity of celestial objects along the line of sight.
The focal plane array will also carry the largest digital camera ever built with, the most sensitive set of light detectors ever assembled for a space mission, using 106 CCDs with nearly 1 billion pixels covering an area of 2.8 square metres
After launch, Gaia will always point away from the Sun. L2 offers a stable thermal environment, a clear view of the Universe as the Sun, Earth and Moon are always outside the instruments’ fields of view, and a moderate radiation environment. However Gaia must still be shielded from the heat of the Sun by a giant shade to keep its instruments in permanent shadow. A ‘skirt’ will unfold consisting of a dozen separate panels. These will deploy to form a circular disc about 10 m across. This acts as both a sunshade, to keep the telescopes stable at below –100°C, and its surface will be partially covered with solar panels to generate electricity.
Once testing is completed the payload module will be mated to the service module at the beginning of next year and Gaia will be launched from Europe’s Spaceport in French Guiana at the end of 2013.
Find out more about the mission here