\bf The LBV AG Car in its Current Active Phase

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Session 63 -- Intrinsic and Cataclysmic Variables
Display presentation, Thursday, 9:20-4:00, Heller Lounge Room

[63.06] \bf The LBV AG Car in its Current Active Phase

O.L. Lupie (CSC, STScI), C. Leitherer (STScI), A. Damineli Neto (Univ. of Sao Paolo), L. Drissen (STScI), T. Idiart (Univ. of Sao Paolo), C. Robert (STScI), A. Nota (STScI), B. Altner (ARC, Landover), W. Schmutz (Swiss Fed. Inst. for Tech., Zurich), S. Shore (GSFC)

With an emphasis on our polarization monitoring program, we present our observations to date of AG CARINAE, the prototype Luminous Blue Variable (LBV). The star is experiencing an active phase, increasing in brightness since 1990. The variability, which is semi-periodic on time scales 10-15 years, may culminate in an eruptive episode. Although AG Car is a well-studied LBV, the geometry and physics of its environment are extremely complex. To obtain a better description of AG Car, the team has been collecting many observations during the last year: UBVRI photo-polarimetry and visual spectroscopy (Brazilian National Observatory), UV spectropolarimetry with the Hubble Space Telescope Faint Object Spectrograph, UBV photometry (Port Alegre Observatory), IUE and H-alpha spectroscopy (LaSilla). UV polarization observations were selected as part of the campaign in order to probe for asymmetric structures ejected from the star in the innermost unresolved region (within 100 stellar radii). The ground based photo-polarization monitoring program enables us to track the polarimetric variability of the entire complex and to assist in the difficult task of separating the interstellar and intrinsic polarization components. We have found that the UV and optical polarization and position angle are strongly variable in time and structure is evident across the UV resonance scattering lines. The UV and optical spectroscopy show that the Teff is decreasing, the bolometric luminosty is remaining constant, and the structure and ionization state of the wind is evolving. We will discuss how these data support models which incorporate circumstellar disks, jets, and/or plumes to explain the mass loss characteristics.

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