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Glindemann, Andreas; Algomedo, J.; Amestica, Rodrigo; Ballester, P.; Bauvir, Bertrand; Bugueño, E.; Correia, Serge; Delgado, Francisco; Delplancke, F.; Dérie, F.; Duhoux, Ph.; Folco, E. Di; Gennai, A.; Gilli, Bruno; Giordano, P.; Gitton, Ph.; Guisard, Stéphane; Housen, Nico; Huxley, Alexis; Kervella, P.; Kiekebusch, M.; Koehler, Betrand; Lévêque, S.; Longinotti, Antonio; Ménardi, Serge; Morel, S.; Paresce, Francesco; Duc, Than Phan; Richichi, A.; Schöller, M.; Tarenghi, M.; Wallander, Anders; Wittkowski, M.; Wilhelm, Rainer

doi:10.1023/a:1026145709077

Cited by 21 publications

(12 citation statements)

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“…The near-infrared K-band interferometric data of γ Sagittae were obtained with the ESO Very Large Telescope Interferometer (VLTI, Glindemann et al 2003), the instrument VINCI (Kervella et al 2003), and the two VLTI test siderostats on June 28, July 8, July 11, July 15, August 8, September 12, and September 18, 2002. These data are public commissioning data released from the VLTI 1 .…”

Section: Vlti/vinci Observationsmentioning

confidence: 99%

Tests of stellar model atmospheres by optical interferometry

Wittkowski¹,

Hummel

Aufdenberg

et al. 2006

A&A

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Context. Optical interferometry allows a measurement of the intensity profile across a stellar disc, leading to a direct test and calibration of theoretical model atmospheres as well as to a precise determination of fundamental stellar parameters. Aims. We present a comparison of the visual and near-infrared intensity profile of the M0 giant γ Sagittae to plane-parallel ATLAS 9 as well as to plane-parallel and spherical PHOENIX model atmospheres. Methods. We use previously described visual interferometric data obtained with the Navy Prototype Optical Interferometer (NPOI) in July 2000. We apply the recently developed technique of coherent integration, and thereby obtain visibility data of more spectral channels (526-852 nm) and with higher precision than before. In addition, we employ new measurements of the near-infrared K-band (∼2200 nm) diameter of γ Sagittae obtained with the instrument VINCI at the ESO VLT Interferometer (VLTI) in 2002. Results. The spherical PHOENIX model leads to a precise definition of the Rosseland angular diameter and a consistent high-precision diameter value for our NPOI and VLTI/VINCI data sets of Θ Ross = 6.06 ± 0.02 mas, with the Hipparcos parallax corresponding to R Ross = 55 ± 4 R , and with the bolometric flux corresponding to an effective temperature T eff = 3805 ± 55 K. Our visual visibility data close to the first minimum and in the second lobe constrain the limb-darkening effect and are generally consistent with the model atmosphere predictions. The visual closure phases exhibit a smooth transition between 0 and π. Conclusions. The agreement between the NPOI and VINCI diameter values increases the confidence in the model atmosphere predictions from optical to near-infrared wavelengths as well as in the calibration and accuracy of both interferometric facilities. The consistent night-by-night diameter values of VINCI give additional confidence in the given uncertainties. The closure phases suggest a slight deviation from circular symmetry, which may be due to surface features, an asymmetric extended layer, or a faint unknown companion.

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Section: Vlti/vinci Observationsmentioning

confidence: 99%

Tests of stellar model atmospheres by optical interferometry

Wittkowski¹,

Hummel

Aufdenberg

et al. 2006

A&A

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“…For a recent technical description of the VLTI, see for instance Glindemann et al (2003); for the VINCI instrument, see Kervella et al (2003Kervella et al ( , 2004.…”

Section: Vinci Observations and Data Reductionmentioning

confidence: 99%

Tests of stellar model atmospheres by optical interferometry

Wittkowski¹,

Aufdenberg

Driebe

et al. 2006

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Aims. We present coordinated near-infrared K-band interferometric and optical spectroscopic observations of the M 1.5 giant α Cet (Menkar) obtained with the instruments VINCI and UVES at the 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. Methods. 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 of R = 80 000-110 000 allows us to confront in detail observed and model-predicted profiles of atomic lines and molecular bands. Results. We show that our derived PHOENIX model atmosphere for Menkar is consistent with both the measured strength of the limbdarkening in the near-infrared K-band and the profiles of spectral bands around selected atomic lines and TiO bandheads from 370 nm to 1000 nm. At the detailed level of our high spectral resolution, however, noticeable discrepancies between observed and synthetic spectra exist. We obtain a high-precision Rosseland angular diameter of Θ Ross = 12.20 mas ± 0.04 mas. Together with the Hipparcos parallax of 14.82 mas ± 0.83 mas, it corresponds to a Rosseland radius of R Ross = 89 ± 5R , and together with the bolometric flux based on available spectrophotometry, to an effective temperature of T eff = 3795 K ± 70 K. The luminosity based on these values is L = 1460 L ± 300 L . Relying on stellar evolutionary tracks, these values correspond to a mass M = 2.3 M ± 0.2 M and a surface gravity log g = 0.9 ± 0.1 (cgs). Conclusions. 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.

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“…In this paper we present direct angular diameter measurements of four M dwarfs with spectral types ranging from M0V to M5.5V obtained with the Very Large Telescope Interferometer (VLTI) and two 8-meter-telescopes (Glindemann et al 2001). The first two sections describe the observations and the data reduction.…”

Section: Introductionmentioning

confidence: 99%

First radius measurements of very low mass stars with the VLTI

Ségransan

Kervella

Forveille

et al. 2003

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186

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Abstract. We present 4 very low mass stars radii measured with the VLTI using the 2.2 µm VINCI test instrument. The observations were carried out during the commissioning of the 104-meter-baseline with two 8-meter-telescopes. We measure angular diameters of 0.7-1.5 mas with accuracies of 0.04-0.11 mas, and for spectral type ranging from M0V to M5.5V. We determine an empirical mass-radius relation for M dwarfs based on all available radius measurements. The observed relation agrees well with theoretical models at the present accuracy level, with possible discrepancy around 0.5-0.8 M that needs to be confirmed. In the near future, dozens of M dwarfs radii will be measured with 0.1-1% accuracy, with the VLTI, thanks to the improvements expected from the near infrared instrument AMBER. This will bring strong observational constraints on both atmosphere and interior physics.

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Cited by 21 publications

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Tests of stellar model atmospheres by optical interferometry

Tests of stellar model atmospheres by optical interferometry

Tests of stellar model atmospheres by optical interferometry

First radius measurements of very low mass stars with the VLTI

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