Month: August 2019
Explore further © 2010 PhysOrg.com Sharp Develops Mass-Production Technology for Triple-Junction Thin-Film Solar Cells This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. (PhysOrg.com) — Sanyo has announced its development of the world’s most energy efficient solar module, the HIT-N230. The module was unveiled at a press conference run by Sanyo Electric’s Solar Division. Citation: Sanyo announces world’s most efficient solar module (2010, June 16) retrieved 18 August 2019 from https://phys.org/news/2010-06-sanyo-world-efficient-solar-module.html Sanyo is a major manufacturer of solar panels, with three factories in Japan, one in Hungary serving Europe, and a fifth in Mexico that serves the US market. The N series of modules are produced in Japan and consist of solar cells of the Hetero-junction with Intrinsic Thin-layer (HIT) type.HIT solar cells contain a single thin crystalline wafer of silicon surrounded by ultra-thin amorphous layers of silicon. They are characterized by high efficiency at high temperatures, and increased output power even during high summertime temperatures. The high conversion efficiency of HIT cells means more capacity can be installed compared to conventional crystalline silicon solar cells.The new N230 solar cell module is claimed to have an energy conversion efficiency of 20.7 percent, which makes it the most efficient solar module produced so far. The unprecedented efficiency was achieved by increasing the number of solar cell tabs from two to three and making each tab thinner. They also applied AG coated glass to the cells, and this reduces the amount of scattering and reflection of light. The increase in energy conversion efficiency could make the solar modules useful in areas with less than ideal amounts of sunshine. Sanyo is already one of the leading manufacturers of solar cells and modules, and the company is currently expanding its solar cell module production at Kaizuka City and Ohtsu City in Japan in response to increased demand. In total Sanyo plans to nearly double its HIT solar cell production from the current level of 340 MW to 600 MW by March next year.National and local installation subsidies in Japan have seen the local market expand rapidly, and this has also been helped by the national government’s new program for purchasing surplus electricity generated by solar installations.The 230W model N230 and 225W N225 will both be officially launched in Japan in autumn this year and in Europe in 2011.
(Phys.org)—A team of researchers with members from institutions in Spain, France and Egypt has demonstrated that hydrogen atoms on graphene yield a magnetic moment and furthermore, that such moments can order ferromagnetically over relatively large distances. In their paper published in the journal Science the group describes experiments they carried out in attempting to cause a sheet of graphene to become magnetic, how they found evidence that it was possible using hydrogen atoms, and the ways such a material might be used in industrial applications. Shawna Hollen with the University of New Hampshire, and Jay Gupta with Ohio State University, offer some insights into the work done by the team in the same journal issue with a Perspectives piece—they also outline the hurdles that still need to be overcome before magnetic graphene might be used in real applications. A picture of hydrogen atoms in graphene. Credit: CIC nanoGUNE Credit: AlexanderAlUS/Wikipedia/CC BY-SA 3.0 More information: H. Gonzalez-Herrero et al. Atomic-scale control of graphene magnetism by using hydrogen atoms, Science (2016). DOI: 10.1126/science.aad8038AbstractIsolated hydrogen atoms absorbed on graphene are predicted to induce magnetic moments. Here we demonstrate that the adsorption of a single hydrogen atom on graphene induces a magnetic moment characterized by a ~20–millielectron volt spin-split state at the Fermi energy. Our scanning tunneling microscopy (STM) experiments, complemented by first-principles calculations, show that such a spin-polarized state is essentially localized on the carbon sublattice opposite to the one where the hydrogen atom is chemisorbed. This atomically modulated spin texture, which extends several nanometers away from the hydrogen atom, drives the direct coupling between the magnetic moments at unusually long distances. By using the STM tip to manipulate hydrogen atoms with atomic precision, it is possible to tailor the magnetism of selected graphene regions. Explore further Citation: Researchers demonstrate hydrogen atoms on graphene yield a magnetic moment (2016, April 22) retrieved 18 August 2019 from https://phys.org/news/2016-04-hydrogen-atoms-graphene-yield-magnetic.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. © 2016 Phys.org Graphene’s superior qualities as a material have been well documented, though one of its drawbacks has not been highlighted as much—it is not magnetic. If it were, it could conceivably be used in many more applications. That has led to efforts to do things to a sheet of graphene that would cause it to become magnetic, one of which is by adding hydrogen atoms to its surface, creating what has been called graphane. Unfortunately, stability has been an issue, making the process difficult to control. In this new effort, the researchers have taken a different approach—they took advantage of the fact that magnetism occurs in graphene when an imbalance occurs in two sub-lattices that are part of the whole— that means the number of atoms that exist in an individual sublattice can be caused to be unequal due to such things as point defects or geometric shape. That allows a hydrogen adatom to bond with a carbon pz-orbital. The end result is magnetic moments being formed in the honeycomb lattice, with such moments aligning ferromagnetically when they are on the same sublattice, and antiferromagnetically when they are on an opposing sublattice.Such a material, Hollen and Gupta note, might allow for storing information at much higher densities than has ever been seen before, but before that can happen, they also note, several hurdles must be overcome, such as realizing atomic scale precision with the process on a large scale. Journal information: Science A new way to make higher quality bilayer graphene
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Citation: Small long-serving satellite observes ammonia emission from the center of our galaxy (2017, January 16) retrieved 18 August 2019 from https://phys.org/news/2017-01-small-long-serving-satellite-ammonia-emission.html Odin was launched on February 20, 2001 with the aim of studying the depletion of the ozone layer in the atmosphere and searching for water and oxygen in interstellar space. With a mass of about 250 kilograms, the spacecraft has dimensions of 2.0 x 1.1 meters (3.8 meters when fully deployed in orbit). The satellite is equipped with an advanced radiometer using a 1.1-meter telescope and a spectrograph, called the Optical Spectrograph and Infrared Imaging System (OSIRIS).Odin was originally designed to be operational for about two years, but the spacecraft is still in good health and is currently functioning nominally. During the astrophysics part of its mission, the satellite has observed water in comets and detected molecular oxygen in interstellar clouds. Now, a team of Swedish researchers that includes Odin mission scientists has presented new results proving that the spacecraft can still conduct significant detections.”Recently, Odin has made complementary observations of the 572 GHz NH3 line towards the Sgr A +50 km s−1 cloud and circumnuclear disk (CND). (…) Significant NH3 emission has been observed in both the +50 km s−1 cloud and the CND. Clear NH3 absorption has also been detected in many of the spiral arm features along the line of sight from the sun to the core of our galaxy,” the scientists wrote in the paper.The observations were carried out in April 2015 and April 2016 as part of a larger survey studying the Sagittarius A complex radio source consisting of Sgr A*, the supernova remnant Sagittarius A East and the spiral structure Sagittarius A West.According to the paper, the spacecraft detected a very large velocity width (80 km s−1) of the ammonia emission associated with the shock region in the southwestern part of the CND. The researchers propose that it may suggest a formation scenario similar to that of gas-phase water in shocks and outflows.”The very high gas-phase water abundance determined for the shock region at CND SW by Karlsson et al. (2015) is similar to that found in the red-ward high-velocity wings of the Sgr A molecular clouds, and likely results from shock heating causing release of pre-existing grain surface water, possibly combined with high temperature shock chemistry,” the paper reads.The authors concluded that the high-quality spectra obtained by Odin clearly demonstrate the satellite’s continuing capabilities. It shows that it is possible to build a comparatively cheap, but complicated spacecraft that can remain in high quality operation for a long mission lifetime. © 2017 Phys.org More information: Odin observations of ammonia in the Sgr A +50 km/s Cloud and Circumnuclear Disk, arXiv:1701.02536 [astro-ph.GA] arxiv.org/abs/1701.02536AbstractContext. The Odin satellite is now into its sixteenth year of operation, much surpassing its design life of two years. One of the sources which Odin has observed in great detail is the Sgr A Complex in the centre of the Milky Way. Aims. To study the presence of NH3 in the Galactic Centre and spiral arms. Methods. Recently, Odin has made complementary observations of the 572 GHz NH3 line towards the Sgr A +50 km/s Cloud and Circumnuclear Disk (CND). Results. Significant NH3 emission has been observed in both the +50 km/s Cloud and the CND. Clear NH3 absorption has also been detected in many of the spiral arm features along the line of sight from the Sun to the core of our Galaxy. Conclusions. The very large velocity width (80 km/s) of the NH3 emission associated with the shock region in the southwestern part of the CND may suggest a formation/desorption scenario similar to that of gas-phase H2O in shocks/outflows. (Phys.org)—Completing its 16th year in orbit, a small Swedish astrophysics and aeronomy satellite named “Odin” has proven that it is still capable of carrying out important observations of space. The spacecraft has lately observed ammonia (NH3) emissions from an astronomical radio source known as Sagittarius A* (Sgr A* for short) at the center of the Milky Way galaxy. The results of these observations were published January 10 in a paper available on arXiv.org. Astronomers discover molecular and atomic clouds associated with a superbubble in LMC Explore further Artist’s rendition of the Odin spacecraft in orbit. Credit: SNSB
Citation: Radio emission detected from a gamma-ray pulsar (2017, July 5) retrieved 18 August 2019 from https://phys.org/news/2017-07-radio-emission-gamma-ray-pulsar.html © 2017 Phys.org Astronomers discover bubble-like structure associated with the pulsar PSR J1015−5719 This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Gamma-ray pulsars are rotating neutron stars emitting gamma-ray photons. Some of them also showcase radio emission that is often difficult to detect. This is most probably due to the fact that their narrow radio beams miss the sightline towards Earth.Located nearly 2,000 light years away from the Earth, J1732−3131 has a rotation period of about 196 milliseconds and is one such gamma-ray pulsar with hart-to-identify radio emission. The pulsar was found thanks to the data provided by the large area telescope (LAT) onboard NASA’s Fermi Gamma-ray Space Telescope. So far, only a faint radio signal from this pulsar was detected at 34 MHz in 2012.More recently, Maan’s team, motivated by previous faint detections, conducted follow-up observations of J1732−3131 between March 2014 and April 2015, using the Ooty radio telescope (ORT), located in Muthorai, India. This 530-meter-long and 30-meter-wide cylindrical paraboloid telescope allowed the researchers to observe the pulsar at 327 MHz, which resulted in detection of a faint periodic radio signal.”We report an extensive follow-up of the pulsar at 327 MHz with the Ooty radio telescope. Using the previously observed radio characteristics, and with an effective integration time of 60 hours, we present a detection of the pulsar at a confidence level of 99.82 percent,” the authors of the study wrote in the paper.The astronomers estimate that the 327 MHz mean flux density of J1732−3131 is between 0.5 and 0.8 mJy and the spectral index in the range from −2.4 to −3.0.More importantly, however, the 1,400 MHz pseudo-luminosity of the pulsar is only between 2.2 and 8.9 μJy kpc2, which suggests that J1732−3131 is one of the least luminous pulsars known to date.According to the scientists, their research provides new clues about gamma-ray pulsars in general, which could improve their understanding of these peculiar neutron stars. They noted that some of the radio-quiet gamma-ray pulsars might actually be very faint radio sources, and therefore not detectable in the radio searches using current generation telescopes. That is why the researchers call for more studies of such pulsars using more powerful radio telescopes.”The high sensitivity of upcoming radio telescopes like square kilometre array (SKA) and the 500-meter Aperture Spherical Telescope (FAST) will enable radio detection, and facilitate better studies of such pulsars,” the paper reads.SKA is a large, multi-radio telescope network being built in Australia and South Africa, which is expected to start initial observations in 2020. FAST is the world’s largest filled-aperture radio telescope, located in China. It achieved first light in September 2016, and is currently undergoing testing and commissioning. Explore further (Phys.org)—A team of astronomers led by Yogesh Maan of the Netherlands Institute for Radio Astronomy (ASTRON) has discovered radio emission from the gamma-ray pulsar known as J1732−3131. The study, presented in a paper published June 26 on arXiv.org, provides more details about J1732−3131, which was originally detected as a radio-quiet pulsar. Phase-aligned radio and gamma-ray profiles of J1732−3131. The continuous blue line shows the 327 MHz average profile from 2014 observations and the dashed-dotted-dashed red curve shows the gamma-ray profile. The horizontal extent of the grey shade on either side of the radio profile indicates the uncertainty in phase corresponding to 1σ error in DM. For clarity, both the profiles are duplicated and plotted over a range spanning two rotations of the pulsar. Credit: Maan et al., 2017. More information: Detection of radio emission from the gamma-ray pulsar J1732-3131 at 327 MHz, arXiv:1706.08613 [astro-ph.HE] arxiv.org/abs/1706.08613AbstractAlthough originally discovered as a radio-quiet gamma-ray pulsar, J1732-3131 has exhibited intriguing detections at decameter wavelengths. We report an extensive follow-up of the pulsar at 327 MHz with the Ooty radio telescope. Using the previously observed radio characteristics, and with an effective integration time of 60 hrs, we present a detection of the pulsar at a confidence level of 99.82%. The 327 MHz mean flux density is estimated to be 0.5-0.8 mJy, which establishes the pulsar to be a steep spectrum source and one of the least-luminous pulsars known to date. We also phase-aligned the radio and gamma-ray profiles of the pulsar, and measured the phase-offset between the main peaks in the two profiles to be 0.24±0.06. We discuss the observed phase-offset in the context of various trends exhibited by the radio-loud gamma-ray pulsar population, and suggest that the gamma-ray emission from J1732-3131 is best explained by outer magnetosphere models. Details of our analysis leading to the pulsar detection, and measurements of various parameters and their implications relevant to the pulsar’s emission mechanism are presented.
European eel. Credit: Wikipedia/CC BY-SA 3.0 A team of researchers with members from Japan, Sweden, Denmark and Germany has found evidence showing that European eel spawn across a 2000 km wide region of the North Atlantic Ocean. In their paper published in the journal Biology Letters, the group describes their study of recently hatched eel larvae in the North Atlantic Ocean, and what they found. Study shows European eel migration not as uniform and simple as thought More information: Michael J. Miller et al. Spawning by the European eel across 2000 km of the Sargasso Sea, Biology Letters (2019). DOI: 10.1098/rsbl.2018.0835 © 2019 Science X Network Explore further
Citation: Fermi observations provide insights into the nature of Terzan 5 globular cluster (2019, June 3) retrieved 18 August 2019 from https://phys.org/news/2019-06-fermi-insights-nature-terzan-globular.html Three new millisecond pulsars discovered in Terzan 5 globular cluster Observations of globular clusters (GCs) in our Milky Way galaxy are of high importance for astronomers as they are among the oldest objects in the universe. Therefore, they could serve as natural laboratories for the study of stellar evolution processes.Discovered about a half-century ago, Terzan 5 is a 12-billion-year-old galactic GC located some 19,000 light years away. The cluster has a particularly high central stellar density, high metallicity, and also the highest stellar interaction rate of all GCs in the Milky Way. Terzan 5 is known to host 37 out of 130 millisecond pulsars (MSPs) detected so far, what makes it a record holder when it comes to the largest number of MSPs in a galactic GC. Previous studies of this cluster have also shown that it contains at least two distinct stellar populations with different ages and iron content. This could suggest that Terzan 5 may not be a “true” globular cluster, but a result of a merger of two clusters, for instance, or a remnant of a disrupted galaxy.In order to get more detailed information about Terzan 5, which could verify these possibilities, an international team of astronomers led by Hambeleleni Ndiyavala of North-West University in Potchefstroom, South Africa, decided to analyze new data obtained by the Fermi spacecraft. This dataset allowed the researchers to model the broadband spectral energy distribution (SED) in the cluster.”We therefore aimed to gather more data on Terzan 5 and model the updated SED in a leptonic scenario,” the astronomers wrote in the paper.In particular, the spectral model described in the study postulates four spectral components, namely: low-energy synchrotron radiation (LESR), high-energy synchrotron radiation (HESR), curvature radiation (CR) and inverse Compton (IC). The model also allowed the astronomers to constrain the MSP population’s distribution of spin-down luminosity.According to the study, the updated SED in Terzan 5 is most likely due to a cumulative pulsed emission from a population of embedded MSPs. Moreover, it could be as well attributed to unpulsed emission from the interaction of leptonic winds with ambient magnetic and soft-photon fields.”We obtained new Fermi data that we could fit using a model for the cumulative CR from a population of MSPs embedded within Terzan 5. These data also proved to be constraining for the low-energy tail of the unpulsed IC component, yielding a particle efficiency of ηp~3 percent, depending on the choice of several parameters, notably〈 ̇Evis〉and NMSP,tot,” the paper reads.In concluding remarks, the astronomers underlined the importance of further studies of Terzan 5 and similar clusters to get a more comprehensive view on the nature and properties of galactic GCs in general. They added that such instruments like the Cherenkov Telescope Array (CTA) could be much helpful in identifying new very-high-energy (VHE) GCs.”This will allow us to further scrutinize competing emission models, as well as developing new, more complete and comprehensive ones that might explain the spatial and spectral properties of galactic GCs at an ever increasing level of detail,” the authors of the paper noted. This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. © 2019 Science X Network More information: Hambeleleni Ndiyavala, et al. Probing the pulsar population of Terzan 5 via spectral modeling. arXiv:1905.10229v1 [astro-ph.HE]: arxiv.org/abs/1905.10229 Using NASA’s Fermi Gamma-ray Space Telescope, astronomers have collected important data that could disclose the real nature of the globular cluster Terzan 5. The new study, presented in a paper published May 24 on arXiv.org, delivers new information regarding the cluster’s pulsar population and its broadband emission spectrum. Explore further Different spectral components for Terzan 5 predicted by the leptonic models of Kopp et al. (2013) and Harding et al. (2008); Harding & Kalapotharakos (2015). Image credit: Ndiyavala et al., 2019.
However, with time his art became more restrictive and nuanced. Following that, his pictorial space became vacant and less detailed where figures were reduced to their bare structural essentials.In his on-going exhibition Building dreams from very little…, compositions of lithographs, watercolours and drawings, have certain reiterative images like a ball of thread symbolising the thread of human destiny; a rib-cage visible through the parched paper-thin skin. Hore’s deftly delineated figures serve as negative manifestations of community, ideology and a nation undergoing cataclysmic changes. Hore’s body of work is a facsimile impression of the unending poverty and violence in the world. ‘My paintings are personal, a response, almost a conversation, with my surroundings,’ said Hore.When: Till 20 DecemberWhere: Art Heritage Gallery