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  • richardmitnick 9:10 pm on March 5, 2021 Permalink | Reply
    Tags: "Comet Catalina suggests comets delivered carbon to rocky planets", , , , , , , SOFIA- Stratospheric Observatory for Infrared Astronomy, University of Minnesota Twin Cities   

    From University of Minnesota Twin Cities: “Comet Catalina suggests comets delivered carbon to rocky planets” 

    u-minnesota-bloc

    From University of Minnesota Twin Cities

    March 5, 2021

    Rhonda Zurn
    College of Science and Engineering, Twin Cities
    612-626-7959
    rzurn@umn.edu

    1
    This illustration of a comet from the Oort Cloud as it passes through the inner solar system with dust and gas evaporating into its tail. SOFIA’s observations of Comet Catalina reveal that it’s carbon-rich, suggesting that comets delivered carbon to the terrestrial planets like Earth and Mars as they formed in the early solar system. Credit: NASA/DLR SOFIA/Lynette Cook.

    In early 2016, an icy visitor from the edge of our solar system hurtled past Earth. It briefly became visible to stargazers as Comet Catalina before it slingshotted past the Sun to disappear forevermore out of the solar system.

    Among the many observatories that captured a view of this comet, which appeared near the Big Dipper, was the Stratospheric Observatory for Infrared Astronomy (SOFIA), NASA’s telescope on an airplane.

    NASA/DLR SOFIA modified Boeing 747 aircraft.

    Using one of its unique infrared instruments, SOFIA was able to pick out a familiar fingerprint within the dusty glow of the comet’s tail—carbon.

    Now this one-time visitor to our inner solar system is helping explain more about our own origins as it becomes apparent that comets like Catalina could have been an essential source of carbon on planets like Earth and Mars during the early formation of the solar system.

    New results from SOFIA, a joint project of NASA and the DLR German Aerospace Center, were published in the Planetary Science Journal.

    “Carbon is key to learning about the origins of life,” said the paper’s lead author, Charles “Chick” Woodward, an astrophysicist and professor in the University of Minnesota Twin Cities Minnesota Institute of Astrophysics. “We’re still not sure if Earth could have trapped enough carbon on its own during its formation, so carbon-rich comets could have been an important source delivering this essential element that led to life as we know it.”

    Frozen in Time

    Originating from the Oort Cloud at the farthest reaches of our solar system, Comet Catalina and others of its type have such long orbits that they arrive on our celestial doorstep relatively unaltered.

    Milky Way Galaxy from Sun to Interstellar Space beyond the Oort Cloud. Credit: NASA/ JPL-Caltech.

    This makes them effectively frozen in time, offering researchers rare opportunities to learn about the early solar system from which they come.

    SOFIA’s infrared observations were able to capture the composition of the dust and gas as it evaporated off the comet, forming its tail. The observations showed that Comet Catalina is carbon-rich, suggesting that it formed in the outer regions of the primordial solar system, which held a reservoir of carbon that could have been important for seeding life.

    While carbon is a key ingredient of life, early Earth and other terrestrial planets of the inner solar system were so hot during their formation that elements like carbon were lost or depleted. While the cooler gas giants like Jupiter and Neptune could support carbon in the outer solar system, Jupiter’s jumbo size may have gravitationally blocked carbon from mixing back into the inner solar system.

    Primordial Mixing

    So how did the inner rocky planets evolve into the carbon-rich worlds that they are today?

    Researchers think that a slight change in Jupiter’s orbit allowed small, early precursors of comets to mix carbon from the outer regions into the inner regions, where it was incorporated into planets like Earth and Mars.

    Comet Catalina’s carbon-rich composition helps explain how planets that formed in the hot, carbon-poor regions of the early solar system evolved into planets with the life-supporting element.

    “All terrestrial worlds are subject to impacts by comets and other small bodies, which carry carbon and other elements,” Woodward said. “We are getting closer to understanding exactly how these impacts on early planets may have catalyzed life.”

    Observations of additional new comets are needed to learn if there are many other carbon-rich comets in the Oort Cloud, which would further support that comets delivered carbon and other life-supporting elements to the terrestrial planets. As the world’s largest airborne observatory, SOFIA’s mobility allows it to quickly observe newly discovered comets as they make a pass through the solar system.

    SOFIA is a joint project of NASA and the DLR German Aerospace Center. NASA’s Ames Research Center in California’s Silicon Valley manages the SOFIA program, science, and mission operations in cooperation with the Universities Space Research Association, headquartered in Columbia, Maryland, and the German SOFIA Institute at the University of Stuttgart. The aircraft is maintained and operated by NASA’s Armstrong Flight Research Center Building 703, in Palmdale, California.

    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-minnesota-campus-twin-cities

    The University of Minnesota, Twin Cities (often referred to as the U of M, UMN, Minnesota, or simply the U) is a public research university in Minneapolis and Saint Paul, MN. The Twin Cities campus comprises locations in Minneapolis and St. Paul approximately 3 miles (4.8 km) apart, and the St. Paul location is in neighboring Falcon Heights. The Twin Cities campus is the oldest and largest in the University of Minnesota system and has the sixth-largest main campus student body in the United States, with 51,327 students in 2019-20. It is the flagship institution of the University of Minnesota System, and is organized into 19 colleges, schools, and other major academic units.

    The University was included in a list of Public Ivy universities in 2001. Legislation passed in 1851 to develop the university, and the first college classes were held in 1867. The university is categorized as a Doctoral University – Highest Research Activity (R1) in the Carnegie Classification of Institutions of Higher Education. Minnesota is a member of the Association of American Universities and is ranked 14th in research activity, with $881 million in research and development expenditures in the fiscal year ending June 30, 2015.

    University of Minnesota faculty, alumni, and researchers have won 26 Nobel Prizes and three Pulitzer Prizes. Notable University of Minnesota alumni include two vice presidents of the United States, Hubert Humphrey and Walter Mondale.

     
  • richardmitnick 12:47 pm on January 16, 2021 Permalink | Reply
    Tags: "Conductive nature in crystal structures revealed at magnification of 10 million times", , , , MBE-molecular beam epitaxy, Metallic lines in a perovskite crystal, , University of Minnesota Twin Cities   

    From University of Minnesota Twin Cities: “Conductive nature in crystal structures revealed at magnification of 10 million times” 

    u-minnesota-bloc

    From University of Minnesota Twin Cities

    January 15, 2021

    Media Contacts
    Main Line
    University Public Relations
    (612) 624-5551
    unews@umn.edu

    Rhonda Zurn
    College of Science and Engineering, Twin Cities
    612-626-7959
    rzurn@umn.edu

    1
    Using advanced analytical scanning transmission electron microscopy (STEM) at a magnification of 10 million times, University of Minnesota researchers were able to isolate and image the structure and composition of the metallic line defect in a perovskite crystal BaSnO3. This image shows the atomic arrangement of both the BaSnO3 crystal (on the left) and the metallic line defect.

    In groundbreaking materials research, a team led by University of Minnesota Professor K. Andre Mkhoyan has made a discovery that blends the best of two sought-after qualities for touchscreens and smart windows—transparency and conductivity.

    The researchers are the first to observe metallic lines in a perovskite crystal. Perovskites abound in the Earth’s center, and barium stannate (BaSnO3) is one such crystal. However, it has not been studied extensively for metallic properties because of the prevalence of more conductive materials on the planet like metals or semiconductors. The finding was made using advanced transmission electron microscopy (TEM), a technique that can form images with magnifications of up to 10 million.

    The research is published in Science Advances, a peer-reviewed scientific journal published by the American Association for the Advancement of Science (AAAS).

    “The conductive nature and preferential direction of these metallic line defects mean we can make a material that is transparent like glass and at the same time very nicely directionally conductive like a metal,” said Mkhoyan, a TEM expert and the Ray D. and Mary T. Johnson/Mayon Plastics Chair in the Department of Chemical Engineering and Materials Science at the University of Minnesota’s College of Science and Engineering. “This gives us the best of two worlds. We can make windows or new types of touch screens transparent and at the same time conductive. This is very exciting.”

    Defects, or imperfections, are common in crystals—and line defects (the most common among them is the dislocation) are a row of atoms that deviate from the normal order. Because dislocations have the same composition of elements as the host crystal, the changes in electronic band structure at the dislocation core, due to symmetry-reduction and strain, are often only slightly different than that of the host. The researchers needed to look outside the dislocations to find the metallic line defect, where defect composition and resulting atomic structure are vastly different.

    “We easily spotted these line defects in the high-resolution scanning transmission electron microscopy images of these BaSnO3 thin films because of their unique atomic configuration and we only saw them in the plan view,” said Hwanhui Yun, a graduate student in the Department of Chemical Engineering and Materials Science and a lead author of the study.

    For this study, BaSnO3 films were grown by molecular beam epitaxy (MBE)—a technique to fabricate high-quality crystals—in a lab at the University of Minnesota Twin Cities. Metallic line defects observed in these BaSnO3 films propagate along film growth direction, which means researchers can potentially control how or where line defects appear—and potentially engineer them as needed in touchscreens, smart windows, and other future technologies that demand a combination of transparency and conductivity.

    “We had to be creative to grow high-quality BaSnO3 thin films using MBE. It was exciting when these new line defects came into light in the microscope,” said Bharat Jalan, associate professor and Shell Chair in the Department of Chemical Engineering and Materials Science, who heads up the lab that grows a variety of perovskite oxide films by MBE.

    Perovskite crystals (ABX3) contain three elements in the unit cell. This gives it freedom for structural alterations such as composition and crystal symmetry, and the ability to host a variety of defects. Because of different coordination and bonding angles of the atoms in the line defect core, new electronic states are introduced and the electronic band structure is modified locally in such a dramatic way that it turns the line defect into metal.

    “It was fascinating how theory and experiment agreed with each other here,” said Turan Birol, assistant professor in the Department of Chemical Engineering and Materials Science and an expert in density functional theory (DFT). “We could verify the experimental observations of the atomic structure and electronic properties of this line defect with first principles DFT calculations.”

    Members of the research team include University of Minnesota Ph.D. students and postdoctoral fellows Hwanhui Yun, Mehmet Topsakal (now associate scientist at Brookhaven National Laboratory), and Abhinav Prakash (postdoc researcher Argonne National Laboratory); and University of Minnesota faculty members K. Andre Mkhoyan, Bharat Jalan, Turan Birol, and Jong Seok Jeong.

    This research was supported in part by SMART, one of seven centers of nCORE, a Semiconductor Research Corporation program, sponsored by National Institute of Standards and Technology, and by the National Science Foundation (NSF) through the University of Minnesota Materials Research Science and Engineering Center (MRSEC). The team also worked with the University of Minnesota Characterization Facility. The MBE growth work was supported partially by the NSF and the Air Force Office of Scientific Research.

    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-minnesota-campus-twin-cities

    The University of Minnesota, Twin Cities (often referred to as the U of M, UMN, Minnesota, or simply the U) is a public research university in Minneapolis and Saint Paul, MN. The Twin Cities campus comprises locations in Minneapolis and St. Paul approximately 3 miles (4.8 km) apart, and the St. Paul location is in neighboring Falcon Heights. The Twin Cities campus is the oldest and largest in the University of Minnesota system and has the sixth-largest main campus student body in the United States, with 51,327 students in 2019-20. It is the flagship institution of the University of Minnesota System, and is organized into 19 colleges, schools, and other major academic units.

    The University was included in a list of Public Ivy universities in 2001. Legislation passed in 1851 to develop the university, and the first college classes were held in 1867. The university is categorized as a Doctoral University – Highest Research Activity (R1) in the Carnegie Classification of Institutions of Higher Education. Minnesota is a member of the Association of American Universities and is ranked 14th in research activity, with $881 million in research and development expenditures in the fiscal year ending June 30, 2015.

    University of Minnesota faculty, alumni, and researchers have won 26 Nobel Prizes and three Pulitzer Prizes. Notable University of Minnesota alumni include two vice presidents of the United States, Hubert Humphrey and Walter Mondale.

     
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