The Atmospheric Imaging Assembly (AIA) provides multiple simultaneous highresolution full-disk images of the corona and transition region up to 0.5 R above the solar limb with 1.5-arcsec spatial resolution and 12-second temporal resolution. The AIA consists of four telescopes that employ normal-incidence, multilayer-coated optics to provideThe Solar Dynamics Observatory

The Helioseismic and Magnetic Imager (HMI) instrument and investigation as a part of the NASA Solar Dynamics Observatory (SDO) is designed to study convection-zone dynamics and the solar dynamo, the origin and evolution of sunspots, active regions, and complexes of activity, the sources and drivers of solar magnetic activity and disturbances, links between the internal processes and dynamics of the corona and heliosphere, and precursors of solar disturbances for space-weather forecasts. A brief overview of the instrument, investigation objectives, and standard data products is presented.

Alfvén waves have been invoked as a possible mechanism for the heating of the Sun's outer atmosphere, or corona, to millions of degrees and for the acceleration of the solar wind to hundreds of kilometers per second. However, Alfvén waves of sufficient strength have not been unambiguously observed in the solar atmosphere. We used images of high temporal and spatial resolution obtained with the Solar Optical Telescope onboard the Japanese Hinode satellite to reveal that the chromosphere, the region sandwiched between the solar surface and the corona, is permeated by Alfvén waves with strong amplitudes on the order of 10 to 25 kilometers per second and periods of 100 to 500 seconds. Estimates of the energy flux carried by these waves and comparisons with advanced radiative magnetohydrodynamic simulations indicate that such Alfvén waves are energetic enough to accelerate the solar wind and possibly to heat the quiet corona.

We report here, for the Ðrst time, on spatial oscillations of coronal loops, which were detected in extreme-ultraviolet wavelengths (171 with the T ransition Region and Coronal Explorer, in the tem-A) perature range of MK. The observed loop oscillations occurred during a Ñare that began at T e B 1.0È1.5 1998 July 14, 12 : 55 UT and are most prominent during the Ðrst 20 minutes. The oscillating loops connect the penumbra of the leading sunspot to the Ñare site in the trailing portion. We identiÐed Ðve oscillating loops with an average length of L \ 130,000^30,000 km. The transverse amplitude of the oscillations is A \ 4100^1300 km, and the mean period is T \ 280^30 s. The oscillation mode appears to be a standing wave mode (with Ðxed nodes at the footpoints). We investigate di †erent MHD wave modes and Ðnd that the fast kink mode with a period q \ 205(L /1010 cm~3)1@2 cm)(n e /109 (B/10 G)~1 s provides the best agreement with the observed period. We propose that the onset of loop oscillations in distant locations is triggered by a signal or disturbance that propagates from the central Ñare site with a radial speed of B700 km s~1. Because the observed loop oscillation periods are comparable to photospheric 5 minute oscillations, a resonant coupling between the two systems is possible. We further Ðnd evidence for global extreme-UV dimming in the entire active region possibly associated with a coronal mass ejection.

The Interface Region Imaging Spectrograph (IRIS) small explorer spacecraft provides simultaneous spectra and images of the photosphere, chromosphere, transition region, and corona with 0.33 -0.4 arcsec spatial resolution, two-second temporal resolution, and 1 km s −1 velocity resolution over a field-of-view of up to 175 arcsec × 175 arcsec. . IRIS is sensitive to emission from plasma at temperatures between 5000 K and 10 MK and will advance our understanding of the flow of mass and energy through an interface region, formed by the chromosphere and transition region, between the photosphere and corona. This highly structured and dynamic region not only acts as the conduit of all mass and energy feeding into the corona and solar wind, it also requires an order of magnitude more energy to heat than the corona and solar wind combined. The IRIS investigation includes a strong numerical modeling component based on advanced radiative-MHD codes to facilitate interpretation of observations of this complex region. Approximately eight Gbytes of data (after compression) are acquired by B. De Pontieu (B) ·Harvard-Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138, USA