Mid-infrared view of cool evolved stars with the Very Large Telescope Interferometer

Two interferometric instruments at ESO's Very Large Telescope Interferometer (VLTI) - MIDI and AMBER operating in the mid-infrared (8-13 μm) and the near-infrared (JHK), respectively - have proven to be very powerful to study the physical properties of the circumstellar material around evolved stars. With the "spectro-interferometric" capability of MIDI and AMBER, we can disentangle spectral and spatial information on the observed object. VLTI observations have confirmed our pictures on the circumstellar environment of cool evolved stars in some cases but brought about entirely unexpected pictures in other cases. Here, we present our recent results obtained with VLTI/MIDI.

[1]  C. Keller.  NATIONAL OPTICAL ASTRONOMY OBSERVATORIES , 1999 .

[2]  Cecile Loup,et al.  An Empirical formula for the mass-loss rates of dust-enshrouded red supergiants and oxygen-rich asymptotic giant branch stars , 2005 .

[3]  Keiichi Ohnaka,et al.  Spatially resolved dusty torus toward the red supergiant WOH G64 in the Large Magellanic Cloud , 2008, 0803.3823.

[4]  Michitoshi Yoshida,et al.  Evidence for a Companion to BM Gem, a Silicate Carbon Star , 2008, 0804.4040.

[5]  James B. Kaler.  The coolest stars. , 1990 .

[6]  G. Meynet,et al.  Stellar evolution with rotation XI. Wolf-Rayet star populations at different metallicities , 2005 .

[7]  Cecile Loup,et al.  MASS-LOSS RATES AND LUMINOSITY FUNCTIONS OF DUST-ENSHROUDED AGB STARS AND RED SUPERGIANTS IN THE LMC , 1999 .

[8]  Sebastien Morel,et al.  Mid-infrared interferometry of the Mira variable RR Sco with the VLTI MIDI instrument , 2005 .

[9]  Mark R. Morris,et al.  MECHANISMS FOR MASS LOSS FROM COOL STARS. , 1987 .

[10]  Piet B. W. Schwering,et al.  Two supergiants in the Large Magellanic Cloud with thick dust shells , 1986 .

[11]  Keiichi Ohnaka,et al.  High angular resolution N-band observation of the silicate carbon star IRAS08002-3803 with the VLTI/MIDI instrument - Dusty environment spatially resolved , 2005, astro-ph/0509746.

[12]  Keiichi Ohnaka,et al.  Asymmetric silicate dust distribution toward the silicate carbon star BM Geminorum , 2008, 0807.3342.

[13]  C. H. Smith,et al.  Circumstellar dust emission in five Large Magellanic Cloud supergiants , 1993 .

[14]  Daniel Schaerer,et al.  Grids of stellar models. II. From 0.8 to 120 M_solar at Z=0.008 , 1993 .

[15]  I. Yamamura,et al.  The origin of silicate carbon stars: ISO/SWS observation of V778 Cygni 2000 , 2000 .

[16]  Keiichi Ohnaka,et al.  Temporal variations of the outer atmosphere and the dust shell of the carbon-rich Mira variable V Ophiuchi probed with VLTI/MIDI , 2007 .