HelioWiki Home Page - Recent changes [en]

SolarNuggets

Hhudson — Thu, 14 May 2026 10:50:24 GMT

← Older revision		Revision as of 10:50, 14 May 2026
(One intermediate revision by the same user not shown)
Line 1:		Line 1:
	Welcome to the [[SolarNuggets]] collection, which extends the series of [[RHESSI]] Nuggets. The following is a time-ordered list of the latest Nuggets added to the HelioWiki. An [[:Category:Nugget\|alphabetical list of the SolarNuggets]] is also available as well as [[:Category:RHESSI Nugget List\|yearly lists]]. One can search on author, topic, IAU flare identifier, etc.). We welcome volunteer authors - please see our page of [[Help:For_Authors\| help for authors]] or just send an email to the Curator at (hugh.hudson@glasgow.ac.uk).		Welcome to the [[SolarNuggets]] collection, which extends the series of [[RHESSI]] Nuggets. The following is a time-ordered list of the latest Nuggets added to the HelioWiki. An [[:Category:Nugget\|alphabetical list of the SolarNuggets]] is also available as well as [[:Category:RHESSI Nugget List\|yearly lists]]. One can search on author, topic, IAU flare identifier, etc.). We welcome volunteer authors - please see our page of [[Help:For_Authors\| help for authors]] or just send an email to the Curator at (hugh.hudson@glasgow.ac.uk).

			{{Nugget Badge
			\|title = X-ray Log Letters‎‎
			\|number = 526
			\|first_author = Hugh HUDSON
			\|second_author = and Ed CLIVER
			\|\|publish_date = 18 May 2026
			\|description = Replacing ABCMX with a new comprehensive and quantitative QSabcmxyz catalog
			\|image=Icon526.png}}


	{{Nugget Badge		{{Nugget Badge

File:Icon526.png

Hhudson — Thu, 14 May 2026 10:46:04 GMT

Hhudson uploaded File:Icon526.png

New page

X-ray Log Letters

Hhudson — Thu, 14 May 2026 10:42:04 GMT

Conclusions

← Older revision		Revision as of 10:42, 14 May 2026
(6 intermediate revisions by the same user not shown)
Line 19:		Line 19:
	Flares of a wide range of brightnesses were immediately apparent, and		Flares of a wide range of brightnesses were immediately apparent, and
	[https://www.noaa.gov NOAA]		[https://www.noaa.gov NOAA]
	ionospheric physicist Don Baker (Ref. [1]) came up with the ~~classification~~.		ionospheric physicist Don Baker (Ref. [1]) came up with a classification
			that matched decades of peak flux to letters: Cnn would mean nn x 10<sup>-4</sup>,
			and the basic flux level 1.0 x 10<sup>-6</sup> W/m<sup>2</sup> would be class C1.0.
	Initially it was just CMX ("Common", "Medium", "Extreme")		Initially it was just CMX ("Common", "Medium", "Extreme")
	Each flare has a peak flux in the standard 1-8 Å band,		Each flare has a peak flux in the standard 1-8 Å band,
Line 45:		Line 47:
	Low background solar X-ray fluxes during solar minima allowed the GOES		Low background solar X-ray fluxes during solar minima allowed the GOES
	detector technology to detect fainter events, and so two new decades were		detector technology to detect fainter events, and so two new decades were
	added to the letter string: A and B, with no descriptive ~~term ("Boring" and~~		added to the letter string: A and B, with no particular descriptive
	~~"Anemic" come to mind)~~.		interpretation.
	Thus we ~~have~~ ABCMX.		Thus we arrived at the current letter string ABCMX.

	== The SphinX breakthrough (to the bottom) ==		== The SphinX breakthrough (to the bottom) ==
Line 68:		Line 70:
	below the original CMX range (Ref. [3]).		below the original CMX range (Ref. [3]).
	Excesses above this level are due to weak flares and quiescent active regions.		Excesses above this level are due to weak flares and quiescent active regions.
			Translated to the GOES calibration, the weakest events are measured in units of
			10<sup>-10</sup> W/m<sup>2</sup>.
	</i>]]		</i>]]

Line 73:		Line 77:

	At the top end of the GOES soft X-ray distribution, a handful of the most		At the top end of the GOES soft X-ray distribution, a handful of the most
	extreme events had saturated the 1-8 Å readout.		extreme events had saturated the GOES 1-8 Å readout.
	Ref. [4] describes an evenhanded patching of these items, together with a		Ref. [4] describes an evenhanded patching of these items, together with a
	~~correcting~~ for a systematic offset (Ref. [2]).		correction for a systematic offset (Ref. [2]).
	This produced a list of 37 >X10 events after background subtraction.		This produced a list of 37 >X10 events after background subtraction.
	This basic manipulation departs from tradition, and so we provide this		This basic manipulation departs from tradition, and so we provide this
Line 85:		Line 89:
	[https://heliowiki.smce.nasa.gov/wiki/index.php/The_1859_Space_Weather_Event_Revisited Carrington event]		[https://heliowiki.smce.nasa.gov/wiki/index.php/The_1859_Space_Weather_Event_Revisited Carrington event]
	might have been in that category.		might have been in that category.

			A sample of the newly lettered catalog is here, representing a signal-to-background requirement of 1 (flare
			doubles the preflare level), resulting in a reduction of total number from 48,131 to 42,469 for the timespan
			1974-2023.
			The new letter string is QSabcmxyz, pleasingly symmetric.
			SOL1984-02-10T22:47 C9.1 m1.21
			SOL1984-02-11T01:31 C3.7 c3.78
			SOL1984-02-11T02:45 M2.9 m4.07
			SOL1984-02-11T03:44 C2.0 c1.93
			SOL1984-02-11T04:33 C2.1 c1.78
			SOL1984-02-11T04:56 C2.1 c2.23
			SOL1984-02-11T09:06 C2.6 c2.46
			SOL1984-02-11T10:09 C1.8 c1.43
			SOL1984-02-11T12:16 C3.0 c3.19
			SOL1984-02-11T14:24 C4.8 c6.03
			The catalog contains 37 y-class events (previously X10 or S), but no z-class examples because the Sun refuses to
			cooperate. At the C->c level, many events get downgraded because of background subtraction, but the systematic
			historical scale adjustment described in Ref. [2] tends to compensate for that.

	== Conclusions ==		== Conclusions ==

			See the [https://www.astro.gla.ac.uk/users/hsh3f/QSabcmxyz.html further discussion] of how QSabcmxyz works, or to access it directly click [https://www.astro.gla.ac.uk/users/hsh3f/QSabcmxyz.txt here] for a 2-MB text listing.

	== References ==		== References ==

X-ray Log Letters

Hhudson — Mon, 11 May 2026 18:31:11 GMT

Most of No. 526

New page

{{Infobox Nugget |name = Nugget
|title = X-ray Log Letters
|number = 526
|first_author = Hugh HUDSON and
|second_author = Ed CLIVER
|publish_date = May 18, 2026
|next_nugget = TBD
|previous_nugget = {{#ask: [[Category:Nugget]] [[RHESSI Nugget Index::525]]}}
}}

== Introduction ==

As all students of solar activity know, the
[https://www.stce.be/educational/classification naming scheme]
for solar flares involves the letters ABCMX.
These date from the dawn of the space age, when the first
[https://en.wikipedia.org/wiki/SOLRAD SOLRAD] satellites began to monitor
solar X-ray emission.
Flares of a wide range of brightnesses were immediately apparent, and
[https://www.noaa.gov NOAA]
ionospheric physicist Don Baker (Ref. [1]) came up with the classification.
Initially it was just CMX ("Common", "Medium", "Extreme")
Each flare has a peak flux in the standard 1-8 Å band,
and the range of magnitudes of flare peak fluxes is so great that it's most
convenient to record the
[https://en.wikipedia.org/wiki/Common_logarithm logarithm] of the
flux.
This convention moved directly into the
[https://www.swpc.noaa.gov/products/goes-x-ray-flux GOES]
satellite era, and from 1974 the standardized flux measurements
have come from this series of spacecraft (Ref. [2]).

In standard units a C-class flare has a peak flux greater than 10-7
W/m2, with M-class and X-class greater by powers of 10.
Conventionally a flare 10% brighter than the threshold, with peak flux
1.1 x 10-7 W/m2, would then become a C1.1 flare.
The letter thus represents the truncated logarithm of the peak flux.
The magnitudes are not rounded off and represent the solar X-ray flux
conventionally in a 1-min integration interval.
A background quiescent solar emission level is not subtracted; these routine
observations show the total solar X-ray flux in "Sun-as-a-star" mode.
Weaker events near the background level, which can indeed exceed C1 during
active times, will thus not be quite as energetic as their name implies.

Low background solar X-ray fluxes during solar minima allowed the GOES
detector technology to detect fainter events, and so two new decades were
added to the letter string: A and B, with no descriptive term ("Boring" and
"Anemic" come to mind).
Thus we have ABCMX.

== The SphinX breakthrough (to the bottom) ==

The first routine flare monitoring with sufficient sensitivity to
detect the solar quiescent X-ray flux appeared with the SphinX
instrument from the
[https://scholar.google.com/citations?user=vDLMZPIAAAAJ&hl=pl Sylwester]
group at Wroc&lstrok;aw (Ref. [3]).
For 1-8 Å this turned out to be about two decades below the A level.
Hence, two more letters: Q "quiet" and S "small", leading to the more complete
string QSABCMX.
Figure 1 shows SphinX data from the 2009
[https://en.wikipedia.org/wiki/Solar_cycle solar minimum].

[[File:526f1.png|center|thumb|600px|caption|Figure 1: 
SphinX observations from solar minimum 2009.
The regions marked with blue show the detection of the corona, at levels far
below the original CMX range (Ref. [3]).
Excesses above this level are due to weak flares and quiescent active regions.
]]

== The greatest events (to the top) ==

At the top end of the GOES soft X-ray distribution, a handful of the most
extreme events had saturated the 1-8 Å readout.
Ref. [4] describes an evenhanded patching of these items, together with a
correcting for a systematic offset (Ref. [2]).
This produced a list of 37 >X10 events after background subtraction.
This basic manipulation departs from tradition, and so we provide this
[greatest flares]
catalog using the letter system "QSabcmxyz".
To translate, the new "y" class is the old "X10" class, sometimes now called
"S" (Ref. 5]), and the new catalog lists 37 of them.
The new "z" class has no examples yet (but we're hopeful), although the
[https://heliowiki.smce.nasa.gov/wiki/index.php/The_1859_Space_Weather_Event_Revisited Carrington event]
might have been in that category.

== Conclusions ==

== References ==

[1] "Sentinels of the sun: forecasting space weather," B. Poppe and K. Jorden, 2006

[2] [https://www.sciencedirect.com/science/article/pii/B9780128143278000196 "GOES-R Series Solar X-ray and Ultraviolet Irradiance"]

[3] [http://adsabs.harvard.edu/abs/2011SoSyR..45..182G "Soft X-ray variability over the present minimum of solar activity as observed by SphinX"]

[4] [https://ui.adsabs.harvard.edu/abs/2024SoPh..299...39H "The Greatest GOES Soft X-ray Flares"]

[5] [https://ui.adsabs.harvard.edu/abs/2025ApJ...979L..16T "The Occurrence of Powerful Flares Stronger than X10 Class in Solar Cycles"]

File:526f1.png

Hhudson — Mon, 11 May 2026 18:17:13 GMT

Hhudson uploaded File:526f1.png

New page

How Extreme Can Solar Flares Get? A Statistical View

Hhudson — Tue, 05 May 2026 19:06:07 GMT

Introduction

← Older revision		Revision as of 19:06, 5 May 2026
Line 21:		Line 21:
	focusing explicitly on the statistical structure		focusing explicitly on the statistical structure
	of the tail of the flare-intensity distribution function.		of the tail of the flare-intensity distribution function.
			Note that a [https://heliowiki.smce.nasa.gov/wiki/index.php/How_energetic_can_solar_flares_become%3F recent Nugget]
			dealt with this subject from a different observational point of view.

	[[File:525f1.png\|center\|thumb\|600px\|caption\|Figure 1: <i>		[[File:525f1.png\|center\|thumb\|600px\|caption\|Figure 1: <i>

SolarNuggets

Hhudson — Tue, 05 May 2026 13:27:45 GMT

← Older revision		Revision as of 13:27, 5 May 2026
(One intermediate revision by the same user not shown)
Line 1:		Line 1:
	Welcome to the [[SolarNuggets]] collection, which extends the series of [[RHESSI]] Nuggets. The following is a time-ordered list of the latest Nuggets added to the HelioWiki. An [[:Category:Nugget\|alphabetical list of the SolarNuggets]] is also available as well as [[:Category:RHESSI Nugget List\|yearly lists]]. One can search on author, topic, IAU flare identifier, etc.). We welcome volunteer authors - please see our page of [[Help:For_Authors\| help for authors]] or just send an email to the Curator at (hugh.hudson@glasgow.ac.uk).		Welcome to the [[SolarNuggets]] collection, which extends the series of [[RHESSI]] Nuggets. The following is a time-ordered list of the latest Nuggets added to the HelioWiki. An [[:Category:Nugget\|alphabetical list of the SolarNuggets]] is also available as well as [[:Category:RHESSI Nugget List\|yearly lists]]. One can search on author, topic, IAU flare identifier, etc.). We welcome volunteer authors - please see our page of [[Help:For_Authors\| help for authors]] or just send an email to the Curator at (hugh.hudson@glasgow.ac.uk).

			{{Nugget Badge
			\|title = How Extreme Can Solar Flares Get? A Statistical View‎‎
			\|number = 525
			\|first_author = Lapo Ceccarelli
			\|second_author = and Daniela CASTRO-CAMILO
			\|\|publish_date = 4 May 2026
			\|description = A proper statistical treatment of the prospects for an extreme solar flare event
			\|image=Icon525.png}}

	{{Nugget Badge		{{Nugget Badge

How Extreme Can Solar Flares Get? A Statistical View

Hhudson — Tue, 05 May 2026 13:21:24 GMT

← Older revision		Revision as of 13:21, 5 May 2026
Line 48:		Line 48:
	The GPD distribution for exceedances <i>y = X - u > 0</i> is defined as:		The GPD distribution for exceedances <i>y = X - u > 0</i> is defined as:

	[[File:525eq2.png\|thumb\|center\|~~500px~~]]		[[File:525eq2.png\|thumb\|center\|600px]]

	where σ<sub>u</sub> > 0 is the scale parameter above threshold <i>u</i>		where σ<sub>u</sub> > 0 is the scale parameter above threshold <i>u</i>

File:525eq2.png

Hhudson — Tue, 05 May 2026 13:18:15 GMT

Hhudson uploaded a new version of File:525eq2.png

New page

File:525eq1.png

Hhudson — Tue, 05 May 2026 13:17:45 GMT

Hhudson uploaded a new version of File:525eq1.png

New page

File:525eq2.png

Hhudson — Tue, 05 May 2026 13:13:13 GMT

Hhudson deleted page File:525eq2.png Deleted old revision 20260505131215!525eq2.png

File:525eq2.png

Hhudson — Tue, 05 May 2026 13:12:15 GMT

Hhudson uploaded a new version of File:525eq2.png

New page

How Extreme Can Solar Flares Get? A Statistical View

Hhudson — Tue, 05 May 2026 13:06:51 GMT

← Older revision		Revision as of 13:06, 5 May 2026
(2 intermediate revisions by the same user not shown)
Line 20:		Line 20:
	Value Theory ([https://en.wikipedia.org/wiki/Extreme_value_theory EVT]),		Value Theory ([https://en.wikipedia.org/wiki/Extreme_value_theory EVT]),
	focusing explicitly on the statistical structure		focusing explicitly on the statistical structure
	of the tail of the ~~occurrence~~ distribution function.		of the tail of the flare-intensity distribution function.

	[[File:525f1.png\|center\|thumb\|600px\|caption\|Figure 1: <i>		[[File:525f1.png\|center\|thumb\|600px\|caption\|Figure 1: <i>
Line 42:		Line 42:
	[[File:525eq1.png\|thumb\|center\|500px]]		[[File:525eq1.png\|thumb\|center\|500px]]

	where μ is the real-valued "location parameter", σ>0 is the		where μ is the real-valued "location parameter", σ > 0 is the
	"scale parameter", and ξ is the "shape parameter" governing the		"scale parameter", and ξ is the "shape parameter" governing the
	behaviour of the tail of the distribution, i.e. the greatest values.		behaviour of the tail of the distribution, i.e. the greatest values.
Line 92:		Line 92:
	[[File:525f3.png\|center\|thumb\|600px\|caption\|Figure 3: <i>		[[File:525f3.png\|center\|thumb\|600px\|caption\|Figure 3: <i>
	Return Level plot for the selected GEV model. The horizontal dashed		Return Level plot for the selected GEV model. The horizontal dashed
	line corresponds to the estimated magnitude of the Carrington event,		line corresponds to the estimated magnitude of the
			[https://heliowiki.smce.nasa.gov/wiki/index.php/The_1859_Space_Weather_Event_Revisited Carrington event],
	while the vertical ones represent the 95% confidence interval for		while the vertical ones represent the 95% confidence interval for
	its return period.		its return period.

File:Icon525.png

Hhudson — Thu, 30 Apr 2026 19:06:41 GMT

Hhudson uploaded File:Icon525.png

New page

How Extreme Can Solar Flares Get? A Statistical View

Hhudson — Thu, 30 Apr 2026 17:36:31 GMT

Introduction

@@ Line 2: / Line 2: @@
 |title = How Extreme Can Solar Flares Get? A Statistical View
 |number = 525
-|first_author = Lapo
+|first_author = Lapo CECCARELLI
-|second_author = Daniela
+|second_author = Daniela CASTRO-CAMILO
 |publish_date = May 4, 2026
 |next_nugget = TBD
@@ Line 11: / Line 11: @@
 == Introduction ==
-[[File:525 eq1.png|thumb|center|500px|Gobbledygook]]
+Quantifying the upper limits of solar flare activity is central to

File:525eq1.png

Hhudson — Tue, 28 Apr 2026 19:06:23 GMT

Hhudson uploaded File:525eq1.png

New page

File:525f3.png

Hhudson — Tue, 28 Apr 2026 18:58:27 GMT

Hhudson uploaded File:525f3.png

New page

File:525f2.png

Hhudson — Tue, 28 Apr 2026 18:58:07 GMT

Hhudson uploaded File:525f2.png

New page

File:525f1.png

Hhudson — Tue, 28 Apr 2026 18:57:50 GMT

Hhudson uploaded File:525f1.png

New page

File:525eq2.png

Hhudson — Tue, 28 Apr 2026 18:56:40 GMT

Hhudson uploaded File:525eq2.png

New page

How Extreme Can Solar Flares Get? A Statistical View

Hhudson — Tue, 28 Apr 2026 08:39:31 GMT

New page

{{Infobox Nugget |name = Nugget
|title = How Extreme Can Solar Flares Get? A Statistical View
|number = 525
|first_author = Lapo
|second_author = Daniela
|publish_date = May 4, 2026
|next_nugget = TBD
|previous_nugget = {{#ask: [[Category:Nugget]] [[RHESSI Nugget Index::524]]}}
}}

== Introduction ==

[[File:525 eq1.png|thumb|center|500px|Gobbledygook]]

File:525 eq1.png

Hhudson — Tue, 28 Apr 2026 06:58:01 GMT

Hhudson uploaded File:525 eq1.png

New page

SolarNuggets

Hhudson — Mon, 27 Apr 2026 09:22:08 GMT

Adjusted No. 524 one-liner

← Older revision		Revision as of 09:22, 27 April 2026
(One intermediate revision by the same user not shown)
Line 2:		Line 2:

	{{Nugget Badge		{{Nugget Badge
	\|title = ~~An Unusual Long-Lived Radio Burst Oscillating~~ in ~~Frequency~~		\|title = Observations of Slow Elemental Abundance Decay in Association to CME
	\|number = 524		\|number = 524
	\|first_author = Saara TAKALA		\|first_author = Saara TAKALA
	\|\|publish_date = 27 April 2026		\|\|publish_date = 27 April 2026
	\|description = Soft X-ray spectroscopy tracks abundance variations in a CME		\|description = Soft X-ray spectroscopy tracks coronal abundance variations associated with a CME
	\|image=Icon524.png}}		\|image=Icon524.png}}

File:Icon524.png

Hhudson — Thu, 23 Apr 2026 14:03:18 GMT

Hhudson uploaded File:Icon524.png

New page

SolarNuggets

Hhudson — Thu, 23 Apr 2026 14:02:36 GMT

No. 524

← Older revision		Revision as of 14:02, 23 April 2026
Line 1:		Line 1:
	Welcome to the [[SolarNuggets]] collection, which extends the series of [[RHESSI]] Nuggets. The following is a time-ordered list of the latest Nuggets added to the HelioWiki. An [[:Category:Nugget\|alphabetical list of the SolarNuggets]] is also available as well as [[:Category:RHESSI Nugget List\|yearly lists]]. One can search on author, topic, IAU flare identifier, etc.). We welcome volunteer authors - please see our page of [[Help:For_Authors\| help for authors]] or just send an email to the Curator at (hugh.hudson@glasgow.ac.uk).		Welcome to the [[SolarNuggets]] collection, which extends the series of [[RHESSI]] Nuggets. The following is a time-ordered list of the latest Nuggets added to the HelioWiki. An [[:Category:Nugget\|alphabetical list of the SolarNuggets]] is also available as well as [[:Category:RHESSI Nugget List\|yearly lists]]. One can search on author, topic, IAU flare identifier, etc.). We welcome volunteer authors - please see our page of [[Help:For_Authors\| help for authors]] or just send an email to the Curator at (hugh.hudson@glasgow.ac.uk).

			{{Nugget Badge
			\|title = An Unusual Long-Lived Radio Burst Oscillating in Frequency
			\|number = 524
			\|first_author = Saara TAKALA
			\|\|publish_date = 27 April 2026
			\|description = Soft X-ray spectroscopy tracks abundance variations in a CME
			\|image=Icon524.png}}

	{{Nugget Badge		{{Nugget Badge

Observations of Slow Elemental Abundance Decay in Association to CME

Hhudson — Wed, 22 Apr 2026 19:45:48 GMT

← Older revision		Revision as of 19:45, 22 April 2026
(One intermediate revision by the same user not shown)
Line 14:		Line 14:
	The causes of these variations depend upon physical conditions, and		The causes of these variations depend upon physical conditions, and
	precise measurements of the elemental distribution can help		precise measurements of the elemental distribution can help
	to understand ~~the~~ structures ~~(see~~ Figure 1 for a snapshot of the		to understand these structures and their dynamics.
			See Figure 1 for a snapshot of the
	complexity of the		complexity of the
	[https://en.wikipedia.org/wiki/Solar_corona corona]).		[https://en.wikipedia.org/wiki/Solar_corona corona]);
	~~This~~ shows the state of the corona after the flare/CME event discussed		this shows the state of the corona after the flare/CME event discussed
	here.		here.

	[[File:524f1.png\|center\|thumb\|400px\|caption\|Figure 1: <i>		[[File:524f1.png\|center\|thumb\|400px\|caption\|Figure 1: <i>
	EUVI 304 å image showing the prominent soft X-ray loops observed		EUVI 304 å image showing the prominent soft X-ray loops observed
	above AR 13712 soon after the CME eruption		above AR 13712 soon after the CME eruption (arrow).
	</i>]]		</i>]]

Line 72:		Line 73:
	levels was not observed for any of the elements (Figure 2).		levels was not observed for any of the elements (Figure 2).

	[[File:524f2.png\|center\|thumb\|~~400px~~\|caption\|Figure 2: <i>		[[File:524f2.png\|center\|thumb\|600px\|caption\|Figure 2: <i>
	Temporal evolution of elemental abundances for Al, Ca, Mg (top		Temporal evolution of elemental abundances for Al, Ca, Mg (top
	panel), Fe, Si (middle panel) and S, Ar (bottom panel).		panel), Fe, Si (middle panel) and S, Ar (bottom panel).
Line 84:		Line 85:
	loops for hours after the CME eruption.		loops for hours after the CME eruption.

			[[File:524f3.png\|center\|thumb\|600px\|caption\|Figure 3: <i>
			STIX 30% (cyan), 50% (violet), and 70% (magenta) contours of the 6-10 keV
			emission source obtained with the CLEAN imaging method and
			projected onto FSI/EUI 171 Å images.
			</i>]]

File:524f1.png

Hhudson — Wed, 22 Apr 2026 19:39:21 GMT

Hhudson uploaded File:524f1.png

New page

File:524f3.png

Hhudson — Wed, 22 Apr 2026 19:38:31 GMT

Hhudson uploaded File:524f3.png

New page

File:524f2.png

Hhudson — Wed, 22 Apr 2026 19:38:03 GMT

Hhudson uploaded File:524f2.png

New page

Observations of Slow Elemental Abundance Decay in Association to CME

Hhudson — Wed, 22 Apr 2026 19:31:58 GMT

No. 524 initial

New page

{{Infobox Nugget |name = Nugget
|title = Observations of Slow Elemental Abundance Decay in Association to CME
|number = 524
|first_author = Saara TAKALA
|publish_date = April 27, 2026
|next_nugget = TBD
|previous_nugget = {{#ask: [[Category:Nugget]] [[RHESSI Nugget Index::523]]}}
}}

== Introduction ==

The abundances of the elements constituting the solar atmosphere
can vary with position, and vary with time as well.
The causes of these variations depend upon physical conditions, and
precise measurements of the elemental distribution can help
to understand the structures (see Figure 1 for a snapshot of the
complexity of the
[https://en.wikipedia.org/wiki/Solar_corona corona]).
This shows the state of the corona after the flare/CME event discussed
here.

[[File:524f1.png|center|thumb|400px|caption|Figure 1: 
EUVI 304 å image showing the prominent soft X-ray loops observed
above AR 13712 soon after the CME eruption
]]

The most powerful perturbations of the solar atmosphere are
[solar flares]
and
[https://en.wikipedia.org/wiki/Coronal_mass_ejection coronal mass ejections].
Over the past decades, notable relationships have been reported
between these phenomena.
Flares are known to affect the plasma
composition near the flare site, temporarily reducing or increasing
the abundances of certain elements during the event (Ref. [1]), but the
effects of associated CMEs on these spectral signatures have yet
to be determined.

The focus of our study (Ref. [2]) was the eruptive event SOL2024-06-24
from Active Region (AR) 13712, where a CME was observed in association
with a long-duration M1 flare.
The event was characterized by
long-lasting post-eruption loops rising high above the solar surface.
We investigate the temporal evolution of elemental abundances during
the event from spectral fits to
[https://en.wikipedia.org/wiki/Sunstorm_(spacecraft) SUNSTORM 1]
data, and analyze the results in relation to the CME.

== Observations ==

SUNSTORM 1 was a two-unit low-Earth orbit CubeSat carrying the
XFM-CS instrument, a spectrometer measuring solar X-ray emission
in a wide dynamic range [3].
These data clearly resolve
[http://hyperphysics.phy-astr.gsu.edu/hbase/quantum/xrayc.html K-shell]
emissions from several elements.
These direct 2->1 transitions directly reflect the elemental abundances.
We analyzed the spectra from the flare in the 1-12 keV range
via a two-temperature model with variable abundances.
SUNSTORM observations are complemented by EUV observations from SDO
AIA, Solar Orbiter FSI/EUI and STEREO-A EUVI (Figure 1).
Additionally,
we use imaging results from Solar Orbiter STIX to investigate the
evolution of the X-ray source during the event.

== Results ==

Spectral fitting results show a depletion in elemental abundances
for Al, Ca, Mg, Fe, Si and S after CME liftoff, while Ar increased
slightly.
Hours after the eruptive event, recovery back to pre-eruption
levels was not observed for any of the elements (Figure 2).

[[File:524f2.png|center|thumb|400px|caption|Figure 2: 
Temporal evolution of elemental abundances for Al, Ca, Mg (top
panel), Fe, Si (middle panel) and S, Ar (bottom panel).
The horizontal lines indicate photospheric abundances.
]]

The STIX 6-10 keV images reveal the dominant source of emission
during the event to have been a large, expanding coronal loop-top source
(Figure 3).
Prominent emission can be observed at the top of the
loops for hours after the CME eruption.

== References ==

[1] [https://iopscience.iop.org/article/10.3847/1538-4357/abd9c3 "The FIP and Inverse-FIP Effects in Solar Flares"]

[2] [https://www.aanda.org/articles/aa/full_html/2025/12/aa56226-25/aa56226-25.html "Quantifying CME effects on plasma parameters and elemental abundance recovery during an M1 flare event with X-ray spectroscopy"]

[3] [https://www.sciencedirect.com/science/article/pii/S0168900222003370?via%3Dihub "SUNSTORM 1/X-ray Flux Monitor for CubeSats (XFM-CS): Instrument characterization and first results"]

An Unusual Long-Lived Radio Burst Oscillating in Frequency

Hhudson — Wed, 22 Apr 2026 12:56:12 GMT

← Older revision		Revision as of 12:56, 22 April 2026
Line 32:		Line 32:

	[[File:523f1.png\|center\|thumb\|600px\|caption\|Figure 1: <i>		[[File:523f1.png\|center\|thumb\|600px\|caption\|Figure 1: <i>
	The dynamic radio spectrum f the frequency-oscillating burst,		The dynamic radio spectrum of the frequency-oscillating burst,
	as recorded by the Ond&rcaron;ejov radio spectrograph on 4 May 2024, between 07:30 and		as recorded by the Ond&rcaron;ejov radio spectrograph on 4 May 2024, between 07:30 and
	09:40 UT, in the 1000--1800 MHz range.		09:40 UT, in the 1000--1800 MHz range.

SolarNuggets

Hhudson — Wed, 22 Apr 2026 08:26:09 GMT

← Older revision		Revision as of 08:26, 22 April 2026
(One intermediate revision by the same user not shown)
Line 1:		Line 1:
	Welcome to the [[SolarNuggets]] collection, which extends the series of [[RHESSI]] Nuggets. The following is a time-ordered list of the latest Nuggets added to the HelioWiki. An [[:Category:Nugget\|alphabetical list of the SolarNuggets]] is also available as well as [[:Category:RHESSI Nugget List\|yearly lists]]. One can search on author, topic, IAU flare identifier, etc.). We welcome volunteer authors - please see our page of [[Help:For_Authors\| help for authors]] or just send an email to the Curator at (hugh.hudson@glasgow.ac.uk).		Welcome to the [[SolarNuggets]] collection, which extends the series of [[RHESSI]] Nuggets. The following is a time-ordered list of the latest Nuggets added to the HelioWiki. An [[:Category:Nugget\|alphabetical list of the SolarNuggets]] is also available as well as [[:Category:RHESSI Nugget List\|yearly lists]]. One can search on author, topic, IAU flare identifier, etc.). We welcome volunteer authors - please see our page of [[Help:For_Authors\| help for authors]] or just send an email to the Curator at (hugh.hudson@glasgow.ac.uk).

			{{Nugget Badge
			\|title = An Unusual Long-Lived Radio Burst Oscillating in Frequency
			\|number = 523
			\|first_author = Marian KARLICKÝ,
			\|second_author = Robert SYCH and Alena ZEMANOVÁ
			\|\|publish_date = 20 April 2026
			\|description = Remarkable decimetric signatures of structured outflows from a flaring active region
			\|image=Icon523.png}}

	{{Nugget Badge		{{Nugget Badge

File:Icon523.png

Hhudson — Wed, 22 Apr 2026 08:21:58 GMT

Hhudson uploaded File:Icon523.png

New page