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Temperature and density structure of a recurring active region jet

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Peer-reviewed

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Authors

Mulay, SM 
Zanna, GD 

Abstract

We present a study of a recurring jet observed on October 31, 2011 by SDO/AIA, Hinode/XRT and Hinode/EIS. We discuss the physical parameters of the jet such as density, differential emission measure, peak temperature, velocity and filling factor obtained using imaging and spectroscopic observations. A differential emission measure (DEM) analysis was performed at the region of the jet-spire and the footpoint using EIS observations and also by combining AIA and XRT observations. The DEM curves were used to create synthetic spectra with the CHIANTI atomic database. The plasma along the line-of-sight in the jet-spire and jet-footpoint was found to be peak at 2.0 MK. We calculated electron densities using the Fe XII ($\lambda186/\lambda$195) line ratio in the region of the spire (Ne = 7.6x1010 cm−3) and the footpoint (1.1x1011 cm−3). The plane-of-sky velocity of the jet is found to be 524 km/s. The resulting EIS DEM values are in good agreement with those obtained from AIA-XRT. There is no indication of high temperatures, such as emission from Fe XVII ($\lambda254.87)(logT[K]=6.75)seeninthejetspire.Incaseofthejetfootpoint,syntheticspectrapredictweakcontributionsfromCaXVII(\lambda192.85)andFeXVII(\lambda254.87).Withfurtherinvestigation,weconfirmedemissionfromtheFeXVIII(\lambda$93.932) line in the AIA 94 \AA channel in the region of the footpoint. We also found good agreement between the estimated and predicted Fe XVIII count rates. A study of the temporal evolution of the jet-footpoint and the presence of high-temperature emission from the Fe XVIII (log T [K] = 6.85) line leads us to conclude that the hot component in the jet-footpoint was present initially that the jet had cooled down by the time EIS observed it.

Description

Keywords

Sun: corona, Sun: atmosphere, Sun: transition region, Sun: UV radiation

Journal Title

Astronomy and Astrophysics

Conference Name

Journal ISSN

0004-6361
1432-0746

Volume Title

Publisher

EDP Sciences
Sponsorship
Science and Technology Facilities Council (ST/L000636/1)
Science and Technology Facilities Council (PP/E004857/2)
Science and Technology Facilities Council (ST/P000673/1)
Science and Technology Facilities Council (ST/P000665/1)
Science and Technology Facilities Council (ST/P000843/1)
Science and Technology Facilities Council (ST/J00054X/1)
SMM acknowledges support from the Cambridge Trust, University of Cambridge, UK. HEM and GDZ acknowledge the support of STFC. The authors also thank Mr. Paul Wright from University of Glasgow, UK for his valuable comments. AIA data are courtesy of SDO (NASA) and the AIA consortium. CHIANTI is a collaborative project involving George Mason University, the University of Michigan (USA), and the University of Cambridge (UK). Hinode is a Japanese mission developed and launched by ISAS/JAXA, with NAOJ as domestic partner and NASA and STFC (UK) as international partners. It is operated by these agencies in co-operation with ESA and NSC (Norway).