The circumstellar environment of evolved stars as seen by VLTI/MIDI

K. Ohnaka, J. Bergeat, T. Driebe, U. Graser, K. H. Hofmann, R. Köhler, Ch Leinert, B. Lopez, F. Malbet, S. Morel, F. Paresce, G. Perrin, Th Preibisch, A. Richichi, D. Schertl, M. Schöller, H. Sol, G. Weigelt, M. Wittkowski

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


We present the results of the first mid-infrared interferometric observations of the Mira variable RR Sco with the VLTI/MIDI, together with K-band observations using VLTI/VINCI.The uniform-disk diameter was found to be 18mas between 8 and 10 μm, while it gradually increases at wavelengths longer than 10 μm to reach 24 mas at 13 μm. These uniform-disk diameters in the mid-infrared are significantly larger than the K-band uniform-disk diameter of 10.2±0.5 mas measured using VLTI/VINCI, three weeks after the MIDI observations. Our model calculations show that optically thick emission from a warm molecular envelope consisting of H2O and SiO can cause the apparent mid-infrared diameter to be much larger than the continuum diameter, and this can explain the mid-infrared angular sizes roughly twice as large as that measured in the K band. The observed increase of the uniform-disk diameter longward of 10 μm can be explained by an optically thin dust shell consisting of corundum and silicate grains.

Original languageEnglish
Title of host publicationThe Power of Optical/IR Interferometry
Subtitle of host publicationRecent Scientific Results and 2nd Generation Instrumentation: Proceedings of the ESO Workshop held in Garching, Germany, 4-8 April 2005
EditorsAndrea Richichi, Francoise Delplancke, Francesco Paresce, Alain Chelli
Number of pages5
Publication statusPublished - 2008
Externally publishedYes

Publication series

NameESO Astrophysics Symposia
ISSN (Print)1431-2433
ISSN (Electronic)1611-6143

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Physics and Astronomy (miscellaneous)


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