Dear friends,
You might be interested in my recent paper on "The Role of Type II Spicules in the Upper Solar Atmosphere," which can be downloaded at http://arxiv.org/abs/1207.7048
Cheers, Jim
ABSTRACT: We examine the suggestion that most of the hot plasma in the Sun's corona comes from type II spicule material that is heated as it is ejected from the chromosphere. This contrasts with the traditional view that the corona is filled via chromospheric evaporation that results from coronal heating. We explore the observational consequences of a hypothetical spicule dominated corona and conclude from the large discrepancy between predicted and actual observations that only a small fraction of the hot plasma can be supplied by spicules (<2% in active regions and <5% in the quiet Sun). The red-blue asymmetries of EUV spectral lines and the ratio of lower transition region (LTR; T<0.1 MK) to coronal emission measures are both predicted to be 2 orders of magnitude larger than observed. Furthermore, hot spicule material would cool dramatically by adiabatic expansion as it rises into the corona, so coronal heating would be required to maintain the high temperatures that are seen at all altitudes. The necessity of coronal heating is inescapable. Traditional coronal heating models predict far too little emission from the LTR, and we suggest that this emission comes primarily from the bulk of the spicule material that is heated to <0.1 MK and is visible in He II (304 A) as it falls back to the surface.
******************************************************************************** James A. Klimchuk NASA Goddard Space Flight Center Solar Physics Lab, Code 671 Bldg. 21, Rm. 158 Greenbelt, MD 20771 USA
Phone: 1-301-286-9060 Fax: 1-301-286-7194 E-mail: James.A.Klimchuk@nasa.govmailto:James.A.Klimchuk@nasa.gov Homepage: https://sedupdate.gsfc.nasa.gov/sed/index.cfm?fuseAction=people.jumpBio&... No endorsement by NASA is implied for any correspondence related to my role as an officer of professional organizations (American Geophysical Union, International Astronomical Union, American Astronomical Society).
********************************************************************************
Hey, great paper! Glad that someone looked into that.
Cheers,
Piet
On 7/31/12 7:47 AM, Klimchuk, James A. (GSFC-6710) wrote:
Dear friends,
You might be interested in my recent paper on “The Role of Type
II Spicules in the Upper Solar Atmosphere,” which can be downloaded at http://arxiv.org/abs/1207.7048
Cheers,
Jim
ABSTRACT:
We examine the suggestion that most of the hot plasma in the Sun's
corona comes from type II spicule material that is heated as it is
ejected from the chromosphere. This contrasts with the traditional
view that the corona is filled via chromospheric evaporation that
results from coronal heating. We explore the observational
consequences of a hypothetical spicule dominated corona and conclude
from the large discrepancy between predicted and actual observations
that only a small fraction of the hot plasma can be supplied by
spicules (<2% in active regions and <5% in the quiet Sun). The
red-blue asymmetries of EUV spectral lines and the ratio of lower
transition region (LTR; T<0.1 MK) to coronal emission measures
are both predicted to be 2 orders of magnitude larger than observed.
Furthermore, hot spicule material would cool dramatically by
adiabatic expansion as it rises into the corona, so coronal heating
would be required to maintain the high temperatures that are seen at
all altitudes. The necessity of coronal heating is inescapable.
Traditional coronal heating models predict far too little emission
from the LTR, and we suggest that this emission comes primarily from
the bulk of the spicule material that is heated to <0.1 MK and
is visible in He II (304 A) as it falls back to the surface.
James A. Klimchuk
NASA Goddard Space Flight Center
Solar Physics Lab, Code 671
Bldg. 21, Rm. 158
Greenbelt, MD 20771
USA
Phone: 1-301-286-9060
Fax: 1-301-286-7194
E-mail: James.A.Klimchuk@nasa.gov mailto:James.A.Klimchuk@nasa.gov
Homepage: https://sedupdate.gsfc.nasa.gov/sed/index.cfm?fuseAction=people.jumpBio&...
No endorsement by NASA is implied for any correspondence related to my role as an officer of professional organizations (American Geophysical Union, International Astronomical Union, American Astronomical Society).
Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
It may be a great paper, but why is there no citation of Scudder's work?
Hugh
On 31 Jul 2012, at 16:12, Petrus Martens wrote:
Hey, great paper! Glad that someone looked into that.
Cheers,
Piet
On 7/31/12 7:47 AM, Klimchuk, James A. (GSFC-6710) wrote:
Dear friends,
You might be interested in my recent paper on “The Role of Type
II Spicules in the Upper Solar Atmosphere,” which can be downloaded at http://arxiv.org/abs/1207.7048
Cheers,
Jim
ABSTRACT:
We examine the suggestion that most of the hot plasma in the Sun's
corona comes from type II spicule material that is heated as it is
ejected from the chromosphere. This contrasts with the traditional
view that the corona is filled via chromospheric evaporation that
results from coronal heating. We explore the observational
consequences of a hypothetical spicule dominated corona and conclude
from the large discrepancy between predicted and actual observations
that only a small fraction of the hot plasma can be supplied by
spicules (<2% in active regions and <5% in the quiet Sun). The
red-blue asymmetries of EUV spectral lines and the ratio of lower
transition region (LTR; T<0.1 MK) to coronal emission measures
are both predicted to be 2 orders of magnitude larger than observed.
Furthermore, hot spicule material would cool dramatically by
adiabatic expansion as it rises into the corona, so coronal heating
would be required to maintain the high temperatures that are seen at
all altitudes. The necessity of coronal heating is inescapable.
Traditional coronal heating models predict far too little emission
from the LTR, and we suggest that this emission comes primarily from
the bulk of the spicule material that is heated to <0.1 MK and
is visible in He II (304 A) as it falls back to the surface.
James A. Klimchuk
NASA Goddard Space Flight Center
Solar Physics Lab, Code 671
Bldg. 21, Rm. 158
Greenbelt, MD 20771
USA
Phone: 1-301-286-9060
Fax: 1-301-286-7194
E-mail: James.A.Klimchuk@nasa.gov mailto:James.A.Klimchuk@nasa.gov
Homepage: https://sedupdate.gsfc.nasa.gov/sed/index.cfm?fuseAction=people.jumpBio&...
No endorsement by NASA is implied for any correspondence related to my role as an officer of professional organizations (American Geophysical Union, International Astronomical Union, American Astronomical Society).
Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
<martens.vcf>_______________________________________________ Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
On 7/31/12 8:27 AM, Hugh S. Hudson wrote:
It may be a great paper, but why is there no citation of Scudder's work?
Would have been useful. I don't think Jim's results invalidate Scudder's results though.
Piet
Hugh
On 31 Jul 2012, at 16:12, Petrus Martens wrote:
Hey, great paper! Glad that someone looked into that.
Cheers,
Piet
On 7/31/12 7:47 AM, Klimchuk, James A. (GSFC-6710) wrote:
Dear friends,
You might be interested in my recent paper on “The Role of Type
II Spicules in the Upper Solar Atmosphere,” which can be downloaded at http://arxiv.org/abs/1207.7048
Cheers,
Jim
ABSTRACT:
We examine the suggestion that most of the hot plasma in the Sun's
corona comes from type II spicule material that is heated as it is
ejected from the chromosphere. This contrasts with the traditional
view that the corona is filled via chromospheric evaporation that
results from coronal heating. We explore the observational
consequences of a hypothetical spicule dominated corona and conclude
from the large discrepancy between predicted and actual observations
that only a small fraction of the hot plasma can be supplied by
spicules (<2% in active regions and <5% in the quiet Sun). The
red-blue asymmetries of EUV spectral lines and the ratio of lower
transition region (LTR; T<0.1 MK) to coronal emission measures
are both predicted to be 2 orders of magnitude larger than observed.
Furthermore, hot spicule material would cool dramatically by
adiabatic expansion as it rises into the corona, so coronal heating
would be required to maintain the high temperatures that are seen at
all altitudes. The necessity of coronal heating is inescapable.
Traditional coronal heating models predict far too little emission
from the LTR, and we suggest that this emission comes primarily from
the bulk of the spicule material that is heated to <0.1 MK and
is visible in He II (304 A) as it falls back to the surface.
James A. Klimchuk
NASA Goddard Space Flight Center
Solar Physics Lab, Code 671
Bldg. 21, Rm. 158
Greenbelt, MD 20771
USA
Phone: 1-301-286-9060
Fax: 1-301-286-7194
E-mail: James.A.Klimchuk@nasa.gov mailto:James.A.Klimchuk@nasa.gov
Homepage: https://sedupdate.gsfc.nasa.gov/sed/index.cfm?fuseAction=people.jumpBio&...
No endorsement by NASA is implied for any correspondence related to my role as an officer of professional organizations (American Geophysical Union, International Astronomical Union, American Astronomical Society).
Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
<martens.vcf>_______________________________________________ Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
Right, Piet. They are totally unrelated.
Jim
-----Original Message----- From: loops-bounces@solar.physics.montana.edu [mailto:loops- bounces@solar.physics.montana.edu] On Behalf Of Petrus Martens Sent: Tuesday, July 31, 2012 10:33 AM To: loops@solar.physics.montana.edu Subject: Re: [Loops] type II spicule paper
On 7/31/12 8:27 AM, Hugh S. Hudson wrote:
It may be a great paper, but why is there no citation of Scudder's work?
Would have been useful. I don't think Jim's results invalidate Scudder's results though.
Piet
Hugh
On 31 Jul 2012, at 16:12, Petrus Martens wrote:
Hey, great paper! Glad that someone looked into that.
Cheers,
Piet
On 7/31/12 7:47 AM, Klimchuk, James A. (GSFC-6710) wrote:
Dear friends,
You might be interested in my recent paper on "The Role of
Type II Spicules in the Upper Solar Atmosphere," which can be downloaded at http://arxiv.org/abs/1207.7048
Cheers,
Jim
ABSTRACT:
We examine the suggestion that most of the hot plasma in the Sun's
corona comes from type II spicule material that is heated as it is
ejected from the chromosphere. This contrasts with the traditional
view that the corona is filled via chromospheric evaporation that
results from coronal heating. We explore the observational
consequences of a hypothetical spicule dominated corona and conclude
from the large discrepancy between predicted and actual observations
that only a small fraction of the hot plasma can be supplied by
spicules (<2% in active regions and <5% in the quiet Sun). The
red-blue asymmetries of EUV spectral lines and the ratio of lower
transition region (LTR; T<0.1 MK) to coronal emission measures
are both predicted to be 2 orders of magnitude larger than observed.
Furthermore, hot spicule material would cool dramatically by
adiabatic expansion as it rises into the corona, so coronal heating
would be required to maintain the high temperatures that are seen at
all altitudes. The necessity of coronal heating is inescapable.
Traditional coronal heating models predict far too little emission
from the LTR, and we suggest that this emission comes primarily from
the bulk of the spicule material that is heated to <0.1 MK and
is visible in He II (304 A) as it falls back to the surface.
James A. Klimchuk
NASA Goddard Space Flight Center
Solar Physics Lab, Code 671
Bldg. 21, Rm. 158
Greenbelt, MD 20771
USA
Phone: 1-301-286-9060
Fax: 1-301-286-7194
E-mail: James.A.Klimchuk@nasa.gov
mailto:James.A.Klimchuk@nasa.gov
Homepage:
https://sedupdate.gsfc.nasa.gov/sed/index.cfm?fuseAction=people.jump
Bio&&iPhonebookId=15844
No endorsement by NASA is implied for any correspondence related to my role as an officer of professional organizations (American Geophysical Union, International Astronomical Union, American
Astronomical Society).
Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
<martens.vcf>_______________________________________________ Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
Actually, my use of "Scudder" was shorthand for "plasma kinetic effects." I don't regard these as unrelated to "heating" in general; I doubt that a paper can draw general conclusions in this area without a discussion of that physics.
I note that your definition of evaporation is inconsistent with our normal usage for flares, where non-thermal particles can do the dirty work. But perhaps I will read on past this point!
Cheers
Hugh
On 31 Jul 2012, at 16:45, Klimchuk, James A. (GSFC-6710) wrote:
Right, Piet. They are totally unrelated.
Jim
-----Original Message----- From: loops-bounces@solar.physics.montana.edu [mailto:loops- bounces@solar.physics.montana.edu] On Behalf Of Petrus Martens Sent: Tuesday, July 31, 2012 10:33 AM To: loops@solar.physics.montana.edu Subject: Re: [Loops] type II spicule paper
On 7/31/12 8:27 AM, Hugh S. Hudson wrote:
It may be a great paper, but why is there no citation of Scudder's work?
Would have been useful. I don't think Jim's results invalidate Scudder's results though.
Piet
Hugh
On 31 Jul 2012, at 16:12, Petrus Martens wrote:
Hey, great paper! Glad that someone looked into that.
Cheers,
Piet
On 7/31/12 7:47 AM, Klimchuk, James A. (GSFC-6710) wrote:
Dear friends,
You might be interested in my recent paper on "The Role of
Type II Spicules in the Upper Solar Atmosphere," which can be downloaded at http://arxiv.org/abs/1207.7048
Cheers,
Jim
ABSTRACT:
We examine the suggestion that most of the hot plasma in the Sun's
corona comes from type II spicule material that is heated as it is
ejected from the chromosphere. This contrasts with the traditional
view that the corona is filled via chromospheric evaporation that
results from coronal heating. We explore the observational
consequences of a hypothetical spicule dominated corona and conclude
from the large discrepancy between predicted and actual observations
that only a small fraction of the hot plasma can be supplied by
spicules (<2% in active regions and <5% in the quiet Sun). The
red-blue asymmetries of EUV spectral lines and the ratio of lower
transition region (LTR; T<0.1 MK) to coronal emission measures
are both predicted to be 2 orders of magnitude larger than observed.
Furthermore, hot spicule material would cool dramatically by
adiabatic expansion as it rises into the corona, so coronal heating
would be required to maintain the high temperatures that are seen at
all altitudes. The necessity of coronal heating is inescapable.
Traditional coronal heating models predict far too little emission
from the LTR, and we suggest that this emission comes primarily from
the bulk of the spicule material that is heated to <0.1 MK and
is visible in He II (304 A) as it falls back to the surface.
James A. Klimchuk
NASA Goddard Space Flight Center
Solar Physics Lab, Code 671
Bldg. 21, Rm. 158
Greenbelt, MD 20771
USA
Phone: 1-301-286-9060
Fax: 1-301-286-7194
E-mail: James.A.Klimchuk@nasa.gov
mailto:James.A.Klimchuk@nasa.gov
Homepage:
https://sedupdate.gsfc.nasa.gov/sed/index.cfm?fuseAction=people.jump
Bio&&iPhonebookId=15844
No endorsement by NASA is implied for any correspondence related to my role as an officer of professional organizations (American Geophysical Union, International Astronomical Union, American
Astronomical Society).
Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
<martens.vcf>_______________________________________________ Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
Hugh,
Actually, my use of "Scudder" was shorthand for "plasma kinetic effects." I don't regard these as unrelated to "heating" in general; I doubt that a paper can draw general conclusions in this area without a discussion of that physics.
Given the densities in spicules, I doubt that kinetic effects will play a significant role. What specifically did you have in mind that would invalidate my analysis?
I note that your definition of evaporation is inconsistent with our normal usage for flares, where non-thermal particles can do the dirty work. But perhaps I will read on past this point!
Remember, this paper is about spicules, not evaporation! I do make the side point that spicules and heat flux driven evaporation are fundamentally different. I also make the point that no non-thermal beam flare simulations that I, George Fisher, or Joel Allred are aware of produce anything that resembles a spicule. Do you know of any that we don't?
Thanks, Jim
Cheers
Hugh
On 31 Jul 2012, at 16:45, Klimchuk, James A. (GSFC-6710) wrote:
Right, Piet. They are totally unrelated.
Jim
-----Original Message----- From: loops-bounces@solar.physics.montana.edu [mailto:loops- bounces@solar.physics.montana.edu] On Behalf Of Petrus Martens Sent: Tuesday, July 31, 2012 10:33 AM To: loops@solar.physics.montana.edu Subject: Re: [Loops] type II spicule paper
On 7/31/12 8:27 AM, Hugh S. Hudson wrote:
It may be a great paper, but why is there no citation of Scudder's work?
Would have been useful. I don't think Jim's results invalidate Scudder's results though.
Piet
Hugh
On 31 Jul 2012, at 16:12, Petrus Martens wrote:
Hey, great paper! Glad that someone looked into that.
Cheers,
Piet
On 7/31/12 7:47 AM, Klimchuk, James A. (GSFC-6710) wrote:
Dear friends,
You might be interested in my recent paper on "The Role of
Type II Spicules in the Upper Solar Atmosphere," which can be downloaded at http://arxiv.org/abs/1207.7048
Cheers,
Jim
ABSTRACT:
We examine the suggestion that most of the hot plasma in the Sun's
corona comes from type II spicule material that is heated as it is
ejected from the chromosphere. This contrasts with the traditional
view that the corona is filled via chromospheric evaporation that
results from coronal heating. We explore the observational
consequences of a hypothetical spicule dominated corona and conclude
from the large discrepancy between predicted and actual observations
that only a small fraction of the hot plasma can be supplied by
spicules (<2% in active regions and <5% in the quiet Sun). The
red-blue asymmetries of EUV spectral lines and the ratio of lower
transition region (LTR; T<0.1 MK) to coronal emission measures
are both predicted to be 2 orders of magnitude larger than observed.
Furthermore, hot spicule material would cool dramatically by
adiabatic expansion as it rises into the corona, so coronal heating
would be required to maintain the high temperatures that are seen at
all altitudes. The necessity of coronal heating is inescapable.
Traditional coronal heating models predict far too little emission
from the LTR, and we suggest that this emission comes primarily from
the bulk of the spicule material that is heated to <0.1 MK and
is visible in He II (304 A) as it falls back to the surface.
James A. Klimchuk
NASA Goddard Space Flight Center
Solar Physics Lab, Code 671
Bldg. 21, Rm. 158
Greenbelt, MD 20771
USA
Phone: 1-301-286-9060
Fax: 1-301-286-7194
E-mail: James.A.Klimchuk@nasa.gov
mailto:James.A.Klimchuk@nasa.gov
Homepage:
https://sedupdate.gsfc.nasa.gov/sed/index.cfm?fuseAction=people.jump
Bio&&iPhonebookId=15844
No endorsement by NASA is implied for any correspondence related to my role as an officer of professional organizations (American Geophysical Union, International Astronomical Union, American
Astronomical Society).
Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
<martens.vcf>_______________________________________________
Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
Hi Hugh,
Do you mean velocity filtration, where the corona is simply particles from the tail of the chromospheric distribution function? That theory has been largely discredited. But how does it apply to my paper anyway? I have addressed the suggestion that the corona is due to spicule material that is heated as it is ejected. This is completely different, no?
Thanks, Jim
-----Original Message----- From: loops-bounces@solar.physics.montana.edu [mailto:loops- bounces@solar.physics.montana.edu] On Behalf Of Hugh S. Hudson Sent: Tuesday, July 31, 2012 10:27 AM To: A mailing list for scientists involved in the observation and modeling of solar loop structures Subject: Re: [Loops] type II spicule paper
It may be a great paper, but why is there no citation of Scudder's work?
Hugh
On 31 Jul 2012, at 16:12, Petrus Martens wrote:
Hey, great paper! Glad that someone looked into that.
Cheers,
Piet
On 7/31/12 7:47 AM, Klimchuk, James A. (GSFC-6710) wrote:
Dear friends,
You might be interested in my recent paper on "The Role of Type
II Spicules in the Upper Solar Atmosphere," which can be downloaded at http://arxiv.org/abs/1207.7048
Cheers,
Jim
ABSTRACT:
We examine the suggestion that most of the hot plasma in the Sun's
corona comes from type II spicule material that is heated as it is
ejected from the chromosphere. This contrasts with the traditional
view that the corona is filled via chromospheric evaporation that
results from coronal heating. We explore the observational
consequences of a hypothetical spicule dominated corona and conclude
from the large discrepancy between predicted and actual observations
that only a small fraction of the hot plasma can be supplied by
spicules (<2% in active regions and <5% in the quiet Sun). The
red-blue asymmetries of EUV spectral lines and the ratio of lower
transition region (LTR; T<0.1 MK) to coronal emission measures
are both predicted to be 2 orders of magnitude larger than observed.
Furthermore, hot spicule material would cool dramatically by
adiabatic expansion as it rises into the corona, so coronal heating
would be required to maintain the high temperatures that are seen at
all altitudes. The necessity of coronal heating is inescapable.
Traditional coronal heating models predict far too little emission
from the LTR, and we suggest that this emission comes primarily from
the bulk of the spicule material that is heated to <0.1 MK and
is visible in He II (304 A) as it falls back to the surface.
James A. Klimchuk
NASA Goddard Space Flight Center
Solar Physics Lab, Code 671
Bldg. 21, Rm. 158
Greenbelt, MD 20771
USA
Phone: 1-301-286-9060
Fax: 1-301-286-7194
E-mail: James.A.Klimchuk@nasa.gov
mailto:James.A.Klimchuk@nasa.gov
Homepage:
https://sedupdate.gsfc.nasa.gov/sed/index.cfm?fuseAction=people.jumpB
io&&iPhonebookId=15844
No endorsement by NASA is implied for any correspondence related to my role as an officer of professional organizations (American Geophysical Union, International Astronomical Union, American Astronomical Society).
Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
<martens.vcf>_______________________________________________ Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
Do you mean velocity filtration, where the corona is simply particles from the tail of the chromospheric distribution function? That theory has been largely discredited.
I'm not sure I agree with this… In any case, the solar wind electron distribution is strongly controlled by the strahl/suprathermals (and the collisions between the core and protons). I believe we see good evidence of the ambipolar electric field (at 1 AU, where it is quite weak).
cheers, Stuart
Piet,
my empirical view about velocity filtration, see p.378-380 in "Physics of the Solar Corona".
Cheers, Markus
On Jul 31, 2012, at 8:20 AM, Petrus Martens wrote:
Do you mean velocity filtration, where the corona is simply particles from the
tail of the chromospheric distribution function? That theory has been largely discredited.
That's news to me. Do you have a reference?
Piet
<martens.vcf>_______________________________________________ Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
____________________________________________ Dr. Markus J. Aschwanden Solar & Astrophysics Laboratory Lockheed Martin Advanced Techology Center Org. ADBS, Bldg. 252 3251 Hanover St., Palo Alto, CA 94304, USA Phone: 650-424-4001, FAX: 650-424-3994 URL: http://www.lmsal.com/~aschwand/ e-mail: aschwanden@lmsal.com _______________________________________ ____________________________________
Stephen Anderson did a very thorough analysis of how Coulomb collisions affect the model.
http://adsabs.harvard.edu/abs/1994ApJ...437..860A
dana
----------------------------------------------------------- Dana Longcope | Dept. of Physics Professor | Montana State University (406) 994-7851 | Bozeman, MT 59717 dana@solar.physics.montana.edu
On Jul 31, 2012, at 9:20 AM, Petrus Martens wrote:
Do you mean velocity filtration, where the corona is simply particles from the
tail of the chromospheric distribution function? That theory has been largely discredited.
That's news to me. Do you have a reference?
Piet
<martens.vcf>_______________________________________________ Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
So, Anderson concluded that the velocity filtration model needed to be redone with Coulomb collisions included. Dorelly and Scudder came back in 2003 with a paper concluding that "the electron heat flux is determined by the essentially collisionless high-energy tail" of the distribution:
http://adsabs.harvard.edu/abs/2003JGRA..108.1294D
Does that mean the coulomb collisions don't really affect prediction of energy transport? I haven't followed the trail of citations any farther...
Charles
On 2012 Jul 31, , at 9:27 AM, Dana Longcope wrote:
Stephen Anderson did a very thorough analysis of how Coulomb collisions affect the model.
http://adsabs.harvard.edu/abs/1994ApJ...437..860A
dana
Dana Longcope | Dept. of Physics Professor | Montana State University (406) 994-7851 | Bozeman, MT 59717 dana@solar.physics.montana.edu
On Jul 31, 2012, at 9:20 AM, Petrus Martens wrote:
Do you mean velocity filtration, where the corona is simply
particles from the
tail of the chromospheric distribution function? That theory has been largely discredited.
That's news to me. Do you have a reference?
Piet
<martens.vcf>_______________________________________________ Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
________________________________________________________________________ Charles Kankelborg AC7NY | 260C EPS Building | "If Christ is risen, nothing else matters. Physics Department | And if Christ is not risen --- nothing else Montana State University | matters." Bozeman, MT 59717 | Phone: 406-994-7853 | --Jaroslav Pelikan FAX: 406-994-4452 | http://solar.physics.montana.edu/kankel/
On 7/31/12 10:42 AM, Charles C. Kankelborg wrote:
So, Anderson concluded that the velocity filtration model needed to be redone with Coulomb collisions included. Dorelly and Scudder came back in 2003 with a paper concluding that "the electron heat flux is determined by the essentially collisionless high-energy tail" of the distribution:
http://adsabs.harvard.edu/abs/2003JGRA..108.1294D
Does that mean the coulomb collisions don't really affect prediction of energy transport? I haven't followed the trail of citations any farther...
Ah, now I remember! The mean-free-path for high energy electrons is of the order of the loop length (has to be be; if it is longer there is no coronal heating, if it is much shorter likewise). So chromospheric electrons in some energy range will contribute to coronal heating. Now the question is whether there will be enough of them.
Cheers,
Piet
Charles
On 2012 Jul 31, , at 9:27 AM, Dana Longcope wrote:
Stephen Anderson did a very thorough analysis of how Coulomb collisions affect the model.
http://adsabs.harvard.edu/abs/1994ApJ...437..860A
dana
Dana Longcope | Dept. of Physics Professor | Montana State University (406) 994-7851 | Bozeman, MT 59717 dana@solar.physics.montana.edu
On Jul 31, 2012, at 9:20 AM, Petrus Martens wrote:
Do you mean velocity filtration, where the corona is simply
particles from the
tail of the chromospheric distribution function? That theory has been largely discredited.
That's news to me. Do you have a reference?
Piet
<martens.vcf>_______________________________________________ Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
Charles Kankelborg AC7NY | 260C EPS Building | "If Christ is risen, nothing else matters. Physics Department | And if Christ is not risen --- nothing else Montana State University | matters." Bozeman, MT 59717 | Phone: 406-994-7853 | --Jaroslav Pelikan FAX: 406-994-4452 | http://solar.physics.montana.edu/kankel/
Yes, clearly. And the high energy tail of electrons accelerated in the chromosphere can easily be associated with type II spicules. Jim's theory is all wet in other words ;-) And if you start believing in Scudders ideas on coronal heating through velocity filtration I've got a good deal on a bridge between Brooklyn and Manhattan I can recommend.
Best wishes, Viggo
On Jul 31, 2012, at 18:57 , Petrus Martens wrote:
On 7/31/12 10:42 AM, Charles C. Kankelborg wrote:
So, Anderson concluded that the velocity filtration model needed to be redone with Coulomb collisions included. Dorelly and Scudder came back in 2003 with a paper concluding that "the electron heat flux is determined by the essentially collisionless high-energy tail" of the distribution:
http://adsabs.harvard.edu/abs/2003JGRA..108.1294D
Does that mean the coulomb collisions don't really affect prediction of energy transport? I haven't followed the trail of citations any farther...
Ah, now I remember! The mean-free-path for high energy electrons is of the order of the loop length (has to be be; if it is longer there is no coronal heating, if it is much shorter likewise). So chromospheric electrons in some energy range will contribute to coronal heating. Now the question is whether there will be enough of them.
Cheers,
Piet
Charles
On 2012 Jul 31, , at 9:27 AM, Dana Longcope wrote:
Stephen Anderson did a very thorough analysis of how Coulomb collisions affect the model.
http://adsabs.harvard.edu/abs/1994ApJ...437..860A
dana
Dana Longcope | Dept. of Physics Professor | Montana State University (406) 994-7851 | Bozeman, MT 59717 dana@solar.physics.montana.edu
On Jul 31, 2012, at 9:20 AM, Petrus Martens wrote:
Do you mean velocity filtration, where the corona is simply particles from the
tail of the chromospheric distribution function? That theory has been largely discredited.
That's news to me. Do you have a reference?
Piet
<martens.vcf>_______________________________________________ Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
Charles Kankelborg AC7NY | 260C EPS Building | "If Christ is risen, nothing else matters. Physics Department | And if Christ is not risen --- nothing else Montana State University | matters." Bozeman, MT 59717 | Phone: 406-994-7853 | --Jaroslav Pelikan FAX: 406-994-4452 | http://solar.physics.montana.edu/kankel/
======================================================== Viggo H. Hansteen http://www.astro.uio.no/~viggoh Institutt for teoretisk astrofysikk tel: +47-22856120 PB 1029, Blindern fax: +47-22856505 N-0315 Oslo, Norway Viggo.Hansteen@astro.uio.no ========================================================
And if you start believing in Scudders ideas on coronal heating through velocity filtration I've got a good deal on a bridge between Brooklyn and Manhattan I can recommend.
Too late! I already bought it.
Piet
Best wishes, Viggo
On Jul 31, 2012, at 18:57 , Petrus Martens wrote:
On 7/31/12 10:42 AM, Charles C. Kankelborg wrote:
So, Anderson concluded that the velocity filtration model needed to be redone with Coulomb collisions included. Dorelly and Scudder came back in 2003 with a paper concluding that "the electron heat flux is determined by the essentially collisionless high-energy tail" of the distribution:
http://adsabs.harvard.edu/abs/2003JGRA..108.1294D
Does that mean the coulomb collisions don't really affect prediction of energy transport? I haven't followed the trail of citations any farther...
Ah, now I remember! The mean-free-path for high energy electrons is of the order of the loop length (has to be be; if it is longer there is no coronal heating, if it is much shorter likewise). So chromospheric electrons in some energy range will contribute to coronal heating. Now the question is whether there will be enough of them.
Cheers,
Piet
Charles
On 2012 Jul 31, , at 9:27 AM, Dana Longcope wrote:
Stephen Anderson did a very thorough analysis of how Coulomb collisions affect the model.
http://adsabs.harvard.edu/abs/1994ApJ...437..860A
dana
Dana Longcope | Dept. of Physics Professor | Montana State University (406) 994-7851 | Bozeman, MT 59717 dana@solar.physics.montana.edu mailto:dana@solar.physics.montana.edu
On Jul 31, 2012, at 9:20 AM, Petrus Martens wrote:
Do you mean velocity filtration, where the corona is simply particles from the
tail of the chromospheric distribution function? That theory has been largely discredited.
That's news to me. Do you have a reference?
Piet
<martens.vcf>_______________________________________________ Loops mailing list Loops@solar.physics.montana.edu mailto:Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
Loops mailing list Loops@solar.physics.montana.edu mailto:Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
Charles Kankelborg AC7NY | 260C EPS Building | "If Christ is risen, nothing else matters. Physics Department | And if Christ is not risen --- nothing else Montana State University | matters." Bozeman, MT 59717 | Phone: 406-994-7853 | --Jaroslav Pelikan FAX: 406-994-4452 | http://solar.physics.montana.edu/kankel/
======================================================== Viggo H. Hansteen http://www.astro.uio.no/~viggoh Institutt for teoretisk astrofysikk tel: +47-22856120 PB 1029, Blindern fax: +47-22856505 N-0315 Oslo, Norway Viggo.Hansteen@astro.uio.no
mailto:Viggo.Hansteen@astro.uio.no
This is probably one of those bridges with a troll underneath, please be careful.
On 31 Jul 2012, at 18:27, Petrus Martens wrote:
And if you start believing in Scudders ideas on coronal heating through velocity filtration I've got a good deal on a bridge between Brooklyn and Manhattan I can recommend.
Too late! I already bought it.
Piet
Best wishes, Viggo
On Jul 31, 2012, at 18:57 , Petrus Martens wrote:
On 7/31/12 10:42 AM, Charles C. Kankelborg wrote:
So, Anderson concluded that the velocity filtration model needed to be redone with Coulomb collisions included. Dorelly and Scudder came back in 2003 with a paper concluding that "the electron heat flux is determined by the essentially collisionless high-energy tail" of the distribution:
http://adsabs.harvard.edu/abs/2003JGRA..108.1294D
Does that mean the coulomb collisions don't really affect prediction of energy transport? I haven't followed the trail of citations any farther...
Ah, now I remember! The mean-free-path for high energy electrons is of the order of the loop length (has to be be; if it is longer there is no coronal heating, if it is much shorter likewise). So chromospheric electrons in some energy range will contribute to coronal heating. Now the question is whether there will be enough of them.
Cheers,
Piet
Charles
On 2012 Jul 31, , at 9:27 AM, Dana Longcope wrote:
Stephen Anderson did a very thorough analysis of how Coulomb collisions affect the model.
http://adsabs.harvard.edu/abs/1994ApJ...437..860A
dana
Dana Longcope | Dept. of Physics Professor | Montana State University (406) 994-7851 | Bozeman, MT 59717 dana@solar.physics.montana.edu <mailto:dana@solar.physics.montana.edu
On Jul 31, 2012, at 9:20 AM, Petrus Martens wrote:
> Do you mean velocity filtration, where the corona is simply > particles from the tail of the chromospheric distribution function? That theory has been largely discredited.
That's news to me. Do you have a reference?
Piet
<martens.vcf>_______________________________________________ Loops mailing list Loops@solar.physics.montana.edu mailto:Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
Loops mailing list Loops@solar.physics.montana.edu <mailto:Loops@solar.physics.montana.edu
Charles Kankelborg AC7NY | 260C EPS Building | "If Christ is risen, nothing else matters. Physics Department | And if Christ is not risen --- nothing else Montana State University | matters." Bozeman, MT 59717 | Phone: 406-994-7853 | --Jaroslav Pelikan FAX: 406-994-4452 | http://solar.physics.montana.edu/kankel/
======================================================== Viggo H. Hansteen http://www.astro.uio.no/~viggoh Institutt for teoretisk astrofysikk tel: +47-22856120 PB 1029, Blindern fax: +47-22856505 N-0315 Oslo, Norway Viggo.Hansteen@astro.uio.no
mailto:Viggo.Hansteen@astro.uio.no
<martens.vcf>_______________________________________________ Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
My little nail for Jack Scudders velocity filtration coffin: Title: Kinetic electrons in high-speed solar wind streams: Formation of high-energy tails Authors: Lie-Svendsen, Øystein; Hansteen, Viggo H.; Leer, Egil Publication: Journal of Geophysical Research, Volume 102, Issue A3, p. 4701-4718 (JGR Homepage) Publication Date: 03/1997 Origin: AGU Keywords: Interplanetary Physics: Solar wind plasma, Interplanetary Physics: Sources of the solar wind, Solar Physics, Astrophysics, and Astronomy: Corona, and Astronomy: Coronal holes DOI: 10.1029/96JA03632 Bibliographic Code: 1997JGR...102.4701L Abstract
We study the evolution of the electron velocity distribution function in high-speed solar wind streams from the collision-dominated corona and into the collisionless interplanetary space. The model we employ solves the kinetic transport equation with the Fokker-Planck collision operator to describe Coulomb collisions between electrons. We use a test particle approach, where test electrons are injected into a prescribed solar wind background. The density, temperature, and electric field associated with the background are computed from fluid models. The test electrons are in thermal equilibrium with the background at the base of the corona, and we study the evolution of the velocity distribution of the test electrons as a function of altitude. We find that velocity filtration, due to the energy dependence of the Coulomb cross section, is a small effect and is not capable of producing significant beams in the distribution or a temperature moment that increases with altitude. The distribution function is mainly determined by the electric field and the expanding geometry and consists of a population with an almost isotropic core which is bound in the electrostatic potential and a beam-like high-energy tail which escapes. The trapped electrons contribute significantly to the even moments of the distribution function but almost nothing to the odd moments; the drift speed and energy flux moments are carried solely by the tail. In order to describe the high-speed solar wind observed near 0.3 AU by the Helios spacecraft, we use a multifluid model where ions are heated preferentially. The resulting test electron distribution at 0.3 AU, in this background, is in very good agreement with the velocity distributions observed by the Helios spacecraft.
1) Electron temperatures are low -> polarization electric field is weak, so no matter how you describe them the electrons don't contribute much to the SW heat flux. 2) Observations at 0.3 AU can be reproduced without any Scudder magic.
Best wishes, Viggo
On Jul 31, 2012, at 18:42 , Charles C. Kankelborg wrote:
So, Anderson concluded that the velocity filtration model needed to be redone with Coulomb collisions included. Dorelly and Scudder came back in 2003 with a paper concluding that "the electron heat flux is determined by the essentially collisionless high-energy tail" of the distribution:
http://adsabs.harvard.edu/abs/2003JGRA..108.1294D
Does that mean the coulomb collisions don't really affect prediction of energy transport? I haven't followed the trail of citations any farther...
Charles
On 2012 Jul 31, , at 9:27 AM, Dana Longcope wrote:
Stephen Anderson did a very thorough analysis of how Coulomb collisions affect the model.
http://adsabs.harvard.edu/abs/1994ApJ...437..860A
dana
Dana Longcope | Dept. of Physics Professor | Montana State University (406) 994-7851 | Bozeman, MT 59717 dana@solar.physics.montana.edu
On Jul 31, 2012, at 9:20 AM, Petrus Martens wrote:
Do you mean velocity filtration, where the corona is simply particles from the
tail of the chromospheric distribution function? That theory has been largely discredited.
That's news to me. Do you have a reference?
Piet
<martens.vcf>_______________________________________________ Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
Charles Kankelborg AC7NY | 260C EPS Building | "If Christ is risen, nothing else matters. Physics Department | And if Christ is not risen --- nothing else Montana State University | matters." Bozeman, MT 59717 | Phone: 406-994-7853 | --Jaroslav Pelikan FAX: 406-994-4452 | http://solar.physics.montana.edu/kankel/
Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
======================================================== Viggo H. Hansteen http://www.astro.uio.no/~viggoh Institutt for teoretisk astrofysikk tel: +47-22856120 PB 1029, Blindern fax: +47-22856505 N-0315 Oslo, Norway Viggo.Hansteen@astro.uio.no ========================================================
I think this community ought to be made aware that there is a more fundamental issue at stake regarding chromospheric (and coronal) fine structure in general:
What is the relationship between the magnetic field and the plasma?
http://adsabs.harvard.edu/abs/2012ApJ...755L..11J
The Sun will eventually decide what is going on if we can get the right observational clues.
Perhaps the decadal survey will recognize the urgent need to measure magnetism throughout the solar atmosphere, since simulations cannot be expected to answer this question anytime soon.
Phil
Interesting movies Phil. Does Hinode H-alpha also see super-Alfvenic apparent motions in spicules?
Charles
On 2012 Jul 31, , at 7:27 PM, Philip Judge wrote:
I think this community ought to be made aware that there is a more fundamental issue at stake regarding chromospheric (and coronal) fine structure in general:
What is the relationship between the magnetic field and the plasma?
http://adsabs.harvard.edu/abs/2012ApJ...755L..11J
The Sun will eventually decide what is going on if we can get the right observational clues.
Perhaps the decadal survey will recognize the urgent need to measure magnetism throughout the solar atmosphere, since simulations cannot be expected to answer this question anytime soon.
Phil
Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
______________________________________________________________________ Charles Kankelborg AC7NY | Yet Lord restore thine image, heare 260C EPS Building | my call: Physics Department | And though my hard heart scarce to thee Montana State University | can grone, Bozeman, MT 59717 | Remember that thou once didst write Phone: 406-994-7853 | on stone. FAX: 406-994-4452 | --George Herbert, The Sinner http://solar.physics.montana.edu/kankel/
Hi Jim,
Just scanned through, will send you comments after a thorough reading, but looks like a fair discussion. Couple of points though:
Are "A" waves a viable energetic supply to the corona? They get no mention and I understand that the net effect of their dissipation would be nanoflares-like heating distribution.
Btw, in addition to the above, discriminatory studies of quiet and coronal hole plasmas hold the key to the down-up (evaporative) vs up-down (type 2 "initiated") mass components of the mass cycle. It is a real push to expect the original energy supply for them to be different, but in one the coronal backwash is missing. The (detailed) study of the multi-component line profiles between the two should show the relative weighting of evaporative processes (regardless of their origin - see above) in the QS. My student has done a pretty detailed study of this and is about to submit a paper on her results - I will distribute to the list once submitted.
Last point: why can't type-Ii spicules be the manifestation of nanoflares in a stratified inhomogeneous plasma?
Cheers, Scott
Sent from my iPhone
Dr. Scott W. McIntosh High Altitude Observatory NCAR/UCAR, Boulder CO off: (303) 497-1544 mob: (720) 340-6263
On Jul 31, 2012, at 7:47, "Klimchuk, James A. (GSFC-6710)" james.a.klimchuk@nasa.gov wrote:
Dear friends,
You might be interested in my recent paper on “The Role of Type II Spicules in the Upper Solar Atmosphere,” which can be downloaded at http://arxiv.org/abs/1207.7048
Cheers, Jim
ABSTRACT: We examine the suggestion that most of the hot plasma in the Sun's corona comes from type II spicule material that is heated as it is ejected from the chromosphere. This contrasts with the traditional view that the corona is filled via chromospheric evaporation that results from coronal heating. We explore the observational consequences of a hypothetical spicule dominated corona and conclude from the large discrepancy between predicted and actual observations that only a small fraction of the hot plasma can be supplied by spicules (<2% in active regions and <5% in the quiet Sun). The red-blue asymmetries of EUV spectral lines and the ratio of lower transition region (LTR; T<0.1 MK) to coronal emission measures are both predicted to be 2 orders of magnitude larger than observed. Furthermore, hot spicule material would cool dramatically by adiabatic expansion as it rises into the corona, so coronal heating would be required to maintain the high temperatures that are seen at all altitudes. The necessity of coronal heating is inescapable. Traditional coronal heating models predict far too little emission from the LTR, and we suggest that this emission comes primarily from the bulk of the spicule material that is heated to <0.1 MK and is visible in He II (304 A) as it falls back to the surface.
James A. Klimchuk NASA Goddard Space Flight Center Solar Physics Lab, Code 671 Bldg. 21, Rm. 158 Greenbelt, MD 20771 USA
Phone: 1-301-286-9060 Fax: 1-301-286-7194 E-mail: James.A.Klimchuk@nasa.gov Homepage: https://sedupdate.gsfc.nasa.gov/sed/index.cfm?fuseAction=people.jumpBio&... No endorsement by NASA is implied for any correspondence related to my role as an officer of professional organizations (American Geophysical Union, International Astronomical Union, American Astronomical Society).
Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
Hi Scott,
From: loops-bounces@solar.physics.montana.edu [mailto:loops-bounces@solar.physics.montana.edu] On Behalf Of Scott W. McIntosh Sent: Tuesday, July 31, 2012 10:46 AM To: A mailing list for scientists involved in the observation andmodeling of solar loop structures Cc: (Loops@solar.physics.montana.edu) Subject: Re: [Loops] type II spicule paper
Hi Jim,
Just scanned through, will send you comments after a thorough reading, but looks like a fair discussion. Couple of points though:
Are "A" waves a viable energetic supply to the corona? They get no mention and I understand that the net effect of their dissipation would be nanoflares-like heating distribution.
*** In principle, Alfven waves could be heating the corona, at least in the quiet Sun, as your recent work suggests. And indeed, wave heating would likely fit into the classification of nanoflares, since there would be an impulsive energy release from the perspective of an individual magnetic flux strand. But my paper isn’t attempting to address the nature of coronal heating. It simply means to show that there must be an energy release in the corona in order to explain the hot plasma that we observe there. Ejecting hot material at the tips of spicules isn’t enough if you buy my analysis.
Btw, in addition to the above, discriminatory studies of quiet and coronal hole plasmas hold the key to the down-up (evaporative) vs up-down (type 2 "initiated") mass components of the mass cycle. It is a real push to expect the original energy supply for them to be different, but in one the coronal backwash is missing. The (detailed) study of the multi-component line profiles between the two should show the relative weighting of evaporative processes (regardless of their origin - see above) in the QS. My student has done a pretty detailed study of this and is about to submit a paper on her results - I will distribute to the list once submitted.
*** I look forward to the paper. Regarding multi-component line profiles (weakly red shifted line core with a blue wing component), I would make the following point. The core emission likely comes from hot material that is cooling and draining, regardless of whether the hot material came from evaporation or spicules. The blue wing emission that is seen in lines <2 MK likely comes from spicules. Coronal nanoflares (reconnection, waves, whatever) are expected to produce blue wing emission only in very hot (>3 MK) lines, at least according to the modeling work that Spiros and I did in 2006. So, my picture is that the corona is comprised of unresolved strands. Most are dominated by coronal heating and some are dominated by type II spicules.
Last point: why can't type-Ii spicules be the manifestation of nanoflares in a stratified inhomogeneous plasma?
Depends on where the nanoflares occur. Nanoflares that occur in the transition region or corona (in plasma that is originally hotter than 10^4 K) will not produce ejections of cold material. I have a discussion of this in the paper. Nanoflares that occur deep in the chromosphere, below the eventual spicule, can produce cold ejections.
Thanks for the comments! Jim
Cheers, Scott
Sent from my iPhone
Dr. Scott W. McIntosh High Altitude Observatory NCAR/UCAR, Boulder CO off: (303) 497-1544 mob: (720) 340-6263
On Jul 31, 2012, at 7:47, "Klimchuk, James A. (GSFC-6710)" <james.a.klimchuk@nasa.govmailto:james.a.klimchuk@nasa.gov> wrote: Dear friends,
You might be interested in my recent paper on “The Role of Type II Spicules in the Upper Solar Atmosphere,” which can be downloaded at http://arxiv.org/abs/1207.7048
Cheers, Jim
ABSTRACT: We examine the suggestion that most of the hot plasma in the Sun's corona comes from type II spicule material that is heated as it is ejected from the chromosphere. This contrasts with the traditional view that the corona is filled via chromospheric evaporation that results from coronal heating. We explore the observational consequences of a hypothetical spicule dominated corona and conclude from the large discrepancy between predicted and actual observations that only a small fraction of the hot plasma can be supplied by spicules (<2% in active regions and <5% in the quiet Sun). The red-blue asymmetries of EUV spectral lines and the ratio of lower transition region (LTR; T<0.1 MK) to coronal emission measures are both predicted to be 2 orders of magnitude larger than observed. Furthermore, hot spicule material would cool dramatically by adiabatic expansion as it rises into the corona, so coronal heating would be required to maintain the high temperatures that are seen at all altitudes. The necessity of coronal heating is inescapable. Traditional coronal heating models predict far too little emission from the LTR, and we suggest that this emission comes primarily from the bulk of the spicule material that is heated to <0.1 MK and is visible in He II (304 A) as it falls back to the surface.
******************************************************************************** James A. Klimchuk NASA Goddard Space Flight Center Solar Physics Lab, Code 671 Bldg. 21, Rm. 158 Greenbelt, MD 20771 USA
Phone: 1-301-286-9060 Fax: 1-301-286-7194 E-mail: James.A.Klimchuk@nasa.govmailto:James.A.Klimchuk@nasa.gov Homepage: https://sedupdate.gsfc.nasa.gov/sed/index.cfm?fuseAction=people.jumpBio&... No endorsement by NASA is implied for any correspondence related to my role as an officer of professional organizations (American Geophysical Union, International Astronomical Union, American Astronomical Society).
********************************************************************************
_______________________________________________ Loops mailing list Loops@solar.physics.montana.edumailto:Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
No one has doubted that there is heating at great heights. Question is where the bulk of the nanoflares occur. As you know I think there are good reasons (the bulk of magnetic field does not rise high into the corona, except perhaps in coronal holes) to believe they occur in the vicinity of the transition region (including the upper chromosphere). V.
On Jul 31, 2012, at 17:14 , Klimchuk, James A. (GSFC-6710) wrote:
Last point: why can't type-Ii spicules be the manifestation of nanoflares in a stratified inhomogeneous plasma?
Depends on where the nanoflares occur. Nanoflares that occur in the transition region or corona (in plasma that is originally hotter than 10^4 K) will not produce ejections of cold material. I have a discussion of this in the paper. Nanoflares that occur deep in the chromosphere, below the eventual spicule, can produce cold ejections.
======================================================== Viggo H. Hansteen http://www.astro.uio.no/~viggoh Institutt for teoretisk astrofysikk tel: +47-22856120 PB 1029, Blindern fax: +47-22856505 N-0315 Oslo, Norway Viggo.Hansteen@astro.uio.no ========================================================
Hi Viggo,
Indeed, I reference your paper, though I don't discuss it. But the main point to Hugh is that this type of heating (in the corona, transition region, or even upper chromosphere) won't produce spicules.
Cheers, Jim
From: loops-bounces@solar.physics.montana.edu [mailto:loops-bounces@solar.physics.montana.edu] On Behalf Of Viggo Hansteen Sent: Tuesday, July 31, 2012 1:31 PM To: A mailing list for scientists involved in the observation and modeling of solar loop structures Subject: Re: [Loops] type II spicule paper
No one has doubted that there is heating at great heights. Question is where the bulk of the nanoflares occur. As you know I think there are good reasons (the bulk of magnetic field does not rise high into the corona, except perhaps in coronal holes) to believe they occur in the vicinity of the transition region (including the upper chromosphere). V.
On Jul 31, 2012, at 17:14 , Klimchuk, James A. (GSFC-6710) wrote:
Last point: why can't type-Ii spicules be the manifestation of nanoflares in a stratified inhomogeneous plasma?
Depends on where the nanoflares occur. Nanoflares that occur in the transition region or corona (in plasma that is originally hotter than 10^4 K) will not produce ejections of cold material. I have a discussion of this in the paper. Nanoflares that occur deep in the chromosphere, below the eventual spicule, can produce cold ejections.
======================================================== Viggo H. Hansteen http://www.astro.uio.no/~viggoh Institutt for teoretisk astrofysikk tel: +47-22856120 PB 1029, Blindern fax: +47-22856505 N-0315 Oslo, Norway Viggo.Hansteen@astro.uio.nomailto:Viggo.Hansteen@astro.uio.no ========================================================
jim,
interesting paper:), robertus
On 31 Jul 2012, at 14:47, Klimchuk, James A. (GSFC-6710) wrote:
Dear friends,
You might be interested in my recent paper on “The Role of Type II Spicules in the Upper Solar Atmosphere,” which can be downloaded at http://arxiv.org/abs/1207.7048
Cheers, Jim
ABSTRACT: We examine the suggestion that most of the hot plasma in the Sun's corona comes from type II spicule material that is heated as it is ejected from the chromosphere. This contrasts with the traditional view that the corona is filled via chromospheric evaporation that results from coronal heating. We explore the observational consequences of a hypothetical spicule dominated corona and conclude from the large discrepancy between predicted and actual observations that only a small fraction of the hot plasma can be supplied by spicules (<2% in active regions and <5% in the quiet Sun). The red-blue asymmetries of EUV spectral lines and the ratio of lower transition region (LTR; T<0.1 MK) to coronal emission measures are both predicted to be 2 orders of magnitude larger than observed. Furthermore, hot spicule material would cool dramatically by adiabatic expansion as it rises into the corona, so coronal heating would be required to maintain the high temperatures that are seen at all altitudes. The necessity of coronal heating is inescapable. Traditional coronal heating models predict far too little emission from the LTR, and we suggest that this emission comes primarily from the bulk of the spicule material that is heated to <0.1 MK and is visible in He II (304 A) as it falls back to the surface.
James A. Klimchuk NASA Goddard Space Flight Center Solar Physics Lab, Code 671 Bldg. 21, Rm. 158 Greenbelt, MD 20771 USA
Phone: 1-301-286-9060 Fax: 1-301-286-7194 E-mail: James.A.Klimchuk@nasa.gov Homepage: https://sedupdate.gsfc.nasa.gov/sed/index.cfm?fuseAction=people.jumpBio&... No endorsement by NASA is implied for any correspondence related to my role as an officer of professional organizations (American Geophysical Union, International Astronomical Union, American Astronomical Society).
Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
Dear All,
Jim mentions a recent paper of mine as submitted. It is now published, ApJ, 754, 153 (2012). This paper deals with the dynamics of active regions as observed by EIS. I think all of our recent results make a strong case for Solar-C.
I hope everyone is having a good summer.
Regards,
George
________________________________ From: loops-bounces@mithra.physics.montana.edu [mailto:loops-bounces@mithra.physics.montana.edu] On Behalf Of Klimchuk, James A. (GSFC-6710) Sent: Tuesday, July 31, 2012 9:48 AM To: (Loops@solar.physics.montana.edu) Subject: [Loops] type II spicule paper
Dear friends,
You might be interested in my recent paper on "The Role of Type II Spicules in the Upper Solar Atmosphere," which can be downloaded at http://arxiv.org/abs/1207.7048
Cheers, Jim
ABSTRACT: We examine the suggestion that most of the hot plasma in the Sun's corona comes from type II spicule material that is heated as it is ejected from the chromosphere. This contrasts with the traditional view that the corona is filled via chromospheric evaporation that results from coronal heating. We explore the observational consequences of a hypothetical spicule dominated corona and conclude from the large discrepancy between predicted and actual observations that only a small fraction of the hot plasma can be supplied by spicules (<2% in active regions and <5% in the quiet Sun). The red-blue asymmetries of EUV spectral lines and the ratio of lower transition region (LTR; T<0.1 MK) to coronal emission measures are both predicted to be 2 orders of magnitude larger than observed. Furthermore, hot spicule material would cool dramatically by adiabatic expansion as it rises into the corona, so coronal heating would be required to maintain the high temperatures that are seen at all altitudes. The necessity of coronal heating is inescapable. Traditional coronal heating models predict far too little emission from the LTR, and we suggest that this emission comes primarily from the bulk of the spicule material that is heated to <0.1 MK and is visible in He II (304 A) as it falls back to the surface.
******************************************************************************** James A. Klimchuk NASA Goddard Space Flight Center Solar Physics Lab, Code 671 Bldg. 21, Rm. 158 Greenbelt, MD 20771 USA
Phone: 1-301-286-9060 Fax: 1-301-286-7194 E-mail: James.A.Klimchuk@nasa.govmailto:James.A.Klimchuk@nasa.gov Homepage: https://sedupdate.gsfc.nasa.gov/sed/index.cfm?fuseAction=people.jumpBio&...
No endorsement by NASA is implied for any correspondence related to my role as an officer of professional organizations (American Geophysical Union, International Astronomical Union, American Astronomical Society).
********************************************************************************
Jim,
interesting paper, but I still have not seen convincing evidence that material at chromospheric temperatures travelling upwards gets heated to coronal temperatures. It is clear that all the SDO AIA bands have significant contributions from lines formed below 1 MK (2011,A&A,535, A46) as we discussed at the last loop meeting. Some residual emission above 1 MK might be present but there are a lot of uncertainties..
cheers
Giulio --
Hi Giulio,
Maria Madjarska says the same thing. And it makes me happy! It only strengthens the case that spicules do not provide the corona with much, if any, of its hot plasma. Keep pushing this result!!
Thanks, Jim
James A. Klimchuk NASA/GSFC James.A.Klimchuk@nasa.gov ________________________________________ From: loops-bounces@solar.physics.montana.edu [loops-bounces@solar.physics.montana.edu] On Behalf Of Giulio Del Zanna [G.Del-Zanna@damtp.cam.ac.uk] Sent: Thursday, August 09, 2012 3:27 AM To: A mailing list for scientists involved in the observation and modeling of solar loop structures Subject: Re: [Loops] type II spicule paper
Jim,
interesting paper, but I still have not seen convincing evidence that material at chromospheric temperatures travelling upwards gets heated to coronal temperatures. It is clear that all the SDO AIA bands have significant contributions from lines formed below 1 MK (2011,A&A,535, A46) as we discussed at the last loop meeting. Some residual emission above 1 MK might be present but there are a lot of uncertainties..
cheers
Giulio -- _______________________________________________ Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
Dear Jim,
I did not think that somebody seriously believes that the vast amount of rather cool spicular plasma launched towards the corona provides the material of the corona. There are 2 to 3 orders of magnitude too much of mass. Most of the material comes back under the action of the gravity. Some part goes to the sheath of spicules but this is not clear. However, in case of a tall spicule like the top of macro-spicules or giant spicules above polar regions (called before at total eclipses a spike and now called an EUV event in He+ and CIV), a SXR jetlet can often be observed in hot coronal lines, with large upwards velocities. Small redshifts are also observed around, at TR temperature. There is little doubt that they are guided and confined by the coronal magnetic field, extracting some free energy during the explosive phase, such that they participate in both the mass supply and the heating of the corona. I thought a general consensus exists about that, is not?
Your paper is a brilliant 1D demonstration concerning the chromospheric spicules. What about considering a filling factor? For cool spicules it is of small values and at TR temperatures, it is of very low values. At coronal temperature, it could be zero?
Best,
S.
Le 09/08/2012 16:06, Klimchuk, James A. (GSFC-6710) a écrit :
Hi Giulio,
Maria Madjarska says the same thing. And it makes me happy! It only strengthens the case that spicules do not provide the corona with much, if any, of its hot plasma. Keep pushing this result!!
Thanks, Jim
James A. Klimchuk NASA/GSFC James.A.Klimchuk@nasa.gov ________________________________________ From: loops-bounces@solar.physics.montana.edu [loops-bounces@solar.physics.montana.edu] On Behalf Of Giulio Del Zanna [G.Del-Zanna@damtp.cam.ac.uk] Sent: Thursday, August 09, 2012 3:27 AM To: A mailing list for scientists involved in the observation and modeling of solar loop structures Subject: Re: [Loops] type II spicule paper
Jim,
interesting paper, but I still have not seen convincing evidence that material at chromospheric temperatures travelling upwards gets heated to coronal temperatures. It is clear that all the SDO AIA bands have significant contributions from lines formed below 1 MK (2011,A&A,535, A46) as we discussed at the last loop meeting. Some residual emission above 1 MK might be present but there are a lot of uncertainties..
cheers
Giulio
Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops _______________________________________________ Loops mailing list Loops@solar.physics.montana.edu https://mithra.physics.montana.edu/mailman/listinfo/loops
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