NOAO >   Observing Info >   Approved Programs >   2009B-0274

# Proposal Information for 2009B-0274

PI: Nathan Smith, University of California Berkeley, nathans@astro.berkeley.edu
Address: Astronomy Department, 601 Campbell Hall, Berkeley, CA 94720, USA

Title: IR Variability of Eta Carinae: The 2009 Event

Abstract: Every 5.5 years, \eta Carinae experiences a dramatic spectroscopic event'' when high-excitation lines in its UV, optical, and IR spectrum disappear, and its hard X-ray and radio continuum flux crash. This periodicity has been attributed to an eccentric binary system with a shell ejection occurring at periastron, and the next periastron event will occur in January 2009. The last event in June/July 2003 was poorly observed because the star was very low in the sky, but this next event is perfectly suited for an intense ground-based monitoring campaign. Mid-IR images and spectra with T-ReCS provide a direct measure of changes in the current bolometric luminosity and a direct measure of the mass in dust formation episodes that may occur at periastron in the colliding wind shock. Near-IR emission lines trace related changes in the post-event wind and ionization changes in the circumstellar environment needed to test specific models for the cause of \eta Car's variability as it recovers from its recent event''. Because the nebular geometry is known very well from previous observations in this program, monitoring the changes in nebular ionization will yield a 3-D map of the changing asymmetric UV radiation field geometry in the binary system, and the first estimate of the orientation of its orbit. \bf Note: This proposal was originally granted long term status in Band 1 in 2008B, but the program was not carried over to 2009B. Here I am requesting only the final two epochs in 2009B to complete the program.

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 NOAO >   Observing Info >   Approved Programs >   2009B-0274