NOAO >   Observing Info >   Approved Programs >   2006B-0417

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Proposal Information for 2006B-0417


PI: MICHAEL SHARA, Amer. Mus. Nat. History, MSHARA@AMNH.ORG
Address: ASTROPHYSICS, CPW at 79TH STREET, NEW YORK, NY 10024-5192, USA

CoI: DAVID ZUREK, AMNH

Title: Deep Narrowband Imagery of Z Cam - A Nova AND a Dwarf Nova

Abstract: Cataclysmic variables (classical novae and dwarf novae) are binary star systems in which a red dwarf transfers hydrogen-rich matter, via an accretion disk, to its white dwarf companion. In dwarf novae, an instability is believed to episodically dump much of the accretion disk onto the white dwarf. The liberation of gravitational potential energy then brightens these systems up to a hundred-fold every few weeks or months. Thermonuclear-powered eruptions a thousand times more luminous occur in classical novae, accompanied by significant mass ejection and formation of clearly visible shells. Theory predicts that the white dwarfs in all dwarf novae must eventually accrete enough mass to undergo classical nova eruptions, but not a single dwarf nova has ever been shown to have undergone a classical nova eruption. GALEX NUV+FUV imagery shows the shell of the prototypical dwarf nova Z Cam to be an order of magnitude more extended than any detected around any classical nova. The derived shell mass (from KPNO spectroscopy) matches that of classical novae, and is inconsistent with the mass expected from a steady dwarf nova wind. Thus the shell mass and morphology observationally link, for the first time, a dwarf nova with the classical nova process. We are requesting 2 nights of 4 meter time to determine the extent and morphology of the nova optical ejecta, and to rule out possible contamination by interstellar cirrus.


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