April 20, 2012, 12:00 pm - 1:00 pm
April 20, 2012, 12:00 pm - 1:00 pm, Heliophysics Director's Seminar
SDO: A Tale of Two Comets
Dr. Dean Pesnell,NASA Goddard Space Flight Center
On July 5, 2011 SDO watched a comet fly across the disk of the Sun and evaporate, disappearing from the AIA telescopes. This was the first time the death of a comet had been witnessed. Five months later SDO used its near-realtime capability to let the world watch Comet Lovejoy disappear behind the limb of the Sun only to re-appear, the first sungrazing comet to do so in the era of space-based comet watching. I will show the observations of these comets and discuss what we hope to accomplish in the future with SDO, SOHO, STEREO A&B, and the other satellites in the Heliophysics Great Observatory.
Combining Models and SDO Data to Solve the Coronal Heating Problem
Dr. Nickie Viall, NASA Goddard Space Flight Center
Coronal plasma in active regions is typically measured to be at temperatures near ~1-3 MK. Is the majority of the coronal plasma in hydrostatic equilibrium, maintained at these temperatures through a form of quasi-steady heating, or is it heated by nanoflares, undergoing continuous heating and cooling cycles? Addressing this question is complicated by the fact that the corona is optically thin: many thousands of independently heated flux tubes contribute to the total emission along a given line of sight. In order to understand coronal heating, many past studies have analyzed and modeled emission from isolated, transient features ('coronal loops') within active regions. In this study, we move beyond isolated features and analyze all of the emission in an entire active region, accounting for emission along the line of sight from all of the contributing flux tubes. We investigate light curves systematically using SDO/AIA observations. We also model the active region corona as a line-of-sight integration of many thousands of completely independently heated strands. We demonstrate that despite the superposition of randomly heated strands, different distributions of nanoflare cadences produce distinct signatures in the light curves observed with the multi-wavelength and high time cadence SDO/AIA data. We conclude that the majority of the active region plasma is not maintained in hydrostatic equilibrium, rather it is undergoing dynamic heating and cooling cycles. The observed emission is consistent with heating through impulsive nanoflares, whose energy is a function of location within the active region.
The Helioviewer Project: Solar Data Visualization and Exploration
Mr. Keith Hughitt,NASA Goddard Space Flight Center
As the amount of solar data available to scientists continues to increase at faster and faster rates, it is important that there exist simple tools for navigating this data quickly with a minimal amount of effort. The Helioviewer project is an effort to create free and open-source tools for exploring solar and heliospheric physics data in a simple and intuitive manner. Currently we provide access to over 10 million images from the SOHO, STEREO, and SDO missions with new data sources planned for the near future. Users can access near-real time data, create movies on the fly, and interact with other solar and heliospheric services like the SDO cut-out service and the Heliophysics Event Knowledgebase (HEK). We provide an overview of the various Helioviewer Project components and discuss plans for future development