RHESSI Detection of X-ray Emission from a Quiet-Sun Filament Eruption

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|second_author =Adi Foord
|second_author =Adi Foord
|publish_date = 13 April 2015
|publish_date = 13 April 2015
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|previous_nugget = [http://sprg.ssl.berkeley.edu/~tohban/wiki/index.php/Soft_X-ray_emission_in_kink-unstable_coronal_loops]
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|previous_nugget = [http://sprg.ssl.berkeley.edu/~tohban/wiki/index.php/Soft_X-ray_emission_in_kink-unstable_coronal_loops Kink instability]
|next_nugget = SWFs
|next_nugget = SWFs
|number = 250
|number = 250
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Quiescent  
Quiescent  
-
[filaments]  
+
[http://scied.ucar.edu/solar-filament filaments]  
can lie outside  
can lie outside  
-
[solar active regions],
+
[http://www.solarmonitor.org solar active regions],
and are often much longer than the diameter of a typical active region.   
and are often much longer than the diameter of a typical active region.   
Despite their name, many  
Despite their name, many  
-
[erupt]  
+
[http://www.nasa.gov/content/solar-filament-eruption-canyon-of-fire/#.VSdlrrpy_BI erupt]  
and can be associated with a fast coronal mass ejection  
and can be associated with a fast coronal mass ejection  
-
([CME]).  
+
([http://en.wikipedia.org/wiki/Coronal_mass_ejection CME]).  
When they interact with Earth, these fast CMEs can excite major geomagnetic
When they interact with Earth, these fast CMEs can excite major geomagnetic
storms.   
storms.   
Line 27: Line 27:
from active regions is important to understanding the origin of
from active regions is important to understanding the origin of
[solar magnetic activity] and  
[solar magnetic activity] and  
-
[space weather].   
+
[http://www.swpc.noaa.gov space weather].   
== The "Canyon of Fire" Eruption ==
== The "Canyon of Fire" Eruption ==
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quadrant of the sun on September 29, 2013.   
quadrant of the sun on September 29, 2013.   
This eruption, associated with a fast CME that did impact Earth, received  
This eruption, associated with a fast CME that did impact Earth, received  
-
considerable media attention and was nicknamed the "Canyon of Fire."   
+
considerable media attention and was nicknamed the  
 +
[http://www.nasa.gov/content/solar-filament-eruption-canyon-of-fire/#.VSdlrrpy_BI "Canyon of Fire"].  
The  
The  
-
[X-ray detectors]  
+
[http://www.swpc.noaa.gov/products/goes-x-ray-flux X-ray detectors]  
aboard the GOES weather satellites registered a weak,  
aboard the GOES weather satellites registered a weak,  
C-level flare during the period of the eruption.   
C-level flare during the period of the eruption.   
These X-ray photometers provide no information about the source
These X-ray photometers provide no information about the source
location of the X-ray emission, but the GOES  
location of the X-ray emission, but the GOES  
-
[soft X-ray imager]  
+
[http://sxi.ngdc.noaa.gov soft X-ray imager]  
confirmed the origin of the X-ray burst to be, indeed, in the quiet Sun  
confirmed the origin of the X-ray burst to be, indeed, in the quiet Sun  
at the location of the erupting filament.  
at the location of the erupting filament.  
Line 52: Line 53:
peak emission are superimposed on an image in the 304Å band of the
peak emission are superimposed on an image in the 304Å band of the
Atmospheric Imaging Assembly  
Atmospheric Imaging Assembly  
-
([AIA])  
+
([http://aia.lmsal.com AIA])  
on the Solar Dynamics Observatory
on the Solar Dynamics Observatory
-
([SDO]).   
+
([http://sdo.gsfc.nasa.gov SDO]).   
[[File:250f1.png|800px|center|thumb|'''Figure 1''': Enhanced AIA 304-Å band image at 23:23 UT on September 29, 2013, with superimposed RHESSI 3 – 9 keV contours (30, 50, 70, and 90% of peak).  The RHESSI image is for an integration time of one minute using detectors 7 – 9 and the CLEAN algorithm.
[[File:250f1.png|800px|center|thumb|'''Figure 1''': Enhanced AIA 304-Å band image at 23:23 UT on September 29, 2013, with superimposed RHESSI 3 – 9 keV contours (30, 50, 70, and 90% of peak).  The RHESSI image is for an integration time of one minute using detectors 7 – 9 and the CLEAN algorithm.
Line 66: Line 67:
It followed the westward movement of the ribbon and also moved somewhat  
It followed the westward movement of the ribbon and also moved somewhat  
along its length, toward the north.   
along its length, toward the north.   
-
There is an active region to the east
+
There is an active region to the west
of the southern end of the ribbons, but the RHESSI source is clearly
of the southern end of the ribbons, but the RHESSI source is clearly
associated with the ribbon of the erupted quiescent filament, not
associated with the ribbon of the erupted quiescent filament, not
Line 108: Line 109:
== References ==
== References ==
-
[1] K. Harvey
+
[1] [http://adsabs.harvard.edu/abs/1984SoPh...91..127H "He I 10830 observations of the 3N/M4.0 flare of 4 September, 1982"]
-
[2] Martin-Feynman
+
[2] [http://adsabs.harvard.edu/abs/1995JGR...100.3355F "The initiation of coronal mass ejections by newly emerging magnetic flux"]
-
[3] Holman-Foord
+
[3] [http://adsabs.harvard.edu/abs/2015AAS...22513708F "RHESSI Detection of X-ray Emission from a Quiescent Filament Eruption"]

Revision as of 06:05, 10 April 2015


Nugget
Number: 250
1st Author: Gordon Holman
2nd Author: Adi Foord
Published: 13 April 2015
Next Nugget: SWFs
Previous Nugget: Kink instability
List all



Contents

Introduction

Quiescent filaments can lie outside solar active regions, and are often much longer than the diameter of a typical active region. Despite their name, many erupt and can be associated with a fast coronal mass ejection (CME). When they interact with Earth, these fast CMEs can excite major geomagnetic storms. Obtaining an understanding of the connection between quiescent filament eruptions and flares, CMEs, and filament eruptions from active regions is important to understanding the origin of [solar magnetic activity] and space weather.

The "Canyon of Fire" Eruption

An impressive quiescent filament eruption originated from the northwestern quadrant of the sun on September 29, 2013. This eruption, associated with a fast CME that did impact Earth, received considerable media attention and was nicknamed the "Canyon of Fire". The X-ray detectors aboard the GOES weather satellites registered a weak, C-level flare during the period of the eruption. These X-ray photometers provide no information about the source location of the X-ray emission, but the GOES soft X-ray imager confirmed the origin of the X-ray burst to be, indeed, in the quiet Sun at the location of the erupting filament.

An examination of RHESSI light curves shows that RHESSI also observed emission at the time of the GOES flare at X-ray energies, but at energies up to 12 keV. The location of the RHESSI emission is shown in Figure 1. Contours of 3-9 keV emission observed by RHESSI at the time of the GOES peak emission are superimposed on an image in the 304Å band of the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory (SDO).

Figure 1: Enhanced AIA 304-Å band image at 23:23 UT on September 29, 2013, with superimposed RHESSI 3 – 9 keV contours (30, 50, 70, and 90% of peak). The RHESSI image is for an integration time of one minute using detectors 7 – 9 and the CLEAN algorithm. Note the interesting concentration at one ribbon, and not both.

The AIA image shows two bright ribbons that formed below the original location of the filament and gradually spread apart as the filament erupted, a pattern of evolution typical of two-ribbon flares (Ref. [1]). The RHESSI source is located along part of the western ribbon. It followed the westward movement of the ribbon and also moved somewhat along its length, toward the north. There is an active region to the west of the southern end of the ribbons, but the RHESSI source is clearly associated with the ribbon of the erupted quiescent filament, not the active region. Why is the RHESSI source located along only a small fraction of the extended ribbon? The answer appears to be a small dipolar region that emerged earlier in the day before the start of the filament eruption. It emerged below the filament at about the solar latitude where the RHESSI source is later observed. The dipole field builds to a strength exceeding 1,000 Gauss. This field strength slowly decays during the filament eruption and decays more rapidly during the flare. Magnetic reconnection of the dipolar field with the field of the filament arcade was likely the driver of enhanced local plasma heating responsible for the thermal bremsstrahlung emission from the hot plasma observed by RHESSI. Emerging flux regions such as this small dipole are frequently associated with quiescent filament eruptions and may be involved in triggering the eruption (Ref. [2]). The observations and their interpretation are described in Ref. [3]. Additional associations of RHESSI X-ray emission with quiescent filament eruptions have been identified. Analysis of these events will provide valuable insights into the origin and evolution of quiescent filament eruptions and solar eruptive events in general.

Conclusions

The event described in this Nugget reveals the presence of intense energy release even in the quiet Sun, in the form of an otherwise innocuous-looking quiescent filament. The power of the the CME that resulted, and its interplanetary development, do not have the same kind of associations with a solar flare as in an active-region event. Nevertheless high temperatures and non-thermal effects result, and hard X-ray observations such as those of RHESSI (or more sensitive ones) can diagnose them.

References

[1] "He I 10830 observations of the 3N/M4.0 flare of 4 September, 1982"

[2] "The initiation of coronal mass ejections by newly emerging magnetic flux"

[3] "RHESSI Detection of X-ray Emission from a Quiescent Filament Eruption"

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