NOAO > Observing Info > Approved Programs > 2009B-0524
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NOAO > Observing Info > Approved Programs > 2009B-0524 |
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PI: Jayadev Rajagopal, CTIO/NOAO, jrajagopal@ctio.noao.edu
Address: Casilla 603, La Serena, Chile
CoI: Eric J. Bakker, New Mexico Tech / Magdalena Ridge Observatory
Title: The circumbinary disk and environs of post-AGB stars at high resolution and deep contrast
Abstract:
HR 4049 is a prototype for a class of post-AGB stars which are
single-line spectroscopic binaries showing extreme metal-deficiency in
their photospheres and a large IR excess. These properties are
attributed to the presence of a stable circumbinary dust and gas disk in
a Keplerian orbit. Currently, only the hottest inner regions of this
disk has been detected through interferometric techniques. However IR
SEDs, CO mm wave measurements and likely disk-formation scenarios
suggest more extended circumstellar structure. In some cases, like the
Red Rectangle, a bipolar nebula is known to exist. The formation and
structure of the disk and any extended nebula are very poorly
understood. Here we propose high resolution imaging in the near-IR of
the circumstellar environment of HR 4049 and a small sample of very
similar post-AGB binaries with the Gemini AO imager, NICI. We will
measure the extent of the Keplerian disk, confirm the existence, and
determine the structure of the faint extended nebula by masking out the
very bright inner rim and central binary. The orientation of the disk
will probe the interplay of angular momentum between the binary and the
disk, a key to the formation and continued stability of a dust disk
around the binary. The existence and shape of the outer nebulae will
directly test various models for the formation mechanism of the disk.
The disk and nebula are also key components in the evolution of these
objects to Planetary Nebulae.
National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360
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NOAO > Observing Info > Approved Programs > 2009B-0524 |
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