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Proposal Information for 2003B-0049


PI: Nathan Smith, University of Colorado, nathans@casa.colorado.edu
Address: Center for Astrophysics and Space Astronomy, 389 UCB, Boulder, CO 80304, USA

Title: Variability in the Near-IR Spectrum of Eta Carinae

Abstract: In the summer of 2003, \eta Carinae will experience a dramatic ``spectroscopic event'', when high-excitation lines in its UV, optical, and IR spectrum will disappear for a few months, and its hard X-ray and radio flux will crash. This behavior is apparently part of a 5.5 year cycle discovered in near-IR data; the periodicity has been attributed to a possible binary system, but in many ways the changes also resemble a shell ejection. The truth may lie in between. Regardless, the 5.5 year cycle provides an important key to understanding this particular unstable massive star, and the evolution of massive stars in general. The next event in 2003 will be studied intensively as part of a ``treasury'' project with HST/STIS. To maximize this large project's scientific return, we need to obtain critical ground-based IR spectra that cannot be obtained with STIS. Our near-IR spectroscopy over the last 3 years has already yielded surprising results, and offers ways to test specific models for the cause of \eta Car's variability. We propose to complete our monitoring of changes in \eta Car's IR spectrum using OSIRIS on the CTIO 4m and SOAR as \eta Car recovers from its ``event'' in 2003.5. This will provide a unique and valuable set of long-slit near-IR spectra covering an entire 5.5 year cycle. We also propose more intensive high-resolution study of a few exciting discoveries made in our previous IR spectroscopy. High resolution near- IR spectra with PHOENIX/Gemini will surpass even HST for investigating the complex kinematic structure of \eta Car's ejecta, which hold important clues to its mass ejection history.


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