Doppler shift of hot coronal lines in a moss area of an active region

N. Dadashi; L. Teriaca; D. Tripathi; S. K. Solanki; T. Wiegelmann

doi:10.1051/0004-6361/201220329

Doppler shift of hot coronal lines in a moss area of an active region

N. Dadashi
, L. Teriaca
, D. Tripathi
, S. K. Solanki
, T. Wiegelmann

Research output: Contribution to journal › Article › peer-review

16 Citations (Scopus)

Abstract

The moss is the area at the footpoint of the hot (3 to 5 MK) loops forming the core of the active region where emission is believed to result from the heat flux conducted down to the transition region from the hot loops. Studying the variation of Doppler shift as a function of line formation temperatures over the moss area can give clues on the heating mechanism in the hot loops in the core of the active regions. We investigate the absolute Doppler shift of lines formed at temperatures between 1 MK and 2 MK in a moss area within active region NOAA 11243 using a novel technique that allows determining the absolute Doppler shift of EUV lines by combining observations from the SUMER and EIS spectrometers. The inner (brighter and denser) part of the moss area shows roughly constant blue shift (upward motions) of 5 km s^-1 in the temperature range of 1 MK to 1.6 MK. For hotter lines the blue shift decreases and reaches 1 km s ^-1 for Fe xv 284 (~2 MK). The measurements are discussed in relation to models of the heating of hot loops. The results for the hot coronal lines seem to support the quasi-steady heating models for nonsymmetric hot loops in the core of active regions.

Original language	English
Article number	A115
Journal	Astronomy and Astrophysics
Volume	548
DOIs	https://doi.org/10.1051/0004-6361/201220329
Publication status	Published - 2012

Bibliographical note

Funding Information:
The SUMER project is financially supported by DLR, CNES, NASA, and the ESA PRODEX programme (Swiss contribution). SoHO is a mission of international cooperation between ESA and NASA. Hinode is a Japanese mission developed and launched by ISAS/JAXA, collaborating with NAOJ as a domestic partner, and NASA and STFC (UK) as international partners. Scientific operation of the Hinode mission is conducted by the Hinode science team organized at ISAS/JAXA. This team mainly consists of scientists from institutes in the partner countries. Support for the post-launch operation is provided by JAXA and NAOJ (Japan), STFC (U.K.), NASA, ESA, and NSC (Norway). Data are courtesy of NASA/SDO and the AIA and HMI science teams. This work has been partially supported by WCU grant No. R31-10016 funded by the Korean Ministry of Education, Science and Technology. N.D. acknowledges a PhD fellowship of the International Max Planck Research School on Physical Processes in the Solar System and Beyond. D.T. would like to thank MPS for supporting his travel and providing excellent hospitality.

Keywords

Sun: UV radiation
Sun: activity
Sun: corona

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10.1051/0004-6361/201220329

Cite this

@article{f55d177d08b44eee87ff8bcd2d2b99da,

title = "Doppler shift of hot coronal lines in a moss area of an active region",

abstract = "The moss is the area at the footpoint of the hot (3 to 5 MK) loops forming the core of the active region where emission is believed to result from the heat flux conducted down to the transition region from the hot loops. Studying the variation of Doppler shift as a function of line formation temperatures over the moss area can give clues on the heating mechanism in the hot loops in the core of the active regions. We investigate the absolute Doppler shift of lines formed at temperatures between 1 MK and 2 MK in a moss area within active region NOAA 11243 using a novel technique that allows determining the absolute Doppler shift of EUV lines by combining observations from the SUMER and EIS spectrometers. The inner (brighter and denser) part of the moss area shows roughly constant blue shift (upward motions) of 5 km s-1 in the temperature range of 1 MK to 1.6 MK. For hotter lines the blue shift decreases and reaches 1 km s -1 for Fe xv 284 (\textasciitilde{}2 MK). The measurements are discussed in relation to models of the heating of hot loops. The results for the hot coronal lines seem to support the quasi-steady heating models for nonsymmetric hot loops in the core of active regions.",

keywords = "Sun: UV radiation, Sun: activity, Sun: corona",

author = "N. Dadashi and L. Teriaca and D. Tripathi and Solanki, \{S. K.\} and T. Wiegelmann",

note = "Funding Information: The SUMER project is financially supported by DLR, CNES, NASA, and the ESA PRODEX programme (Swiss contribution). SoHO is a mission of international cooperation between ESA and NASA. Hinode is a Japanese mission developed and launched by ISAS/JAXA, collaborating with NAOJ as a domestic partner, and NASA and STFC (UK) as international partners. Scientific operation of the Hinode mission is conducted by the Hinode science team organized at ISAS/JAXA. This team mainly consists of scientists from institutes in the partner countries. Support for the post-launch operation is provided by JAXA and NAOJ (Japan), STFC (U.K.), NASA, ESA, and NSC (Norway). Data are courtesy of NASA/SDO and the AIA and HMI science teams. This work has been partially supported by WCU grant No. R31-10016 funded by the Korean Ministry of Education, Science and Technology. N.D. acknowledges a PhD fellowship of the International Max Planck Research School on Physical Processes in the Solar System and Beyond. D.T. would like to thank MPS for supporting his travel and providing excellent hospitality.",

year = "2012",

doi = "10.1051/0004-6361/201220329",

language = "English",

volume = "548",

journal = "Astronomy and Astrophysics",

issn = "0004-6361",

publisher = "EDP Sciences",

}

TY - JOUR

T1 - Doppler shift of hot coronal lines in a moss area of an active region

AU - Dadashi, N.

AU - Teriaca, L.

AU - Tripathi, D.

AU - Solanki, S. K.

AU - Wiegelmann, T.

N1 - Funding Information: The SUMER project is financially supported by DLR, CNES, NASA, and the ESA PRODEX programme (Swiss contribution). SoHO is a mission of international cooperation between ESA and NASA. Hinode is a Japanese mission developed and launched by ISAS/JAXA, collaborating with NAOJ as a domestic partner, and NASA and STFC (UK) as international partners. Scientific operation of the Hinode mission is conducted by the Hinode science team organized at ISAS/JAXA. This team mainly consists of scientists from institutes in the partner countries. Support for the post-launch operation is provided by JAXA and NAOJ (Japan), STFC (U.K.), NASA, ESA, and NSC (Norway). Data are courtesy of NASA/SDO and the AIA and HMI science teams. This work has been partially supported by WCU grant No. R31-10016 funded by the Korean Ministry of Education, Science and Technology. N.D. acknowledges a PhD fellowship of the International Max Planck Research School on Physical Processes in the Solar System and Beyond. D.T. would like to thank MPS for supporting his travel and providing excellent hospitality.

PY - 2012

Y1 - 2012

N2 - The moss is the area at the footpoint of the hot (3 to 5 MK) loops forming the core of the active region where emission is believed to result from the heat flux conducted down to the transition region from the hot loops. Studying the variation of Doppler shift as a function of line formation temperatures over the moss area can give clues on the heating mechanism in the hot loops in the core of the active regions. We investigate the absolute Doppler shift of lines formed at temperatures between 1 MK and 2 MK in a moss area within active region NOAA 11243 using a novel technique that allows determining the absolute Doppler shift of EUV lines by combining observations from the SUMER and EIS spectrometers. The inner (brighter and denser) part of the moss area shows roughly constant blue shift (upward motions) of 5 km s-1 in the temperature range of 1 MK to 1.6 MK. For hotter lines the blue shift decreases and reaches 1 km s -1 for Fe xv 284 (~2 MK). The measurements are discussed in relation to models of the heating of hot loops. The results for the hot coronal lines seem to support the quasi-steady heating models for nonsymmetric hot loops in the core of active regions.

AB - The moss is the area at the footpoint of the hot (3 to 5 MK) loops forming the core of the active region where emission is believed to result from the heat flux conducted down to the transition region from the hot loops. Studying the variation of Doppler shift as a function of line formation temperatures over the moss area can give clues on the heating mechanism in the hot loops in the core of the active regions. We investigate the absolute Doppler shift of lines formed at temperatures between 1 MK and 2 MK in a moss area within active region NOAA 11243 using a novel technique that allows determining the absolute Doppler shift of EUV lines by combining observations from the SUMER and EIS spectrometers. The inner (brighter and denser) part of the moss area shows roughly constant blue shift (upward motions) of 5 km s-1 in the temperature range of 1 MK to 1.6 MK. For hotter lines the blue shift decreases and reaches 1 km s -1 for Fe xv 284 (~2 MK). The measurements are discussed in relation to models of the heating of hot loops. The results for the hot coronal lines seem to support the quasi-steady heating models for nonsymmetric hot loops in the core of active regions.

KW - Sun: UV radiation

KW - Sun: activity

KW - Sun: corona

UR - https://www.scopus.com/pages/publications/84870530377

U2 - 10.1051/0004-6361/201220329

DO - 10.1051/0004-6361/201220329

M3 - Article

AN - SCOPUS:84870530377

SN - 0004-6361

VL - 548

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

M1 - A115

ER -

Doppler shift of hot coronal lines in a moss area of an active region

Abstract

Bibliographical note

Keywords

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