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Trio create model to explain massive heat in the Suns corona

first_img(Phys.org)—A trio of researchers, two with Ecole Polytechnique and the other with Université Paris, all in France, has created a computer model that is meant to show how it is that so much heat is in the sun’s corona. In their paper published in the journal Nature, Tahar Amari, Jean-François Luciani and Jean-Jacques Aly describe their model, how it came about and why they think it is accurate. Emissions from various layers of the solar atmosphere, using data from the NASA Iris mission. Credit: Tahar Amari /Centre de physique théorique.CNRS-Ecole Polytechnique. FRANCE Citation: Trio create model to explain massive heat in the Sun’s corona (2015, June 11) retrieved 18 August 2019 from https://phys.org/news/2015-06-trio-massive-sun-corona.html Exploring the solar magnetic Mangrove and below . This movie shows an observer (author) looking at and exploring the solar magnetic Mangrove , and diving below the surface of the Sun. This movie was created using the CAVE virtual reality system of TechViz (Paris). Credit: Tahar Amari /Centre de physique théorique.CNRS-Ecole Polytechnique.FRANCE The trio point to other observable phenomena that help bolster the credence of their theory—the fact that the temperature of the corona does not vary much over the course of sunspot cycles, for example, which they say is because the sun’s magnetic field is not sensitive to it, because they are deeply rooted in the sun—their model describes shallow activity. Also, they note that other researchers have found evidence of solar tornadoes, which in a way are similar to the trees describe by the model and which can also transport heat up and off the surface. And finally, other observations have revealed that spectral lines of some elements are split into multiple components on the surface, which they team suggests would occur if there happened to be a magnetic field like the one they use in their model.More research will have to be conducted both by the research team and others, of course, to see if the model will continue to hold up under scrutiny. 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: Small-scale dynamo magnetism as the driver for heating the solar atmosphere, Nature 522, 188–191 (11 June 2015) DOI: 10.1038/nature14478AbstractThe long-standing problem of how the solar atmosphere is heated has been addressed by many theoretical studies, which have stressed the relevance of two specific mechanisms, involving magnetic reconnection and waves, as well as the necessity of treating the chromosphere and corona together. But a fully consistent model has not yet been constructed and debate continues, in particular about the possibility of coronal plasma being heated by energetic phenomena observed in the chromosphere. Here we report modelling of the heating of the quiet Sun, in which magnetic fields are generated by a subphotospheric fluid dynamo intrinsically connected to granulation. We find that the fields expand into the chromosphere, where plasma is heated at the rate required to match observations (4,500 watts per square metre) by small-scale eruptions that release magnetic energy and drive sonic motions. Some energetic eruptions can even reach heights of 10 million metres above the surface of the Sun, thereby affecting the very low corona. Extending the model by also taking into account the vertical weak network magnetic field allows for the existence of a mechanism able to heat the corona above, while leaving unchanged the physics of chromospheric eruptions. Such a mechanism rests on the eventual dissipation of Alfvén waves generated inside the chromosphere and that carry upwards the required energy flux of 300 watts per square metre. The model shows a topologically complex magnetic field of 160 gauss on the Sun’s surface, agreeing with inferences obtained from spectropolarimetric observations, chromospheric features (contributing only weakly to the coronal heating) that can be identified with observed spicules and blinkers, and vortices that may be possibly associated with observed solar tornadoes8. Explore further Emissions from various layers of the solar atmosphere, using data from the NASA Iris mission. Credit: Tahar Amari /Centre de physique théorique.CNRS-Ecole Polytechnique. FRANCE © 2015 Phys.orgcenter_img SOHO and Hinode offer new insight into solar eruptions Model of the complex magnetic field on the Sun’s surface, resembling the roots and branches of mangroves, rooted in the boiling Sun. Credit: Tahar Amari /Centre de physique théorique.CNRS-Ecole Polytechnique.FRANCE Solar disk image taken in 2011 with large scale atmosphere during as visible during an eclipse in 2008. Credit: Tahar Amari /Centre de physique théorique.CNRS-Ecole Polytechnique.FRANCE & Eclipse S.Habbal and M. DruckMuller. This movie shows the heating obtained by the model at the heart of the discovery. The model allows a closer look at high resolution of Sun horizon. The boiling pan of plasma just underneath the surface of the Sun, generates and feed the magnetic field that emerges above and create the magnetic Mangrove, whose roots dance like flames as they are heated. Credit: Tahar Amari /Centre de physique théorique.CNRS-Ecole Polytechnique.FRANCE. Model of the complex magnetic field on the Sun’s surface, resembling the roots and branches of mangroves, rooted in the boiling Sun. Credit: Tahar Amari /Centre de physique théorique.CNRS-Ecole Polytechnique.FRANCE For some time space scientists have been perplexed by research results that show the sun’s corona is millions of degrees hotter than its surface. In this new effort, the researchers built a model that describes how that might occur and then offer some evidence to back up their claims.Scientists know that on the sun’s surface, rotating areas of gas create what are known as dynamos—where plasma causes charges to come about. In their model, the researchers suggest that when such dynamos “dump” their energy, it causes small eruptions to come about on the surface, allowing energy to dissipate out to the corona. The team describes their model as resembling a mangrove forest. The roots of the trees represent surface magnetic fields—energy makes its way up the trees and dissipates near the top like oxygen from tree leaves into the atmosphere, and that is how the energy reaches the corona. Journal information: Naturelast_img read more

How Dumb Is This Apple iPod Antitrust Suit

first_img This story originally appeared on Fortune Magazine Register Now » December 9, 2014 Growing a business sometimes requires thinking outside the box. Free Webinar | Sept. 9: The Entrepreneur’s Playbook for Going Global Bonney Sweeney, the antitrust attorney at Robbins Geller Rudman & Dowd who claims to represent the interests of 8 million aggrieved Apple customers, now represents nobody but a roomful of lawyers.On Monday, Sweeney lost her last plaintiff, a resident of New Jersey named Marianna Rosen. It turns out the “supracompetitive” price Rosen claims to have paid in 1988 for an iPod (“greater than she would have paid, but for the antitrust violations alleged herein”) was charged to her law firm’s credit card.Although U.S. District Judge Yvonne Gonzalez Rogers gave Sweeney until Tuesday to find a new plaintiff, the case may yet get tossed out on a technicality. That’s not what Apple — which should be able to win this one on the facts — says it wants.It may be what Sweeney et al. deserve.I hadn’t thought much about class action law before this case, so I appreciated the backgrounder Daniel Fisher filed last week. According to Fisher, who covers law and finance for Forbes, it can be a dirty business.“Class-action lawyers,” he writes, “are a well-defined group of players who must establish a reputation for fighting hard in every case and racking up as much expenses on the defense side as they can, in order to induce companies to come to the settlement table. That’s where they make their money, and the convenient fiction that they are suing on behalf of consumers collapses as they get down to the real negotiations, which are over the fee they will be paid without any objections from their supposed opponents across the table.“But for the whole process to work, they still need clients. And those clients must have a case. Defense lawyers have slowly but steadily woken up to the fact that those clients often come with baggage — Bill Lerach, the founder of the predecessor to Robbins Geller, went to jail for paying his clients to appear in securities class actions — and they are digging into their backgrounds to find out if they can even serve as plaintiffs. This must strike some plaintiff lawyers as strange, since everybody knows the “client” is just a vehicle for assembling a case that often is already loaded in their computer, ready to be filed. But it’s the law, and Judge Rogers may just decide that this long-running case has met an insuperable barrier.”It would be a fitting end for a case that’s already been through more than its share of twists and turns.It began in January 2005 when Rosen and two other plaintiffs accused Apple of illegally tying the iPod to the iTunes music store. See iThe Apple iTunes Anti-Trust Litigation.According to CNET, their complaint had to be rewritten when a court ruled that what Apple had done — build a service that only played songs purchased on iTunes or ripped from a CD — was perfectly legal.That’s when the litigants shifted their focus to a pair of Apple security updates — 7.0 and 7.4 — that barred competing music stores from syncing with iTunes. The claim is that the updates had no purpose but to protect Apple’s iTunes monopoly.Apple ought to be able to knock that one out of the park. See iTunes Version History.Meanwhile, Apple’s lawyers have managed to pick off all three of the original plaintiffs. Sweeney says there are plenty more where those three came from. We’ll hear about them on Wednesday. 4 min readlast_img read more