VLTI/AMBER Studies of the Atmospheric Structure and Fundamental Parameters of Red Giant and Supergiant Stars

Arroyo-Torres, B.Univ Valencia, Dept Astron & Astrofis, E-46100 Burjassot, Spain. (author)

We present recent near-IR interferometric studies of red giant and super giant stars, which are aimed at obtaining information on the structure of the atmospheric layers and constraining the fundamental parameters of these objects. The observed visibilities of six red supergiants (RSGs), and also of one of the five red giants observed, indicate large extensions of the molecular layers, as previously observed for Mira stars. These extensions are not predicted by hydrostatic PHOENIX model atmospheres, hydrodynamical (RED) simulations of stellar convection, or self-excited pulsation models. All these models based on parameters of RSGs lead to atmospheric structures that are too compact compared to our observations. We discuss how alternative processes might explain the atmospheric extensions for these objects. As the continuum appears to be largely free of contamination by molecular layers, we can estimate reliable Rosseland angular radii for our stars. Together with distances and bolometric fluxes, we estimate the effective temperatures and luminosities of our targets, locate them in the HR diagram, and compare their positions to recent evolutionary tracks.

Wittkowski, M.ESO, Garching, Germany. (author)
Marcaide, J. M.Univ Valencia, Dept Astron & Astrofis, E-46100 Burjassot, Spain.;Donostia Int Phys Ctr, Donostia San Sebastian, Spain. (author)
Abellan, F. J.Univ Valencia, Dept Astron & Astrofis, E-46100 Burjassot, Spain. (author)
Chiavassa, A.Univ Nice Sophia Antipolis, Lab Lagrange, CNRS, Observ Cote Azur, Sophia Anitpolis, France. (author)
Fabregat, J.Univ Valencia, Astron Observ, E-46003 Valencia, Spain. (author)
Freytag, BerndUppsala universitet,Teoretisk astrofysik(Swepub:uu)befre677 (author)
Guirado, J. C.Univ Valencia, Dept Astron & Astrofis, E-46100 Burjassot, Spain.;Univ Valencia, Astron Observ, E-46003 Valencia, Spain. (author)
Hauschildt, P. H.Hamburger Sternwarte, Hamburg, Germany. (author)
Marti-Vidal, I.Chalmers, Onsala Space Observ, Gothenburg, Sweden. (author)
Quirrenbach, A.Heidelberg Univ, Zentrum Astron, Landessternwarte, D-69115 Heidelberg, Germany. (author)
Scholz, M.Heidelberg Univ, Zentrum Astron, Inst Theoret Astrophys, D-69115 Heidelberg, Germany.;Univ Sydney, Sch Phys, Sydney Inst Astron, Sydney, NSW 2006, Australia. (author)
Wood, P. R.Australian Natl Univ, Res Sch Astron & Astrophys, Canberra, ACT, Australia. (author)
Univ Valencia, Dept Astron & Astrofis, E-46100 Burjassot, Spain.ESO, Garching, Germany. (creator_code:org_t)

In:WHY GALAXIES CARE ABOUT AGB STARS III: ASTRONOMICAL SOC PACIFIC, s. 91-969781583818794

By the author/editor: Arroyo-Torres, B ...; Wittkowski, M.; Marcaide, J. M.; Abellan, F. J.; Chiavassa, A.; Fabregat, J.; show more...; Freytag, Bernd; Guirado, J. C.; Hauschildt, P. H ...; Marti-Vidal, I.; Quirrenbach, A.; Scholz, M.; Wood, P. R.; show less...

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NATURAL SCIENCES: NATURAL SCIENCES; and Physical Science ...; and Astronomy Astrop ...

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