AAS 206th Meeting, 29 May - 2 June 2005
Session 32 Highlights in Laboratory Astrophysics
Poster, Wednesday, 10:00am-7:00pm, Thursday, 9:20am-2:00pm, June 1, 2005, Ballroom A

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[32.14] Density Measurements Using the L-shell Spectra of Si V, S VII, and Ar IX

J. K. Lepson (SSL), P. Beiersdorfer (LLNL), M. F. Gu (Stanford)

The extreme ultraviolet and soft x-ray spectral regions contain many emission lines that can be used over a wide temperature range to determine elemental abundances and as diagnostics for plasma properties, such as plasma density, temperature, and magnetic field. We present one such diagnostic here, using the ratio of the M2 to 3F and M2 to 3G lines in neon-like ions to measure plasma density. We used the Flexible Atomic Code to perform density-dependent calculations for neon-like argon, sulfur, and silicon over a range of densities from Ne = 105 to Ne = 1015. We employed the Lawrence Livermore electron beam ion traps to test these density diagnostics with plasma densities similar to stellar coronae (Ne ~1011). We applied the spectral diagnostic to Chandra LETGS observations to determine density estimates for the corona of Procyon, which yielded a range of Ne = 1010.4 -- 1011.4.

This work was supported by a Space Astrophysics Research and Analysis grant from NASA under Work Order W-19,878, and was performed under the auspices of the Department of Energy by the University of California Lawrence Livermore National Laboratory under Contract No. W-7405-Emg-48.

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Bulletin of the American Astronomical Society, 37 #2
© 2005. The American Astronomical Soceity.