ACTIVE REGION MOSS: DOPPLER SHIFTS FROM HINODE/EXTREME-ULTRAVIOLET IMAGING SPECTROMETER OBSERVATIONS

Tripathi, Durgesh; Mason, Helen E; Klimchuk, James A

doi:10.1088/0004-637X/753/1/37

Title: ACTIVE REGION MOSS: DOPPLER SHIFTS FROM HINODE/EXTREME-ULTRAVIOLET IMAGING SPECTROMETER OBSERVATIONS

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Abstract

Studying the Doppler shifts and the temperature dependence of Doppler shifts in moss regions can help us understand the heating processes in the core of the active regions. In this paper, we have used an active region observation recorded by the Extreme-ultraviolet Imaging Spectrometer (EIS) on board Hinode on 2007 December 12 to measure the Doppler shifts in the moss regions. We have distinguished the moss regions from the rest of the active region by defining a low-density cutoff as derived by Tripathi et al. in 2010. We have carried out a very careful analysis of the EIS wavelength calibration based on the method described by Young et al. in 2012. For spectral lines having maximum sensitivity between log T = 5.85 and log T = 6.25 K, we find that the velocity distribution peaks at around 0 km s{sup -1} with an estimated error of 4-5 km s{sup -1}. The width of the distribution decreases with temperature. The mean of the distribution shows a blueshift which increases with increasing temperature and the distribution also shows asymmetries toward blueshift. Comparing these results with observables predicted from different coronal heating models, we find that these results are consistent with both steadymore »« less

Authors:

Tripathi, Durgesh ^[1]; Mason, Helen E ^[2]; Klimchuk, James A ^[3]

Inter-University Centre for Astronomy and Astrophysics, Pune University Campus, Pune 411007 (India)
Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA (United Kingdom)
NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

Publication Date:: Sun Jul 01 00:00:00 EDT 2012

OSTI Identifier:: 22036946

Resource Type:: Journal Article

Journal Name:: Astrophysical Journal

Additional Journal Information:: Journal Volume: 753; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X

Country of Publication:: United States

Language:: English

Subject:: 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTRONOMY; ASTROPHYSICS; DENSITY; DOPPLER EFFECT; EMISSION SPECTRA; EXTREME ULTRAVIOLET RADIATION; HEATING; SOLAR CORONA; SUN; TEMPERATURE DEPENDENCE; VELOCITY

Citation Formats


                    Tripathi, Durgesh, Mason, Helen E, and Klimchuk, James A. ACTIVE REGION MOSS: DOPPLER SHIFTS FROM HINODE/EXTREME-ULTRAVIOLET IMAGING SPECTROMETER OBSERVATIONS.  United States: N. p., 2012. 
        Web.  doi:10.1088/0004-637X/753/1/37.

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                    Tripathi, Durgesh, Mason, Helen E, & Klimchuk, James A. ACTIVE REGION MOSS: DOPPLER SHIFTS FROM HINODE/EXTREME-ULTRAVIOLET IMAGING SPECTROMETER OBSERVATIONS.  United States.  https://doi.org/10.1088/0004-637X/753/1/37

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                    Tripathi, Durgesh, Mason, Helen E, and Klimchuk, James A. 2012.  
        "ACTIVE REGION MOSS: DOPPLER SHIFTS FROM HINODE/EXTREME-ULTRAVIOLET IMAGING SPECTROMETER OBSERVATIONS".  United States.  https://doi.org/10.1088/0004-637X/753/1/37.

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@article{osti_22036946,

  title        = {ACTIVE REGION MOSS: DOPPLER SHIFTS FROM HINODE/EXTREME-ULTRAVIOLET IMAGING SPECTROMETER OBSERVATIONS},

  author       = {Tripathi, Durgesh and Mason, Helen E and Klimchuk, James A},

  abstractNote = {Studying the Doppler shifts and the temperature dependence of Doppler shifts in moss regions can help us understand the heating processes in the core of the active regions. In this paper, we have used an active region observation recorded by the Extreme-ultraviolet Imaging Spectrometer (EIS) on board Hinode on 2007 December 12 to measure the Doppler shifts in the moss regions. We have distinguished the moss regions from the rest of the active region by defining a low-density cutoff as derived by Tripathi et al. in 2010. We have carried out a very careful analysis of the EIS wavelength calibration based on the method described by Young et al. in 2012. For spectral lines having maximum sensitivity between log T = 5.85 and log T = 6.25 K, we find that the velocity distribution peaks at around 0 km s{sup -1} with an estimated error of 4-5 km s{sup -1}. The width of the distribution decreases with temperature. The mean of the distribution shows a blueshift which increases with increasing temperature and the distribution also shows asymmetries toward blueshift. Comparing these results with observables predicted from different coronal heating models, we find that these results are consistent with both steady and impulsive heating scenarios. However, the fact that there are a significant number of pixels showing velocity amplitudes that exceed the uncertainty of 5 km s{sup -1} is suggestive of impulsive heating. Clearly, further observational constraints are needed to distinguish between these two heating scenarios.},

  doi          = {10.1088/0004-637X/753/1/37},

  url          = {https://www.osti.gov/biblio/22036946},
  journal      = {Astrophysical Journal},

  issn         = {0004-637X},

  number       = 1,

  volume       = 753,

  place        = {United States},

  year         = {Sun Jul 01 00:00:00 EDT 2012},

  month        = {Sun Jul 01 00:00:00 EDT 2012}

}

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