Coronal Loops Workshop 6, La Roche-en-Ardenne, Belgi um, 25-27 Jun 2013 Density of active region Density of active region outflows derived from Fe outflows derived from Fe XIV 264/274 XIV 264/274 Naomasa KITAGAWA & Takaaki YOKOYAMA The University of Tokyo, Japan
15
Embed
Density of active region outflows derived from Fe XIV 264/274
Density of active region outflows derived from Fe XIV 264/274. Naomasa KITAGAWA & Takaaki YOKOYAMA The University of Tokyo, Japan. Discovery of AR outflows. In dark location v=50-150 km s -1 Persistent Emanated from ‘open’ region. Fe XII intensity. Doppler vel. Width. (Doschek 2008). - PowerPoint PPT Presentation
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Coronal Loops Workshop 6, La Roche-en-Ardenne, Belgium, 25-27 Jun 2013
Density of active region outflows Density of active region outflows derived from Fe XIV 264/274derived from Fe XIV 264/274
Naomasa KITAGAWA & Takaaki YOKOYAMAThe University of Tokyo, Japan
Coronal Loops Workshop 6, La Roche-en-Ardenne, Belgium, 25-27 Jun 2013
Discovery of AR outflows
• In dark location• v=50-150 km s-1
• Persistent• Emanated from ‘open’ region
Fe XII intensity Doppler vel. Width(Doschek 2008)
Coronal Loops Workshop 6, La Roche-en-Ardenne, Belgium, 25-27 Jun 2013
Upflows from footpoints of active region loopsLine profile= EBW + Main component
Intensity
VNT
(Hara et al. 2008)
EBW
Coronal Loops Workshop 6, La Roche-en-Ardenne, Belgium, 25-27 Jun 2013
R-B asymmetry
• Ubiquitous EBWs in footpoint regions (De Pontieu et al. 2009)• Spatial correspondence with propagating disturbances in fan
loops (Tian et al. 2011)
(Tian et al. 2011)
(De Pontieu et al. 2009)
Coronal Loops Workshop 6, La Roche-en-Ardenne, Belgium, 25-27 Jun 2013
DEM of AR outflows
• FIP bias of outflows: 3–5– Coronal origin
i.e. not the photospheric
Total emission
EBWAsymmetries of the emission lines peak in the coronal temperature (around Fe XII).
Fe VIII Si X S X
Fe XII Fe XIII Fe XV
(Brooks & Warren 2012)
Coronal Loops Workshop 6, La Roche-en-Ardenne, Belgium, 25-27 Jun 2013
Motivation• Properties revealed so far
– Persistency– Location: AR edge
• Boundary of close & open field?– Doppler velocity: 50-150 km s-1
– DEM: close to AR• What should we know about AR outflows?
– Driving mechanism– Source (in terms of height)
• Density (ne) of AR outflows ITSELF is one of the key clues to approach the nature of them. cf. ) Density of outflow regions– 7x108 cm-3 (Doschek et al. 2008, Fe XII total emission)– 108.4-8.9 cm-3 (Brooks & Warren 2012, Fe XIII total emission)
Coronal Loops Workshop 6, La Roche-en-Ardenne, Belgium, 25-27 Jun 2013
Simultaneous fitting for Fe XIV 264/274
• Wavelength calibration– Each component in Fe XIV 264/274 must
have the same Doppler velocity because the emission comes from Fe XIV.
• Double-Gaussian fitting
c
v1264264
c
v1274274 264
274
264
274
EBW
Main
⇒
Histogram for 274/264
Coronal Loops Workshop 6, La Roche-en-Ardenne, Belgium, 25-27 Jun 2013
Density diagnostics of AR outflows e
274
264 NRI
I
CHIANTI ver.7 (Dere et al. 1997, Landi et al. 2013)
Outflow region
Main component EBW
Density map for each component
Coronal Loops Workshop 6, La Roche-en-Ardenne, Belgium, 25-27 Jun 2013
Density: EBW vs. Main component• EBW (outflows): ~ 108.7 cm-3
• Main: ~ 109.2 cm-3
EBW (outflows)
Maincomponent
Main component
EBW
EBWs (outflows) are more tenuous than the main component.
Coronal Loops Workshop 6, La Roche-en-Ardenne, Belgium, 25-27 Jun 2013
Column depth of AR outflows
• EBW: 108.2±0.6 cm• Main: 107.7±0.2 cmAlthough emission of AR outflows is weak, they dominate in terms of the volume.
),( e2e
*
TnGn
Ihfh (h* for two components were calculated separately.)
Coronal Loops Workshop 6, La Roche-en-Ardenne, Belgium, 25-27 Jun 2013
Density diagnostics without fitting• Derivation of Ne from I264/I274 at e
ach spectral bin.
)(
)()(
274
264e
N
......
spectrum
“-Ne diagram”
Wavelength scale is adjusted. Wavelength scale is adjusted.
△: solution: diagram
Coronal Loops Workshop 6, La Roche-en-Ardenne, Belgium, 25-27 Jun 2013
-Ne diagram in AR10978
• AR core– log Ne()≃9.5
• Outflow region– Dip around 274.1Å
(v~ 100 km s-1)
AR core Outflow region
It is confirmed that outflows are more tenuous than the dominant, rest component.
Coronal Loops Workshop 6, La Roche-en-Ardenne, Belgium, 25-27 Jun 2013
Discussion
(1) noutflow < nMain
– The outflows observed here were not likely produced as a result of impulsive heating (e.g., nanoflare).
• However, this is not decisive because we do not know whether the two components in emission lines come from the same magnetic structure or not.
(2) h*outflow > h*
Main
– The volume of the outflows is larger than that of the main component, contrary to their weakness in emission line profiles.
(3) Doppler velocities indicate blueshift for log T≥5.8. – Different from fan loops
Driving mechanism in somewhat steady manner is required.
Coronal Loops Workshop 6, La Roche-en-Ardenne, Belgium, 25-27 Jun 2013
Summary of results
• EIS observation on AR10978• Density measurement
– Main: ≃109.2 cm-3
– Outflows: ≃ 108.7 cm-3 • Column depth
– Main: 107.7±0.2 cm– Outflows: 108.2±0.6 cm
• Verification by “-Ne diagram”
Histogram for Ne
Outflows
Main
Coronal Loops Workshop 6, La Roche-en-Ardenne, Belgium, 25-27 Jun 2013