Dear colleagues please find at the following link the preprint of a work accepted for publication on the ApJ Letters, showing new strong evidence of finely-structured loops with impulsive nanoflare activity in active regions:
http://arxiv.org/abs/1106.1591
The abstract is below.
Best regards Fabio Reale
Solar Dynamics Observatory discovers thin high temperature strands in coronal active regions
Authors: Fabio Reale, Massimiliano Guarrasi, Paola Testa, Edward E. DeLuca, Giovanni Peres, Leon Golub
http://arxiv.org/find/astro-ph/1/au:+Golub_L/0/1/0/all/0/1
Abstract: One scenario proposed to explain the million degrees solar corona is a finely-stranded corona where each strand is heated by a rapid pulse. However, such fine structure has neither been resolved through direct imaging observations nor conclusively shown through indirect observations of extended superhot plasma. Recently it has been shown that the observed difference in appearance of cool and warm coronal loops (~1 MK, ~2-3 MK, respectively) -- warm loops appearing "fuzzier" than cool loops -- can be explained by models of loops composed of subarcsecond strands, which are impulsively heated up to ~10 MK. That work predicts that images of hot coronal loops (>~6 MK) should again show fine structure. Here we show that the predicted effect is indeed widely observed in an active region with the Solar Dynamics Observatory, thus supporting a scenario where impulsive heating of fine loop strands plays an important role in powering the active corona.
Hi Fabio,
Nice paper! Congratulations.! You could have cited the paper on the fuzziness (Tripathi et al. 2009 ApJ) along with your simulation paper (Gurazzi et al.2010)...
Cheers, -Durgesh
Assistant Professor IUCAA, Post Bag - 4 Ganeshkhind Pune 411007 India Ph.No: +91(0)2025604224
----- Original Message ----- From: "Fabio Reale" reale@astropa.unipa.it To: "A mailing list for scientists involved in the observation and modeling of solar loop structures" loops@solar.physics.montana.edu Sent: Thursday, 9 June, 2011 2:22:04 PM Subject: [Loops] [1106.1591] Solar Dynamics Observatory discovers thin high temperature strands in coronal active regions
Dear colleagues please find at the following link the preprint of a work accepted for publication on the ApJ Letters, showing new strong evidence of finely-structured loops with impulsive nanoflare activity in active regions:
http://arxiv.org/abs/1106.1591
The abstract is below.
Best regards Fabio Reale
Solar Dynamics Observatory discovers thin high temperature strands in coronal active regions
Authors: Fabio Reale, Massimiliano Guarrasi, Paola Testa, Edward E. DeLuca, Giovanni Peres, Leon Golub
Abstract: One scenario proposed to explain the million degrees solar corona is a finely-stranded corona where each strand is heated by a rapid pulse. However, such fine structure has neither been resolved through direct imaging observations nor conclusively shown through indirect observations of extended superhot plasma. Recently it has been shown that the observed difference in appearance of cool and warm coronal loops (~1 MK, ~2-3 MK, respectively) -- warm loops appearing "fuzzier" than cool loops -- can be explained by models of loops composed of subarcsecond strands, which are impulsively heated up to ~10 MK. That work predicts that images of hot coronal loops (>~6 MK) should again show fine structure. Here we show that the predicted effect is indeed widely observed in an active region with the Solar Dynamics Observatory, thus supporting a scenario where impulsive heating of fine loop strands plays an important role in powering the active corona.
_______________________________________________ Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
Dear Loop-sters:
Please find a paper on "Emission Measure Distribution and Heating of Two Active Region Cores". I have appended the abstract below and the paper could be downloaded from the following link:
http://arxiv.org/abs/1107.4480
Abstract: Using data from the Extreme-ultraviolet Imaging Spectrometer aboard Hinode, we have studied the coronal plasma in the core of two active regions. Concentrating on the area between opposite polarity moss, we found emission measure distributions having an approximate power-law form EM$\propto T^{2.4}$ from $\log,T = 5.5$ up to a peak at $\log,T = 6.55$. We show that the observations compare very favorably with a simple model of nanoflare-heated loop strands. They also appear to be consistent with more sophisticated nanoflare models. However, in the absence of additional constraints, steady heating is also a viable explanation.
Hope some of you will find it useful.
Cheers, -Durgesh
A nice paper and an important contribution to the debate. But the jury is still out. We may never resolve this without real spectroscopic evidence of the very hot component. Where is our future spectroscopy coming from??
Alan Gabriel
Le 09/06/2011 10:52, Fabio Reale a écrit :
Hi Alan,
We have two "cunning plans":
(1) there is a rocket proposal for a new grazing incident spectrograph - Ken Kobayashi, Leon, Jonathan or Kelly can provide more details.
(2) A group at GSFC has had some success with microcalorimeters for solar use. Simon Bandler and Jay may have additional comments on this. The baseline detector would give ~2ev spectral resolution from 0.5-6kev, with a high resolution inner array of 32x32 pixels (~2"/pixel on a rocket) and a lower resolution outer array. The development work has proceeded to the point that we are likely to propose a solar rocket this year for the microcalorimeter.
Both of these operate in the soft wavelength band where we can more easily see coronal heating.
Ed
On 6/9/11 7:56 AM, Alan Gabriel wrote:
Thanks, Ed. I did in fact just give a talk at the IAS that described the GI x-ray spectrometer and I plan to talk about it when I visit MSSL at the end of July. I'll have the writeup with me at the Loops V workshop, if anyone wants details.
Leon
On 6/9/2011 8:32 AM, Ed DeLuca wrote:
Alan, in reply to you: The Japanese have chosen "Plan B" for the Solar-C mission, and according to Saku Tsuneta, they are moving forward with the project in spite of the horrible disaster they must deal with. Plan B is a high spatial and spectral resolution imaging/spectrometer (~0.2") involving two instruments and a very high spatial resolution EUV/UV imager. The combination covers the entire atmosphere from the chromosphere to X-ray solar flares (see white paper to the US decadal survey). So Solar-C, if approved by funding agencies and implemented, should clarify a lot of the issues dealing with loops and how they are heated.
In addition, there is the Lockheed SMEX IRIS mission undergoing development, and there are also a number of interesting rocket experiments either under construction or proposed.
To the group: Please add whatever else I may have overlooked.
George Doschek
________________________________
From: loops-bounces@mithra.physics.montana.edu [mailto:loops-bounces@mithra.physics.montana.edu] On Behalf Of Alan Gabriel Sent: Thursday, June 09, 2011 7:56 AM To: A mailing list for scientists involved in the observation and modeling ofsolar loop structures Subject: Re: [Loops] [1106.1591] Solar Dynamics Observatory discovers thin high temperature strands in coronal active regions
A nice paper and an important contribution to the debate. But the jury is still out. We may never resolve this without real spectroscopic evidence of the very hot component. Where is our future spectroscopy coming from??
Alan Gabriel
Le 09/06/2011 10:52, Fabio Reale a écrit :
Dear colleagues please find at the following link the preprint of a work accepted for publication on the ApJ Letters, showing new strong evidence of finely-structured loops with impulsive nanoflare activity in active regions:
http://arxiv.org/abs/1106.1591
The abstract is below.
Best regards Fabio Reale
Solar Dynamics Observatory discovers thin high temperature strands in coronal active regions
Authors: Fabio Reale, Massimiliano Guarrasi, Paola Testa, Edward E. DeLuca, Giovanni Peres, Leon Golub
Abstract: One scenario proposed to explain the million degrees solar corona is a finely-stranded corona where each strand is heated by a rapid pulse. However, such fine structure has neither been resolved through direct imaging observations nor conclusively shown through indirect observations of extended superhot plasma. Recently it has been shown that the observed difference in appearance of cool and warm coronal loops (~1 MK, ~2-3 MK, respectively) -- warm loops appearing "fuzzier" than cool loops -- can be explained by models of loops composed of subarcsecond strands, which are impulsively heated up to ~10 MK. That work predicts that images of hot coronal loops (>~6 MK) should again show fine structure. Here we show that the predicted effect is indeed widely observed in an active region with the Solar Dynamics Observatory, thus supporting a scenario where impulsive heating of fine loop strands plays an important role in powering the active corona.
_______________________________________________ Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
George et al.,
As I think you all saw from Ed DeLuca's message (I don't think that "loops-bounce" in the "From" header means your message has been rejected, right?), there are two instrument concepts being discussed these days for direct spectroscopic imaging at X-ray wavelengths. I think that the 5-25A wavelength range has excellent potential for addressing the controversies we're all embroiled in now. So in addition to the instruments George has mentioned, there are some new concepts that may have a chance of being tried out in the next few years. If NASA has adequate funding, we may get to see them flown soon.
Leon
On 6/9/2011 9:01 AM, Doschek, George wrote:
I first tried to send my message with the Plan B white paper as an attachment, but unfortunately it exceeded the allowed e-mail size. So rather than wait for a judgment from the moderator, I cancelled my message and have resent it without the attachment.
George
________________________________
From: loops-bounces@mithra.physics.montana.edu [mailto:loops-bounces@mithra.physics.montana.edu] On Behalf Of Leon Golub Sent: Thursday, June 09, 2011 9:26 AM To: loops@mithra.physics.montana.edu Subject: Re: [Loops] [1106.1591] Solar Dynamics Observatory discovers thin high temperature strands in coronal active regions
George et al.,
As I think you all saw from Ed DeLuca's message (I don't think that "loops-bounce" in the "From" header means your message has been rejected, right?), there are two instrument concepts being discussed these days for direct spectroscopic imaging at X-ray wavelengths. I think that the 5-25A wavelength range has excellent potential for addressing the controversies we're all embroiled in now. So in addition to the instruments George has mentioned, there are some new concepts that may have a chance of being tried out in the next few years. If NASA has adequate funding, we may get to see them flown soon.
Leon
On 6/9/2011 9:01 AM, Doschek, George wrote:
Alan, in reply to you: The Japanese have chosen "Plan B" for the Solar-C mission, and according to Saku Tsuneta, they are moving forward with the project in spite of the horrible disaster they must deal with. Plan B is a high spatial and spectral resolution imaging/spectrometer (~0.2") involving two instruments and a very high spatial resolution EUV/UV imager. The combination covers the entire atmosphere from the chromosphere to X-ray solar flares (see white paper to the US decadal survey). So Solar-C, if approved by funding agencies and implemented, should clarify a lot of the issues dealing with loops and how they are heated.
In addition, there is the Lockheed SMEX IRIS mission undergoing development, and there are also a number of interesting rocket experiments either under construction or proposed.
To the group: Please add whatever else I may have overlooked.
George Doschek
________________________________
From: loops-bounces@mithra.physics.montana.edu [mailto:loops-bounces@mithra.physics.montana.edu] On Behalf Of Alan Gabriel Sent: Thursday, June 09, 2011 7:56 AM To: A mailing list for scientists involved in the observation and modeling ofsolar loop structures Subject: Re: [Loops] [1106.1591] Solar Dynamics Observatory discovers thin high temperature strands in coronal active regions
A nice paper and an important contribution to the debate. But the jury is still out. We may never resolve this without real spectroscopic evidence of the very hot component. Where is our future spectroscopy coming from??
Alan Gabriel
Le 09/06/2011 10:52, Fabio Reale a écrit :
Dear colleagues please find at the following link the preprint of a work accepted for publication on the ApJ Letters, showing new strong evidence of finely-structured loops with impulsive nanoflare activity in active regions:
http://arxiv.org/abs/1106.1591
The abstract is below.
Best regards Fabio Reale
Solar Dynamics Observatory discovers thin high temperature strands in coronal active regions
Authors: Fabio Reale, Massimiliano Guarrasi, Paola Testa, Edward E. DeLuca, Giovanni Peres, Leon Golub
Abstract: One scenario proposed to explain the million degrees solar corona is a finely-stranded corona where each strand is heated by a rapid pulse. However, such fine structure has neither been resolved through direct imaging observations nor conclusively shown through indirect observations of extended superhot plasma. Recently it has been shown that the observed difference in appearance of cool and warm coronal loops (~1 MK, ~2-3 MK, respectively) -- warm loops appearing "fuzzier" than cool loops -- can be explained by models of loops composed of subarcsecond strands, which are impulsively heated up to ~10 MK. That work predicts that images of hot coronal loops (>~6 MK) should again show fine structure. Here we show that the predicted effect is indeed widely observed in an active region with the Solar Dynamics Observatory, thus supporting a scenario where impulsive heating of fine loop strands plays an important role in powering the active corona.
_______________________________________________ Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
Here is my reply with attachment:
Alan, in reply to you: The Japanese have chosen "Plan B" for the Solar-C mission, and according to Saku Tsuneta, they are moving forward with the project in spite of the horrible disaster they must deal with. Plan B is a high spatial and spectral resolution imaging/spectrometer (~0.2") involving two instruments and a very high spatial resolution EUV/UV imager. The combination covers the entire atmosphere from the chromosphere to X-ray solar flares (see attached white paper to the US decadal survey). So Solar-C, if approved by funding agencies and implemented, should clarify a lot of the issues dealing with loops and how they are heated.
In addition, there is the Lockheed SMEX IRIS mission undergoing development, and there are also a number of interesting rocket experiments either under construction or proposed.
To the group: Please add whatever else I may have overlooked.
George Doschek
________________________________
From: loops-bounces@mithra.physics.montana.edu [mailto:loops-bounces@mithra.physics.montana.edu] On Behalf Of Alan Gabriel Sent: Thursday, June 09, 2011 7:56 AM To: A mailing list for scientists involved in the observation and modeling ofsolar loop structures Subject: Re: [Loops] [1106.1591] Solar Dynamics Observatory discovers thin high temperature strands in coronal active regions
A nice paper and an important contribution to the debate. But the jury is still out. We may never resolve this without real spectroscopic evidence of the very hot component. Where is our future spectroscopy coming from??
Alan Gabriel
Le 09/06/2011 10:52, Fabio Reale a écrit :
Dear colleagues please find at the following link the preprint of a work accepted for publication on the ApJ Letters, showing new strong evidence of finely-structured loops with impulsive nanoflare activity in active regions:
http://arxiv.org/abs/1106.1591
The abstract is below.
Best regards Fabio Reale
Solar Dynamics Observatory discovers thin high temperature strands in coronal active regions
Authors: Fabio Reale, Massimiliano Guarrasi, Paola Testa, Edward E. DeLuca, Giovanni Peres, Leon Golub
Abstract: One scenario proposed to explain the million degrees solar corona is a finely-stranded corona where each strand is heated by a rapid pulse. However, such fine structure has neither been resolved through direct imaging observations nor conclusively shown through indirect observations of extended superhot plasma. Recently it has been shown that the observed difference in appearance of cool and warm coronal loops (~1 MK, ~2-3 MK, respectively) -- warm loops appearing "fuzzier" than cool loops -- can be explained by models of loops composed of subarcsecond strands, which are impulsively heated up to ~10 MK. That work predicts that images of hot coronal loops (>~6 MK) should again show fine structure. Here we show that the predicted effect is indeed widely observed in an active region with the Solar Dynamics Observatory, thus supporting a scenario where impulsive heating of fine loop strands plays an important role in powering the active corona.
_______________________________________________ Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
loops@solar.physics.montana.edu