skip to main content

Title: High-resolution observations of the shock wave behavior for sunspot oscillations with the interface region imaging spectrograph

We present the first results of sunspot oscillations from observations by the Interface Region Imaging Spectrograph. The strongly nonlinear oscillation is identified in both the slit-jaw images and the spectra of several emission lines formed in the transition region and chromosphere. We first apply a single Gaussian fit to the profiles of the Mg II 2796.35 Å, C II 1335.71 Å, and Si IV 1393.76 Å lines in the sunspot. The intensity change is ∼30%. The Doppler shift oscillation reveals a sawtooth pattern with an amplitude of ∼10 km s{sup –1} in Si IV. The Si IV oscillation lags those of C II and Mg II by ∼6 and ∼25 s, respectively. The line width suddenly increases as the Doppler shift changes from redshift to blueshift. However, we demonstrate that this increase is caused by the superposition of two emission components. We then perform detailed analysis of the line profiles at a few selected locations on the slit. The temporal evolution of the line core is dominated by the following behavior: a rapid excursion to the blue side, accompanied by an intensity increase, followed by a linear decrease of the velocity to the red side. The maximum intensity slightly lagsmore » the maximum blueshift in Si IV, whereas the intensity enhancement slightly precedes the maximum blueshift in Mg II. We find a positive correlation between the maximum velocity and deceleration, a result that is consistent with numerical simulations of upward propagating magnetoacoustic shock waves.« less
Authors:
; ; ; ; ; ; ;  [1] ; ; ; ; ; ; ; ; ; ;  [2] ; ;  [3] more »; « less
  1. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
  2. Lockheed Martin Solar and Astrophysics Laboratory, 3251 Hanover Street, Org. ADBS, Bldg. 252, Palo Alto, CA 94304 (United States)
  3. Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029, Blindern, NO-0315 Oslo (Norway)
Publication Date:
OSTI Identifier:
22356947
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 786; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCELERATION; AMPLITUDES; CHROMOSPHERE; COMPUTERIZED SIMULATION; CORRELATIONS; DOPPLER EFFECT; EMISSION; LINE WIDTHS; NONLINEAR PROBLEMS; PLASMA INSTABILITY; RED SHIFT; RESOLUTION; SAWTOOTH OSCILLATIONS; SHOCK WAVES; SPECTRA; SUN; SUNSPOTS; VELOCITY