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Optical and UV investigation of the envelope of AG Carinae

Published online by Cambridge University Press:  12 April 2016

Roberto Viotti ,
Aldo Altamore ,
Corinne Rossi  and
Angelo Cassatella
Roberto Viotti
Affiliation:
Istituto Astrofisica Spaziale, CNR, Frascati, Italy
Aldo Altamore
Affiliation:
Istituto Astronomico, Universita’ La Sapienza, Roma, Italy
Corinne Rossi
Affiliation:
Istituto Astronomico, Universita’ La Sapienza, Roma, Italy
Angelo Cassatella
Affiliation:
IUE Observatory, ESA, Madrid, Spain

Extract

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The galactic LBV object AG Car is unique for assembling several interesting features: (i) a light curve typical of Hubble-Sandage variables, (ii) a largely variable P Cygni-type spectrum, (iii) a strong IR excess, and especially (iv) a small ring nebula. Caputo and Viotti (1970) found that during 1949-59 the AG Car spectrum varied between A1 and B0 equivalent spectral types. A dramatic evolution occurred in recent years, when the visual magnitude gradually faded from V=6 in 1981 to V=8 in 1985, followed by a rise of the line excitation from Aeq in 1981 (Wolf and Stahl 1982), to Beq in 1983 (Viotti et al. 1984), and to 0fpe/WN9 in January 1985 (Stahl 1986). This behaviour has represented a unique chance to follow a LBV in different spectral ranges during its major photometric and spectral changes. In the following we present the results of a long term monitoring of the star and of its nebula in the optical and UV. We propose that AG Car evolved in recent times from a red supergiant phase, and that the present LBV phase is characterized by a critical structure of the stellar atmosphere.

Type
Section II: Poster Papers, A Brief List of Catalogs, and Index
Information
International Astronomical Union Colloquium , Volume 113: Physics of Luminous Blue Variables , 1989 , pp. 268 - 270
Copyright
Copyright © Kluwer 1989

References

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