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ZusammenfassungDie inklusionsbezogenen Einstellungen von Lehrkräften gelten als wesentliche Prädiktoren für deren pädagogisches und inklusionsbezogenes Wahrnehmen und Handeln sowie den Erfolg (inklusiven) Unterrichts. In zahlreichen Studien wurden die Einstellungen von (angehenden) Lehrkräften sowie potenzielle Einflussfaktoren darauf untersucht. Unberücksichtigt blieben jedoch bisher weitgehend die Lehrkräfte an beruflichen Schulen. Daher geht die vorliegende Studie der Frage nach, welche Ausprägungen inklusionsbezogener Einstellungen bei Lehrkräften an beruflichen Schulen in Deutschland vorliegen. Zudem wird die Frage verfolgt, welche Zusammenhänge sich bei ihnen zwischen den Einstellungen zu Inklusion und potenziellen Einflussfaktoren zeigen. Unter Einsatz eines standardisierten Fragebogens, der punktuell um offene Fragen ergänzt wurde, wurden 662 Lehrkräfte an beruflichen Schulen in vier Bundesländern Deutschlands (Hamburg, Sachsen-Anhalt, Schleswig-Holstein, Thüringen) befragt. Die Einstellungen zur Inklusion fallen insgesamt neutral aus. Mittels linearer Regressionsanalyse kann gezeigt werden, dass berufliche und private Erfahrungen mit Menschen mit besonderen Bedürfnissen, Erfahrungen in inklusiven Klassen und die inklusionsbezogene Qualifizierung einen signifikanten Einfluss auf die persönliche Bereitschaft als eine Dimension der Einstellungen haben. Zudem zeigen die allgemeine und in besonderer Weise die inklusionsbezogene Selbstwirksamkeit einen positiven Effekt auf die Einstellungen. Des Weiteren zeigt sich, dass das Lehr-Lernverständnis einen Einfluss auf die Einstellungen zur Inklusion allgemein hat (ein instruktional orientiertes Verständnis hängt mit negativeren Einstellungen zusammen) und dass das Inklusionsverständnis der Lehrkräfte mit der persönlichen Bereitschaft zusammenhängt. Vor dem Hintergrund dieser Studie scheinen inklusionsbezogene Fortbildungen zur Erhöhung inklusionsbezogener Einstellungen sowie die Verbesserung von Ressourcen und Rahmenbedingungen besonders erfolgversprechend für die Umsetzung von Inklusion zu sein.

Digitalization of health care and the availability of suitable end devices lead to an increase in the use of telehealth applications. Most research on telehealth focuses on patients or organizations (like hospitals), while the role of physicians in this context is often neglected. In case of serious and chronic diseases, they play two major roles in the use of telehealth. Firstly, they may influence the patient’s decision whether to use it at all (if more than one option is available, they may also influence the patient’s choice of software). Secondly, if there is a need for a physicians’ participation (eg, in telecare), an adoption decision by the physician to use the system is necessary. We develop a model to understand a physician’s motivations to recommend the use of telehealth software to patients and to adopt it himself. The results demonstrate that physicians recommend telehealth based on their own use intention and the perceived performance improvements in patient treatment. Further, their own use intention is dependent on the usefulness of the system for their work. Potential disadvantages like decreased patient autonomy or cost of the system use do not influence the physician’s decisions.

We model the intention of patients to use a telehealth app for the management of a chronic disease. Our model integrates the health belief model with a model of information technology acceptance to reflect the technology- and health-related parts of the intention. The intention of non-using patients to use the app is influenced by their hedonic motivation and social influence. An analysis of sub-groups reveals deeper insights: Patients without access to the app would use it based on the expected performance and their self-efficacy. Patients who do not use the app despite having access to it would use it if influenced by their social environment and if they perceive their disease to be severe. A third group does not even know whether they can use the app. The results show that proper education of patients and people influencing them is necessary even in the case of chronic diseases.

Aims. We combined bispectrum speckle interferometry, adaptive optics (AO) imaging polarimetry, and radiative transfer modeling of polarized light to derive various physical properties of the proto-planetary nebula Frosty Leo. Methods. We performed bispectrum K � -band speckle interferometry and H -a ndK-band imaging polarimetry of Frosty Leo using the ESO 3.6 m telescope and the AO-equipped CIAO instrument of the 8 m Subaru telescope, respectively. Two-dimensional radiative transfer modeling was carried out in order to obtain a quantitative interpretation of our observations. Results. Our diffraction-limited speckle image shows distinct hourglass-shaped, point-symmetric bipolar lobes, an equatorial dust lane, and complex clumpy structures in the lobes. Our polarimetric data display a centro-symmetric polarization vector pattern with P ∼ 30–50% in the bipolar lobes and a polarization disk between them. The polarization images also reveal an elongated region with low polarization along a position angle of −45 ◦ . The observations suggest that this region has a low dust density and was carved out by a jet-like outflow. Our radiative transfer modeling can simultaneously explain the observed spectral energy distribution, the intensity distribution of the hourglass-shaped lobes, and our polarization images if we use two grain species with sizes of 0.005 ≤ a ≤ 2.0 μm at latitudes between −2 ◦ and +2 ◦ ,a nd 0.005 ≤ a ≤ 0.7 μm in the bipolar lobes. Assuming a distance of 3 kpc, an expansion velocity of 25 km s −1 , and a gas-to-dust mass ratio of 160, we derive a dust mass of the disk of 2.85 × 10 −3 M� , a gas mass-loss rate of ) ( ) ( *

We present mid-IR long-baseline interferometric observations of the red supergiant WOH G64 in the Large Magellanic Cloud with MIDI at the ESO's Very Large Telescope Interferometer (VLTI). Our MIDI observations of WOH G64 are the first VLTI observations to spatially resolve an individual stellar source in an extragalactic system. Our 2-D radiative transfer modeling reveals the presence of a geometrically and optically thick torus seen nearly pole-on. This model brings WOH G64 in much better agreement with the current evolutionary tracks for a 25 M⊙ star — about a half of the previous estimate of 40 M⊙ — and solves the serious discrepancy between theory and observation which existed for this object.

We present mid-IR spectro-interferometry of the Seyfert type 1 nucleus of NGC 3783. The dusty circumnuclear environment is spatially resolved and the wavelength dependence of the compact emission is discussed. The observations were carried out with the MIDI instrument at the Very Large Telescope Interferometer in the N-band. Spectra and visibilities were derived with a spectral resolution of 30 in the wavelength range from 8 to 13 micron. For the interpretation we developed a simple dusty disk model with small and variable covering factor. At baselines of 65 and 69 m, visibilities in the range of 0.4 to 0.7 were measured. The N-band spectra show a monotonic increase of the measured flux with wavelength with no apparent silicate feature around 10 micron. We find that the mid-IR emission from the nucleus can be reproduced by an extended dust disk or torus with a small covering factor of the radiating dust clouds. Our mid-IR observations of NGC 3783 are consistent with a clumpy circumnuclear dust environment. The interpretation in terms of a dusty torus with low covering factor supports a clumpy version of the unified scheme for AGN. The inferred sizes and luminosities are in good agreement with dust reverberation sizes and bolometric luminosities from optical and X-ray observations., 5 pages, 3 figures; letter accepted by A&A

Aims: We present J, H, K interferometry with a spectral resolution of 35 for the Mira variable S Orionis. We aim at measuring the diameter variation as a function of wavelength that is expected due to molecular layers lying above the continuum-forming photosphere. Methods: Visibility data of S Ori were obtained at phase 0.78 with the VLTI/AMBER instrument using the fringe tracker FINITO at 29 spectral channels between 1.29 and 2.32 mu. Apparent uniform disk (UD) diameters were computed for each spectral channel. In addition, the visibility data were directly compared to predictions by recent self-excited dynamic model atmospheres. Results: S Ori shows significant variations in the visibility values as a function of spectral channel that can only be described by a clear variation in the apparent angular size with wavelength. The closure phase values are close to zero at all spectral channels, indicating the absence of asymmetric intensity features. The apparent UD angular diameter is smallest at about 1.3 and 1.7 mu and increases by a factor of ~1.4 around 2.0 mu. The minimum UD angular diameter is 8.1 pm 0.5 mas, corresponding to ~420 R_sun. The S Ori visibility data and the apparent UD variations can be explained reasonably well by a dynamic atmosphere model that includes molecular layers. Conclusions: The measured visibility and UD diameter variations with wavelength resemble and generally confirm the predictions by recent dynamic model atmospheres. [abridged], Comment: 4 pages including 1 table and 4 color figures. Accepted for publication as a Letter in Astronomy and Astrophysics

We present the first NIR interferometric observations of the LBV η Carinae with high spectral resolution [Weigelt et al., 2007. Near-infrared interferometry of η Carinae with spectral resolutions of 1500 and 12000 using AMBER/VLTI. A&A 464, 87.]. Our observations demonstrate the potential of AMBER/VLTI to unveil new structures on the scales of milliarcseconds. The aim of this work is to study the wavelength dependence of η Car’s optically thick wind region with a high spatial resolution of 5 mas (11 AU) and high spectral resolution. The observations were carried out with three 8.2 m VLTI Unit Telescopes. The raw data are interferograms obtained with spectral resolutions of λ /Δ λ = 1500 (MR-K mode) and 12 000 (HR-K mode). The observations were performed in the wavelength range around both the HeI 2.059 μm and the Brγ 2.166 μm emission lines. The spectrally dispersed AMBER interferograms allow us to investigate the wavelength dependence of the visibility, differential phase, and closure phase of η Car. If we fit [Hillier, D.J., Davidson, K., Ishibashi, K., Gull, T., 2001. On the Nature of the Central Source in η Carinae. ApJ 553, 837] model visibilities (Hillier et al., 2001) to the observed AMBER visibilities, we obtain 50% encircled-energy diameters of 4.3, 6.5, and 9.6 mas in the 2.17 μm continuum, the HeI, and the Brγ emission lines, respectively. We find good agreement between the measured visibilities and the predictions of the radiative transfer model of Hillier et al. (2001). Our observations support theoretical models of anisotropic winds from fast-rotating, luminous hot stars with enhanced high-velocity mass loss near the polar regions.

We have used mid-infrared long-baseline interferometry with MIDI at the VLTI to resolve the circumstellar material around the Herbig Ae star HR 5999, providing the first direct measurement of its angular size, and to derive constraints on the spatial distribution of the dust. A set of ten spectrally dispersed (8-13 micron) interferometric measurements of HR 5999 was obtained. The characteristic size of the emission region depends on the projected baseline length and position angle, and it ranges between ~ 5-15 milliarcseconds (Gauss FWHM), corresponding to remarkably small physical sizes of ~ 1-3 AU. To derive constraints on the geometrical distribution of the dust, we compared our interferometric measurements to 2D, frequency-dependent radiation transfer simulations of circumstellar disks and envelopes. For disk models with radial power-law density distributions, the relatively weak but very extended emission from outer disk regions (>~ 3 AU) leads to model visibilities that are significantly lower than the observed visibilities, making these models inconsistent with the MIDI data. Disk models in which the density is truncated at outer radii of ~ 2-3 AU, on the other hand, provide good agreement with the data. A satisfactory fit to the observed MIDI visibilities of HR 5999 is found with a model of a geometrically thin disk that is truncated at 2.6 AU and seen under an inclination angle of 58 degr. Neither models of a geometrically thin disk seen nearly edge-on, nor models of spherical dust shells can achieve agreement between the observed and predicted visibilities. The reason why the disk is so compact remains unclear; we speculate that it has been truncated by a close binary companion., accepted for publication by Astronomy & Astrophysics

We present the near-infrared speckle interferometry for LP And in the H and $K^{\prime}$ bands with diffraction-limited resolutions of 56 and 72 mas, new $\it JHKLM$ photometry, and the results of our radiative transfer modelling of this carbon star. The reconstructed visibility reveals a spherically-symmetric envelope surrounding the central star. To determine the physical parameters of the latter and the properties of its dusty envelope, we performed extensive radiative transfer calculations. The well-defined spectral energy distribution of LP And in the entire range from the near-IR to millimeter wavelengths (including the absorption feature visible in the stellar continuum at 3 ${\mu}$m and the shapes of the dust emission bands at 11 and 27 ${\mu}$m), together with our H -band visibility can be reproduced by a spherical dust envelope with parameters that are very similar to those of CW Leo (IRC +10 216), the best studied carbon star. For the newly estimated pulsation period $P = 617 \pm 6$ days and distance $D = 740 \pm 100$ pc, our model of LP And changes its luminosity $L_{\star}$ between 16 200 and 2900 $L_{\odot}$, its effective temperature $T_{\star}$ between 3550 and 2100 K, and its radius $R_{\star}$ between 340 and 410 $R_{\odot}$. The model estimates the star's mass-loss rate $\dot{M} \approx 1.9 \times 10^{-5}$ $M_{\odot}$ yr - 1 , assuming a constant outflow velocity $v = 14$ km s -1 . If the latter also applied to the innermost parts of the dusty envelope, then presently the star would be losing mass at a rate $\dot{M} \approx 6.0 \times 10^{-5}$ $M_{\odot}$ yr -1 . However, we believe that the inner wind velocity must actually be closer to $v \approx 4$ km s -1 instead, as wind acceleration is expected in the dust-formation zone. The dusty envelope of LP And extends from $R_1 \approx 2$ $R_{\star}$ to distances of $R_2 \approx 3$ pc from the star. The total mass of the envelope lost by the central star is $M = 3.2$ $M_{\odot}$ assuming a dust-to-gas mass ratio of $\rho_{\rm d}/\rho$ = 0.0039. The circumstellar optical depth towards the star is $\tau_{V} = 25$ in the visual. The dust model contains small silicon carbide grains, inhomogeneous grains made of a mixture of SiC and incompletely amorphous carbon, and thin mantles made of iron-magnesium sulfides. This dust mixture perfectly fits the infrared continuum and both the 11.3 ${\mu}$m and 27 ${\mu}$m emission bands. We find that our $K^{\prime}$-band visibility could not be fitted by our spherical model, so we discuss possible reasons for this interesting result. More observations are required in order to determine what causes this effect. If slight deviations from spherical geometry in its envelope are the reason, then the object's evolutionary stage would be even more similar to that of CW Leo. It appears that LP And is a highly-evolved intermediate-mass star (initial mass $M^0_{\star}$ ≈ 4 $M_{\odot}$) at the end of its AGB phase.

LINC-NIRVANA is a Fizeau (imaging) interferometer exploiting the full spatial resolution of a 23 m class telescope in the combined beam of the Large Binocular Telescope supported through Multi-Conjugated Adaptive Optics (MCAO). By means of science cases, we show how LINC-NIRVANA takes advantage of the MCAO, increasing the sky coverage of the instrument and the field of view for the Fringe and Flexure tracker. We introduce the MCAO system of LINC-NIRVANA in detail, which in a first step will be installed with two deformable mirrors per arm and has the provision to be upgraded with a third mirror. The MCAO system implements several novel concepts proposed for extremely large telescopes, such as layer oriented MCAO, optical co-adding of guide stars, or Multiple Field of View sensing. LINC-NIRVANA will demonstrate some of the concepts for the first time on sky. To cite this article: W. Gaessler et. al., C. R. Physique 6 (2005).

We present a new method, the regularized and space-variant Building Block method, which is able to reconstruct diffraction-limited aperture-synthesis images from Large Binocular Telescope (LBT) LINC-NIRVANA data. Images with the diffraction-limited resolution of a 22.8 m single-dish telescope can be derived if raw images are taken at several different hour angles. We simulated computer-generated and laboratory LBT interferograms that are similar to the data which can be obtained with the LINC-NIRVANA beam combiner instrument. From the simulated data, diffraction-limited images were reconstructed with the regularized Building Block method, which is an extension of the Building Block method (Hofmann & Weigelt 1993, AA Lucy 1974. AJ, 79, 745) and the Ordered Subsets Expectation Maximization (OSEM) method (Hudson & Larkin 1994, IEEE Trans. Med. Imag., 13, 601; Bertero & Boccacci 2000, A&AS, 144, 181). Our image reconstruction studies were performed with computer-simulated J-band and laboratory H-band raw data of a galaxy with simulated total magnitudes of J = 16 m to 18 m and H = 16 m to 19 m , respectively. One of the faintest structures in the images has a brightness of J ∼ 25 m . The simulated reference stars within the isoplanatic patch have magnitudes of J = 20 m -21 m and H = 19 m . All three methods are able to reconstruct diffraction-limited images with almost the same quality. Furthermore, raw data with space-variant point spread functions were simulated, and diffraction-limited images were reconstructed using the space-variant version of the Building Block method.

International audience; We present the results of the first mid-infrared interferometric observations of the Mira variable RR Sco with the MID-infrared Interferometer (MIDI) coupled to the European Southern Observatory's (ESO) Very Large Telescope Interferometer (VLTI), together with K-band observations using VLTI VINCI. The observations were carried out in June 2003, when the variability phase of the object was 0.6, using two unit telescopes (UT1 and UT3), as part of the Science Demonstration Time (SDT) program of the instrument. Projected baseline lengths ranged from 73 to 102 m, and a spectral resolution of 30 was employed in the observations, which enabled us to obtain the wavelength dependence of the visibility in the region between 8 and 13 μm. The uniform-disk diameter was found to be 18 mas between 8 and 10 μm, while it gradually increases at wavelengths longer than 10 μm to reach 24 mas at 13 μm. The uniform-disk diameter between 8 and 13 μm is significantly larger than the K-band uniform-disk diameter of 10.2 ± 0.5 mas measured using VLTI VINCI with projected baseline lengths of 15-16 m, 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. We find that the warm molecular envelope model extending to ˜2.3 R\star with a temperature of ˜1400 K and column densities of H2O and SiO of 3 × 1021 cm-2 and 1 × 1020 cm-2, respectively, can reproduce the observed uniform-disk diameters between 8 and 10 μm. The observed increase of the uniform-disk diameter longward of 10 μm can be explained by an optically thin dust shell consisting of silicate and corundum grains. The inner radius of the optically thin dust shell is derived to be 7-8 R\star with a temperature of ˜700 K, and the optical depth at 10 μm is found to be ˜0.025. Based on observations made with the Very Large Telescope Interferometer of the European Southern Observatory.

Circumstellar disks and outflows play a fundamental role in star formation. Infrared spectro-interferometry allows the inner accretion-ejection region to be resolved. We measured interferometric visibilities, wavelength-differential phases, and closure phases of MWC 297 with a spectral resolution of 12000. To interpret our MWC 297 observations, we employed disk-wind models. The measured continuum visibilities confirm previous results that the continuum-emitting region of MWC 297 is remarkably compact. We derive a continuum ring-fit radius of ~2.2 mas (~0.56 AU at a distance of 250 pc), which is ~5.4 times smaller than the 3 AU dust sublimation radius expected for silicate grains (in the absence of radiation-shielding material). The strongly wavelength-dependent and asymmetric Br gamma-emitting region is more extended (~2.7 times) than the continuum-emitting region. At the center of the Br gamma line, we derive a Gaussian fit radius of ~6.3 mas HWHM (~1.6 AU). To interpret the observations, we employ a magneto-centrifugally driven disk-wind model consisting of an accretion disk, which emits the observed continuum radiation, and a disk wind, which emits the Br gamma line. The calculated wavelength-dependent model intensity distributions and Br gamma line profiles are compared with the observations (i.e., K-band spectrum, visibilities, differential phases, and closure phases). The closest fitting model predicts a continuum-emitting disk with an inner radius of ~0.3 AU and a disk wind ejection region with an inner radius of ~0.5 AU (~17.5 stellar radii). We obtain a disk-wind half-opening angle (the angle between the rotation axis and the innermost streamline of the disk wind) of ~80 degrees, which is larger than in T Tau models, and a disk inclination angle of ~20 degrees (i.e., almost pole-on)., Astron. & Astrophys. accepted

International audience; B[e] supergiants are luminous, massive post-main sequence stars exhibiting non-spherical winds, forbidden lines, and hot dust in a disc-like structure. The physical properties of their rich and complex circumstellar environment (CSE) are not well understood, partly because these CSE cannot be easily resolved at the large distances found for B[e] supergiants (typically $\ga 1$~kpc). From mid-IR spectro-interferometric observations obtained with VLTI/MIDI we seek to resolve and study the CSE of the Galactic B[e] supergiant CPD-57\degr\,2874. For a physical interpretation of the observables (visibilities and spectrum) we use our ray-tracing radiative transfer code (FRACS), which is optimised for thermal spectro-interferometric observations. Thanks to the short computing time required by FRACS ($

We report near-IR spectroscopic observations of the Eta Carinae massive binary system during 2008-2009 using VLT/CRIRES. We detect a strong, broad absorption wing in He I 10833 extending up to -1900 km/s across the 2009.0 spectroscopic event. Archival HST/STIS ultraviolet and optical data shows a similar high-velocity absorption (up to -2100 km/s) in the UV resonance lines of Si IV 1394, 1403 across the 2003.5 event. UV lines from low-ionization species, such as Si II 1527, 1533 and C II 1334, 1335, show absorption up to -1200 km/s, indicating that the absorption with v from -1200 to -2100 km/s originates in a region markedly faster and more ionized than the nominal wind of the primary star. Observations obtained at the OPD/LNA during the last 4 spectroscopic cycles (1989-2009) also display high-velocity absorption in He I 10833 during periastron. Based on the OPD/LNA dataset, we determine that material with v < -900 km/s is present in the phase range 0.976 < phi < 1.023 of the spectroscopic cycle, but absent in spectra taken at phi < 0.947 and phi > 1.049. Therefore, we constrain the duration of the high-velocity absorption to be 95 to 206 days (or 0.047 to 0.102 in phase). We suggest that the high-velocity absorption originates from shocked gas in the wind-wind collision zone, at distances of 15 to 45 AU in the line-of-sight to the primary star. Using 3-D hydrodynamical simulations of the wind-wind collision zone, we find that the dense high-velocity gas is in the line-of-sight to the primary star only if the binary system is oriented in the sky so that the companion is behind the primary star during periastron, corresponding to a longitude of periastron of omega ~ 240 to 270 degrees. We study a possible tilt of the orbital plane relative to the Homunculus equatorial plane and conclude that our data are broadly consistent with orbital inclinations in the range i=40 to 60 degrees., 18 pages, 15 figures, accepted for publication in A&A; high-resolution PDF version available also at http://www.mpifr.de/staff/jgroh/etacar.html

Dusty Wolf-Rayet stars are few but remarkable in terms of dust production rates (up to one millionth of solar mass per year). Infrared excesses associated to mass-loss are found in the sub-types WC8 and WC9. Few WC9d stars are hosting a "pinwheel" nebula, indirect evidence of a companion star around the primary. While few other WC9d stars have a dust shell which has been barely resolved so far, the available angular resolution offered by single telescopes is insufficient to confirm if they also host "pinwheel" nebulae or not. In this article, we present the possible detection of such nebula around the star WR118. We discuss about the potential of interferometry to image more "pinwheel" nebulae around other WC9d stars., Comment: To be published soon in the conference proceeding

Most Wolf-Rayet stars (WR) of WC9 sub-type exhibit a dusty circumstellar envelope, but it is still a matter of debate how dust can form in their harsh environment. In a few cases, a pinwheel-like structure of the dusty envelope has been detected. Therefore, it has been suggested that dust formation in all dusty WR stars might be linked to colliding winds in a binary system. We probed the innermost region of the circumstellar dust shell of the deeply embedded WR star WR 118. We carried out spectro-interferometric observations using the AMBER instrument of ESO's Very Large Telescope Interferometer in low-spectral resolution mode (R = 35). The K-band observations were obtained with three 1.8 m telescopes spanning projected baselines between 9.2 and 40.1 m. At high spatial frequencies, the AMBER visibilities exhibit a prominent lobe, indicating that the envelope contains one or several zones with a large local intensity gradient. The strong closure phase signal clearly shows that the circumstellar envelope of WR 118 can only be described by an asymmetric intensity distribution. We show that a pinwheel nebula seen at low inclination is consistent with the AMBER data. Its size was determined to be 13.9+-1.1 mas. WR 118 possibly harbors a pinwheel nebula, which suggests a binary nature of the system. According to our best model, the period of the system would be ~60 days (for d=3 kpc), making WR 118 the shortest-period pinwheel nebula known so far., Letter accepted in A&A for publication

We obtained near-infrared long-baseline interferometry of IRC+10420 with the AMBER instrument of ESO's Very Large Telescope Interferometer (VLTI) in low and high spectral resolution (HR) mode to probe the photosphere and the innermost circumstellar environment of this rapidly evolving yellow hypergiant. In the HR observations, the visibilities show a noticeable drop across the Brackett gamma (BrG) line on all three baselines, and we found differential phases up to -25 degrees in the redshifted part of the BrG line and a non-zero closure phase close to the line center. The calibrated visibilities were corrected for AMBER's limited field-of-view to appropriately account for the flux contribution of IRC+10420's extended dust shell. We derived FWHM Gaussian sizes of 1.05 +/- 0.07 and 0.98 +/- 0.10 mas for IRC+10420's continuum-emitting region in the H and K bands, respectively, and the BrG-emitting region can be fitted with a geometric ring model with a diameter of 4.18 +0.19/-0.09 mas, which is approximately 4 times the stellar size. The geometric model also provides some evidence that the BrG line-emitting region is elongated towards a position angle of 36 degrees, well aligned with the symmetry axis of the outer reflection nebula. The HR observations were further analyzed by means of radiative transfer modeling using CMFGEN and the 2-D Busche & Hillier codes. Our spherical CMFGEN model poorly reproduces the observed line shape, blueshift, and extension, definitively showing that the IRC+10420 outflow is asymmetric. Our 2-D radiative transfer modeling shows that the blueshifted BrG emission and the shape of the visibility across the emission line can be explained with an asymmetric bipolar outflow with a high density contrast from pole to equator (8-16), where the redshifted light is substantially diminished., paper accepted for publication in A&A main journal (16 pages, 9 figures); please note that the astro-ph latex compilation shifts Fig. 7 to the very end of the paper

Context. The star HD 87643, exhibiting the "B[e] phenomenon", has one of the most extreme infrared excesses for this object class. It harbours a large amount of both hot and cold dust, and is surrounded by an extended reflection nebula. Aims. One of our major goals was to investigate the presence of a companion in HD87643. In addition, the presence of close dusty material was tested through a combination of multi-wavelength high spatial 5Aresolution observations. Methods. We observed HD 87643 with high spatial resolution techniques, using the near-IR AMBER/VLTI interferometer with baselines ranging from 60 m to 130 m and the mid-IR MIDI/VLTI interferometer with baselines ranging from 25 m to 65 m. These observations are complemented by NACO/VLT adaptive-optics-corrected images in the K and L-bands, ESO-2.2m optical Wide-Field Imager large-scale images in the B, V and R-bands, Results. We report the direct detection of a companion to HD 87643 by means of image synthesis using the AMBER/VLTI instrument. The presence of the companion is confirmed by the MIDI and NACO data, although with a lower confidence. The companion is separated by ~ 34 mas with a roughly north-south orientation. The period must be large (several tens of years) and hence the orbital parameters are not determined yet. Binarity with high eccentricity might be the key to interpreting the extreme characteristics of this system, namely a dusty circumstellar envelope around the primary, a compact dust nebulosity around the binary system and a complex extended nebula witnessing past violent ejections.

We present spatially resolved high-spectral resolution K-band observations of the red supergiant Betelgeuse (alpha Ori) using AMBER at the Very Large Telescope Interferometer (VLTI). Betelgeuse was observed between 2.28 and 2.31 micron using baselines of 16, 32, and 48m with spectral resolutions of 4800 -- 12000. Spectrally dispersed interferograms have been obtained in the 2nd, 3rd, and 5th lobes, which represents the highest spatial resolution (9 mas) achieved for Betelgeuse, corresponding to 5 resolution elements over its stellar disk. The AMBER data in the continuum can be reasonably fitted by a uniform disk with a diameter of 43.19+/-0.03 mas or a limb-darkening disk with 43.56+/-0.06 mas. The K-band interferometric data taken at various epochs suggest that Betelgeuse seen in the continuum shows much smaller deviations from the above uniform/limb-darkened disk than predicted by 3-D convection simulations. On the other hand, our AMBER data in the CO lines reveal that the blue and red wings of the CO lines originate in spatially distinct regions over the stellar disk, indicating an inhomogeneous velocity field. Our AMBER data in the CO lines can be roughly explained by a simple model, in which a patch of CO gas is moving outward or inward at velocities of 10--15 km s^-1, while the CO gas in the remaining region in the atmosphere is moving in the opposite direction at the same velocities. The AMBER data are also consistent with the presence of warm molecular layers at ~1.4--1.5 Rstar with a CO column density of ~1 x 10^20 cm^-2. Our AMBER observations of Betelgeuse are the first spatially resolved study of the so-called macroturbulence in a stellar atmosphere other than the Sun. The spatially resolved CO gas motion is likely to be related to convective motion or intermittent mass ejections in clumps or arcs., Comment: 17 pages, 6 figures, accepted for publication in Astronomy and Astrophysics

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.

We present interferometric near-infrared observations of the Luminous Blue Variable (LBV) η Car using the Very Large Telescope Interferometer (VLTI) and the AMBER instrument of the European Southern Observatory (ESO). A high spatial resolution of 5 mas (~11.5 AU) and a high spectral resolution R = λ/Δλ=1500 and 12000 were obtained. Some of the data was recorded using the fringe tracker FINITO. The observations were obtained in the wavelength range around both the He I 2.059 μm and the Brγ 2.166 μm emission lines. The AMBER interferograms allow the investigation of the wavelength dependence of η Car's visibility, wavelength-differential phase, and closure phase. If we fit Hillier et al. model visibilities to the observations, we obtain 50% encircled-energy diameters of 4.2, 6.5 and 9.6 mas in the 2.17 μm continuum, the He I, and the Brγ emission lines, respectively. In the continuum, an elongation along a position angle of 120° ± 15° was derived from the visibilities. The VLTI observations support theoretical models of anisotropic winds from fast-rotating, luminous hot stars with enhanced high-velocity mass loss near the pole.

Silicate carbon stars show the 10 micron silicate emission, despite their carbon-rich photospheres. They are considered to have circumbinary or circum-companion disks, which serve as a reservoir of oxygen-rich material shed by mass loss in the past. We present N-band spectro-interferometric observations of the silicate carbon star BM Gem using MIDI at the Very Large Telescope Interferometer (VLTI). Our aim is to probe the spatial distribution of oxygen-rich dust with high spatial resolution. BM Gem was observed with VLTI/MIDI at 44--62 m baselines using the UT2-UT3 and UT3-UT4 baseline configurations. The N-band visibilities observed for BM Gem show a steep decrease from 8 to ~10 micron and a gradual increase longward of ~10 micron, reflecting the optically thin silicate emission feature emanating from sub-micron-sized amorphous silicate grains. The differential phases obtained at baselines of ~44--46 m show significant non-zero values (~ -70 degrees) in the central part of the silicate emission feature between ~9 and 11 micron, revealing a photocenter shift and the asymmetric nature of the silicate emitting region. The observed N-band visibilities and differential phases can be fairly explained by a simple geometrical model in which the unresolved star is surrounded by a ring with azimuthal brightness modulation. The best-fit model is characterized by a broad ring (~70 mas across at 10 micron) with a bright region which is offset from the unresolved star by ~20 mas at a position angle of ~280 degrees. This model can be interpreted as a system with a circum-companion disk and is consistent with the spectroscopic signatures of an accretion disk around an unseen companion recently discovered in the violet spectrum of BM Gem., Comment: 7 pages, 3 figures, accepted for publication in A&A

We present mid-infrared long-baseline interferometric observations of the symbiotic Mira star RX Pup obtained with the VLTI/MIDI instrument in prism mode within the framework of the Science Demonstration Time (SDT) program in Feb. 2004. Four visibility measurements have been carried out using the unit telescopes UT2 and UT3, with projected baseline lengths ranging from 34.7 to 46.5 m.As we show by means of radiative transfer modelin with the code DUSTY [3], the wavelength dependence of the visibility and the N-band spectrum measured with MIDI can be interpreted as thesignature of a circumstellar dust shell which is dominated by silicate dust.

Infrared spectroscopic observations of asymptotic giant branch (AGB) stars with the Infrared Space Observatory (ISO) have revealed the existence of a quasi-static, warm, dense molecular envelope close to the star (e.g., Tsuji et al. [4], Yamamura et al. [5], Cami et al. [1], Matsuura et al. [2]). Although this warm molecular envelope is most likely to play an important role in mass loss, its formation mechanism is not yet understood. The first midinfrared spectro-interferometric observations of the Mira variable RR Sco (period 281 days, distance 320 pc) using MIDI have revealed that optically thick emission from dense, warm molecular layers (H2O and SiO) as well as dust thermal emission can make the N -band angular size more than twice as large as that in the K band (Ohnaka et al. [3]). The physical properties of the warm molecular layers derived from the MIDI observations (Tmol ∼ 1400 K, Rmol ∼ 2.3 R , H2O column density 3 × 10 cm−2, SiO column density 10 cm−2) have turned out to be consistent with those derived for other Mira variables from ISO observations. Here we present the results of MIDI observations of RR Sco at the second epoch.

Intermediateand low-mass stars experience slow, but massive mass loss, while moving along the asymptotic giant branch (AGB) during the late stage of their evolution. Mira-type AGB stars are of particular interest, because they exhibit complicated physical and chemical processes such as largeamplitude stellar pulsation, shock waves, grain formation, and momentum transfer from photons to dust grains. Our MIDI observations of the oxygenrich Mira variable RR Sco have revealed that optically thick emission from dense, warm molecular layers (H2O and SiO) as well as dust thermal emission can make the N -band angular size more than twice as large as that in the K band (Ohnaka et al. [1]). Here we present the results of MIDI observations of Mira variables RS Lib and RT Sco. While RS Lib is an oxygen-rich Mira variable, RT Sco is classified as an S-type Mira variable. S stars are characterized by C/O ratios close to unity, which means that neither oxygen-bearing molecules nor carbon-bearing molecules are abundant in their photosphere. Such peculiar chemical composition is expected to affect the structure of the outer atmosphere, where molecule/dust formation takes place. Therefore, a comparative study on Mira variables with different chemical compositions is useful for better understanding the physical properties of the outer atmosphere as well as of the innermost region of the dust shell.

We have used long-baseline mid-infrared interferometric observations with MIDI at the VLTI to resolve the circumstellar material around the Herbig Ae star HR 5999 and to provide the first direct measurement of its angular size. The obtained visibilities range between ~ 0.5 and ~ 0.9 at 10μm. This implies that the mid-infrared emission from HR 5999 is clearly resolved, but has a compact structure not much larger than the resolution limit of the MIDI observations. The characteristic size of the emission region depends on the position angles, and ranges between 10 and 25 milli-arcseconds (corresponding to ~ 2–5 AU) for a uniform-disk model, and 5–15 mas (~ 1–3 AU) for a Gauss model (FWHM). We find a dependence of the characteristic size on the projected baseline position angle, which suggests asymmetry of the emission region. To derive constraints on the geometry of the dust distribution, we compare our interferometric measurements to 2D, frequency-dependent radiation transfer simulations of circumstellar disks.

Silicate carbon stars are a puzzle to date, because they exhibit prominent silicate emission features at ∼10 and ∼18 μm despite their carbon-rich photospheres. Since their discovery in the IRAS LRS by Little-Marenin [1] and Willems & de Jong [5], several scenarios have been proposed for these peculiar objects, and the scenarios widely accepted at the moment suggest that silicate carbon stars have a companion, possibly a main-sequence star, and that oxygen-rich material is shed by mass loss when the primary star was an M giant and this oxygen-rich material is stored in a circumbinary disk (Morris [3]; Lloyd-Evans [2]) or in a circumstellar disk around the companion (Yamamura et al. [6]) until the primary star becomes a carbon star. Observations with high spatial resolution within the silicate emission feature in the mid-infrared would be the most direct approach for investigating the dust environment around silicate carbon stars. VLTI/MIDI provides us with an excellent opportunity to directly study the circumstellar environment of silicate carbon stars in the 10 μm region, exactly where silicate emission from the oxygen-rich reservoir is located. Here we present the results of MIDI observations of the silicate carbon star Hen 38 (IRAS08002-3803).

We present near-infrared speckle interferometry of the OH/IR star OH 104.9+2.4 in the K’ band obtained with the 6m telescope of the Special Astrophysical Observatory (SAO) in Sep. 2002 and Oct. 2003. At a wavelength of λ = 2.13 μ m the diffraction-limited resolution of 74 mas was attained. The reconstructed visibility reveals a spherically symmetric, circumstellar dust shell (CDS) surrounding the central star. The visibility function shows that the stellar contribution to the total flux at λ = 2.13 μ m is less than 30% at all phases, indicating a rather large optical depth of the CDS. The azimuthally averaged 1-dimensional Gaussian visibility fit yields a diameter of 47 ± 3 mas (FHWM), which corresponds to 112 ± 13 AU for an adopted distance of D = 2.38 ± 0.24 kpc.To determine the structure and the roperties of the CDS of OH 104.9+2.4, radiative transfer calculations using the code DUSTY cite{rie:ie95} were performed to simultaneously model its visibility and the spectral energy distribution (SED). Since OH 104.9+2.4 is highly variable, the observational data taken into consideration for the modeling correspond to different phases of the object’s variability cycle. This offers the possibility to derive several physical parameters of the central star and its CDS as a function of phase

We report on our project of coordinated VLTI/VLBA observations of the atmospheres and circumstellar environments of evolved stars. We illustrate in general the potential of interferometric measurements to study stellar atmospheres and envelopes, and demonstrate in particular the advantages of a coordinated multi-wavelength approach including near/mid-infrared as well as radio interferometry. We have so far made use of VLTI observations of the near- and mid-infrared stellar sizes and of concurrent VLBA observations of the SiO maser emission. To date, this project includes studies of the Mira stars S Ori and RR Aql as well as of the supergiant AH Sco. These sources all show strong silicate emission features in their mid-infrared spectra. In addition, they each have relatively strong SiO maser emission. The results from our first epochs of S Ori measurements have recently been published and the main results are reviewed here. The S Ori maser ring is found to lie at a mean distance of about 2 stellar radii, a result that is virtually free of the usual uncertainty inherent in comparing observations of variable stars widely separated in time and stellar phase. We discuss the status of our more recent S Ori, RR Aql, and AH Sco observations, and present an outlook on the continuation of our project.

Context: Optical long-baseline interferometry is moving a crucial step forward with the advent of general-user scientific instruments that equip large aperture and hectometric baseline facilities, such as the Very Large Telescope Interferometer (VLTI). Aims: AMBER is one of the VLTI instruments that combines up to three beams with low, moderate and high spectral resolutions in order to provide milli-arcsecond spatial resolution for compact astrophysical sources in the near-infrared wavelength domain. Its main specifications are based on three key programs on young stellar objects, active galactic nuclei central regions, masses, and spectra of hot extra-solar planets. Methods: These key science goals led to scientific specifications, which were used to propose and then validate the instrument concept. AMBER uses single-mode fibers to filter the entrance signal and to reach highly accurate, multiaxial three-beam combination, yielding three baselines and a closure phase, three spectral dispersive elements, and specific self-calibration procedures. Results: The AMBER measurements yield spectrally dispersed calibrated visibilities, color-differential complex visibilities, and a closure phase allows astronomers to contemplate rudimentary imaging and highly accurate visibility and phase differential measurements. AMBER was installed in 2004 at the Paranal Observatory. We describe here the present implementation of the instrument in the configuration with which the astronomical community can access it. Conclusions: .After two years of commissioning tests and preliminary observations, AMBER has produced its first refereed publications, allowing assessment of its scientific potential.

We present the first multi-epoch N-band spectro-interferometric observations of the carbon-rich Mira variable V Oph using MIDI at the ESO's Very Large Telescope Interferometer. Our MIDI observations were carried out at three different phases 0.18, 0.49, and 0.65, using three different baselines configurations (UT2-UT4, UT1-UT4, and UT2-UT3) with projected baseline lengths of 42-124 m. The wavelength dependence of the uniform-disk diameters obtained at all epochs is characterized by a roughly constant region between 8 and 10 micron with a slight dip centered at ~9.5 micron and a gradual increase longward of 10 micron. These N-band angular sizes are significantly larger than the estimated photospheric size of V Oph. The angular sizes observed at different epochs reveal that the object appears smaller at phase 0.49 (minimum light) with uniform-disk diameters of ~5-12 mas than at phases 0.18 (~12-20 mas) and 0.65 (~9-15 mas). We interpret these results with a model consisting of optically thick C2H2 layers and an optically thin dust shell. Our modeling suggests that the C2H2 layers around V Oph are more extended (~1.7-1.8 Rstar) at phases 0.18 and 0.65 than at phase 0.49 (~1.4 Rstar) and that the C2H2 column densities appear to be the smallest at phase 0.49. We also find that the dust shell consists of amorphous carbon and SiC with an inner radius of ~2.5 Rstar, and the total optical depths at phases 0.18 and 0.65 are higher than that at phase 0.49. Our MIDI observations and modeling indicate that carbon-rich Miras also have extended layers of polyatomic molecules as previously confirmed in oxygen-rich Miras., Comment: 14 pages, 10 figures, accepted for publication in A&A

International audience; We present the first high spatial and spectral resolution observations of the circumstellar envelope (CSE) of a B[e] supergiant (CPD-57°2874), performed with the Very Large Telescope Interferometer (VLTI). Spectra, visibilities and closure phase were obtained using the beam-combiner instruments AMBER (near-IR interferometry with three 8.3 m Unit Telescopes or UTs) and MIDI (mid-IR interferometry with two UTs). The interferometric observations of the CSE are well fitted by an elliptical Gaussian model with FWHM diameters varying linearly with wavelength. Typical diameters measured are ≃1.8×3.4 mas or ≃4.5×8.5 AU (adopting a distance of 2.5 kpc) at 2.2 μm, and ≃12×15 mas or ≃30×38 AU at 12 μm. The size of the region emitting the Brγ flux is ≃2.8×5.2 mas or ≃7.0×13.0 AU. The major-axis position angle of the elongated CSE in the mid-IR (≃144°) agrees well with previous polarimetric data, hinting that the hot-dust emission originates in a disk-like structure. In addition to the interferometric observations we also present new optical (UBVR_cI_c) and near-IR (JHKL) broadband photometric observations of CPD-57°2874. Our spectro-interferometric VLTI observations and data analysis support the non-spherical CSE paradigm for B[e] supergiants. Based on observations collected at the European Southern Observatory, Paranal, Chile, within the AMBER science demonstration time programme 074.A-9026 and the MIDI open time programme 074.D-0101.

The regularized and space-variant Building Block method allow the reconstruction of diffraction-limited aperture-synthesis images from Large Binocular Telescope (LBT) LINC-NIRVANA data. Images with the diffraction-limited resolution of a 22.8 m single-dish telescope can be reconstructed if raw images are taken at several different hour angles. Computer-generated and laboratory LBT interferograms were simulated that are similar to the data which can be obtained with the LINC-NIRVANA beam combiner instrument. From the simulated interferograms, diffraction-limited images were reconstructed with the regularized Building Block method, which is an extension of the Building Block method. We compare the Building Block reconstructions to images obtained with the Richardson-Lucy (RL) method and the Ordered Subsets Expectation Maximization (OSEM) method. Our image reconstruction studies were performed with computer-simulated J-band and laboratory H-band raw data of a galaxy with simulated total magnitudes of J = 16 to 18 and H = 16 to 19, respectively. One of the faintest structures in the images has a brightness of J~25. The simulated reference stars within the isoplanatic patch have magnitudes of J = 20 - 21 and H = 19. All three methods are able to reconstruct diffraction-limited images of similar quality.

We present the results of N -band spectro-interferometric observations of the silicate carbon star Hen 38 (IRAS08002-3803) with the MID-infrared Interferometric instrument (MIDI) at the Very Large Telescope Interferometer (VLTI) of the European Southern Observatory (ESO). Our observations of IRAS08002-3803 with baseline lengths of 39-47 m have spatially resolved the dusty environment of a silicate carbon star for the first time and revealed an unexpected wavelength dependence of the angular size in the N band: the uniform-disk diameter is found to be constant and ~36 mas (72 R * ) between 8 and 10 μ m, while it steeply increases longward of 10 μ m to reach ~53 mas (106 R * ) at 13 μ m. Neither spherical shell models nor axisymmetric disk models consisting of silicate grains alone can simultaneously explain the observed wavelength dependence of the visibility and the spectral energy distribution (SED). We propose that the circumstellar environment of IRAS08002-3803 may consist of two grain species coexisting in the disk: silicate and a second grain species, for which we consider amorphous carbon, large silicate grains, and metallic iron grains. Comparison of the observed visibilities and SED with our models shows that such disk models can fairly - though not entirely satisfactorily - reproduce the observed SED and N -band visibilities. Our MIDI observations and the radiative transfer calculations lend support to the picture where oxygen-rich material around IRAS08002-3803 is stored in a circumbinary disk surrounding the carbon-rich primary star and its putative low-luminosity companion.

We present K-band interferometric and optical spectroscopic observations of Menkar obtained with the instruments VINCI and UVES at Paranal Observatory. Spherically symmetric PHOENIX stellar model atmospheres are constrained by comparison to our interferometric and spectroscopic data, and high-precision fundamental parameters of Menkar are obtained. Our high-precision VLTI/VINCI observations in the first and second lobes of the visibility function directly probe the model-predicted strength of the limb darkening effect in the K-band and the stellar angular diameter. The high spectral resolution of UVES allows us to confront observed and model-predicted profiles of atomic lines and molecular bands. We show that our derived PHOENIX model atmosphere for Menkar is consistent with both the measured strength of the limb-darkening in the near-infrared K-band and the profiles of spectral bands around selected atomic lines and TiO bandheads. At the detailed level of our high spectral resolution, however, noticeable discrepancies between observed and synthetic spectra exist. We obtain a Rosseland angular diameter of Theta_Ross=12.20 mas pm 0.04 mas. Together with the Hipparcos parallax, it corresponds to R_Ross=89 pm 5 R_sun, and together with the bolometric flux to T_eff=3795 K pm 70 K.Our approach illustrates the power of combining interferometry and high-resolution spectroscopy to constrain and calibrate stellar model atmospheres. The simultaneous agreement of the model atmosphere with our interferometric and spectroscopic data increases confidence in the reliability of the modelling of this star, while discrepancies at the detailed level of the high resolution spectra can be used to further improve the underlying model., Comment: 11 pages, 5 figures, accepted by A&A. Also available from http://www.aanda.org/articles/aa/pdf/forth/aa6032_06.pdf

We present the first interferometric NIR observations of the LBV ? Carinae with high spectral resolution. The observations were carried out with three 8.2 m VLTI Unit Telescopes in the K-band. The raw data are spectrally dispersed interferograms obtained with spectral resolutions of 1,500 (MR-K mode) and 12,000 (HR-K mode). The observations were performed in the wavelength range around both the He I 2.059 ?m and the Br? 2.166 ?m emission lines. The spectrally dispersed AMBER interferograms allow the investigation of the wavelength dependence of the visibility, differential phase, and closure phase of ? Car. In the K-band continuum, a diameter of 4.0+/-0.2 mas (Gaussian FWHM) was measured for ? Car's optically thick wind region, whereas the Br? and He I emission line regions are larger. If we fit Hillier et al. model visibilities to the observed AMBER visibilities, we obtain 50% encircled-energy diameters of 4.3, 6.5 and 9.6 mas in the 2.17 ?m continuum, the He I, and the Br?emission lines, respectively. In the continuum near the Br? line, an elongation along a position angle of 128° +/- 15° was found, consistent with previous VLTI/VINCI measurements. We find good agreement between the measured visibilities and the predictions of the radiative transfer model of Hillier et al. For the interpretation of the non-zero differential and closure phases measured within the Br? line, we present a simple geometric model of an inclined, latitude-dependent wind zone. Our observations support theoretical models of anisotropic winds from fast-rotating, luminous hot stars with enhanced high-velocity mass loss near the polar regions.

We present the results of the first mid-infrared interferometric observations of the Mira variable RRSco with the VLTI/MIDI, together with K-band observations using VLTI/VINCI.The uniform-disk diameter was found to be 18mas between 8 and 10μm, while it gradually increases at wavelengths longer than 10μm to reach 24mas at 13μm.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 10μm can be explained by an optically thin dust shell consisting of corundum and silicate grains.

On the way to the Extremely Large Telescopes (ELT) the Large Binocular Telescope (LBT) is an intermediate step. The two 8.4m mirrors create a masked aperture of 23m. LINC-NIRVANA is an instrument taking advantage of this opportunity. It will get, by means of Multi-Conjugated Adaptive Optics (MCAO), a moderate Strehl Ratio over a 2 arcmin field of view, which is used for Fizeau (imaging) interferometry in J,H and K. Several MCAO concepts, which are proposed for ELTs, will be proven with this instrument. Studies of sub-systems are done in the laboratory and the option to test them on sky are kept open. We will show the implementation of the MCAO concepts and control aspects of the instrument and present the road map to the final installation at LBT. Major milestones of LINC-NIRVANA, like preliminary design review or final design review are already done or in preparation. LINC-NIRVANA is one of the few MCAO instruments in the world which will see first light and go into operation within the next years.

LINC-NIRVANA is an imaging interferometer for the Large Binocular Telescope (LBT) and will make use of multi-conjugated adaptive optics (MCAO) with two 349 actuators deformable mirrors (DM), two 672 actuator deformable secondary mirrors and a total of 4 wavefront sensors (WFS) by using 8 or 12 natural guide stars each. The goal of the MCAO is to increase sky coverage and achieve a medium Strehl-ratio over the 2 arcmin field of view. To test the concepts and prototypes, a laboratory setup of one MCAO arm is being built. We present the layout of the MCAO prototype, planned and accomplished tests, especially for the used Xinetics DMs, and a possible setup for a test on sky with an existing 8m class telescope.

LINC-NIRVANA is a near-­infrared (1-­2.4 micron) beam-­combiner instrument for the Large Binocular Telescope (LBT). LINC-NIRVANA is being built by a consortium of groups at the Max-­Planck-­Institut fur Astronomie in Heidelberg, the Osservatorio Astrofisico di Arcetri in Florence, the Universitat zu Koln, and the Max-­Planck-­Institut fur Radioastronomie in Bonn. The MPI fur Radioastronomie is responsible for the near­-infrared detector for the fringe and flexure tracking system (FFTS). We describe the design and construction of the detector control electronics as well as the first laboratory measurements of performance parameters of the NIR detector for the fringe and flexure tracking system of the LBT LINC-NIRVANA instrument. This detector has to record LBT interferograms of suitable reference stars in the FOV at a frame rate of the order of 200 frames per second using, for example, 32 x 32-­pixel subframes. Moreover, special noise reduction techniques have to be applied. The fringe-­tracker interferograms are required for monitoring and closed-­loop correction of the atmospheric optical path difference of the two LBT wavefronts (see C. Straubmeier et al., "A fringe and flexure tracking system for LINC-NIRVANA: basic design and principle of operation"). We will describe our laboratory measurements of maximum frame rate, readout noise, photometric stability, and other important parameters together with first measurements of laboratory simulations of LBT interferograms.

We present near-infrared speckle interferometry of the OH/IR star OH 104.9+2.4 in the $K'$ band obtained with the 6m telescope of the Special Astrophysical Observatory (SAO). At a wavelength of λ = 2.12 micron the diffraction-limited resolution of 74 mas was attained. The reconstructed visibility reveals a spherically symmetric, circumstellar dust shell (CDS) surrounding the central star. The visibility function shows that the stellar contribution to the total flux at λ = 2.12 micron is less than ~50%, indicating a rather large optical depth of the CDS. The azimuthally averaged 1-dimensional Gaussian visibility fit yields a diameter of 47 +/- 3 mas (FHWM), which corresponds to 112 +/- 13 AU for an adopted distance of D = 2.38 +\- 0.24 kpc. To determine the structure and the properties of the CDS of OH 104.9+2.4, radiative transfer calculations using the code DUSTY were performed to simultaneously model its visibility and the spectral energy distribution (SED). We found that both the ISO spectrum and the visibility of OH 104.9+2.4 can be well reproduced by a radiative transfer model with an effective temperature T eff = 2500 +/- 500 K of the central source, a dust temperature T in = 1000 +/- 200 K at the inner shell boundary R in = 9.1 R star = 25.4 AU, an optical depth tau = 6.5 +/- 0.3 at 2.2 micron, and dust grain radii ranging from a min = 0.005 +/- 0.003 micron to a max = 0.2 +/- 0.02 micron with a power law with index -3.5. It was found that even minor changes in a max have a major impact on both the slope and the curvature of the visibility function, while the SED shows only minor changes. Our detailed analysis demonstrates the potential of dust shell modeling constrained by both the SED and visibilities.

AMBER (Astronomical Multiple BEam Recombiner) is a 3 aperture interferometric recombiner operating between 1 and 2.5 um, for the Very Large Telescope Interferometer (VLTI). The control software of the instrument, based on the VLT Common Software, has been written to comply with specific features of the AMBER hardware, such as the Infrared detector read out modes or piezo stage drivers, as well as with the very specific operation modes of an interferomtric instrument. In this respect, the AMBER control software was designed to insure that all operations, from the preparation of the observations to the control/command of the instrument during the observations, would be kept as simple as possible for the users and operators, opening the use of an interferometric instrument to the largest community of astronomers. Peculiar attention was given to internal checks and calibration procedures both to evaluate data quality in real time, and improve the successes of long term UV plane coverage observations.

LINC-NIRVANA is a Fizeau interferometer for the Large Binocular Telescope (LBT) doing imaging in the near infrared (J,H,K - band). Multi-conjugated adaptive optics is used to increase sky coverage and to get diffraction limited images over a 2 arcminute field of view. The control system consists of five independent loops, which are mediated through a master control. Due to the configuration, LINC-NIRVANA has no delay line like other interferometers. To remove residual atmospheric piston, the system must control both the primary and secondary mirrors, in addition to a third, dedicated piston mirror. This leads to a complex and interlocked control scheme and software. We will present parts of the instrument software design, which was developed in an object-oriented manner using UML. Several diagram types were used to structure the overall system and to evaluate the needs and interfaces of each sub-system to each other.

B[e] stars are among the most peculiar objects in the sky. This spectral type, characterised by allowed and forbidden emission lines, and a large infrared excess, does not represent an homogenous class of objects, but instead, a mix of stellar bodies seen in all evolutionary status. Among them, one can find Herbig stars, planetary nebulae central stars, interacting binaries, supermassive stars, and even "unclassified" B[e] stars: systems sharing properties of several of the above. Interferometry, by resolving the innermost regions of these stellar systems, enables us to reveal the true nature of these peculiar stars among the peculiar B[e] stars., Comment: Proceeding submitted to the editors, to be published in the conference proceeding

It is well known that the evolution of white dwarfs (WDs) depends sensitively on the question whether they have “thin” or “thick” envelopes of H and He (see Wood 1995). Standard evolutionary caluclations (e.g. Paczynksi 1971) show that at the tip of the Asymptotic Giant Branch the envelope masses are tightly correlated with the mass of the hydrogen exhausted core (≈ total mass). Accordingly, the masses of hydrogen, M H, and helium, M He, on top of the degenerate C/O interiors decrease by orders of magnitudes with increasing stellar mass. In contrast, many applications of WD calculations consider only single values of q H,He = log(M H,He/M *) asuming either “thick” or “thin” envelopes.