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3-D Structure of Sunspots using Imaging SpectroscopyWe use the Interferometric BIdimensional Spectrometer (IBIS) of the INAF/Arcetri Astrophysical Observatory and installed at the National Solar Observatory (NSO) Dunn Solar Telescope, to understand the structure of sunspots. Using the spectral lines FeI 6301.5 A, FeII 7224.4 A, and CaII 8542.6 A, we examine the spectroscopic variation of sunspot penumbral and umbral structures at the heights of formation of these lines. These high resolution observations were acquired on 2004 July 30-31, of active region NOAA 10654, using the high order NSO adaptive optics system. We map the spatio-temporal variation of Doppler signatures in these spectral lines, from the photosphere to the chromosphere. From a 70-minute temporal average of individual 32-second cadence Doppler observations we find that the averaged velocities decrease with height, about 3.5 times larger in the deeper photosphere (FeII 7224.4 A; height-of-formation approx. 50 km) than in the upper photosphere FeI 6301.5 A; height-of-formation approx. 350 km), There is a remarkable coherence of Doppler signals over the height difference of 300 km. From a high-speed animation of the Doppler sequence we find evidence for what appears to be ejection of high speed gas concentrations from edges of penumbral filaments into the surrounding granular photosphere. The Evershed flow persists a few arcseconds beyond the traditionally demarcated penumbra-granulation boundary. We present these and other results and discuss the implications of these measurements for sunspot models.
Document ID
20060047791
Acquisition Source
Marshall Space Flight Center
Document Type
Conference Paper
Authors
Balasubramaniam, K. S.
(National Solar Observatory Sunspot, NM, United States)
Gary, G. Allen
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Reardon, K.
(Observatorie Astofisico di Arcetri Florence, Italy)
Date Acquired
August 23, 2013
Publication Date
January 1, 2006
Subject Category
Solar Physics
Meeting Information
Meeting: National Solar Observatory Workshop
Location: Sunspot, NM
Country: United States
Start Date: July 18, 2005
End Date: July 22, 2005
Distribution Limits
Public
Copyright
Other

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