Advertisement

Optical and UV Investigation of the Envelope of AG Carinae

  • Roberto Viotti
  • Aldo Altamore
  • Corinne Rossi
  • Angelo Cassatella
Conference paper
Part of the Astrophysics and Space Science Library book series (ASSL, volume 157)

Abstract

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 Al and BO 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 Be£ 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 thatAG 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.

Keywords

Light Curve Stellar Atmosphere Visual Magnitude Strong Fell Unique Chance 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Bandiera, R., et al. 1988, this volume.Google Scholar
  2. Caputo, F., Viotti, R.: 1970, Astron. Astrophys. 7, 266.ADSGoogle Scholar
  3. Friedjung, M., Muratorio, G.: 1987, Astron. Astrophys. 188, 100.ADSGoogle Scholar
  4. Stahl, 0.: 1986, Astron. Astrophys. 164, 321.ADSGoogle Scholar
  5. Viotti, R.: 1987, in Instabilities in Luminous Early Type Stars, H.Lamers and C. de Loore eds., Reidel, Dordrecht, p.257.Google Scholar
  6. Viotti, R. et al.: 1984, NASA Conference Publ. 2349, p.231.Google Scholar
  7. Viotti, R. et al.: 1988, Astron. Astrophys. 190, 333.ADSGoogle Scholar
  8. Wolf, B., Stahl, 0.: 1982, Astron. Astrophys. 112, 111.ADSGoogle Scholar

Copyright information

© Kluwer Academic Publishers 1989

Authors and Affiliations

  • Roberto Viotti
    • 1
  • Aldo Altamore
    • 2
  • Corinne Rossi
    • 2
  • Angelo Cassatella
    • 3
  1. 1.Istituto Astrofisica Spaziale, CNRFrascatiItaly
  2. 2.Istituto AstronomicoUniversita’ La SapienzaRomaItaly
  3. 3.IUE Observatory, ESAMadridSpain

Personalised recommendations