Density of active region outflows derived from fe xiv 264 274
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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).

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Density of active region outflows derived from fe xiv 264 274

Density of active region outflows derived from Fe XIV 264/274


The University of Tokyo, Japan

Discovery of ar outflows
Discovery of AR outflows 264/274

  • In dark location

  • v=50-150 km s-1

  • Persistent

  • Emanated from ‘open’ region

Fe XII intensity

Doppler vel.


(Doschek 2008)

Upflows from footpoints of active region loops
Upflows from footpoints of active region loops 264/274

Line profile

= EBW + Main component




(Hara et al. 2008)

R b asymmetry
R-B asymmetry 264/274

(Tian et al. 2011)

  • Ubiquitous EBWs in footpoint regions (De Pontieu et al. 2009)

  • Spatial correspondence with propagating disturbances in fan loops (Tian et al. 2011)

(De Pontieu et al. 2009)

Dem of ar outflows
DEM of AR outflows 264/274

Total emission

(Brooks & Warren 2012)

  • FIP bias of outflows: 3–5

    • Coronal origin

      i.e. not the photospheric



Si X





Asymmetries of the emission lines peak in the coronal temperature (around Fe XII).

Motivation 264/274

  • 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)

Simultaneous fitting for fe xiv 264 274
Simultaneous fitting for Fe XIV 264/274 264/274

  • 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

Histogram for l274/l264



Density diagnostics of ar outflows
Density diagnostics of AR outflows 264/274

CHIANTI ver.7 (Dere et al. 1997, Landi et al. 2013)

Density map for each component

Outflow region

Main component


Density ebw vs main component
Density: EBW vs. Main component 264/274

  • EBW (outflows): ~108.7 cm-3

  • Main: ~109.2 cm-3



Main component

EBW (outflows)


EBWs (outflows) are more tenuous than the main component.

Column depth of ar outflows
Column depth of AR outflows 264/274

(h* for two components were calculated separately.)

  • EBW: 108.2±0.6 cm

  • Main: 107.7±0.2 cm

    Although emission of AR outflows is weak, they dominate in terms of the volume.

Density diagnostics without fitting
Density diagnostics without fitting 264/274

  • Derivation of Ne from I264/I274 at each spectral bin.

“l-Ne diagram”


Wavelength scale is adjusted.


△: solution

: diagram

L n e diagram in ar10978
l 264/274-Ne diagram in AR10978

  • AR core

    • log Ne(l)≃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.

Discussion 264/274

(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.

Summary of results
Summary of results 264/274

  • 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

    “l-Ne diagram”

Histogram for Ne



End 264/274