Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Sun's Loops are Displaying an Optical Illusion

10.07.2013
The Sun's outer atmosphere, or corona, has posed an enduring mystery. Why is it so hot?

The Sun's visible surface is only 10,000 degrees Fahrenheit, but as you move outward the temperature shoots up to millions of degrees. It's like a campfire that feels hotter the farther away you stand.


This photo of the Sun's edge, taken with the Solar Dynamics Observatory Atmospheric Imaging Assembly, shows coronal loops in a variety of sizes. Although the loops appear to have a constant width, like strands of rope, new work suggests that this is an optical illusion. The loops are actually tapered, wider at the top and narrower at the bottom.
Credit: NASA/SDO

To understand how the corona is heated, some astronomers study coronal loops. These structures are shaped like an upside-down U and show where magnetic field lines are funneling solar gases or plasma.

Our best photos of the Sun suggest that these loops are a constant width, like strands of rope. However, new work shows that this is an optical illusion; the loops are actually tapered, wider at the top and narrower at the ends. This finding has important implications for coronal heating.

"You need less energy to heat the corona if the loops have a tapered geometry, which is exactly what we found," says lead author Henry Winter of the Harvard-Smithsonian Center for Astrophysics (CfA).

Winter presented his findings today in a press conference at a meeting of the American Astronomical Society Solar Physics Division in Bozeman, Mont.

Winter and his colleagues constructed a computer model of a tapered loop using basic physics. Then they processed their model to show how it would look when photographed by instruments like the High-resolution Coronal Imager (Hi-C) or the Solar Dynamics Observatory's Atmospheric Imaging Assembly (AIA).

They found that even the best available images wouldn't have the resolution to show the loop's true structure. As a result, a tapered loop would appear tubular even though it wasn't.

"In science we always compare theory to reality. But if your view of reality is incorrect, your theory will be wrong too. What we thought we saw could be just an effect of the instrument," explains Winter.

Historically, as we have gotten better and better photos of coronal loops, they have revealed more and more structure. What first appeared to be a single loop turned out to be made of many smaller strands. The team's work shows that better instruments with higher resolution are still needed to reveal the true shape and structure of the loops.

"Coronal loops are like Russian nesting dolls. We keep pulling them apart but we haven't gotten to the smallest one yet," says Winter.

Winter's co-authors are Chester Curme (Boston University), Katharine Reeves (CfA), and Petrus Martens (Montana State University).

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.

For more information, contact:

David A. Aguilar
Director of Public Affairs
Harvard-Smithsonian Center for Astrophysics
617-495-7462
daguilar@cfa.harvard.edu
Christine Pulliam
Public Affairs Specialist
Harvard-Smithsonian Center for Astrophysics
617-495-7463
cpulliam@cfa.harvard.edu

Christine Pulliam | EurekAlert!
Further information:
http://www.cfa.harvard.edu

More articles from Physics and Astronomy:

nachricht Climate cycles may explain how running water carved Mars' surface features
02.12.2016 | Penn State

nachricht What do Netflix, Google and planetary systems have in common?
02.12.2016 | University of Toronto

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

Im Focus: Fraunhofer ISE Develops Highly Compact, High Frequency DC/DC Converter for Aviation

The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

UTSA study describes new minimally invasive device to treat cancer and other illnesses

02.12.2016 | Medical Engineering

Plasma-zapping process could yield trans fat-free soybean oil product

02.12.2016 | Agricultural and Forestry Science

What do Netflix, Google and planetary systems have in common?

02.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>