Using the Hubble Space Telescope (HST), astronomers have conducted near-ultraviolet through near-infrared observations of a young planetary nebula (PN) known as NGC 6302. Results of the monitoring campaign, presented May 28 on arXiv.org, could help us better understand the nature of this PN. PNe are expanding shells of gas and dust that have been ejected from a star during the process of its evolution from a main sequence star into a red giant or white dwarf. They are relatively rare, but are important for astronomers studying the chemical evolution of stars and galaxies. Located some 3,400 light years away in the constellation Scorpius, NGC 6302 (also known as the Bug Nebula, Butterfly Nebula, or Caldwell 69) is a bi-lobed, pinched-waist PN rich in dust and molecular gas. Its relative proximity makes it a great target for high-resolution imaging aimed at understanding the origin and evolution of bipolar structures in the population of known PNe. Therefore, a group of astronomers led by Joel H. Kastner of the Rochester Institute of Technology (RIT) employed Hubble's Wide Field Camera 3 (WFC3) in order to obtain comprehensive, contemporaneous sets of near-UV through near-IR (243 nm to 1.6 µm) emission-line images of NGC 6302. "Here, we present the full suite of HST/WFC3 images of NGC 6302, along with various line ratio images and a detailed examination of the key results gleaned from these images thus far," the researchers wrote in the paper. Hubble images show that NGC 6302 has a dusty toroidal equatorial structure that bisects the PN's polar lobes, and fine structures (like clumps, knots, and filaments) within the lobes. Such morphology is highly unusual for bipolar PNe, apart from certain multipolar PNe. The study identified an unexpected bright, S-shaped 1.64 µm [Fe II] emission in NGC 6302 that traces the southern interior of the east lobe rim and the northern interior of the west lobe rim. The astronomers assume that this could be a zone of shocks caused by ongoing, fast, collimated winds from the PN's central star. Furthermore, the research found that the object previously identified as the central star of NGC 6302 is in fact a foreground field star. The scientists added that a pair of bubble-like features in the core region of NGC 6302 likely indicates the central star's actual position within the PN's dusty central torus. However, more subarcsecond-resolution observations in the mid-IR and submillimeter wavebands are required to confirm this. In concluding remarks, the authors of the paper noted that the results emphasize the mysterious nature of NGC 6302. "The features revealed by our panchromatic HST/WFC3 images of NGC 6302—in particular, its distinct azimuthal structural zones and nested bubble system, and the surprising misalignment of the central engine's present collimated fast wind direction (as traced by 1.64 µm [Fe II] emission) and the nebula's main axis of symmetry (as defined by its dusty molecular torus, polar-axis clump system, and outer lobe walls)—presents an especially daunting challenge for models of the origin and evolution of bipolar structures in PNe," the scientists concluded. https://phys.org/news/2021-06-astronomers-probe-planetary-nebula-ngc.html
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For the first time, a unique study conducted at Lund University in Sweden has tracked the meteorite flux to Earth over the past 500 million years. Contrary to current theories, researchers have determined that major collisions in the asteroid belt have not generally affected the number of impacts with Earth to any great extent. Researchers have been studying geological series since the 19th century in order to reconstruct how flora, fauna and the climate have changed over millions of years. Until now, however, almost nothing has been known about ancient meteorite flux—which makes sense since impact is rare, and the battered celestial bodies quickly break down as they encounter Earth's oxygen. A new study published in PNAS shows how researchers in Lund have reconstructed meteorite bombardment towards Earth over the past 500 million years. "The research community previously believed that meteorite flux to Earth was connected to dramatic events in the asteroid belt. The new study, however, shows that the flux has instead been very stable," says Birger Schmitz, professor of geology at Lund University. To conduct the study, researchers at Lund University's Astrogeobiology Laboratory dissolved almost ten tons of sedimentary rocks from ancient seabeds in strong acids because the sediment contains residue from the meteorites dating back to when they fell to Earth. Meteorites contain a small fraction of a mineral, a chromium oxide, which is very resistant to degradation. The microscopic chromium oxide grains were sifted out in the laboratory and serve as time capsules with an abundance of information. "The dissolved sediment represents 15 periods over the past 500 million years. In total, we have extracted chromium oxide from almost 10 000 different meteorites. Chemical analyses then enabled us to determine which types of meteorites the grains represent," says Birger Schmitz. A couple of thousand meteorites land on the Earth's surface every year, and approximately 63 000 space rocks have been documented by science. The space rocks originate from the asteroid belt between Mars and Jupiter where battered celestial bodies from gigantic collisions revolve around the sun. "We were very surprised to learn that only one of the 70 largest asteroid collisions that took place over the past 500 million years resulted in an increased flux of meteorites to Earth. For some reason, most of the rocks stay in the asteroid belt," says Birger Schmitz. The study not only upends generally accepted meteorite flux theories; it also provides entirely new perspectives on which types of celestial bodies are at greatest risk of colliding with Earth and where in the solar system they originate. From a geological time perspective, kilometer-sized celestial bodies collide with the Earth on a regular basis. One such event took place 66 million years ago, when a celestial body stretching over 10 kilometers in size hit the Yucatán Peninsula. The impact was part of the reason the Earth went dark and dinosaurs starved to death. "Future impact from even a small asteroid for example in the sea close to a populated area could lead to disastrous outcomes. This study provides important understanding that we can use to prevent this from happening; for example, by attempting to influence the trajectory of rapidly approaching celestial bodies," concludes Birger Schmitz. https://phys.org/news/2021-06-earth-meteorite-impacts-million-years.html
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Using data from NASA's Orbiting Carbon Observatory 3 (OCO-3) instrument on the International Space Station, researchers have released one of the most accurate maps ever made from space of the human influence on carbon dioxide (CO2) in the Los Angeles metropolitan area. The map shows tiny variations in airborne CO2 from one mile of the giant L.A. Basin to the next. The highest CO2 readings, in yellow on the map, are on the west side of downtown L.A. – a densely populated area with congested freeways and CO2-emitting industries. Yellow indicates atmospheric CO2 elevated by five or more molecules out of every million molecules of air, or five parts per million. That's equivalent to the amount that global atmospheric CO2 is rising globally on average every two years The animation shows five adjoining swaths of data the OCO-3 instrument collected over the metropolitan area to create a map of CO2 concentrations that covers about 50 square miles (80 square kilometers). Each pixel is about 1.3 miles (2.2 kilometers); the color indicates how much higher the concentration of CO2 is in that spot than in clean desert air north of the city (measured at NASA's Armstrong Research Center, upper right). Most of the increasing CO2 in the global atmosphere comes from humans burning fossil fuels for energy, and 70% of that comes from cities. Los Angeles has set goals for cutting its carbon emissions. This type of data can help decisionmakers choose the most effective policies to reach those goals and to measure the effectiveness of new regulations. Data from ground level provides critical local measurements, but satellite data is equally necessary because it covers a wider area and also measures CO2 throughout the entire depth of the atmosphere. This animation shows the accumulation of data from NASA’s OCO-3 instrument used to create a map of carbon dioxide (CO2) concentrations that covers about 50 square miles (80 square kilometers) of the Los Angeles metropolitan area. The highest concentrations are in yellow. Credit: NASA/JPL-Caltech The International Space Station, which hosts the OCO-3 instrument, circles Earth between 52 degrees north and 52 degrees south latitudes—about the latitudes of London and Patagonia. Almost all cities on Earth come within its view on average once every three days. The OCO-3 team at NASA's Jet Propulsion Laboratory in Southern California schedules measurements at up to 40 locations a day. Most of these targets are high-CO2-emitting cities. The instrument consists of a telescope and three spectrometers, a kind of instrument that analyzes wavelengths of the electromagnetic spectrum of sunlight to find the spectral "fingerprint" of carbon dioxide. The telescope swivels rapidly to collect as many adjoining swaths of data as possible over a targeted location within two minutes. OCO-3 usually collects a single swath of data as it orbits, like its predecessor the OCO-2 mission (which is still operating), but it's designed to create snapshot maps like this one to give researchers a more complete picture of emissions from cities and other areas of interest. The maps were published this week in a paper in the journal Remote Sensing of Environment. https://phys.org/news/2021-06-nasa-accurate-space-based-view-la.html
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For the first time, a unique study conducted at Lund University in Sweden has tracked the meteorite flux to Earth over the past 500 million years. Contrary to current theories, researchers have determined that major collisions in the asteroid belt have not generally affected the number of impacts with Earth to any great extent. Researchers have been studying geological series since the 19th century in order to reconstruct how flora, fauna and the climate have changed over millions of years. Until now, however, almost nothing has been known about ancient meteorite flux—which makes sense since impact is rare, and the battered celestial bodies quickly break down as they encounter Earth's oxygen. A new study published in PNAS shows how researchers in Lund have reconstructed meteorite bombardment towards Earth over the past 500 million years. "The research community previously believed that meteorite flux to Earth was connected to dramatic events in the asteroid belt. The new study, however, shows that the flux has instead been very stable," says Birger Schmitz, professor of geology at Lund University. To conduct the study, researchers at Lund University's Astrogeobiology Laboratory dissolved almost ten tons of sedimentary rocks from ancient seabeds in strong acids because the sediment contains residue from the meteorites dating back to when they fell to Earth. Meteorites contain a small fraction of a mineral, a chromium oxide, which is very resistant to degradation. The microscopic chromium oxide grains were sifted out in the laboratory and serve as time capsules with an abundance of information. "The dissolved sediment represents 15 periods over the past 500 million years. In total, we have extracted chromium oxide from almost 10 000 different meteorites. Chemical analyses then enabled us to determine which types of meteorites the grains represent," says Birger Schmitz. A couple of thousand meteorites land on the Earth's surface every year, and approximately 63 000 space rocks have been documented by science. The space rocks originate from the asteroid belt between Mars and Jupiter where battered celestial bodies from gigantic collisions revolve around the sun. "We were very surprised to learn that only one of the 70 largest asteroid collisions that took place over the past 500 million years resulted in an increased flux of meteorites to Earth. For some reason, most of the rocks stay in the asteroid belt," says Birger Schmitz. The study not only upends generally accepted meteorite flux theories; it also provides entirely new perspectives on which types of celestial bodies are at greatest risk of colliding with Earth and where in the solar system they originate. From a geological time perspective, kilometer-sized celestial bodies collide with the Earth on a regular basis. One such event took place 66 million years ago, when a celestial body stretching over 10 kilometers in size hit the Yucatán Peninsula. The impact was part of the reason the Earth went dark and dinosaurs starved to death. "Future impact from even a small asteroid for example in the sea close to a populated area could lead to disastrous outcomes. This study provides important understanding that we can use to prevent this from happening; for example, by attempting to influence the trajectory of rapidly approaching celestial bodies," concludes Birger Schmitz. https://phys.org/news/2021-06-earth-meteorite-impacts-million-years.html
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Using data from NASA's Orbiting Carbon Observatory 3 (OCO-3) instrument on the International Space Station, researchers have released one of the most accurate maps ever made from space of the human influence on carbon dioxide (CO2) in the Los Angeles metropolitan area. The map shows tiny variations in airborne CO2 from one mile of the giant L.A. Basin to the next. The highest CO2 readings, in yellow on the map, are on the west side of downtown L.A. – a densely populated area with congested freeways and CO2-emitting industries. Yellow indicates atmospheric CO2 elevated by five or more molecules out of every million molecules of air, or five parts per million. That's equivalent to the amount that global atmospheric CO2 is rising globally on average every two years The animation shows five adjoining swaths of data the OCO-3 instrument collected over the metropolitan area to create a map of CO2 concentrations that covers about 50 square miles (80 square kilometers). Each pixel is about 1.3 miles (2.2 kilometers); the color indicates how much higher the concentration of CO2 is in that spot than in clean desert air north of the city (measured at NASA's Armstrong Research Center, upper right). Most of the increasing CO2 in the global atmosphere comes from humans burning fossil fuels for energy, and 70% of that comes from cities. Los Angeles has set goals for cutting its carbon emissions. This type of data can help decisionmakers choose the most effective policies to reach those goals and to measure the effectiveness of new regulations. Data from ground level provides critical local measurements, but satellite data is equally necessary because it covers a wider area and also measures CO2 throughout the entire depth of the atmosphere. This animation shows the accumulation of data from NASA’s OCO-3 instrument used to create a map of carbon dioxide (CO2) concentrations that covers about 50 square miles (80 square kilometers) of the Los Angeles metropolitan area. The highest concentrations are in yellow. Credit: NASA/JPL-Caltech The International Space Station, which hosts the OCO-3 instrument, circles Earth between 52 degrees north and 52 degrees south latitudes—about the latitudes of London and Patagonia. Almost all cities on Earth come within its view on average once every three days. The OCO-3 team at NASA's Jet Propulsion Laboratory in Southern California schedules measurements at up to 40 locations a day. Most of these targets are high-CO2-emitting cities. The instrument consists of a telescope and three spectrometers, a kind of instrument that analyzes wavelengths of the electromagnetic spectrum of sunlight to find the spectral "fingerprint" of carbon dioxide. The telescope swivels rapidly to collect as many adjoining swaths of data as possible over a targeted location within two minutes. OCO-3 usually collects a single swath of data as it orbits, like its predecessor the OCO-2 mission (which is still operating), but it's designed to create snapshot maps like this one to give researchers a more complete picture of emissions from cities and other areas of interest. The maps were published this week in a paper in the journal Remote Sensing of Environment. https://phys.org/news/2021-06-nasa-accurate-space-based-view-la.html
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67 views ·