[Loops] Very hot plasma above the limb using spectroscopic observations up to Fe XIX

Mon Aug 7 07:32:18 MDT 2017

Hi Helen,

     I concur that the Loops Workshop series is alive and well! It is evolving in a very healthy way, to include more MHD and discussion of heating mechanisms.

     On the importance of high-temperature spectroscopy, I attach the white paper I wrote for the Next Generation Solar Physics Mission study team.

Cheers,
Jim

> -----Original Message-----
> From: Loops [mailto:loops-bounces at solar.physics.montana.edu] On Behalf Of
> hm11 at damtp.cam.ac.uk
> Sent: Sunday, August 06, 2017 2:13 AM
> To: Philip Judge
> Cc: loops at solar.physics.montana.edu
> Subject: Re: [Loops] Very hot plasma above the limb using spectroscopic
> observations up to Fe XIX
> 
> Hi Phil,
> 
> As always you raise some interesting questions, and yes this region was quite
> active, but Susanna tried very carefully to avoid the microflare activity, but the
> question remains as to whether this is really possible.
> 
> Hugh is also right that the time resolution for spectrometers like SUMER and CDS is
> not great. We generally need to combine spectroscopic observations with those from
> SDO/AIA to get the best results. IRIS of course gets around this, but does not have
> good coverage of coronal ions.
> Plenty of results with good old FeXXI though and TR ions. Good work by Vanessa
> (Polito) for example.
> 
> One of the outcomes from the Loops discussions was that we really need another
> high res X-ray spectrometer like SMM BCS and FCS. MAGIXS should provide some
> answers. Another result of discussions was that flying HiC with 171 again would
> address several key questions.
> 
> If you like 'discussion', as we know you do, you really should come to the Loops
> meetings, or perhaps even host it in Boulder! Jeremy Drake came to the one in
> Palermo and stimulated lots of new and interesting discussions, in particular relating
> Solar and stellar connections. We shall soon be seeking offers of venues for 2019.
> Steve Bradshaw is currently 'our Loops leader'.
> 
> Even I thought that perhaps after seven loops workshops, Loops7 being in
> Cambridge, the discussions might have died down, but actually the meeting in
> Palermo was really good, lots of interesting talks and posters, and much animated
> discussion. Also a good mix of old hands and young enthusiastic researchers. Our
> thanks of course went to Fabio, for all his hard work and hospitality. Although the
> temperature outside the Loops was rather high!
> 
> H.
> 
> On Aug 6 2017, Philip Judge wrote:
> 
> >So my email caused a little discussion... excellent... that was why I
> >sent it!
> >
> >Thanks Hugh.  More discussion here?  I would love to hear more insight
> >from interested researchers... personally, I just love the stuff that
> >resolutely refuses to agree with our preconceptions... but it is quite
> >difficult to come up with such things.
> >
> >Thanks for the original posting, Susanna
> >
> >phil
> >
> >
> >On Sat, Aug 5, 2017 at 4:07 PM, Hugh Hudson <hhudson at ssl.berkeley.edu>
> >wrote:
> >
> >> Phil, in addition to exotic mechanisms such as "long-lived
> >> reconnection", one could also look at the Parenti et al. paper from
> >> the point of view of flare physics. Although the authors have done
> >> careful work on the time series, the time resolution of the SUMER and
> >> EIS data is not great. During the interval 27-Apr-2012 16:00 through
> >> 28-apr-2012 10:00, I count 25 flare triggers in the RHESSI catalog,
> >> just for those located in the SW limb region. RHESSI has excellent
> >> time resolution, good sensitivity, and less temporal confusion
> >> because of the shorter time scales of hard X-rays. The total of 25 is
> >> many more than GOES reports, and our past experience with events at
> >> this level is that - though weak - they really look like ordinary
> >> flares. Given the power-law distribution of flare magnitudes, it is
> >> highly likely that many more true flare events below even the RHESSI
> >> threshold may have occurred during this active period.
> >>
> >> You ask "Can you rule out any heating mechanisms?" and I'd be
> >> delighted to see a RHESSI Science Nugget on this topic!
> >>
> >> Hugh
> >>
> >> > On Aug 4, 2017, at 9:06 PM, Philip Judge <judge at ucar.edu> wrote:
> >> >
> >> >
> >> > This looks very nice.  Can you rule out any heating mechanisms?  Is
> >> > the really hot stuff (in)consistent with the emergence and
> >> > dissipation of
> >> new magnetic field from below via a long-lived reconnection due to
> >> the underlying continuous emergence of flux?
> >> >
> >> >
> >> >
> >> > On Thu, Jul 27, 2017 at 3:18 AM, Susanna Parenti <
> >> susanna.parenti at ias.u-psud.fr> wrote:
> >> > Dear all,
> >> >
> >> >   here is a new paper just accepted for publication on the ApJ. It
> >> provides evidence for very hot plasma above the limb observed for an
> >> AR using spectroscopic observations from Fe X to Fe XIX. We quantify
> >> the spatial and temporal properties of this plasma. Main results: the
> >> hot plasma is detected in various places above the limb which are at
> >> different heights; its thermal properties are not changing much over
> >> the duration of the observations (17h) .
> >> >
> >> > Regards,
> >> >
> >> > Susanna Parenti
> >> >
> >> >
> >> >  http://arxiv.org/abs/1707.08445
> >> >
> >> > Spectroscopy of very hot plasma in non-flaring parts of a solar
> >> > limb
> >> active region: spatial and temporal properties.
> >> >
> >> > In this work we investigate the thermal structure of an off-limb
> >> > active
> >> region in various non-flaring areas, as it provides key information
> >> on the way these structures are heated. In particular, we concentrate
> >> in the very hot component (>3 MK) as it is a crucial element to
> >> discriminate between different heating mechanisms. We present an
> >> analysis using Fe and Ca emission lines from both SOHO/SUMER and
> >> HINODE/EIS. A dataset covering all ionization stages from Fe X to Fe
> >> XIX has been used for the thermal analysis (both DEM and EM). Ca XIV
> >> is used for the SUMER-EIS radiometric cross-calibration. We show how
> >> the very hot plasma is present and persistent almost everywhere in
> >> the core of the limb AR. The off-limb AR is clearly structured in Fe
> >> XVIII. Almost everywhere, the EM analysis reveals plasma at 10 MK
> >> (visible in Fe XIX
> >> emission) which is down to 0.1% of EM of the main 3 MK plasma. We
> >> estimate the power law index of the hot tail of the EM to be between
> >> -8.5 and -4.4. However, we leave an open question on the possible
> >> existence of a small minor peak at around 10 MK. The absence in some
> >> part of the AR of Fe XIX and Fe XXIII lines (which fall into our
> >> spectral range) enables us to determine an upper limit on the EM at
> >> such temperatures. Our results include a new Ca XIV 943.59 \AA~
> >> atomic model
> >> >
> >> >
> >> >
> >> >
> >> >
> >> > _______________________________________________
> >> > Loops mailing list
> >> > Loops at solar.physics.montana.edu
> >> > https://mithra.physics.montana.edu/mailman/listinfo/loops
> >> >
> >> >
> >> >
> >> >
> >> > --
> >> > Philip Judge       303-775-9863
> >> > Senior Scientist, HAO, NCAR
> >> > Editor-in Chief,   Open Astronomy
> >> >
> >> > https://www.degruyter.com/view/j/astro
> >> > http://people.hao.ucar.edu/judge/homepage/
> >> >
> >> >
> >> >
> >> >
> >> >
> >> > _______________________________________________
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> >> > Loops at solar.physics.montana.edu
> >> > https://mithra.physics.montana.edu/mailman/listinfo/loops
> >>
> >>
> >
> >
> >
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