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

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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

Naomasa KITAGAWA & Takaaki YOKOYAMA

The University of Tokyo, Japan


Discovery of ar outflows

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)


Upflows from footpoints of active region loops

Upflows from footpoints of active region loops

Line profile

= EBW + Main component

Intensity

EBW

VNT

(Hara et al. 2008)


R b asymmetry

R-B asymmetry

(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

Total emission

(Brooks & Warren 2012)

  • FIP bias of outflows: 3–5

    • Coronal origin

      i.e. not the photospheric

Fe VIII

S X

Si X

Fe XII

Fe XIII

Fe XV

EBW

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


Motivation

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)


Simultaneous fitting for fe xiv 264 274

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

Histogram for l274/l264

Main

EBW


Density diagnostics of ar outflows

Density diagnostics of AR outflows

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

Density map for each component

Outflow region

Main component

EBW


Density ebw vs main component

Density: EBW vs. Main component

  • EBW (outflows): ~108.7 cm-3

  • Main: ~109.2 cm-3

Main

component

Main component

EBW (outflows)

EBW

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


Column depth of ar outflows

Column depth of AR outflows

(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

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

“l-Ne diagram”

spectrum

Wavelength scale is adjusted.

......

△: solution

: diagram


L n e diagram in ar10978

l-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

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.


Summary of results

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

    “l-Ne diagram”

Histogram for Ne

Main

Outflows


Density of active region outflows derived from fe xiv 264 274

End


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