Darkerthanblack metamaterial could lead to more efficient solar cells

first_imgWhen a hyperbolic metamaterial is corrugated, its reflectance is greatly reduced and it becomes “darker than black.” Image credit: E. E. Narimanov, et al. Bending light with better precision Explore further (PhysOrg.com) — If typical black paint absorbs about 85% of incoming light, then a newly designed metamaterial that absorbs up to 99% of incoming light may be considered “darker than black.” By taking advantage of the unique light-scattering properties of metamaterials, researchers have discovered that a hyperbolic metamaterial with a corrugated surface can have a very low reflectance, which could make it promising for high-efficiency solar cells, photodetectors, and radar stealth technology. Citation: ‘Darker-than-black’ metamaterial could lead to more efficient solar cells (2011, September 30) retrieved 18 August 2019 from https://phys.org/news/2011-09-darker-than-black-metamaterial-efficient-solar-cells.html © 2011 PhysOrg.com More information: E. E. Narimanov, et al. “Darker than black: radiation-absorbing metamaterial.” arXiv:1109.5469v1 [physics.optics]via: Physics arXiv Blog The researchers, E. Narimanov, et al., from Purdue University and Norfolk State University, have posted their study on the radiation-absorbing metamaterial at arXiv.org.In their study, the researchers fabricated a hyperbolic metamaterial out of arrays of silver nanowires grown in alumina membranes. They found that this material absorbed about 80% of incoming light. Then, they ground the surface of the metamaterial to produce corrugations and defects, which they predicted would dramatically reduce the light reflection, increasing the absorption. Their measurements showed that the corrugated metamaterial absorbed up to 99% of incoming light, and that the radiation-absorbing capability is applicable to all parts of the electromagnetic spectrum.As the scientists explained, the metamaterial’s very low reflectivity results from one of its hyperbolic properties: an infinite density of photonic states. This “super singularity” greatly increases the amount of light scattering from surface defects and corrugations in the metamaterial. The defects and corrugations scatter light primarily inside the material, basically “sucking” photons inside the hyperbolic medium.The researchers predict that the new metamaterial will provide a new route toward designing radiation-absorbing materials. As light absorption plays a key role in solar cells and many other applications, the researchers plan to investigate these possibilities in the near future. 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.last_img read more

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Scientist finds medium sized Kuiper belt object less dense than water

center_img 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. More information: The density of mid-sized Kuiper belt object 2002 UX25 and the formation of the dwarf planets, arXiv:1311.0553 [astro-ph.EP] arxiv.org/abs/1311.0553AbstractThe formation of the largest objects in the Kuiper belt, with measured densities of ~1.5 g cm-3 and higher, from the coagulation of small bodies, with measured densities below 1 g cm-3 is difficult to explain without invoking significant porosity in the smallest objects. If such porosity does occur, measured densities should begin to increase at the size at which significant porosity is no longer supported. Among the asteroids, this transition occurs for diameters larger than ~350 km. In the Kuiper belt, no density measurements have been made between ~350 km and ~850 km, the diameter range where porosities might first begin to drop. Objects in this range could provide key tests of the rock fraction of small Kuiper belt objects. Here we report the orbital characterization, mass, and density determination of the 2002 UX25 system in the Kuiper belt. For this object, with a diameter of ~650 km, we find a density of 0.82+/-0.11 g cm-3, making it the largest solid known object in the solar system with a measured density below that of pure water ice. We argue that the porosity of this object is unlikely to be above ~20%, suggesting a low rock fraction. If the currently measured densities of Kuiper belt objects are a fair representation of the sample as a whole, creating ~1000 km and larger Kuiper belt objects with rock mass fractions of 70% and higher from coagulation of small objects with rock fractions as low as those inferred from 2002 UX25 is difficult. Explore further Observations of the 2002 UX25 system with HST/HRC and Keck LGS-AO/NIRC2. The northward orientation arrow is 0.25 arcseconds long, for scale. In the first column, we show the image of both 2002 UX25 and its satellite. Credit: arXiv:1311.0553 [astro-ph.EP]last_img read more

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Researchers look at Oort cloud asteroids

first_img What is the difference between asteroids and comets? Sky & Telescope reports on “A fresh look at a nagging problem—asteroids moving in comet-like orbits” where the research “concludes that asteroids must make up about 4 percent of the vast, distant Oort Cloud of comets.” Four researchers wrote that the usual picture of the Oort cloud as a collection of icy comets in the outer reaches of the solar system is incomplete. “We use simulations of the formation of the Oort cloud to show that ~4% of the small bodies in the Oort cloud should have formed within 2.5 au of the Sun, and hence be ice-free rock-iron bodies. If we assume these Oort cloud asteroids have the same size distribution as their cometary counterparts, the Large Synoptic Survey Telescope should find roughly a dozen Oort cloud asteroids during ten years of operations.” Citation: Researchers look at Oort cloud asteroids (2014, December 9) retrieved 18 August 2019 from https://phys.org/news/2014-12-oort-cloud-asteroids.html More information: Eight billion asteroids in the Oort cloud, Monthly Notices of the Royal Astronomical Society, mnras.oxfordjournals.org/conte … /446/2/2059.abstract . On Arxiv: arxiv.org/abs/1410.7403AbstractThe Oort cloud is usually thought of as a collection of icy comets inhabiting the outer reaches of the Solar system, but this picture is incomplete. We use simulations of the formation of the Oort cloud to show that ∼4 per cent of the small bodies in the Oort cloud should have formed within 2.5 au of the Sun, and hence be ice-free rock-iron bodies. If we assume that these Oort cloud asteroids have the same size distribution as their cometary counterparts, the Large Synoptic Survey Telescope should find roughly a dozen Oort cloud asteroids during 10 years of operations. Measurement of the asteroid fraction within the Oort cloud can serve as an excellent test of the Solar system’s formation and dynamical history. Oort cloud asteroids could be of particular concern as impact hazards as their high mass density, high impact velocity, and low visibility make them both hard to detect and hard to divert or destroy. However, they should be a rare class of object, and we estimate globally catastrophic collisions should only occur about once per billion years. Andrew Shannon, Alan Jackson, Dimitri Veras and Mark Wyatt wrote about their research, “Eight billion asteroids in the Oort cloud.” The authors are from Cambridge, Arizona State University and University of Warwick. To address the question of how common asteroids should be in the Oort cloud, they said they performed simulations of the Oort cloud’s formation, “considering small bodies starting with dynamically cold orbits with semimajor axes from 0.5au to 50 au.” Kelly Beatty, Sky & Telescope senior contributing editor, talked about what the researchers set out to explore. They have taken “a fresh look at what-went-where in the early solar system.” Their computer simulations, accepted for publication in Monthly Notices of the Royal Astronomical Society, confirmed that “lots of rocky bodies originally within 2½ astronomical units of the Sun should be lurking among the Oort Cloud’s half trillion comets.”Shannon and co-authors found that Oort cloud asteroids are a minority, perhaps 4 percent of all the bodies out there, said Beatty. The number may seem small “but that’s still 8 billion objects (eerily matching the Weissman-Levison estimate), totaling perhaps a third of Earth’s mass,” Beatty added.Anything for us to worry about? On the one hand, said the study, Oort cloud asteroids could be of particular concern as impact hazards: their high mass density, high impact velocity, and low visibility make them difficult to detect and to divert or destroy. In the Discussion section of the paper, though, they said that “The rarity of Oort cloud asteroids means that Earth impacts of asteroids from the Oort cloud are quite unlikely to be a threat on human timescales. From our rate estimates, we find they should produce globally catastrophic collisions around once per Gigayear, and locally destructive impacts every million years. Thus although evidence of such occurrences may be found in the geologic record, they are not a pressing concern for the immediate future.”Marcus Woo, writing in Wired, meanwhile, wrote that there’s a thin line, as researchers are learning, between comets and asteroids. “Traditionally, comets and asteroids belong to two distinct categories,” said Woo. “In one corner, you have icy comets with long, wispy tails of gas and dust. In the other, you have dim, rocky asteroids in orbit between Mars and Jupiter.” Some astronomers find the distinction is not so clear, with asteroids found that look like comets and vice versa. They have witnessed discovery after discovery, said planetary scientist Henry Hsieh of Academia Sinica in Taiwan in Woo’s article, blurring the line. Hsieh said astronomers are coming around to the idea that asteroids and comets are at two ends of a range of objects. An artist’s rendering of the Oort cloud and the Kuiper belt (inset). Sizes of individual objects have been exaggerated for visibility. Credit: Wikipedia Explore further , arXiv © 2014 Phys.org 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. Journal information: Monthly Notices of the Royal Astronomical Societylast_img read more

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Ultraluminous infrared galaxy with strong ionizedgas outflow discovered

first_img With infrared luminosities of over 1 trillion solar luminosities and star formation rates between 100 and 1,000 solar masses per year, ULIRGs are the most intensely star-forming galaxies in the local universe. Hence, finding new galaxies of this type could be important for improving the understanding of star formation and evolution.A team led by Xiaoyang Chen of Tohoku University in Japan is interested in detecting new objects of the ULIRG population. They are constructing a sample of ULIRGs at intermediate redshifts (between 0.5 an 1.0). For this purpose, they have performed an optical follow-up program for far-infrared sources available in the AKARI Far-Infrared Surveyor (FIS) Bright Source catalog by using optical imaging data from the Sloan Digital Sky Survey (SDSS).Their study resulted in the discovery of a new ULIRG at a redshift of approximately 0.5, which received designation AKARI-FIS-V2 J0916248+073034, or J0916a for short. “In this paper we report a discovery of one ULIRG selected from AKARI 90-μm FIR survey, AKARI-FIS-V2 J0916248+073034 (hereafter J0916a),” the researchers wrote in the paper.According to the study, J0916a has a total infrared luminosity of about 6.13 trillion solar luminosities and an estimated star formation rate of nearly 1,000 solar masses per year. The galaxy’s stellar mass was calculated to be around 94.6 billion solar masses.The researchers found that J0916a showcases signatures of an extremely strong outflow in its emission line profiles. They noted that high- and low-ionization potential lines show large velocity dispersions and shifts in relative to the stellar absorption lines. “J0916a shows extreme outflow not only in the [O III] emission line, but also in the [O II] emission line,” the paper reads.The study reveals that the outflow in J0916a most likely extends to a radius of about 13,000 light years. The astronomers say that this outflow is among the most powerful observed in ULIRGs and quasars at redshifts between 0.3 and 1.6, as it has the mass outflow and energy ejection rates estimated to be at a level of around 500 solar masses per year and approximately 400 tredecillion erg/second respectively.Given that J0916a exhibits such strong outflow and an intense star formation process, the authors of the paper assume that the star-forming region of the galaxy has not yet been severely affected by the outflow.In concluding remarks, the researchers suggest further observations of J0916a in order to reveal the properties and origins of the outflow. For instance, they propose spectroscopy observations with higher spatial and spectral resolution to determine the electron density in the outflowing gas, and integral-field spectroscopy to investigate the structure of the outflow. Explore further More information: Xiaoyang Chen et al. Discovery of a strong ionized-gas outflow in an AKARI-selected Ultra-luminous Infrared Galaxy at z = 0.5. arXiv:1901.05618 [astro-ph.GA]. arxiv.org/abs/1901.05618 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 AKARI Wide-S 90-µm and VLA FIRST 21-cm images of AKARI-FIS-V2 J0916248+073034. Credit: Chen et al., 2019. Researchers study molecular gas in the galaxy Markarian 273 Citation: Ultra-luminous infrared galaxy with strong ionized-gas outflow discovered (2019, January 29) retrieved 18 August 2019 from https://phys.org/news/2019-01-ultra-luminous-infrared-galaxy-strong-ionized-gas.html Japanese astronomers report the identification of a new ultra-luminous infrared galaxy (ULIRG) as part of the search for far-infrared-bright but optically faint objects. The newly detected ULIRG, designated AKARI-FIS-V2 J0916248+073034, exhibits a strong ionized gas outflow. A paper detailing the discovery was published January 17 on arXiv.org.last_img read more

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Man thrashed for failing to answer queries on PM national anthem

first_imgMalda: A man was allegedly assaulted by four persons in a moving train in West Bengal, after he failed to reply to their queries on the prime minister and the national anthem, police said on Friday. The victim,, a migrant labourer, was on his way to Kaliachak in Malda district from Howrah on May 14, when the four persons got into the train and sat next to his seat after he had briefly deboarded at a station, a police officer said.Upon his arrival, they suddenly started asking him questions about Prime Minister Narendra Modi, the national anthem and Chief Minister Mamata Banerjee, he said, adding, the man was roughed up when he could not reply to the queries.The group later got down at Bandel station.A local NGO – Bangla Sankriti Mancha – lodged an FIR yesterday against the accused, based on videos taken by co-passengers, Kaliachak Police Station Inspector-in-Charge Suman Chatterjee said.An investigation into the matter is underway, Chatterjee said.last_img read more

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Uturn Now Rijiju says Dawood lives in Pak

first_imgAfter the government was left red- faced over its contradictory reply in Parliament on the whereabouts of Dawood Ibrahim, junior Indian Home Minister Kiren Rijiju said the underworld don lives in Pakistan and the Centre would continue to pursue the case very seriously.“Government’s consistent stand is that he (Dawood) is in Pakistan and government of India has been providing information to Pakistan about his whereabouts and Pakistani agencies are not cooperating with Indian government. That is well known to everyone,” he told reporters outside Parliament. The minister said he could not say about the clarification to be given by the government in Parliament but requested everyone not to misconstrue a statement which is based on specific questions.  Also Read – Need to understand why law graduate’s natural choice is not legal profession: CJI “So, if necessary, clarifications will be given but what I want to say is that please don’t question the intention of the government, the government is very clear and government’s job is well defined and it is pursuing the case very seriously,” he said.Earlier, replying to a written question of BJP MP Nityanand Rai in the Lok Sabha, Minister of State for Home Haribhai Parathibhai Chaudhary said, “The subject has not been located so far. Extradition process with regard to Dawood Ibrahim would be initiated once the subject is located.”  Interestingly, the government has been maintaining for a long time that Dawood is living in Pakistan with the patronage of Pakistani security establishment.The name of Dawood, who is wanted in connection with 1993 Mumbai serial blasts, figures in almost all the dossiers that have been handed over to Pakistan since the NDA rule in early 2000.last_img read more

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Ayushmann wants to playback for SRK

first_imgHe may have crooned several hit songs for himself, but actor-singer Ayushmann Khurrana says if given a chance he would love to do playback singing for superstar Shah Rukh Khan.Ayushmann, 31, who has sung many popular tracks like Paani Da Rang and Saadi Galli Aaja, feels his voice will match with that of the Chennai Express actor, as he imitates him well.“I don’t know, I would probably love to do playback for Shah Rukh. The voice will match because I mimic him pretty well, so I can sing like him. It will be quite credible,” said Ayushmann. Also Read – A fresh blend of fameThe Dum Laga Ke Haisha actor is currently riding high on the success of his latest song Yahin Hoon Main and with many Bollywood actors like Hrithik Roshan, Sonam Kapoor and Emraan Hashmi featuring in singles, Ayushmann believes the trend will boost up independent music.“More than anything else, it gives a boost to singers, to music. Because, of course in other singles there are actors who are acting, lip syncing, but with me, I am singing…,” he said. The Vicky Donor star shot to fame with the hit number Pani Da Rang and since then has lent his voice to songs like Mitti Di Khushboo and O Herriye. The actor feels he is lucky to get good songs, but credits his team of lyricist and co-composer Rochak Kohli for the success of all his tracks. “Of course I am lucky that way. More than that I am lucky to get the brilliant team. There is no wall, no professional barrier… Lyricists are my juniors from college, Rochak and I did theater together and have been composing since childhood,” he said.last_img read more

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WB Cong hails trump card Priyankas appointment

first_imgKolkata: The West Bengal unit of Congress on Wednesday welcomed Priyanka Gandhi Vadra’s appointment as general secretary for Uttar Pradesh East, and said it would boost the morale of the party ahead of the Lok Sabha polls. Ending years of speculation, Priyanka Gandhi formally entered politics in a move reflecting the party’s intent to go full throttle in the state ahead of the general elections. “We welcome Priyanka Gandhi Vadra’s appointment as Congress general secretary, as it would further boost the morale of the party ahead of Lok Sabha polls. Also Read – Speeding Jaguar crashes into Mercedes car in Kolkata, 2 pedestrians killed “This move will also further strengthen the organisation in the country, especially UP,” senior Congress leader and MP Pradip Bhattacharya said. Several other top state Congress leaders, too, welcomed the move and congratulated Priyanka Gandhi. Carrying posters of Congress president Rahul Gandhi and Priyanka Gandhi, West Bengal Congress workers in different parts of the state celebrated her appointment by distributing sweets and bursting crackers.last_img read more

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