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  • richardmitnick 12:27 pm on February 14, 2019 Permalink | Reply
    Tags: "Pulses from a Dead Star, , , , , , Little Green Men and a Historic Discovery", Pulsars- fast-spinning neutron stars, U Arizona, UA's Mt. Lemmon Sky Center, , Walter Baade-discovered the Crab Nebula   

    From University of Arizona: “Pulses from a Dead Star, Little Green Men and a Historic Discovery” 

    U Arizona bloc

    From University of Arizona

    1
    John Cocke (Photo courtesy of Nathaniel Johnston/njohnstonphotography.com)

    Feb. 8, 2019
    Daniel Stolte

    In January 1969, only months before Neil Armstrong would step onto the moon, three UA scientists were the first to detect the optical flash from a pulsar — a stellar corpse thought to pack at least one-and-a-half times the mass of our sun into a city-sized, fast-spinning neutron star.

    Fifty years ago, a team of three undeterred University of Arizona astrophysicists huddled around a 36-inch telescope inside the dome of the UA’s observatory on top of Kitt Peak.

    U Arizona Steward Observatory at Kitt Peak, AZ, USA, altitude 2,096 m (6,877 ft)

    With cobbled-together electronic equipment, W. John Cocke, Mike Disney and Don Taylor and made a historic discovery: the first detection of light flashes coming from a pulsar, a fast-spinning neutron star.

    On Jan. 15, a public lecture at the UA’s Steward Observatory recounted the discovery. In the audience was none other than Cocke, a member of the original team and now professor emeritus. Cocke spoke to UANews about those few days in January 1969 that spawned a new field in astrophysics: the science of pulsars, ultra-dense corpses of formerly massive stars whose bizarre nature is only surpassed by black holes.

    2
    Located about 6,500 light-years from Earth in the constellation Taurus, the Crab Nebula is still expanding at a rate of more than 600 miles per second. (Image: Adam Block/UA Mt. Lemmon Sky Center)

    U Arizona Catalina Sky Survey, on Mount Lemmon, AR, USA, 9,171 ft (2,795 m)

    What are pulsars, and what can they tell us about the universe?
    Cocke: Pulsars are rotating neutron stars, which are the cores of exploded stars. A pulsar essentially is a rotating magnet, which generates an electric field, and these things are spinning so rapidly that the electric field is sucking material out from the surface of the star. That generates the high-intensity emission in radio, optical and ultraviolet wavelengths, even gamma rays. Out of each magnetic pole comes a continuous beam of electromagnetic emission as the thing rotates around. In order for us to see pulsars, their magnetic field axis has to be offset from the rotation axis, so their beam sweeps around like a lighthouse. As the beam sweeps past the Earth, we can see right down the pole just briefly as it flashes past, creating the sensation of seeing a pulse.

    In a way, pulsars teach us only about the very violent fates of the few stars that are massive enough to blow themselves completely to smithereens or collapse into a neutron star and finally a black hole. Most stars are going to die very, very slowly, and as the universe continues to expand, everything gets cooler and cooler, and the universe then dies, as T.S. Eliot would say, “not with a bang, but a whimper.”

    When your boss, Steward Observatory Director Bart Bok, learned about your observations and what you found, he was “horrified.” Why?
    Cocke: Because only one of us (Taylor) had experience with telescopes and instrumentation. Mike Disney and I were theorists, and the whole thing was so improbable, you see, that nobody, including us, thought that we would actually find something. A month before, I had asked a number of pundits at the American Astronomical Society Meeting whether it was a good idea or just a waste of time to look for this thing in the middle of the Crab Nebula, and they said, “Don’t bother, it won’t pan out.”

    2
    John Cocke next to the 21-inch telescope at Steward Observatory on the UA campus. (Photo courtesy of Nathaniel Johnston/njohnstonphotography.com)

    How did the project come about?
    Cocke: The first radio signals from what we now know are pulsars were detected by by Jocelyn Bell and Antony Hewish in the autumn of 1967.

    Women in STEM – Dame Susan Jocelyn Bell Burnell

    Dame Susan Jocelyn Bell Burnell, discovered pulsars with radio astronomy. Jocelyn Bell at the Mullard Radio Astronomy Observatory, Cambridge University, taken for the Daily Herald newspaper in 1968. Denied the Nobel.

    Dame Susan Jocelyn Bell Burnell 2009

    Dame Susan Jocelyn Bell Burnell (1943 – ), still working from http://www. famousirishscientists.weebly.com

    At that point, radio astronomers were really concerned how something as massive as a star could emit pulses that were only a second or a second and a half long. The first joke that came out was that these were radio signals from advanced civilizations, which became known as the LGM, the “Little Green Men” idea. Of course, nobody really believed that except people wearing tin foil helmets.

    At first the signals were believed to come from white dwarfs (burned-out stars similar to our sun) as they expanded and contracted. But then a very fast pulsating star was discovered in the Vela constellation in the Southern Hemisphere emitting pulses lasting one-tenth of a second, and that blew the white-dwarf theory right out of the water.

    In early November 1968, radio astronomers discovered this thing associated with the Crab Nebula that emitted about 30 pulses per second. At that point, everybody understood that they had to be neutron stars, and I had wondered about looking for optical counterparts of these things for a few months before. This pulsar, then, that was located rather near the Crab Nebula made me think of a very peculiar star in the middle of the Crab Nebula named for its discoverer, Swiss astronomer Walter Baade. He recognized that star was very peculiar and may be the collapsed remnant of the supernova explosion that had created the nebula itself. It is emitting a lot of light and even shows up on old photographic plates taken of the Crab Nebula. Mike Disney and I then teamed together, once we realized we were both theoreticians interested in gaining some experience doing observing. He suggested we cobble together some instrumentation that would allow us to do this.

    How did you go about making the first optical observations of a neutron star?
    Cocke: We were looking into a pretty broad spectrum in the visible light spectrum, and we knew that any optical signal coming through the 36-inch telescope from Baade’s star would be pretty faint. We weren’t really sure what was needed, except that we needed something that allowed us to build up signals in a computer synced to the pulsar itself, so we could gather up enough signal with overlapping pulses coming in that we could build up a detection out of the noise.

    Interestingly, there was a report in the 1950s about an experienced pilot who looked at Baade’s star during a public telescope viewing and remarked that it appeared to flash, but her observation was dismissed. However, we did not know this at the time. We knew there were other groups of astronomers looking at pulsars with slower signal frequency, and they were not having success. We attached a photometer to the telescope and connected that to an off-the-shelf device called CAT – computer of average transients – which had a total memory of 400 bytes and could build up a signal above the noise so you could actually see something interesting. All of this instrumentation was put together properly by Don Taylor, and he became the third member of the team.

    Can you tell us about the night of the discovery?
    Cocke: The first two nights were clear but wasted because I had made a mistake in calculating the Doppler shift due to Earth’s motion through space. A few cloudy nights followed, and we ran out of our allocated observing time. But it turned out that our colleague Bill Tifft was able to give us some of his observing nights because he had to take care of a family emergency. On January 15, within a few minutes of observing, we could see the pulse as it built up on the screen. We moved the telescope off Baade’s star to a nearby star or just a blank spot to see whether or not the signal would still come through like that, and it didn’t. Then we’d move it back on the pulsar but change the frequency setting so it was off, and we didn’t see that signal, so that was a good check. We then rechecked everything and did another round on the proper position and at the proper period, and the pulse would come up again. These were all checks we had to run to make sure this thing was real. On our screen, we saw a big main pulse and a smaller, secondary pulse – the exact pattern we expected from what the radio pulses look like. That was the final clincher.

    Are there any practical applications for pulsar science?
    Cocke: No. (pauses) Sorry about that.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    U Arizona campus

    The University of Arizona (UA) is a place without limits-where teaching, research, service and innovation merge to improve lives in Arizona and beyond. We aren’t afraid to ask big questions, and find even better answers.

    In 1885, establishing Arizona’s first university in the middle of the Sonoran Desert was a bold move. But our founders were fearless, and we have never lost that spirit. To this day, we’re revolutionizing the fields of space sciences, optics, biosciences, medicine, arts and humanities, business, technology transfer and many others. Since it was founded, the UA has grown to cover more than 380 acres in central Tucson, a rich breeding ground for discovery.

    Where else in the world can you find an astronomical observatory mirror lab under a football stadium?

    U Arizona mirror lab


    An entire ecosystem under a glass dome? Visit our campus, just once, and you’ll quickly understand why the UA is a university unlike any other.

     
  • richardmitnick 12:24 pm on January 27, 2019 Permalink | Reply
    Tags: Anything that happens to one photon in an entangled pair will be transferred to the other one as well, , , , Fourth Industrial Revolution, Inquire-Quantum Information Research and Engineering instrument, Quantum communication is a secure method of sending and receiving data that's designed to preclude eavesdropping, , Quantum Information and Materials Group, , U Arizona, Ultrasensitive cameras see things at the single photon level   

    From University of Arizona: “Interdisciplinary UA Researchers Get Tangled Up in Quantum Computing” 

    U Arizona bloc

    From University of Arizona

    Jan. 25, 2019
    Emily Dieckman

    UA researchers are building a quantum hub known as Inquire, which will be the world’s first shared research and training instrument to help researchers in diverse fields benefit from quantum resources.

    1
    Conceptual artwork of a pair of entangled quantum particles interacting. (Photo: Mark Garlick/Science Photo Library)

    Good neighbors often share resources: a cup of sugar, extra lawn chairs, a set of jumper cables. Researchers across campus at the University of Arizona will soon be able to share a less common – and far more valuable – resource to help them further their research: entangled photons, or interlinked pairs of light particles.

    With approximately $1.4 million in funding – $999,999 from the National Science Foundation and about $400,000 from the UA – professor Zheshen Zhang is leading the construction of the Interdisciplinary Quantum Information Research and Engineering instrument, known as Inquire, at the UA. Inquire is the world’s first shared research and training instrument to help researchers in diverse fields – including those with no expertise in quantum information science – benefit from quantum resources.

    Zhang is an assistant professor of materials science and engineering and optical sciences, and the leader of the Quantum Information and Materials Group at the UA. The co-investigators of the Inquire project include Ivan Djordjevic, professor of electrical and computer engineering and optical sciences; Jennifer Barton, director of the BIO5 Institute and professor of biomedical engineering, biosystems engineering, electrical and computer engineering, and optical sciences; Nasser Peyghambarian, professor of optical sciences; and Marek Romanowski, associate professor of biomedical engineering, and materials science and engineering.

    A network of fiber-optic cables will connect an automated quantum information hub in the basement of the Electrical and Computer Engineering building to four other buildings on campus: Biosciences Research Labs, Mines and Metallurgy, Physics and Atmospheric Sciences, and Meinel Optical Sciences.

    “One of the joys of the UA is collaborating with top scholars working in cutting-edge fields,” Barton said. “It seems like science fiction, but Zheshen is building a facility that will create quantum-entangled photons, then deliver them via fiber optics halfway across campus, right into the Translational Bioimaging Resource in the Biosciences Research Labs building.”

    “This is an exciting project that perfectly represents some of the key themes underlying our strategic plan,” said UA President Robert C. Robbins. “To be a leader in the Fourth Industrial Revolution, we must leverage collaboration, stay ahead of the technology curve and provide a high-powered environment where researchers have the tools they need to solve the world’s grand challenges. I look forward to seeing the new opportunities this facility brings once it is completed.”

    Construction on the project already has begun. The expected completion date is September 2021.

    Seeing Individual Photons

    Much like an atom is the smallest unit of matter, a photon is the smallest unit of light. So, while we can see the light of tens of billions of photons in a room lit by a lamp or a courtyard lit by the sun, the human eye – and most microscopes – can’t see individual photons. But sometimes this too-small-to-see information can be important. For example, a biomedical engineering lab might be doing an imaging study on a protein or an organic molecule that’s emitting a signal too weak for traditional cameras to see.

    “You can send your photons to the core facility, which is equipped with an array of ultrasensitive cameras that can see things at the single photon level,” Zhang said.

    Traditionally, researchers used high-powered lasers to illuminate these biological samples, which were sometimes damaged in the process. Using entangled photons as an illumination source provides higher sensitivity, less illuminating power, and the same – or even higher – resolution.

    “Two entangled photons can be worth a million of their classical brethren, potentially allowing us to image deeper without harming tissue,” Barton said.

    High-Precision Probing

    These fiber-optic cables are a two-way street. Researchers can send their photons into the central hub to be imaged by the high-tech microscopes, but the center can also share entangled photons with labs across campus.

    Entangled photons are interlinked pairs. Even when they’re separated by large distances, anything that happens to one photon in an entangled pair will be transferred to the other one as well.

    This relationship has several uses. For example, researchers can use photons as probes to help determine the nature of unidentified materials. The changes a material introduces to a photon, such as a change in color, provide clues to the material’s identity. When one entangled photon in a pair is used as a probe, the material introduces changes to both photons in the entangled pair.

    “Now you can perform a measurement on both photons to learn about the sample being probed,” Zhang said. “You can have twice as much information about the way the material is affecting the photon.”

    Secure Communications

    Entangled photons can also be used in quantum communication, a secure method of sending and receiving data that’s designed to preclude eavesdropping. It works like this: Before Party A shares any sensitive information with Party B, Party A sends a “quantum key,” a series of entangled photons that serves as the code for decrypting future transmissions. Quantum keys are designed so that the very act of decrypting or reading their contents changes their contents.

    If the quantum key arrives with any parts decrypted, the communicating parties know not to use that part of the key to encrypt future transmissions, because it has been “read” by hackers. The communicating parties can simply cut out that part of the key and use a new, shorter quantum key they know is secure.

    Party A and Party B in the above example don’t need to be quantum information scientists. Researchers across all kinds of disciplines can benefit from the unique features of entangled photons, and Inquire’s aim is to allow for just that.

    “This is a key area that the National Science Foundation identifies as one of its 10 Big Ideas and really wants to push forward because it is so interdisciplinary,” Zhang said. “It involves researchers across the boundaries of science, engineering, computer science, physics, chemistry, math, optics – everywhere. The key question is ‘How can everybody speak the same language, and how can they benefit from the progress made in other areas?'”

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    U Arizona campus

    The University of Arizona (UA) is a place without limits-where teaching, research, service and innovation merge to improve lives in Arizona and beyond. We aren’t afraid to ask big questions, and find even better answers.

    In 1885, establishing Arizona’s first university in the middle of the Sonoran Desert was a bold move. But our founders were fearless, and we have never lost that spirit. To this day, we’re revolutionizing the fields of space sciences, optics, biosciences, medicine, arts and humanities, business, technology transfer and many others. Since it was founded, the UA has grown to cover more than 380 acres in central Tucson, a rich breeding ground for discovery.

    Where else in the world can you find an astronomical observatory mirror lab under a football stadium?

    U Arizona mirror lab


    An entire ecosystem under a glass dome? Visit our campus, just once, and you’ll quickly understand why the UA is a university unlike any other.

     
  • richardmitnick 12:48 pm on January 20, 2019 Permalink | Reply
    Tags: ahu (shrine) monuments, Ahu are associated with freshwater sources in a way that they aren't associated with other resources, , Rapa Nui better known as Easter Island, U Arizona   

    From University of Arizona: “Solving the Ancient Mysteries of Easter Island” 

    U Arizona bloc

    From University of Arizona

    Jan. 10, 2019

    1
    Terry Hunt is one of the world’s foremost experts on the Pacific Islands, which includes Rapa Nui, better known as Easter Island.

    New research PLoS One shows that Rapa Nui islanders built their iconic monuments close to freshwater sources.

    The ancient people of Rapa Nui, Chile, better known as Easter Island, built their famous ahu monuments near coastal freshwater sources, according to a team of researchers including faculty at the University of Arizona.

    The island of Rapa Nui is well-known for its elaborate ritual architecture, particularly its numerous statues, or moai, and ahu, the monumental platforms that supported them. Researchers have long wondered why ancient people built these monuments in their respective locations around the island, considering how much time and energy was required to construct them.

    A team of researchers led by Robert DiNapoli of the University of Oregon used quantitative spatial modeling to explore the potential relations between ahu construction locations and subsistence resources, namely, rock mulch agricultural gardens, marine resources and freshwater sources – the three most critical resources on Rapa Nui. Their results suggest that ahu locations are explained by their proximity to the island’s limited freshwater sources.

    “Many researchers, ourselves included, have long speculated associations between ahu, moai and different kinds of resources – water, agricultural land, areas with good marine resources, etc.,” said DiNapoli. “However, these associations had never been quantitatively tested or shown to be statistically significant. Our study presents quantitative spatial modeling clearly showing that ahu are associated with freshwater sources in a way that they aren’t associated with other resources.”

    2
    Locations of ahu with statues on Rapa Nui. Image via PLoS One.

    The proximity of the monuments to freshwater tells us a great deal about the ancient island society, said Terry Hunt, a professor of anthropology at the UA and Dean of the Honors College.

    “The monuments and statues are located in places with access to a resource critical to islanders on a daily basis – fresh water,” said Hunt, who has been researching the Pacific Islands for more than 30 years and has directed archaeological field research on Rapa Nui since 2001. “In this way, the monuments and statues of the islanders’ deified ancestors reflect generations of sharing, perhaps on a daily basis, centered on water, but also food, family and social ties, as well as cultural lore that reinforced knowledge of the island’s precarious sustainability.

    “The sharing points to a critical part of explaining the island’s paradox: despite limited resources, the islanders succeeded by sharing in activities, knowledge and resources for over 500 years until European contact disrupted life with foreign diseases, slave trading and other misfortunes of colonial interests,” Hunt added.

    The researchers currently only have comprehensive freshwater data for the western portion of the island and plan to do a complete survey of the island in order to continue to test their hypothesis of the relation between ahu and freshwater.

    “The issue of water availability, or the lack of it, has often been mentioned by researchers who work on Rapa Nui,” said Carl Lipo of Binghamton University in New York. “When we started to examine the details of the hydrology, we began to notice that freshwater access and statue location were tightly linked together. It wasn’t obvious when walking around – with the water emerging at the coast during low tide, one doesn’t necessarily see obvious indications of water – but as we started to look at areas around ahu, we found that those locations were exactly tied to spots where the fresh groundwater emerges, largely as a diffuse layer that flows out at the water’s edge. The more we looked, the more consistently we saw this pattern. This paper reflects our work to demonstrate that this pattern is statistically sound and not just our perception.”

    Also contributing to this research were Matthew Becker and Tanya Brosnan of California State University, Long Beach, Sean Hixon of Pennsylvania State University, and Alex E. Morrison of the University of Auckland.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    U Arizona campus

    The University of Arizona (UA) is a place without limits-where teaching, research, service and innovation merge to improve lives in Arizona and beyond. We aren’t afraid to ask big questions, and find even better answers.

    In 1885, establishing Arizona’s first university in the middle of the Sonoran Desert was a bold move. But our founders were fearless, and we have never lost that spirit. To this day, we’re revolutionizing the fields of space sciences, optics, biosciences, medicine, arts and humanities, business, technology transfer and many others. Since it was founded, the UA has grown to cover more than 380 acres in central Tucson, a rich breeding ground for discovery.

    Where else in the world can you find an astronomical observatory mirror lab under a football stadium?

    U Arizona mirror lab


    An entire ecosystem under a glass dome? Visit our campus, just once, and you’ll quickly understand why the UA is a university unlike any other.

     
  • richardmitnick 11:25 am on December 27, 2018 Permalink | Reply
    Tags: , , , , Everything around you – your desk your laptop your coffee cup – in fact even you – is made of stardust, Stellar Corpse Reveals Clues to Missing Stardust, U Arizona, Young planetary nebula K4-47, your laptop   

    From University of Arizona: “Stellar Corpse Reveals Clues to Missing Stardust” 

    U Arizona bloc

    From University of Arizona

    Dec. 19, 2018
    Daniel Stolte

    1
    (Nixxphotography/iStock)

    Everything around you – your desk, your laptop, your coffee cup – in fact, even you – is made of stardust, the stuff forged in the fiery furnaces of stars that died before our sun was born. Probing the space surrounding a mysterious stellar corpse, scientists at the University of Arizona have made a discovery that could help solve a long-standing mystery: Where does stardust come from?

    When stars die, they seed the cosmos around them with the elements that go on to coalesce into new stars, planets, asteroids and comets. Most everything that makes up Earth, even life itself, consists of elements made by previous stars, including silicon, carbon, nitrogen and oxygen. But this is not the whole story. Meteorites commonly contain traces of a type of stardust that, until now, was believed to form only in exceptionally violent, explosive events of stellar death known as novae or supernovae – too rare to account for the abundance preserved in meteorites.

    Researchers at the UA used radio telescopes in Arizona and Spain to observe gas clouds in the young planetary nebula K4-47, an enigmatic object approximately 15,000 light-years from Earth. Classified as a nebula, K4-47 is a stellar remnant, which astronomers believe was created when a star not unlike our sun shed some of its material in a shell of outflowing gas before ending its life as a white dwarf.

    To their surprise, the researchers found that some of the elements that make up the nebula – carbon, nitrogen and oxygen – are highly enriched with certain variants that match the abundances seen in some meteorite particles but are otherwise rare in our solar system: so-called heavy isotopes of carbon, nitrogen and oxygen, or 13C, 15N and 17O, respectively. These isotopes differ from their more common forms by containing an extra neutron inside their nucleus.

    Fusing an additional neutron onto an atomic nucleus requires extreme temperatures in excess of 200 million degrees Fahrenheit, leading scientists to conclude those isotopes could only be formed in novae – violent outbursts of energy in aging binary star systems – and supernovae, in which a star blows itself apart in one cataclysmic explosion.

    “The models invoking only novae and supernovae could never account for the amounts of 15 N and 17 O we observe in meteorite samples,” said Lucy Ziurys, senior author of the paper, which is published in the Dec. 20 issue of the journal Nature. “The fact that we’re finding these isotopes in K4-47 tells us that we don’t need strange exotic stars to explain their origin. It turns out your average garden variety stars are capable of producing them as well.”

    2
    At 15,000 light-years, object K4-47 is about seven times farther away than the Twin Jet nebula, making it much more difficult to image. Based on what scientists have learned about K4-47 so far, it may have a similar structure of two lobes extending from the white dwarf in the center. (Image: Sloan Digital Sky Survey)

    In lieu of cataclysmic explosive events forging heavy isotopes, the team suggests they could be produced when an average-size star such as our sun becomes unstable toward the end of its life and undergoes a so-called helium flash, in which super-hot helium from the star’s core punches through the overlaying hydrogen envelope.

    “This process, during which the material has to be spewed out and cooled quickly, produces 13 C, 15 N and 17 O,” explained Ziurys, a professor with dual appointments in the UA’s Steward Observatory and Department of Chemistry and Biochemistry. “A helium flash doesn’t rip the star apart like a supernova does. It’s more like a stellar eruption.”

    The findings have implications for the identification of stardust and the understanding of how common stars create elements such as oxygen, nitrogen and carbon, the authors said.

    The discovery was made possible through a collaboration between disciplines that traditionally have remained relatively separate: astronomy and cosmochemistry. The team used radio telescopes at the Arizona Radio Observatory and Institut de Radioastronomie Millimetrique (IRAM) to observe rotational spectra emitted by the molecules in the K4-47 nebula, which reveal clues about their mass distribution and their identity.

    Arizona Radio Observatory at Kitt Peak, AZ USA, U Arizona Steward Observatory at altitude 2,096 m (6,877 ft)

    IRAM 30m Radio telescope, on Pico Veleta in the Spanish Sierra Nevada,, Altitude 2,850 m (9,350 ft)

    “When Lucy and I started collaborating on this project, we realized that we could reconcile what we found in meteorites and what we observe in space,” said co-author Tom Zega, associate professor of cosmochemistry, planetary materials and astrobiology in the UA’s Lunar and Planetary Laboratory.

    The researchers are eagerly awaiting the discoveries that lie ahead for NASA’s OSIRIS-REx asteroid sample return mission, which is led by the UA. Just two weeks ago, the spacecraft arrived at its target asteroid, Bennu, from which it will collect a sample of pristine material in 2020. One of the mission’s major goals is to understand the evolution of Bennu and the origins of the solar system.

    “You can think of the grains we find in meteorites as stellar ashes, left behind by stars that had long died when our solar system formed,” Zega said. “We expect to find those pre-solar grains on Bennu – they are part of the puzzle of the history of this asteroid, and this research will help define where the material on Bennu came from.”

    “We can now trace where those ashes came from,” Ziurys added. “It’s like an archeology of stardust.”

    “The study of explosive helium burning inside stars will start a new chapter in the story of the origin of the chemical elements,” said Neville “Nick” Woolf, Professor Emeritus at Steward Observatory and the fourth co-author.

    The article’s first author is Deborah Schmidt, a doctoral student at the Steward Observatory.

    This research was funded by the National Science Foundation (Grant No. AST- 1515568) and NASA (Agreement No. NNX15AD94G).

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    U Arizona campus

    The University of Arizona (UA) is a place without limits-where teaching, research, service and innovation merge to improve lives in Arizona and beyond. We aren’t afraid to ask big questions, and find even better answers.

    In 1885, establishing Arizona’s first university in the middle of the Sonoran Desert was a bold move. But our founders were fearless, and we have never lost that spirit. To this day, we’re revolutionizing the fields of space sciences, optics, biosciences, medicine, arts and humanities, business, technology transfer and many others. Since it was founded, the UA has grown to cover more than 380 acres in central Tucson, a rich breeding ground for discovery.

    Where else in the world can you find an astronomical observatory mirror lab under a football stadium?

    U Arizona mirror lab


    An entire ecosystem under a glass dome? Visit our campus, just once, and you’ll quickly understand why the UA is a university unlike any other.

     
  • richardmitnick 1:29 pm on November 29, 2018 Permalink | Reply
    Tags: , , , , , OSIRIS-REx asteroid sample return mission, U Arizona   

    From University of Arizona: “We’re at Bennu! What’s Next?” 

    U Arizona bloc

    From University of Arizona

    Nov. 28, 2018
    Daniel Stolte

    1

    The UA-led OSIRIS-REx mission kicks into high gear while the spacecraft is on its final approach, closing in on asteroid Bennu and scheduled for arrival on Dec. 3. UA mission experts explain what comes next.

    NASA OSIRIS-REx Spacecraft

    Since it launched on Sept. 8, 2016, the spacecraft of the University of Arizona-led OSIRIS-REx asteroid sample return mission has been catching up with its destination, asteroid Bennu, on its trip around the sun. On Dec. 3, the spacecraft is scheduled for arrival. UANews asked mission experts about what lies ahead for the robotic explorer and its human companions here on Earth.

    Once OSIRIS-REx arrives at Bennu, why will it have to stay in orbit for two years before going for the sampling?

    Dante Lauretta, OSIRIS-REx Principal Investigator: “The OSIRIS-REx spacecraft will enter orbit around Bennu by moving at a very slow velocity, relative to the asteroid, on the order of 4 inches (10 centimeters) per second. To accomplish this feat, we must characterize the mass, shape and rotation state of the asteroid. Fortunately, the equations for orbital stability hold even for a very low mass object like Bennu. The challenge lies in the fact that other forces acting on the spacecraft, such as solar radiation pressure, spacecraft outgassing and thermal radiation, are of the same order of magnitude as Bennu’s gravity. The team must perform regular optical navigation-based orbit determination. This process is not required to keep us in orbit. Instead, it is needed for us to understand where in the orbit we are. Although small, these forces can move the spacecraft by as much as 180 degrees along its track within a few short days. If we lost track of the spacecraft position in orbit, we would not know where to point the science instruments to collect our data.”

    Christian Drouet d’Aubigny, OSIRIS-REx Camera Suite Deputy Instrument Scientist: “We need to know exactly where we are with respect to Bennu. To an astronaut, it would be obvious: “The asteroid is over there and all I have to do is point the camera.” But with a robot, it’s always a challenge. The spacecraft knows exactly where it is with respect to stars, because it knows the constellations it sees with great precision, but it doesn’t know exactly where it is with respect to Bennu. When we plan our operations, weeks ahead of time, we have to take into account that when we execute the observation, the spacecraft position with respect to Bennu won’t be known exactly. The spacecraft’s own knowledge of where it is located is based on observations that are at least a day old. It knows where it should be based on where it was yesterday.”

    Bashar Rizk, OSIRIS-REx Camera Suite Instrument Scientist: “We don’t have all the information we need to successfully and safely take a sample from the asteroid at this time. We have given ourselves enough time and margin to gather all the information we need to be able to analyze and chew on that information so it can successfully inform the next step in the process.”

    How does the spacecraft stay in orbit around Bennu?

    Rizk: “Driving a spacecraft around an object like Bennu is a fine art, and we’re learning it as we go along. Unlike a spacecraft that orbits a planet such as Mars, the relative velocities are not high – we are crawling along – but because the gravitational forces are so weak, other effects begin to matter. Our spacecraft is constantly exposed to solar pressure and thermal asymmetry: whichever side happens to be facing the sun gets warmer and emits its own thermal radiation. That radiation carries momentum – a very slight momentum, but given enough time, it is going to make itself felt. In addition, you have the effects of the micro-thrusting maneuvers that help us move around. So far, every aspect about this object has been very successfully predicted, so we have high hopes, but there is no denying that there are challenges.”

    What “eyes” does the spacecraft use to see and study the asteroid?

    d’Aubigny: “The spacecraft has three science cameras – all were built here at the University of Arizona – PolyCam, MapCam and SamCam, plus a suite of wide-angle cameras made by Malin Space Science Systems for Lockheed Martin that are used for navigation. When the asteroid still was far away, we used PolyCam to acquire the first images from 1.2 million miles (2 million kilometers) away because it is the most sensitive of all the OSIRIS-REx cameras. On Nov. 15, when the spacecraft was only 75 miles (120 km) from Bennu, we switched to MapCam. We are progressively switching from higher magnification and narrower field of view to lower magnification and a wider field of view. It’s similar to what you would do with an optical zoom lens, but done with different cameras. MapCam and PolyCam will be used to study the asteroid from up close. MapCam is going to map Bennu’s surface. As we go past the asteroid and see different parts, we will point the spacecraft in various directions, take mosaic images and stitch them together. We’ll go through different phases, getting progressively closer to Bennu, starting from 12.4 miles (20 km) and getting into orbit as close as .9 mile (1.5 km) from the asteroid. The closest approach will be is when we do our reconnaissance passes at 656 feet (200 meters) above the surface. The images with the highest resolution will be taken by PolyCam, which will serve as our high-power telephoto lens. At closest approach, the field of view comes down to a 10-foot-by-10-foot (3 m) square, or approximately the size of a bedroom, and with enough resolving power we could see a pea on a table. Using MapCam, which has not quite the high resolution and magnification of PolyCam, we’re going to map the whole surface down to a scale of one-quarter of a meter (.82 feet), about the size of a soccer ball.”

    How will you prepare for the sampling?

    d’Aubigny: “Based on the images and combined information from all the instruments, such as LIDAR and the spectrometers, we will narrow down the search for sites that are interesting from a science standpoint, have the surface with material of the size we need for sampling and are free of hazards. We have to focus on up to five sites, we will image those with really high resolution with PolyCam from orbit, but also as we narrow down that list, at some point we will have just two – a primary and a secondary samples site – and that is where we will do the close reconnaissance passes.”

    Dani DellaGiustina, Lead Image Processing Scientist: “The first thing we need to do before we can start mapping the surface and finding anything that could pose a hazard to the sampling mechanism is to relate the images taken by our cameras to the shape model of the asteroid. To do this, we take the images and map them into something that is similar to Google Earth, a special framework on which we can co-locate the features. We take two approaches to mapping out hazards: one is old-fashioned counting. Keara Burke, a UA undergraduate student who has taken the initiative to develop software for this project, is leading that work. Her team will count boulders on Bennu’s surface. The other is using a crowdsourcing effort: we want to triage the areas that look really smooth and map them out. For this, we are partnering with CosmoQuest, a citizen science program. Early next year, we’re going to launch “Bennu Mappers,” which will enable citizen scientists to help OSIRIS-REx map the locations and the sizes of all the boulders on Bennu. We define any boulder that is bigger than 8.3 inches (21 cm) as a hazard, because that is the width of the inner chamber of our sampling mechanism and it could become clogged. When we’ve gotten to the point where we’ve mapped the surface to where we have narrowed down two potential sampling sites, we will look at cobbles and pebbles while searching for anything as small as .8 inch (2 cm). Particles that size or smaller are easily ingested by our sampling mechanism.”

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    U Arizona campus

    The University of Arizona (UA) is a place without limits-where teaching, research, service and innovation merge to improve lives in Arizona and beyond. We aren’t afraid to ask big questions, and find even better answers.

    In 1885, establishing Arizona’s first university in the middle of the Sonoran Desert was a bold move. But our founders were fearless, and we have never lost that spirit. To this day, we’re revolutionizing the fields of space sciences, optics, biosciences, medicine, arts and humanities, business, technology transfer and many others. Since it was founded, the UA has grown to cover more than 380 acres in central Tucson, a rich breeding ground for discovery.

    Where else in the world can you find an astronomical observatory mirror lab under a football stadium?

    U Arizona mirror lab


    An entire ecosystem under a glass dome? Visit our campus, just once, and you’ll quickly understand why the UA is a university unlike any other.

     
  • richardmitnick 2:19 pm on October 25, 2018 Permalink | Reply
    Tags: , , , , Phaeton blue asteroid, Rare Blue Asteroid Reveals Itself During Fly-By, U Arizona   

    From University of Arizona: “Rare Blue Asteroid Reveals Itself During Fly-By” 

    U Arizona bloc

    From University of Arizona

    10.25.18
    Teddy Kareta
    UA Lunar and Planetary Laboratory

    1
    An artist’s illustration of what Phaeton might look like up close. (Image: Heather Roper)

    A team led by UA doctoral student Teddy Kareta obtained a rare glimpse of the bizarre, blue asteroid that is responsible for Geminid Meteor Shower.

    Blue asteroids are rare, and blue comets are almost unheard of. An international team led by Teddy Kareta, a doctoral student at the University of Arizona’s Lunar and Planetary Laboratory, investigated (3200) Phaethon, a bizarre asteroid that sometimes behaves like a comet, and found it even more enigmatic than previously thought.

    Kareta presented the results during a press conference on Oct. 23 at the 50th annual meeting of the American Astronomical Society’s Division for Planetary Science in Knoxville, Tennessee.

    Using telescopes in Hawaii and Arizona, the team studied sunlight reflected off Phaethon, which is known to be blue in color. Blue asteroids, which reflect more light in the blue part of the spectrum, make up only a fraction of all known asteroids. A majority of asteroids are dull grey to red, depending on the type of material on their surface.

    Phaethon sets itself apart for two reasons: it appears to be one of the “bluest” of similarly colored asteroids or comets in the solar system; and its orbit takes it so close to the sun that its surface heats up to about 800 degrees Celsius (1,500 degrees Fahrenheit), hot enough to melt aluminum.

    Astronomers have been intrigued by Phaethon for other reasons, too. It has the qualities of both an asteroid and a comet based on its appearance and behavior.

    Phaethon always appears as a dot in the sky, like thousands of other asteroids, and not as a fuzzy blob with a tail, like a comet. But Phaethon is the source of the annual Geminid meteor shower, easily seen in early-to-mid December.

    Meteor showers occur when Earth passes through the trail of dust left behind on a comet’s orbit. When they occur and where they appear to originate from depends on how the comet’s orbit is oriented with respect to the Earth. Phaethon is thought to be the “parent body” of the Geminid meteor shower because its orbit is very similar to the orbit of the Geminid meteors.

    Until Phaeton was discovered in 1983, scientists linked all known meteor showers to active comets and not asteroids.

    “At the time, the assumption was that Phaethon probably was a dead, burnt-out comet,” Kareta said, “but comets are typically red in color, and not blue. So, even though Phaeton’s highly eccentric orbit should scream ‘dead comet,’ it’s hard to say whether Phaethon is more like an asteroid or more like a dead comet.”

    Phaethon also releases a tiny dust tail when it gets closest to the sun in a process that is thought to be similar to a dry riverbed cracking in the afternoon heat. This kind of activity has only been seen on two objects in the entire solar system – Phaeton and one other, similar object that appears to blur the line traditionally thought to set comets and asteroids apart.

    The team obtained several new insights about Phaethon after analyzing data obtained from NASA’s Infrared Telescope Facility on Mauna Kea in Hawaii and the Tillinghast telescope, operated by the Smithsonian Astrophysical Observatory on Mount Hopkins in Arizona. They think Phaethon might be related or have broken off from (2) Pallas, a large blue asteroid farther out in the solar system.

    NASA Infrared Telescope facility Mauna Kea, Hawaii, USA, 4,207 m (13,802 ft) above sea level

    CfA Whipple 1.5 meter Tillinghast telescope

    “Interestingly, we found Phaethon to be even darker than had been previously observed, about half as reflective as Pallas,” Kareta said. “This makes it more difficult to say how Phaethon and Pallas are related.”

    The team also observed that Phaethon’s blue color is the same on all parts of its surface, which indicates it has been cooked evenly by the Sun in the recent past.

    The team is now conducting observations of 2005 UD, another small blue asteroid astronomers think is related to Phaethon, to see if they share the same rare properties. This and follow-up work will help to untangle the mystery of what Phaethon is really like.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    U Arizona campus

    The University of Arizona (UA) is a place without limits-where teaching, research, service and innovation merge to improve lives in Arizona and beyond. We aren’t afraid to ask big questions, and find even better answers.

    In 1885, establishing Arizona’s first university in the middle of the Sonoran Desert was a bold move. But our founders were fearless, and we have never lost that spirit. To this day, we’re revolutionizing the fields of space sciences, optics, biosciences, medicine, arts and humanities, business, technology transfer and many others. Since it was founded, the UA has grown to cover more than 380 acres in central Tucson, a rich breeding ground for discovery.

    Where else in the world can you find an astronomical observatory mirror lab under a football stadium?

    U Arizona mirror lab


    An entire ecosystem under a glass dome? Visit our campus, just once, and you’ll quickly understand why the UA is a university unlike any other.

     
  • richardmitnick 8:01 pm on July 26, 2018 Permalink | Reply
    Tags: , , , , , U Arizona, UA Students Find Foundations for Galaxy's Most Massive Stars   

    From University of Arizona: “UA Students Find Foundations for Galaxy’s Most Massive Stars” 

    U Arizona bloc

    From University of Arizona

    In a unique study, University of Arizona astronomy students searched 101 clouds of gas to find those that may be in the first phases of forming massive stars.

    July 25, 2018
    Emily Walla
    NASA Space Grant Intern

    For three years, Jenny Calahan led fellow undergraduate students at the University of Arizona in research to help unravel the mystery of how the galaxy’s most massive stars are born.

    On July 23, just two months after Calahan graduated with a bachelor’s degree in physics and astronomy, the resulting research paper, Searching for Inflow Towards Massive Starless Clump Candidates Identified in the Bolocam Galactic Plane Survey, was published in The Astrophysical Journal. Her co-authors include students who assisted with the survey and research.

    “There’s still a pretty open question in astronomy when it comes to massive star formation,” Calahan said. “How do stars weighing more than eight solar masses form from clouds of dust and gas?”

    Astronomers understand this process for stars the size of our sun. Particles in clouds are attracted to each other and begin to clump together. Gravity takes hold and the gases flow to the center of the cloud as it collapses. Over millions of years, the gas is put under so much pressure that it begins to burn, and the star is born when nuclear fusion finally begins in the core of the compressed gas.

    Theories about how much gas and time it takes to make a star like our sun can be proven through observations, because each stage of a sun-like star’s life — from the collapse of gas clouds into a pre-stellar core to the star’s expansion into a red giant and collapse into a white dwarf — can be been seen throughout the galaxy.

    But astronomers have yet to understand how stars more than eight times the mass of our sun form. Stars of this size explode into supernovae at the end of their lives, leaving behind black holes or neutron stars.

    “There are a few theories for massive star formation that work in simulations, but we haven’t seen those initial conditions out in the wild universe,” Calahan said.

    One theory is the formation of massive cores, says Yancy Shirley, associate professor in the UA’s Department of Astronomy. The massive cores are dense collections of gas several times larger than the star they create. For massive stars, the cores must be at least 30 times the mass of our sun.

    “People are having trouble finding objects like that,” Shirley said.

    The other theory is that multiple low-mass cores form within a gas clump. The low-mass cores grow as they compete for material in the clump, and eventually, one of the cores grows large enough to form a massive star.

    “This is the debate: which of these two pictures is more correct, or is it some combination of the two?” Shirley said.

    The first step in answering the question is identifying the earliest phase of star formation, so Calahan, under the advisement of Shirley, set out to find clumps showing signs of collapsing gas motion, called “inflow.”

    Calahan selected 101 subjects from a list of more than 2,000 huge, cold and seemingly starless clouds of gas called starless clump candidates, or SCCs.

    Though astronomers have studied SCCs in the past, many of them focused on the brightest and most massive objects. Calahan’s study was unique in that it was a blind survey.

    Ranging in size from a few hundred times the mass of our sun to a few thousand solar masses, the SCCs Calahan selected are a representative sample of all gas clouds that have the potential to form massive stars.

    Using the Arizona Radio Observatory’s 12-meter radio telescope at the UA’s Steward Observatory on Kitt Peak, Calahan detected and tracked radio waves emitted by the molecular gas oxomethylium (HCO+), which emits a specific radio wavelength.

    Arizona Radio Observatory at Kitt Peak, AZ USA, U Arizona Steward Observatory at altitude 2,096 m (6,877 ft)

    Once Shirley and the undergraduate students he advises use the telescope to identify objects of special interest, like collapsing SCCs, the clumps of interest are then further studied using ALMA, which can peer deeper into the gas and find stars or other objects that cannot be seen with the 12-meter telescope.

    ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres

    Oxomethylium, one of the more abundant ion molecules in space, is a highly reactive ion that would not survive in our Earth’s atmosphere. When oxomethylium moves towards an observer, the wavelengths are compressed; when the gas moves away from an observer, the wavelengths are stretched.

    By analyzing the wavelengths, Calahan identified six SCCs that showed the telltale signs of collapse, suggesting that gas collapse happens quickly, accounting for only 6 percent of the formation process of massive stars.

    “One side is falling away from us and one side is falling towards us,” Calahan said.

    “The way we’re using it right now is as a pathfinder,” Shirley said. He and the undergraduate students he advises use the 12-meter telescope to conduct surveys that identify objects of special interest, like collapsing SCC’s. These clumps of interest are then further studied using ALMA, which can peer deeper into the gas and find stars or other objects that cannot be seen with the 12-meter telescope.

    Surveys take many dozens of hours to complete. Calahan and Shirley spent 19 weekends over the course of eight months to study the SCCs.

    “I’ve now seen every part of this research,” Calahan said. “I got to be part of asking the question, observing and doing the data reduction.”

    Groups of undergraduate students traveled with Calahan and Shirley to telescope, where they learned astronomical observation and data analysis techniques.

    “The first time we went up, I learned how to use the telescope and I learned how to analyze the data,” Calahan said. “By the third time, I could teach other students.”

    Shirley has served as adviser to several students who have published the research they did at UA, but Calahan is the first student of his whose paper was accepted before graduation.

    “I don’t think I could have done this at any other university,” Calahan said. “We have the resources and the faculty to teach us how to reduce real-life data and observe on a real-life telescope. That’s really unique to this institution.”

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    U Arizona campus

    The University of Arizona (UA) is a place without limits-where teaching, research, service and innovation merge to improve lives in Arizona and beyond. We aren’t afraid to ask big questions, and find even better answers.

    In 1885, establishing Arizona’s first university in the middle of the Sonoran Desert was a bold move. But our founders were fearless, and we have never lost that spirit. To this day, we’re revolutionizing the fields of space sciences, optics, biosciences, medicine, arts and humanities, business, technology transfer and many others. Since it was founded, the UA has grown to cover more than 380 acres in central Tucson, a rich breeding ground for discovery.

    Where else in the world can you find an astronomical observatory mirror lab under a football stadium?

    U Arizona mirror lab

    An entire ecosystem under a glass dome? Visit our campus, just once, and you’ll quickly understand why the UA is a university unlike any other.

     
  • richardmitnick 12:52 pm on June 15, 2018 Permalink | Reply
    Tags: , , , , Planet-Forming Disks May Resemble Solar System 5 Billion Years Ago, U Arizona   

    From University of Arizona: “Planet-Forming Disks May Resemble Solar System 5 Billion Years Ago” 

    U Arizona bloc

    From University of Arizona

    6.14.18
    Emily Litvack

    The findings, published in The Astrophysical Journal, may provide insights into the birth of our own solar system.

    1
    The Orion Nebula is a star-forming region in the Milky Way, and one of the most famous of the astronomical nebulas. Here, insets show where planetary systems are forming in the Orion. (Image: NASA, ESA, M. Robberto of STScI/ESA, HST Orion Treasury project team, and L. Ricci ESO)

    To make a planet, you need stuff.

    Protoplanetary disks — cosmic frisbees of gas and dust orbiting young stars across the galaxy — spin out new planets. But the size of those planets depends on just how much material these disks have to give.

    A team of scientists led by the University of Arizona has imaged a cluster of protoplanetary disks in the Orion Nebula and discovered that they are smaller than those previously studied in closer, less-dense regions. The smallness of these newly imaged disks suggests that making giant planets such as Jupiter (which is 2.5 times more massive than all the other planets in our solar system combined) could be especially difficult.

    What’s more, the Orion Nebula looks a lot like other planet-forming regions in the Milky Way, meaning our own solar system likely formed in an Orion-like environment. The team’s findings have been published in The Astrophysical Journal.

    The scientists used the largest telescope in the world, an interferometric array of radio telescopes in Chile called ALMA, to observe about 110 protoplanetary disks in the Orion Nebula in the deepest survey of the region yet.

    ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres

    Orion Nebula ESO/VLT

    Orion Nebula M. Robberto NASA ESA Space Telescope Science Institute Hubble

    “The general motivation for the whole field is that we want to understand more about how planets are formed,” says Josh Eisner, a UA professor of astronomy who led the study.

    In their pursuit of that understanding, scientists have spent decades looking to star-forming regions such as Taurus, a mere 500 light-years away (as compared to Orion’s 1,344). While its nearby location makes a slice of the universe such as Taurus easier to observe with less-powerful telescopes, it’s not what one might call a “typical” planet-forming region.

    Orion, on the other hand, with its many stars (and orbiting disks) clustered together in relatively small area, is typical. It requires a more powerful telescope to take sharp observations, but in terms of regions where planets — or entire solar systems — form, it’s a better model.

    “Orion is not at all an oddball region. The disks there look a lot like what we think our solar system looked like when it was a protoplanetary disk,” Eisner says. “And now with the advent of ALMA, we can study regions like Orion well.”

    Based on the images, the team — which also included astronomy and astrophysics graduate student Ryan Boyden, Steward Observatory postdoctoral researchers Nicholas Ballering and Min Fang, Steward Observatory associate astronomer Jinyoung Kim, and Lunar and Planetary Laboratory associate professor Ilaria Pascucci — was able to calculate the mass of protoplanetary disks in the Orion Nebula.

    “Disk mass tells you how much stuff there is in the disk and that gives you a budget for what you can build out of it,” Eisner says. “And what we found was, in this region, mass is actually quite constraining.”

    Unlike those studied in nearby regions such as Taurus, planet-forming disks in the Orion Nebula don’t have enough stuff to build large planets such as Jupiter, for which you would need tens of Earth masses. According to Eisner, this may mean that much of the stuff already has been used to make young planets. Disks in Orion also appear smaller in size than those in Taurus-like regions.

    “It’s pretty tantalizing that Orion looks so different from all these lower-density, closer regions but it’s just one. We want to fill in the data with more of these high-density regions to see if they all look like Orion,” says Eisner, who is already seeking grant funding and telescope observing time to do so.

    The discovery also will be tantalizing for those interested in what our solar system looked like as it was cooking some 5 billion years ago.

    “The initial conditions for planet formation can tell us a lot about the constraints and how the process really unfolds,” Eisner says.

    One theory about our solar system’s formation, called the Nice Model, argues that, early on, the configuration of the planets within a disk was small and compact until resonance finally flung Neptune and Uranus onto longer orbits.

    The fact that the small, compact systems Eisner’s team observed in the Orion’s disks match up so nicely with the initial planetary configuration in the Nice Model, Eisner says, is a compelling hint at the origins of our solar system.

    “The solar system probably formed in an Orion-like environment,” he says. “Now we’ve actually got an idea of what systems there look like.”

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition


    five-ways-keep-your-child-safe-school-shootings

    U Arizona campus

    The University of Arizona (UA) is a place without limits-where teaching, research, service and innovation merge to improve lives in Arizona and beyond. We aren’t afraid to ask big questions, and find even better answers.

    In 1885, establishing Arizona’s first university in the middle of the Sonoran Desert was a bold move. But our founders were fearless, and we have never lost that spirit. To this day, we’re revolutionizing the fields of space sciences, optics, biosciences, medicine, arts and humanities, business, technology transfer and many others. Since it was founded, the UA has grown to cover more than 380 acres in central Tucson, a rich breeding ground for discovery.

    Where else in the world can you find an astronomical observatory mirror lab under a football stadium? An entire ecosystem under a glass dome? Visit our campus, just once, and you’ll quickly understand why the UA is a university unlike any other.

     
  • richardmitnick 3:38 pm on June 8, 2018 Permalink | Reply
    Tags: , , , , How Do You Weigh a Galaxy? Especially the One You're In?, U Arizona   

    From University of Arizona: “How Do You Weigh a Galaxy? Especially the One You’re In?” 

    U Arizona bloc

    From University of Arizona

    June 6, 2018
    Daniel Stolte

    1
    Our Milky Way’s largest neighbor, the Andromeda Galaxy, spans about 220,000 light-years across. Two of its dwarf satellite galaxies, Messier 110 (bottom left) and Messier 32 (above Andromeda’s central bulge), are visible as bright white spots in this image taken by UA astrophotographer Adam Block.

    Pinning down the mass of a galaxy may seem like an esoteric undertaking, but scientists think it holds the key to unraveling the nature of the elusive, yet-to-be-seen dark matter, and the fabric of our cosmos.

    A new technique for estimating the mass of galaxies promises more reliable results, especially when applied to large datasets generated by current and future surveys, according to a research team led by Ekta Patel at the University of Arizona. Published in The Astrophysical Journal, the study is the first to combine the observed full three-dimensional motions of several of the Milky Way’s satellite galaxies with extensive computer simulations to obtain a high-accuracy estimate for the mass of our home galaxy.

    Determining the mass of galaxies plays a crucial part in unraveling fundamental mysteries about the architecture of the universe. According to current cosmological models, a galaxy’s visible matter, such as stars, gas and dust, accounts for a mere 15 percent of its mass. The remaining 85 percent is believed to reside in dark matter, a mysterious component that never has been observed and whose physical properties remain largely unknown. The vast majority of a galaxy’s mass (mostly dark matter) is located in its halo, a vast, surrounding region containing few, if any, stars and whose shape is largely unknown.

    In a widely accepted cosmological model, dark-matter filaments span the entire universe, drawing luminous (“regular”) matter with them. Where they intersect, gas and dust accumulate and coalesce into galaxies. Over billions of years, small galaxies merge to form into larger ones, and as those grow in size and their gravitational pull reaches farther and farther into space, they attract a zoo of other small galaxies, which then become satellite galaxies. Their orbits are determined by their host galaxy, much like the sun’s gravitational pull directs the movement of planets and bodies in the solar system.

    “We now know that the universe is expanding,” says Patel, a fourth-year graduate student in the UA’s Department of Astronomy and Steward Observatory. “But when two galaxies come close enough, their mutual attraction is greater than the influence of the expanding universe, so they begin to orbit each other around a common center, like our Milky Way and our closest neighbor, the Andromeda Galaxy.”

    Local Group. Andrew Z. Colvin 3 March 2011

    Although Andromeda is approaching the Milky Way at 110 kilometers per second, the two won’t merge until about 4.5 billion years from now. According to Patel, tracking Andromeda’s motion is “equivalent to watching a human hair grow at the distance of the moon.”

    2
    An artist’s interpretation of what happens as a satellite merges with its host galaxy: These streams of stars arcing high over the Milky Way are remnants of galaxies and star clusters, mangled and torn apart by our galaxy’s gravitational stresses over billions of years. Extending over much of the northern sky, the streams lie between 13,000 and 130,000 light-years from Earth. (Credit: NASA/JPL-Caltech/R. Hurt/SSC/Caltech)

    Because it’s impossible to “weigh” a galaxy simply by looking at it — much less when the observer happens to be inside of it, as is the case with our Milky Way — researchers deduce a galaxy’s mass by studying the motions of celestial objects as they dance around the host galaxy, led by its gravitational pull. Such objects — also called tracers, because they trace the mass of their host galaxy — can be satellite galaxies or streams of stars created from the scattering of former galaxies that came too close to remain intact.

    Unlike previous methods commonly used to estimate a galaxy’s mass, such as measuring its tracers’ velocities and positions, the approach developed by Patel and her co-authors uses their angular momentum, which yields more reliable results because it doesn’t change over time. The angular momentum of a body in space depends on both its distance and speed. Since satellite galaxies tend to move around the Milky Way in elliptical orbits, their speeds increase as they get closer to our galaxy and decrease as they get farther away. Because the angular momentum is the product of both position and speed, there is no net change regardless of whether the tracer is at its closest or farthest position in its orbit.

    “Think of a figure skater doing a pirouette,” Patel says. “As she draws in her arms, she spins faster. In other words, her velocity changes, but her angular momentum stays the same over the whole duration of her act.”

    The study, which Patel presents on Thursday, June 7, at the 232nd meeting of the of the American Astronomical Society in Denver, is the first to look at the full three-dimensional motions of nine of the Milky Way’s 50 known satellite galaxies at once and compare their angular momentum measurements to a simulated universe containing a total of 20,000 host galaxies that resemble our own galaxy. Together those simulated galaxies host about 90,000 satellite galaxies.

    Patel’s team pinned down the Milky Way’s mass at 0.96 trillion solar masses. Previous estimates had placed our galaxy’s mass between 700 billion and 2 trillion solar masses. The results also reinforce estimates suggesting that the Andromeda Galaxy (M31) is more massive than our Milky Way.

    The authors hope to apply their method to the ever-growing data as they become available by current and future galactic surveys such as the Gaia space observatory and LSST, the Large Synoptic Survey Telescope. According to co-author Gurtina Besla, an assistant professor of astronomy at the UA, constraints on the mass of the Milky Way will improve as new observations are obtained that clock the speed of more satellite galaxies, and as next-generation simulations will provide higher resolution, allowing scientists to get better statistics for the smallest mass tracers, the so-called ultra-faint galaxies.

    “Our method allows us to take advantage of measurements of the speed of multiple satellite galaxies simultaneously to get an answer for what cold dark matter theory would predict for the mass of the Milky Way’s halo in a robust way,” Besla says. “It is perfectly suited to take advantage of the current rapid growth in both observational datasets and numerical capabilities.”

    Additional co-authors on the paper, “Estimating the Mass of the Milky Way Using the Ensemble of Classical Satellite Galaxies,” are Kaisey Mandel at the Institute of Astronomy and the University of Cambridge, U.K., and Sangmo Tony Sohn with the Space Telescope Science Institute in Baltimore.

    Funding for this project was provided by the National Science Foundation and NASA.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    U Arizona campus

    The University of Arizona (UA) is a place without limits-where teaching, research, service and innovation merge to improve lives in Arizona and beyond. We aren’t afraid to ask big questions, and find even better answers.

    In 1885, establishing Arizona’s first university in the middle of the Sonoran Desert was a bold move. But our founders were fearless, and we have never lost that spirit. To this day, we’re revolutionizing the fields of space sciences, optics, biosciences, medicine, arts and humanities, business, technology transfer and many others. Since it was founded, the UA has grown to cover more than 380 acres in central Tucson, a rich breeding ground for discovery.

    Where else in the world can you find an astronomical observatory mirror lab under a football stadium? An entire ecosystem under a glass dome? Visit our campus, just once, and you’ll quickly understand why the UA is a university unlike any other.

     
  • richardmitnick 12:59 pm on February 23, 2018 Permalink | Reply
    Tags: , , , , , , U Arizona   

    From University of Arizona: “UA Leads Project on Big Data and Black Holes” 

    U Arizona bloc

    University of Arizona

    Feb. 21, 2018
    Daniel Stolte

    Chi-Kwan Chan waves his hand a few inches above a matchbox-size device. On a dark computer monitor, a million light dots appear as a solid sheet, each dot representing a light particle.

    1
    The Event Horizon Telescope is a virtual Earth-size telescope, achieving its globe-spanning baseline by combining precisely synchronized observations made at various sites around the world. (Image: Dan Marrone)

    The photon sheet hovers above a black disc simulating a black hole. With a slow turn of the hand, the sheet approaches the black hole. As it passes, the gravitational monster swallows any light particles in its direct path, creating a circular cutout in the sheet of particles. The rest of the particles are on track to move past the black hole, or so it seems. But they don’t get very far: Instead of continuing along their straight lines of travel, their paths bend inward and they loop around the black hole and converge in one point, forming a sphere of photons around it.

    “What you see here is light trapped in the fabric of space and time, curving around the black hole by its massive gravity,” explains Chan, an assistant astronomer at the University of Arizona’s Steward Observatory, who developed the computer simulation as part of his research into how black holes interact with things that happen to be nearby.

    U Arizona Steward Observatory at Kitt Peak, AZ, USA, altitude 2,096 m (6,877 ft)

    The demonstration was part of an event at UA’s Flandrau Science Center & Planetarium on Feb. 16 to kick off a UA-led, international project to develop new technologies that enable scientists to transfer, use and interpret massive datasets.

    Known as Partnerships for International Research and Education program, or PIRE, the effort is funded with $6 million over five years by the National Science Foundation, with an additional $3 million provided by partnering institutions around the world. While the award’s primary goal is to spawn technology that will help scientists take the first-ever picture of the supermassive black hole at the center of our Milky Way, the project’s scope is much bigger.

    What looks like a fun little animation on Chan’s computer screen is in fact a remarkable feat of computing and programming: As the computational astrophysicist drags virtual photons around a virtual black hole, a powerful graphics processor solves complex equations that dictate how each individual light particle would behave under the influence of the nearby black hole — simultaneously and in real time.

    Study Relies on Simulations

    Unlike the crew in the movie “Interstellar,” astrophysicists can’t travel to a black hole and study it from close range. Instead, they have to rely on simulations that mimic black holes based on their physical properties that are known to — or thought to — govern these most extreme objects in the universe.

    Chan belongs to a group of researchers in an international collaboration called the Event Horizon Telescope, or EHT, that is gearing up to capture the first picture of a black hole — not just any black hole, but the supermassive black hole in the center of our galaxy. Called Sagittarius A* (referred to as “Sgr A Star,” pronounced Sag A Star), this object has the mass of more than 4 million suns.

    SGR A* , the supermassive black hole at the center of the Milky Way. NASA’s Chandra X-Ray Observatory

    Since nothing, not even light, can escape a black hole, it casts a silhouette in the background of in-falling plasma that is too small to be resolved by any single telescope. So far, the existence of Sgr A* has been inferred from indirect observations only, such as the intriguing choreography of stars in its vicinity, whose orbits clearly outline an unseen, incomprehensibly large mass.

    “Imaging the black hole at the center of our galaxy from Earth is like trying to read the date on a dime on the East Coast from the UA campus,” says Feryal Özel, a professor of astronomy and physics at Steward and a co-investigator on the project. “There is not one telescope in existence that could do that.”

    The EHT is an array of radio telescopes on five continents that together act as a virtual telescope the size of the Earth — the aperture needed to image “the date on the dime,” or in this case the supermassive black hole Sag A*.

    Event Horizon Telescope Array

    Arizona Radio Observatory
    Arizona Radio Observatory/Submillimeter-wave Astronomy (ARO/SMT)

    ESO/APEX
    Atacama Pathfinder EXperiment

    CARMA Array no longer in service
    Combined Array for Research in Millimeter-wave Astronomy (CARMA)

    Atacama Submillimeter Telescope Experiment (ASTE)
    Atacama Submillimeter Telescope Experiment (ASTE)

    Caltech Submillimeter Observatory
    Caltech Submillimeter Observatory (CSO)

    IRAM NOEMA interferometer
    Institut de Radioastronomie Millimetrique (IRAM) 30m

    James Clerk Maxwell Telescope interior, Mauna Kea, Hawaii, USA
    James Clerk Maxwell Telescope interior, Mauna Kea, Hawaii, USA

    Large Millimeter Telescope Alfonso Serrano
    Large Millimeter Telescope Alfonso Serrano

    CfA Submillimeter Array Hawaii SAO
    Submillimeter Array Hawaii SAO

    ESO/NRAO/NAOJ ALMA Array
    ESO/NRAO/NAOJ ALMA Array, Chile

    South Pole Telescope SPTPOL
    South Pole Telescope SPTPOL

    Future Array/Telescopes

    Plateau de Bure interferometer
    Plateau de Bure interferometer

    NSF CfA Greenland telescope

    Greenland Telescope

    To accomplish this, the individual telescopes must be precisely synced in time. Because existing internet cables and even satellite communication are too coarse to ensure this, the researchers rely on atomic clocks and … FedEx (more on that later).

    “Our PIRE project is a prime example of the kind of innovation you can only get by leveraging the innovative, intellectual capital in academia,” says Dimitrios Psaltis, the principal investigator on the project. “By its very nature, this project is multidisciplinary and requires expertise in areas ranging from detector development to high-performance computing and theoretical physics.”

    At peak activity, the EHT will collect more data than any project before, according to Psaltis, a professor of astronomy and physics at the UA.

    “We’re talking petabytes every single night,” he says, and this is comparable to the three petabytes of video uploaded each day on YouTube. “Post-processing is a huge effort, and we will need additional data to improve the science that we hope will come from these observations.”

    The team uses graphic processing units, or GPUs — processors developed for gaming that are capable of performing many calculations in parallel. This makes them more efficient and energy-saving than “regular” computer processing units, or CPUs.

    “We hope that this technology will transfer to other areas of science and life,” said Joaquin Ruiz, dean of the UA College of Science, at the launch event.

    Applications Could Be Extensive

    The PIRE project is expected to spin off technologies that go beyond the project’s primary goal. The fast processing of large data in real time and the efficient use of resources distributed across the globe will have applications ranging from self-driving cars to renewable energy production and national defense. Examples also include augmented reality applications that are good at fast computing with real-time input and minimum computing resources, Özel explains.

    “This could be used, for example, in visual aids for security efforts around the globe where data connection bandwidth and energy supplies are limited,” she says, “so you want devices that make maximum use of precious resources available in those scenarios.”

    The PIRE project team integrates researchers in the U.S., Germany, Mexico and Taiwan. Education of students and early career scientists is a key component, providing internally collaborative, hands-on experience in instrument technology, high-performance computing, and big and distributed data science. There also are monthly webinars and hackathons, as well as summer schools, that will be sponsored every year.

    Fast and reliable real-time communication channels are crucial in syncing up telescopes scattered around the globe for observations, and improving such technology is one of PIRE’s goals. For now, EHT scientists rely on video chat, phones and whiteboards to keep track of each telescope location’s status. During a rare stretch of a few days in April 2017, skies were mostly clear in all nine observing sites that are part of the EHT array — including Arizona, Hawaii, Chile, Mexico and Antarctica.

    The South Pole Telescope, or SPT, site was incorporated under another NSF grant to the UA, with Dan Marrone as principal investigator. Last year was the first year that the full EHT observed as an array, and the first year in which the SPT participated.

    During that first observation run, the observing stations that together make up the EHT pointed at the Milky Way’s center and collected radio waves originating from the supermassive black hole over the course of several nights. By obtaining the first-ever images of black holes, researchers will be able to directly test Einstein’s theory of general relativity in extreme conditions.

    “Each telescope records its observation data onto a bunch of physical hard drives,” explains Marrone, an associate professor at Steward and a co-investigator on the PIRE award. “Precisely time-stamped, the drives are loaded into crates and delivered to processing centers in Cambridge, Massachusetts, and Bonn, Germany, via FedEx.”

    The EHT data are shipped on physical carriers because current internet data pipelines aren’t up to the scope this endeavor requires. Then data experts combine the literal truckloads of data, synchronize it according to their time stamps and process it to extract the signal from the black hole, which in the raw data is buried under a blanket of noise and error — the inevitable side effects of turning the Earth into one giant telescope.

    “PIRE is an international project that not only will revolutionize worldwide efforts to study black holes, but usher astronomical projects into the era of big and distributed data science,” Psaltis says. “By awarding the PIRE project, the NSF has tasked the UA and its collaborators to contribute solutions that may inform many areas of technology, including the internet of tomorrow.”

    See the full article here .

    Please help promote STEM in your local schools.

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    Stem Education Coalition

    U Arizona campus

    The University of Arizona (UA) is a place without limits-where teaching, research, service and innovation merge to improve lives in Arizona and beyond. We aren’t afraid to ask big questions, and find even better answers.

    In 1885, establishing Arizona’s first university in the middle of the Sonoran Desert was a bold move. But our founders were fearless, and we have never lost that spirit. To this day, we’re revolutionizing the fields of space sciences, optics, biosciences, medicine, arts and humanities, business, technology transfer and many others. Since it was founded, the UA has grown to cover more than 380 acres in central Tucson, a rich breeding ground for discovery.

    Where else in the world can you find an astronomical observatory mirror lab under a football stadium? An entire ecosystem under a glass dome? Visit our campus, just once, and you’ll quickly understand why the UA is a university unlike any other.

     
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