Charles Lindsey

NSO/T Scientific Staff

Areas of Interest

Local helioseismology, infrared solar physics

C. Lindsey (SPRC), D. Braun (SPRC) and S. Jefferies (Bartol) have been getting interesting results from their program in local helioseismology. This research is based on the Bartol-NSO-NASA South Pole Observations of 1987, 1988 and 1990 and proposes to use p-modes that appear in the data to detect subsurface magnetic structure. They have developed a computational technique called Doppler knife-edge diagnostics that are sensitive to horizontal Doppler flows. Their computations show strong evidence of subsurface outflows surrounding active regions extending tens of thousands of kilometers outside of the regions. These flows have velocities of 200400 km/sec, are mostly at depths of several thousand kilometers, and evolve rapidly with time. Lindsey, Braun and Jefferies are planning a program of holographic computations to explore the possibility of locating magnetic structure deep within the solar interior by its Doppler signature, if such structure is moving with respect to the ambient medium.

J. Jefferies, C. Lindsey and post-doc Y. Gu are working on a project to model inhomogeneous chromospheric structure based on theoretical work originally developed by Lindsey and Jefferies to treat LTE radiative transfer in inhomogeneous media. They are now creating inhomogeneous models to match the extensive limb-profile observations in the submillimeter and near-millimeter continua by Lindsey, Jefferies and other colleagues at the Kuiper Airborne Observatory (KAO) and the James Clerk Maxwell Telescope (JCMT) on Mauna Kea.

C. Lindsey and D. Rabin have been involved in a program by T. A. Clark (U. Calgary) to determine the limb profile of infrared CO lines at 4.5 m. The program is based largely on observations of the nearly annular solar eclipse made on 1994 May 10 at the McMath Solar Telescope, in which the line profiles were determined as a function of height by lunar occultation. The program yielded 0.1-arcsecond (75 km) height resolution and showed the lines to be truncated to heights considerably lower than previously thought, leading to the conclusion that the chromospheric medium contains no substantial component cool enough to support CO formation above about 1,200 km.

Lindsey serves as the NSO/KP supervisor for the REU student research program. He organizes the NSO/KP weekly scientific luncheon and often serves as an NSO host for NOAOs Public Evening. He is involved with the NOAO Educational Outreach Program, gives talks and demonstrations at schools, and works individually with students interested in astronomy or solar research.

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NOAO is operated by the Association of U niversities for Research in Astronomy (AURA), Inc. under cooperative agreement with the National Science Foundation
Posted: 06Dec1996