THREE-MINUTE OSCILLATIONS ABOVE SUNSPOT UMBRA OBSERVED WITH THE SOLAR DYNAMICS OBSERVATORY/ATMOSPHERIC IMAGING ASSEMBLY AND NOBEYAMA RADIOHELIOGRAPH
Open Access
- 31 January 2012
- journal article
- Published by American Astronomical Society in The Astrophysical Journal
- Vol. 746 (2), 119
- https://doi.org/10.1088/0004-637x/746/2/119
Abstract
Three-minute oscillations over a sunspot's umbra in AR 11131 were observed simultaneously in UV/EUV emission by the Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) and in radio emission by the Nobeyama Radioheliograph (NoRH). We use 24 hr series of SDO and 8 hr series of NoRH observations to study spectral, spatial, and temporal variations of pulsations in the 5–9 mHz frequency range at different layers of the solar atmosphere. High spatial and temporal resolution of SDO/AIA in combination with long-duration observations allowed us to trace the variations of the cutoff frequency and spectrum of oscillations across the umbra. We found that higher frequency oscillations are more pronounced closer to the umbra's center, while the lower frequencies concentrate on the peripheral parts. We interpreted this discovery as a manifestation of variation of the magnetic field inclination across the umbra at the level of temperature minimum. Possible implications of this interpretation for the diagnostics of sunspot atmospheres are discussed.Other Versions
This publication has 33 references indexed in Scilit:
- Multilevel Analysis of Oscillation Motions in Active Regions of the SunSolar Physics, 2011
- CHROMOSPHERIC RESONANCES ABOVE SUNSPOT UMBRAEThe Astrophysical Journal, 2011
- WAVE PROPAGATION AND SHOCK FORMATION IN DIFFERENT MAGNETIC STRUCTURESThe Astrophysical Journal, 2009
- Models of the Solar Chromosphere and Transition Region from SUMER and HRTS Observations: Formation of the Extreme‐Ultraviolet Spectrum of Hydrogen, Carbon, and OxygenThe Astrophysical Journal Supplement Series, 2008
- The Nature of Running Penumbral Waves RevealedThe Astrophysical Journal, 2007
- Spectropolarimetric Investigation of the Propagation of Magnetoacoustic Waves and Shock Formation in Sunspot AtmospheresThe Astrophysical Journal, 2006
- Observational aspects of sunspot oscillationsPhilosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2005
- Oscillations in the Umbral AtmosphereSolar Physics, 2004
- Oscillations Above SunspotsSolar Physics, 2002
- Observations of sunspot transition region oscillationsSolar Physics, 2000