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1. VEGA: Visible spEctroGraph and polArimeter for the CHARA array: principle and performance

Author

Mourard, D., Clausse, J. M., Marcotto, A., Perraut, K., Tallon-Bosc, I., Bério, Ph., Blazit, A., Bonneau, D., Bosio, S., Bresson, Y., Chesneau, O., Delaa, O., Hénault, F., Hughes, Y., Lagarde, S., Merlin, G., Roussel, A., Spang, A., Stee, Ph., Tallon, M., Antonelli, P., Foy, R., Kervella, P., Petrov, R., Thiebaut, E., Vakili, F., McAlister, H., ten Brummelaar, T., Sturmann, J., Sturmann, L., Turner, N., Farrington, C., Goldfinger, P. J., Mourard, D., Clausse, J. M., Marcotto, A., Perraut, K., Tallon-Bosc, I., Bério, Ph., Blazit, A., Bonneau, D., Bosio, S., Bresson, Y., Chesneau, O., Delaa, O., Hénault, F., Hughes, Y., Lagarde, S., Merlin, G., Roussel, A., Spang, A., Stee, Ph., Tallon, M., Antonelli, P., Foy, R., Kervella, P., Petrov, R., Thiebaut, E., Vakili, F., McAlister, H., ten Brummelaar, T., Sturmann, J., Sturmann, L., Turner, N., Farrington, C., and Goldfinger, P. J.

Abstract

Context. Among optical stellar interferometers, the CHARA Array located at Mt Wilson in California offers the potential of very long baselines (up to 330 m) and the prospect of coupling multiple beam combiners. This paper presents the principle and the measured performance of VEGA, Visible spEctroGraph and polArimeter installed in September 2007 at the coherent focus of the array.

Published
2009
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2. A binary engine fuelling HD 87643's complex circumstellar environment***

Author

Millour, F., Chesneau, O., Borges Fernandes, M., Meilland, A., Mars, G., Benoist, C., Thiébaut, E., Stee, P., Hofmann, K.-H., Baron, F., Young, J., Bendjoya, P., Carciofi, A., Domiciano de Souza, A., Driebe, T., Jankov, S., Kervella, P., Petrov, R. G., Robbe-Dubois, S., Vakili, F., Waters, L. B. F. M., Weigelt, G., Millour, F., Chesneau, O., Borges Fernandes, M., Meilland, A., Mars, G., Benoist, C., Thiébaut, E., Stee, P., Hofmann, K.-H., Baron, F., Young, J., Bendjoya, P., Carciofi, A., Domiciano de Souza, A., Driebe, T., Jankov, S., Kervella, P., Petrov, R. G., Robbe-Dubois, S., Vakili, F., Waters, L. B. F. M., and Weigelt, G.

Abstract

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.

Published
2009
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3. APIC

Author

Allouche, F., Glindemann, A., Aristidi, E., Vakili, F., Allouche, F., Glindemann, A., Aristidi, E., and Vakili, F.

Abstract

Context. For detecting and directly imaging exoplanets, coronagraphic methods are mandatory when the intensity ratio between a star and its orbiting planet can be as large as 106. In 1996, a concept of an achromatic interfero-coronagraph (AIC) was presented for detecting very faint stellar companions, such as exoplanets.

Published
2009
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4. A scene model of exosolar systems for use in planetary detection and characterisation simulations*

Author

Belu, A., Thiébaut, E., Ollivier, M., Lagache, G., Selsis, F., Vakili, F., Belu, A., Thiébaut, E., Ollivier, M., Lagache, G., Selsis, F., and Vakili, F.

Abstract

Context.Instrumental projects that will improve the direct optical finding and characterisation of exoplanets have advanced sufficiently to trigger organized investigation and development of corresponding signal processing algorithms. The first step is the availability of field-of-view (FOV) models. These can then be submitted to various instrumental models, which in turn produce simulated data, enabling the testing of processing algorithms.

Published
2007
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5. Direct constraint on the distance of γ2Velorum from AMBER/VLTI observations*

Author

Millour, F., Petrov, R. G., Chesneau, O., Bonneau, D., Dessart, L., Bechet, C., Tallon-Bosc, I., Tallon, M., Thiébaut, E., Vakili, F., Malbet, F., Mourard, D., Antonelli, P., Beckmann, U., Bresson, Y., Chelli, A., Dugué, M., Duvert, G., Gennari, S., Glück, L., Kern, P., Lagarde, S., Le Coarer, E., Lisi, F., Perraut, K., Puget, P., Rantakyrö, F., Robbe-Dubois, S., Roussel, A., Tatulli, E., Weigelt, G., Zins, G., Accardo, M., Acke, B., Agabi, K., Altariba, E., Arezki, B., Aristidi, E., Baffa, C., Behrend, J., Blöcker, T., Bonhomme, S., Busoni, S., Cassaing, F., Clausse, J.-M., Colin, J., Connot, C., Delboulbé, A., Domiciano de Souza, A., Driebe, T., Feautrier, P., Ferruzzi, D., Forveille, T., Fossat, E., Foy, R., Fraix-Burnet, D., Gallardo, A., Giani, E., Gil, C., Glentzlin, A., Heiden, M., Heininger, M., Hernandez Utrera, O., Hofmann, K.-H., Kamm, D., Kiekebusch, M., Kraus, S., Le Contel, D., Le Contel, J.-M., Lesourd, T., Lopez, B., Lopez, M., Magnard, Y., Marconi, A., Mars, G., Martinot-Lagarde, G., Mathias, P., Mège, P., Monin, J.-L., Mouillet, D., Nussbaum, E., Ohnaka, K., Pacheco, J., Perrier, C., Rabbia, Y., Rebattu, S., Reynaud, F., Richichi, A., Robini, A., Sacchettini, M., Schertl, D., Schöller, M., Solscheid, W., Spang, A., Stee, P., Stefanini, P., Tasso, D., Testi, L., von der Lühe, O., Valtier, J.-C., Vannier, M., Ventura, N., Millour, F., Petrov, R. G., Chesneau, O., Bonneau, D., Dessart, L., Bechet, C., Tallon-Bosc, I., Tallon, M., Thiébaut, E., Vakili, F., Malbet, F., Mourard, D., Antonelli, P., Beckmann, U., Bresson, Y., Chelli, A., Dugué, M., Duvert, G., Gennari, S., Glück, L., Kern, P., Lagarde, S., Le Coarer, E., Lisi, F., Perraut, K., Puget, P., Rantakyrö, F., Robbe-Dubois, S., Roussel, A., Tatulli, E., Weigelt, G., Zins, G., Accardo, M., Acke, B., Agabi, K., Altariba, E., Arezki, B., Aristidi, E., Baffa, C., Behrend, J., Blöcker, T., Bonhomme, S., Busoni, S., Cassaing, F., Clausse, J.-M., Colin, J., Connot, C., Delboulbé, A., Domiciano de Souza, A., Driebe, T., Feautrier, P., Ferruzzi, D., Forveille, T., Fossat, E., Foy, R., Fraix-Burnet, D., Gallardo, A., Giani, E., Gil, C., Glentzlin, A., Heiden, M., Heininger, M., Hernandez Utrera, O., Hofmann, K.-H., Kamm, D., Kiekebusch, M., Kraus, S., Le Contel, D., Le Contel, J.-M., Lesourd, T., Lopez, B., Lopez, M., Magnard, Y., Marconi, A., Mars, G., Martinot-Lagarde, G., Mathias, P., Mège, P., Monin, J.-L., Mouillet, D., Nussbaum, E., Ohnaka, K., Pacheco, J., Perrier, C., Rabbia, Y., Rebattu, S., Reynaud, F., Richichi, A., Robini, A., Sacchettini, M., Schertl, D., Schöller, M., Solscheid, W., Spang, A., Stee, P., Stefanini, P., Tasso, D., Testi, L., von der Lühe, O., Valtier, J.-C., Vannier, M., and Ventura, N.

Abstract

Context.Interferometry can provide spatially resolvedobservations of massive star binary systems and their colliding winds, which thus far have been studied mostly with spatially unresolvedobservations.

Published
2007
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6. AMBER, the near-infrared spectro-interferometric three-telescope VLTI instrument

Author

Petrov, R. G., Malbet, F., Weigelt, G., Antonelli, P., Beckmann, U., Bresson, Y., Chelli, A., Dugué, M., Duvert, G., Gennari, S., Glück, L., Kern, P., Lagarde, S., Le Coarer, E., Lisi, F., Millour, F., Perraut, K., Puget, P., Rantakyrö, F., Robbe-Dubois, S., Roussel, A., Salinari, P., Tatulli, E., Zins, G., Accardo, M., Acke, B., Agabi, K., Altariba, E., Arezki, B., Aristidi, E., Baffa, C., Behrend, J., Blöcker, T., Bonhomme, S., Busoni, S., Cassaing, F., Clausse, J.-M., Colin, J., Connot, C., Delboulbé, A., Domiciano de Souza, A., Driebe, T., Feautrier, P., Ferruzzi, D., Forveille, T., Fossat, E., Foy, R., Fraix-Burnet, D., Gallardo, A., Giani, E., Gil, C., Glentzlin, A., Heiden, M., Heininger, M., Hernandez Utrera, O., Hofmann, K.-H., Kamm, D., Kiekebusch, M., Kraus, S., Le Contel, D., Le Contel, J.-M., Lesourd, T., Lopez, B., Lopez, M., Magnard, Y., Marconi, A., Mars, G., Martinot-Lagarde, G., Mathias, P., Mège, P., Monin, J.-L., Mouillet, D., Mourard, D., Nussbaum, E., Ohnaka, K., Pacheco, J., Perrier, C., Rabbia, Y., Rebattu, S., Reynaud, F., Richichi, A., Robini, A., Sacchettini, M., Schertl, D., Schöller, M., Solscheid, W., Spang, A., Stee, P., Stefanini, P., Tallon, M., Tallon-Bosc, I., Tasso, D., Testi, L., Vakili, F., von der Lühe, O., Valtier, J.-C., Vannier, M., Ventura, N., Petrov, R. G., Malbet, F., Weigelt, G., Antonelli, P., Beckmann, U., Bresson, Y., Chelli, A., Dugué, M., Duvert, G., Gennari, S., Glück, L., Kern, P., Lagarde, S., Le Coarer, E., Lisi, F., Millour, F., Perraut, K., Puget, P., Rantakyrö, F., Robbe-Dubois, S., Roussel, A., Salinari, P., Tatulli, E., Zins, G., Accardo, M., Acke, B., Agabi, K., Altariba, E., Arezki, B., Aristidi, E., Baffa, C., Behrend, J., Blöcker, T., Bonhomme, S., Busoni, S., Cassaing, F., Clausse, J.-M., Colin, J., Connot, C., Delboulbé, A., Domiciano de Souza, A., Driebe, T., Feautrier, P., Ferruzzi, D., Forveille, T., Fossat, E., Foy, R., Fraix-Burnet, D., Gallardo, A., Giani, E., Gil, C., Glentzlin, A., Heiden, M., Heininger, M., Hernandez Utrera, O., Hofmann, K.-H., Kamm, D., Kiekebusch, M., Kraus, S., Le Contel, D., Le Contel, J.-M., Lesourd, T., Lopez, B., Lopez, M., Magnard, Y., Marconi, A., Mars, G., Martinot-Lagarde, G., Mathias, P., Mège, P., Monin, J.-L., Mouillet, D., Mourard, D., Nussbaum, E., Ohnaka, K., Pacheco, J., Perrier, C., Rabbia, Y., Rebattu, S., Reynaud, F., Richichi, A., Robini, A., Sacchettini, M., Schertl, D., Schöller, M., Solscheid, W., Spang, A., Stee, P., Stefanini, P., Tallon, M., Tallon-Bosc, I., Tasso, D., Testi, L., Vakili, F., von der Lühe, O., Valtier, J.-C., Vannier, M., and Ventura, N.

Abstract

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).

Published
2007
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7. AMBER/VLTI interferometric observations of the recurrent Nova RS Ophiuchii 5.5 days after outburst*

Author

Chesneau, O., Nardetto, N., Millour, F., Hummel, C., Domiciano de Souza, A., Bonneau, D., Vannier, M., Rantakyrö, F., Spang, A., Malbet, F., Mourard, D., Bode, M. F., O'Brien, T. J., Skinner, G., Petrov, R. G., Stee, P., Tatulli, E., Vakili, F., Chesneau, O., Nardetto, N., Millour, F., Hummel, C., Domiciano de Souza, A., Bonneau, D., Vannier, M., Rantakyrö, F., Spang, A., Malbet, F., Mourard, D., Bode, M. F., O'Brien, T. J., Skinner, G., Petrov, R. G., Stee, P., Tatulli, E., and Vakili, F.

Abstract

Aims.We report on spectrally dispersed interferometric AMBER/VLTI observations of the recurrent nova RS Ophfive days after the discovery of its outburst on 2006 Feb. 12.

Published
2007
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8. Constraining the wind launching region in Herbig Ae stars: AMBER/VLTI spectroscopy of HD 104237 *

Author

Tatulli, E., Isella, A., Natta, A., Testi, L., Marconi, A., Malbet, F., Stee, P., Petrov, R. G., Millour, F., Chelli, A., Duvert, G., Antonelli, P., Beckmann, U., Bresson, Y., Dugué, M., Gennari, S., Glück, L., Kern, P., Lagarde, S., Le Coarer, E., Lisi, F., Perraut, K., Puget, P., Rantakyrö, F., Robbe-Dubois, S., Roussel, A., Weigelt, G., Zins, G., Accardo, M., Acke, B., Agabi, K., Altariba, E., Arezki, B., Aristidi, E., Baffa, C., Behrend, J., Blöcker, T., Bonhomme, S., Busoni, S., Cassaing, F., Clausse, J.-M., Colin, J., Connot, C., Delboulbé, A., Domiciano de Souza, A., Driebe, T., Feautrier, P., Ferruzzi, D., Forveille, T., Fossat, E., Foy, R., Fraix-Burnet, D., Gallardo, A., Giani, E., Gil, C., Glentzlin, A., Heiden, M., Heininger, M., Hernandez Utrera, O., Hofmann, K.-H., Kamm, D., Kiekebusch, M., Kraus, S., Le Contel, D., Le Contel, J.-M., Lesourd, T., Lopez, B., Lopez, M., Magnard, Y., Mars, G., Martinot-Lagarde, G., Mathias, P., Mège, P., Monin, J.-L., Mouillet, D., Mourard, D., Nussbaum, E., Ohnaka, K., Pacheco, J., Perrier, C., Rabbia, Y., Rebattu, S., Reynaud, F., Richichi, A., Robini, A., Sacchettini, M., Schertl, D., Schöller, M., Solscheid, W., Spang, A., Stefanini, P., Tallon, M., Tallon-Bosc, I., Tasso, D., Vakili, F., von der Lühe, O., Valtier, J.-C., Vannier, M., Ventura, N., Tatulli, E., Isella, A., Natta, A., Testi, L., Marconi, A., Malbet, F., Stee, P., Petrov, R. G., Millour, F., Chelli, A., Duvert, G., Antonelli, P., Beckmann, U., Bresson, Y., Dugué, M., Gennari, S., Glück, L., Kern, P., Lagarde, S., Le Coarer, E., Lisi, F., Perraut, K., Puget, P., Rantakyrö, F., Robbe-Dubois, S., Roussel, A., Weigelt, G., Zins, G., Accardo, M., Acke, B., Agabi, K., Altariba, E., Arezki, B., Aristidi, E., Baffa, C., Behrend, J., Blöcker, T., Bonhomme, S., Busoni, S., Cassaing, F., Clausse, J.-M., Colin, J., Connot, C., Delboulbé, A., Domiciano de Souza, A., Driebe, T., Feautrier, P., Ferruzzi, D., Forveille, T., Fossat, E., Foy, R., Fraix-Burnet, D., Gallardo, A., Giani, E., Gil, C., Glentzlin, A., Heiden, M., Heininger, M., Hernandez Utrera, O., Hofmann, K.-H., Kamm, D., Kiekebusch, M., Kraus, S., Le Contel, D., Le Contel, J.-M., Lesourd, T., Lopez, B., Lopez, M., Magnard, Y., Mars, G., Martinot-Lagarde, G., Mathias, P., Mège, P., Monin, J.-L., Mouillet, D., Mourard, D., Nussbaum, E., Ohnaka, K., Pacheco, J., Perrier, C., Rabbia, Y., Rebattu, S., Reynaud, F., Richichi, A., Robini, A., Sacchettini, M., Schertl, D., Schöller, M., Solscheid, W., Spang, A., Stefanini, P., Tallon, M., Tallon-Bosc, I., Tasso, D., Vakili, F., von der Lühe, O., Valtier, J.-C., Vannier, M., and Ventura, N.

Abstract

Aims.We investigate the origin of the ${\rm Br}\gamma$emission of the Herbig Ae star HD 104237 on Astronomical Unit (AU) scales.

Published
2007
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9. Disk and wind interaction in the young stellar object MWC 297spatially resolved with AMBER/VLTI *

Author

Malbet, F., Benisty, M., de Wit, W.-J., Kraus, S., Meilland, A., Millour, F., Tatulli, E., Berger, J.-P., Chesneau, O., Hofmann, K.-H., Isella, A., Natta, A., Petrov, R. G., Preibisch, T., Stee, P., Testi, L., Weigelt, G., Antonelli, P., Beckmann, U., Bresson, Y., Chelli, A., Dugué, M., Duvert, G., Gennari, S., Glück, L., Kern, P., Lagarde, S., Le Coarer, E., Lisi, F., Perraut, K., Puget, P., Rantakyrö, F., Robbe-Dubois, S., Roussel, A., Zins, G., Accardo, M., Acke, B., Agabi, K., Altariba, E., Arezki, B., Aristidi, E., Baffa, C., Behrend, J., Blöcker, T., Bonhomme, S., Busoni, S., Cassaing, F., Clausse, J.-M., Colin, J., Connot, C., Delboulbé, A., Domiciano de Souza, A., Driebe, T., Feautrier, P., Ferruzzi, D., Forveille, T., Fossat, E., Foy, R., Fraix-Burnet, D., Gallardo, A., Giani, E., Gil, C., Glentzlin, A., Heiden, M., Heininger, M., Hernandez Utrera, O., Kamm, D., Kiekebusch, M., Le Contel, D., Le Contel, J.-M., Lesourd, T., Lopez, B., Lopez, M., Magnard, Y., Marconi, A., Mars, G., Martinot-Lagarde, G., Mathias, P., Mège, P., Monin, J.-L., Mouillet, D., Mourard, D., Nussbaum, E., Ohnaka, K., Pacheco, J., Perrier, C., Rabbia, Y., Rebattu, S., Reynaud, F., Richichi, A., Robini, A., Sacchettini, M., Schertl, D., Schöller, M., Solscheid, W., Spang, A., Stefanini, P., Tallon, M., Tallon-Bosc, I., Tasso, D., Vakili, F., von der Lühe, O., Valtier, J.-C., Vannier, M., Ventura, N., Malbet, F., Benisty, M., de Wit, W.-J., Kraus, S., Meilland, A., Millour, F., Tatulli, E., Berger, J.-P., Chesneau, O., Hofmann, K.-H., Isella, A., Natta, A., Petrov, R. G., Preibisch, T., Stee, P., Testi, L., Weigelt, G., Antonelli, P., Beckmann, U., Bresson, Y., Chelli, A., Dugué, M., Duvert, G., Gennari, S., Glück, L., Kern, P., Lagarde, S., Le Coarer, E., Lisi, F., Perraut, K., Puget, P., Rantakyrö, F., Robbe-Dubois, S., Roussel, A., Zins, G., Accardo, M., Acke, B., Agabi, K., Altariba, E., Arezki, B., Aristidi, E., Baffa, C., Behrend, J., Blöcker, T., Bonhomme, S., Busoni, S., Cassaing, F., Clausse, J.-M., Colin, J., Connot, C., Delboulbé, A., Domiciano de Souza, A., Driebe, T., Feautrier, P., Ferruzzi, D., Forveille, T., Fossat, E., Foy, R., Fraix-Burnet, D., Gallardo, A., Giani, E., Gil, C., Glentzlin, A., Heiden, M., Heininger, M., Hernandez Utrera, O., Kamm, D., Kiekebusch, M., Le Contel, D., Le Contel, J.-M., Lesourd, T., Lopez, B., Lopez, M., Magnard, Y., Marconi, A., Mars, G., Martinot-Lagarde, G., Mathias, P., Mège, P., Monin, J.-L., Mouillet, D., Mourard, D., Nussbaum, E., Ohnaka, K., Pacheco, J., Perrier, C., Rabbia, Y., Rebattu, S., Reynaud, F., Richichi, A., Robini, A., Sacchettini, M., Schertl, D., Schöller, M., Solscheid, W., Spang, A., Stefanini, P., Tallon, M., Tallon-Bosc, I., Tasso, D., Vakili, F., von der Lühe, O., Valtier, J.-C., Vannier, M., and Ventura, N.

Abstract

The young stellar object MWC 297is an embedded B1.5Ve star exhibiting strong hydrogen emission lines and a strong near-infrared continuum excess. This object has been observed with the VLT interferometer equipped with the AMBER instrument during its first commissioning run. AMBER/VLTI is currently the only near infrared interferometer that can observe spectrally dispersed visibilities. MWC 297has been spatially resolved in the continuum with a visibility of $0.50^{+0.08}_{-0.10}$as well as in the Brγemission line where the visibility decreases to $0.33\pm0.06$. This change in the visibility with wavelength can be interpreted by the presence of an optically thick disk responsible for the visibility in the continuum and of a stellar wind traced by the Brγemission line and whose apparent size is 40% larger. We validate this interpretation by building a model of the stellar environment that combines a geometrically thin, optically thick accretion disk model consisting of gas and dust, and a latitude-dependent stellar wind outflowing above the disk surface. The continuum emission and visibilities obtained from this model are fully consistent with the interferometric AMBER data. They agree also with existing optical, near-infrared spectra and other broad-band near-infrared interferometric visibilities. We also reproduce the shape of the visibilities in the Brγline as well as the profile of this line obtained at an higher spectral resolution with the VLT/ISAAC spectrograph, and those of the Hαand Hβlines. The disk and wind models yield a consistent inclination of the system of approximately 20°. A picture emerges in which MWC 297is surrounded by an equatorial flat disk that is possibly still accreting and an outflowing wind that has a much higher velocity in the polar region than at the equator. The AMBER/VLTI unique capability of measuring spectral visibilities therefore allows us for the first time to compare the apparent geometry of a wind with the disk structure in a young stellar system.

Published
2007
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10. Near-infrared interferometry of ηCarinaewith spectral resolutions of 1 500 and 12 000 using AMBER/VLTI*

Author

Weigelt, G., Kraus, S., Driebe, T., Petrov, R. G., Hofmann, K.-H., Millour, F., Chesneau, O., Schertl, D., Malbet, F., Hillier, D. J., Gull, T., Davidson, K., Domiciano de Souza, A., Antonelli, P., Beckmann, U., Bresson, Y., Chelli, A., Dugué, M., Duvert, G., Gennari, S., Glück, L., Kern, P., Lagarde, S., Le Coarer, E., Lisi, F., Perraut, K., Puget, P., Rantakyrö, F., Robbe-Dubois, S., Roussel, A., Tatulli, E., Zins, G., Accardo, M., Acke, B., Agabi, K., Altariba, E., Arezki, B., Aristidi, E., Baffa, C., Behrend, J., Blöcker, T., Bonhomme, S., Busoni, S., Cassaing, F., Clausse, J.-M., Colin, J., Connot, C., Delboulbé, A., Feautrier, P., Ferruzzi, D., Forveille, T., Fossat, E., Foy, R., Fraix-Burnet, D., Gallardo, A., Giani, E., Gil, C., Glentzlin, A., Heiden, M., Heininger, M., Hernandez Utrera, O., Kamm, D., Kiekebusch, M., Le Contel, D., Le Contel, J.-M., Lesourd, T., Lopez, B., Lopez, M., Magnard, Y., Marconi, A., Mars, G., Martinot-Lagarde, G., Mathias, P., Mège, P., Monin, J.-L., Mouillet, D., Mourard, D., Nussbaum, E., Ohnaka, K., Pacheco, J., Perrier, C., Rabbia, Y., Rebattu, S., Reynaud, F., Richichi, A., Robini, A., Sacchettini, M., Schöller, M., Solscheid, W., Spang, A., Stee, P., Stefanini, P., Tallon, M., Tallon-Bosc, I., Tasso, D., Testi, L., Vakili, F., von der Lühe, O., Valtier, J.-C., Vannier, M., Ventura, N., Weis, K., Wittkowski, M., Weigelt, G., Kraus, S., Driebe, T., Petrov, R. G., Hofmann, K.-H., Millour, F., Chesneau, O., Schertl, D., Malbet, F., Hillier, D. J., Gull, T., Davidson, K., Domiciano de Souza, A., Antonelli, P., Beckmann, U., Bresson, Y., Chelli, A., Dugué, M., Duvert, G., Gennari, S., Glück, L., Kern, P., Lagarde, S., Le Coarer, E., Lisi, F., Perraut, K., Puget, P., Rantakyrö, F., Robbe-Dubois, S., Roussel, A., Tatulli, E., Zins, G., Accardo, M., Acke, B., Agabi, K., Altariba, E., Arezki, B., Aristidi, E., Baffa, C., Behrend, J., Blöcker, T., Bonhomme, S., Busoni, S., Cassaing, F., Clausse, J.-M., Colin, J., Connot, C., Delboulbé, A., Feautrier, P., Ferruzzi, D., Forveille, T., Fossat, E., Foy, R., Fraix-Burnet, D., Gallardo, A., Giani, E., Gil, C., Glentzlin, A., Heiden, M., Heininger, M., Hernandez Utrera, O., Kamm, D., Kiekebusch, M., Le Contel, D., Le Contel, J.-M., Lesourd, T., Lopez, B., Lopez, M., Magnard, Y., Marconi, A., Mars, G., Martinot-Lagarde, G., Mathias, P., Mège, P., Monin, J.-L., Mouillet, D., Mourard, D., Nussbaum, E., Ohnaka, K., Pacheco, J., Perrier, C., Rabbia, Y., Rebattu, S., Reynaud, F., Richichi, A., Robini, A., Sacchettini, M., Schöller, M., Solscheid, W., Spang, A., Stee, P., Stefanini, P., Tallon, M., Tallon-Bosc, I., Tasso, D., Testi, L., Vakili, F., von der Lühe, O., Valtier, J.-C., Vannier, M., Ventura, N., Weis, K., and Wittkowski, M.

Abstract

Aims.We present the first NIR spectro-interferometryof the LBV ηCarinae. The observations were performed with the AMBER instrument of the ESO Very Large Telescope Interferometer(VLTI) using baselines from 42 to 89 m. The aim of this work is to study the wavelength dependence of ηCar's optically thick wind region with a high spatial resolution of 5 mas (11 AU) and high spectral resolution.

Published
2007
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11. An asymmetry detected in the disk of κCanis Majoriswith AMBER/VLTI *

Author

Meilland, A., Millour, F., Stee, P., Domiciano de Souza, A., Petrov, R. G., Mourard, D., Jankov, S., Robbe-Dubois, S., Spang, A., Aristidi, E., Antonelli, P., Beckmann, U., Bresson, Y., Chelli, A., Dugué, M., Duvert, G., Gennari, S., Glück, L., Kern, P., Lagarde, S., Le Coarer, E., Lisi, F., Malbet, F., Perraut, K., Puget, P., Rantakyrö, F., Roussel, A., Tatulli, E., Weigelt, G., Zins, G., Accardo, M., Acke, B., Agabi, K., Altariba, E., Arezki, B., Baffa, C., Behrend, J., Blöcker, T., Bonhomme, S., Busoni, S., Cassaing, F., Clausse, J.-M., Colin, J., Connot, C., Delboulbé, A., Driebe, T., Feautrier, P., Ferruzzi, D., Forveille, T., Fossat, E., Foy, R., Fraix-Burnet, D., Gallardo, A., Giani, E., Gil, C., Glentzlin, A., Heiden, M., Heininger, M., Hernandez Utrera, O., Hofmann, K.-H., Kamm, D., Kiekebusch, M., Kraus, S., Le Contel, D., Le Contel, J.-M., Lesourd, T., Lopez, B., Lopez, M., Magnard, Y., Marconi, A., Mars, G., Martinot-Lagarde, G., Mathias, P., Mège, P., Monin, J.-L., Mouillet, D., Nussbaum, E., Ohnaka, K., Pacheco, J., Perrier, C., Rabbia, Y., Rebattu, S., Reynaud, F., Richichi, A., Robini, A., Sacchettini, M., Schertl, D., Schöller, M., Solscheid, W., Stefanini, P., Tallon, M., Tallon-Bosc, I., Tasso, D., Testi, L., Vakili, F., von der Lühe, O., Valtier, J.-C., Vannier, M., Ventura, N., Meilland, A., Millour, F., Stee, P., Domiciano de Souza, A., Petrov, R. G., Mourard, D., Jankov, S., Robbe-Dubois, S., Spang, A., Aristidi, E., Antonelli, P., Beckmann, U., Bresson, Y., Chelli, A., Dugué, M., Duvert, G., Gennari, S., Glück, L., Kern, P., Lagarde, S., Le Coarer, E., Lisi, F., Malbet, F., Perraut, K., Puget, P., Rantakyrö, F., Roussel, A., Tatulli, E., Weigelt, G., Zins, G., Accardo, M., Acke, B., Agabi, K., Altariba, E., Arezki, B., Baffa, C., Behrend, J., Blöcker, T., Bonhomme, S., Busoni, S., Cassaing, F., Clausse, J.-M., Colin, J., Connot, C., Delboulbé, A., Driebe, T., Feautrier, P., Ferruzzi, D., Forveille, T., Fossat, E., Foy, R., Fraix-Burnet, D., Gallardo, A., Giani, E., Gil, C., Glentzlin, A., Heiden, M., Heininger, M., Hernandez Utrera, O., Hofmann, K.-H., Kamm, D., Kiekebusch, M., Kraus, S., Le Contel, D., Le Contel, J.-M., Lesourd, T., Lopez, B., Lopez, M., Magnard, Y., Marconi, A., Mars, G., Martinot-Lagarde, G., Mathias, P., Mège, P., Monin, J.-L., Mouillet, D., Nussbaum, E., Ohnaka, K., Pacheco, J., Perrier, C., Rabbia, Y., Rebattu, S., Reynaud, F., Richichi, A., Robini, A., Sacchettini, M., Schertl, D., Schöller, M., Solscheid, W., Stefanini, P., Tallon, M., Tallon-Bosc, I., Tasso, D., Testi, L., Vakili, F., von der Lühe, O., Valtier, J.-C., Vannier, M., and Ventura, N.

Abstract

Aims.We study the geometry and kinematics of the circumstellar environment of the Be star κCMa in the Brγemission line and its nearby continuum.

Published
2007
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12. Optical configuration and analysis of the AMBER/VLTI instrument

Author

Robbe-Dubois, S., Lagarde, S., Petrov, R. G., Lisi, F., Beckmann, U., Antonelli, P., Bresson, Y., Martinot-Lagarde, G., Roussel, A., Salinari, P., Vannier, M., Chelli, A., Dugué, M., Duvert, G., Gennari, S., Glück, L., Kern, P., Le Coarer, E., Malbet, F., Millour, F., Perraut, K., Puget, P., Rantakyrö, F., Tatulli, E., Weigelt, G., Zins, G., Accardo, M., Acke, B., Agabi, K., Altariba, E., Arezki, B., Aristidi, E., Baffa, C., Behrend, J., Blöcker, T., Bonhomme, S., Busoni, S., Cassaing, F., Clausse, J.-M., Colin, J., Connot, C., Delage, L., Delboulbé, A., Domiciano de Souza, A., Driebe, T., Feautrier, P., Ferruzzi, D., Forveille, T., Fossat, E., Foy, R., Fraix-Burnet, D., Gallardo, A., Giani, E., Gil, C., Glentzlin, A., Heiden, M., Heininger, M., Hernandez Utrera, O., Hofmann, K.-H., Kamm, D., Kiekebusch, M., Kraus, S., Le Contel, D., Le Contel, J.-M., Lesourd, T., Lopez, B., Lopez, M., Magnard, Y., Marconi, A., Mars, G., Mathias, P., Mège, P., Monin, J.-L., Mouillet, D., Mourard, D., Nussbaum, E., Ohnaka, K., Pacheco, J., Perrier, C., Rabbia, Y., Rebattu, S., Reynaud, F., Richichi, A., Robini, A., Sacchettini, M., Schertl, D., Schöller, M., Solscheid, W., Spang, A., Stee, P., Stefanini, P., Tallon, M., Tallon-Bosc, I., Tasso, D., Testi, L., Vakili, F., von der Lühe, O., Valtier, J.-C., Ventura, N., Robbe-Dubois, S., Lagarde, S., Petrov, R. G., Lisi, F., Beckmann, U., Antonelli, P., Bresson, Y., Martinot-Lagarde, G., Roussel, A., Salinari, P., Vannier, M., Chelli, A., Dugué, M., Duvert, G., Gennari, S., Glück, L., Kern, P., Le Coarer, E., Malbet, F., Millour, F., Perraut, K., Puget, P., Rantakyrö, F., Tatulli, E., Weigelt, G., Zins, G., Accardo, M., Acke, B., Agabi, K., Altariba, E., Arezki, B., Aristidi, E., Baffa, C., Behrend, J., Blöcker, T., Bonhomme, S., Busoni, S., Cassaing, F., Clausse, J.-M., Colin, J., Connot, C., Delage, L., Delboulbé, A., Domiciano de Souza, A., Driebe, T., Feautrier, P., Ferruzzi, D., Forveille, T., Fossat, E., Foy, R., Fraix-Burnet, D., Gallardo, A., Giani, E., Gil, C., Glentzlin, A., Heiden, M., Heininger, M., Hernandez Utrera, O., Hofmann, K.-H., Kamm, D., Kiekebusch, M., Kraus, S., Le Contel, D., Le Contel, J.-M., Lesourd, T., Lopez, B., Lopez, M., Magnard, Y., Marconi, A., Mars, G., Mathias, P., Mège, P., Monin, J.-L., Mouillet, D., Mourard, D., Nussbaum, E., Ohnaka, K., Pacheco, J., Perrier, C., Rabbia, Y., Rebattu, S., Reynaud, F., Richichi, A., Robini, A., Sacchettini, M., Schertl, D., Schöller, M., Solscheid, W., Spang, A., Stee, P., Stefanini, P., Tallon, M., Tallon-Bosc, I., Tasso, D., Testi, L., Vakili, F., von der Lühe, O., Valtier, J.-C., and Ventura, N.

Abstract

Aims.This paper describes the design goals and engineering efforts that led to the realization of AMBER (Astronomical Multi BEam combineR) and to the achievement of its present performance.

Published
2007
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13. Interferometric data reduction with AMBER/VLTI. Principle, estimators, and illustration *

Author

Tatulli, E., Millour, F., Chelli, A., Duvert, G., Acke, B., Hernandez Utrera, O., Hofmann, K.-H., Kraus, S., Malbet, F., Mège, P., Petrov, R. G., Vannier, M., Zins, G., Antonelli, P., Beckmann, U., Bresson, Y., Dugué, M., Gennari, S., Glück, L., Kern, P., Lagarde, S., Le Coarer, E., Lisi, F., Perraut, K., Puget, P., Rantakyrö, F., Robbe-Dubois, S., Roussel, A., Weigelt, G., Accardo, M., Agabi, K., Altariba, E., Arezki, B., Aristidi, E., Baffa, C., Behrend, J., Blöcker, T., Bonhomme, S., Busoni, S., Cassaing, F., Clausse, J.-M., Colin, J., Connot, C., Delboulbé, A., Domiciano de Souza, A., Driebe, T., Feautrier, P., Ferruzzi, D., Forveille, T., Fossat, E., Foy, R., Fraix-Burnet, D., Gallardo, A., Giani, E., Gil, C., Glentzlin, A., Heiden, M., Heininger, M., Kamm, D., Kiekebusch, M., Le Contel, D., Le Contel, J.-M., Lesourd, T., Lopez, B., Lopez, M., Magnard, Y., Marconi, A., Mars, G., Martinot-Lagarde, G., Mathias, P., Monin, J.-L., Mouillet, D., Mourard, D., Nussbaum, E., Ohnaka, K., Pacheco, J., Perrier, C., Rabbia, Y., Rebattu, S., Reynaud, F., Richichi, A., Robini, A., Sacchettini, M., Schertl, D., Schöller, M., Solscheid, W., Spang, A., Stee, P., Stefanini, P., Tallon, M., Tallon-Bosc, I., Tasso, D., Testi, L., Vakili, F., von der Lühe, O., Valtier, J.-C., Ventura, N., Tatulli, E., Millour, F., Chelli, A., Duvert, G., Acke, B., Hernandez Utrera, O., Hofmann, K.-H., Kraus, S., Malbet, F., Mège, P., Petrov, R. G., Vannier, M., Zins, G., Antonelli, P., Beckmann, U., Bresson, Y., Dugué, M., Gennari, S., Glück, L., Kern, P., Lagarde, S., Le Coarer, E., Lisi, F., Perraut, K., Puget, P., Rantakyrö, F., Robbe-Dubois, S., Roussel, A., Weigelt, G., Accardo, M., Agabi, K., Altariba, E., Arezki, B., Aristidi, E., Baffa, C., Behrend, J., Blöcker, T., Bonhomme, S., Busoni, S., Cassaing, F., Clausse, J.-M., Colin, J., Connot, C., Delboulbé, A., Domiciano de Souza, A., Driebe, T., Feautrier, P., Ferruzzi, D., Forveille, T., Fossat, E., Foy, R., Fraix-Burnet, D., Gallardo, A., Giani, E., Gil, C., Glentzlin, A., Heiden, M., Heininger, M., Kamm, D., Kiekebusch, M., Le Contel, D., Le Contel, J.-M., Lesourd, T., Lopez, B., Lopez, M., Magnard, Y., Marconi, A., Mars, G., Martinot-Lagarde, G., Mathias, P., Monin, J.-L., Mouillet, D., Mourard, D., Nussbaum, E., Ohnaka, K., Pacheco, J., Perrier, C., Rabbia, Y., Rebattu, S., Reynaud, F., Richichi, A., Robini, A., Sacchettini, M., Schertl, D., Schöller, M., Solscheid, W., Spang, A., Stee, P., Stefanini, P., Tallon, M., Tallon-Bosc, I., Tasso, D., Testi, L., Vakili, F., von der Lühe, O., Valtier, J.-C., and Ventura, N.

Abstract

Aims.In this paper, we present an innovative data reduction method for single-mode interferometry. It has been specifically developed for the AMBER instrument, the three-beam combiner of the Very Large Telescope Interferometer, but it can be derived for any single-mode interferometer.

Published
2007
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14. On-sky observations with an achromatic hybrid phase knife coronagraph in the visible

Author

Abe, L., Beaulieu, M., Vakili, F., Gay, J., Rivet, J.-P., Dervaux, S., Domiciano de Souza, A., Abe, L., Beaulieu, M., Vakili, F., Gay, J., Rivet, J.-P., Dervaux, S., and Domiciano de Souza, A.

Abstract

Context.The four-quadrant phase mask stellar coronagraph, introduced by D. Rouan et al., is capable of achieving very high dynamical range imaging and was studied in the context of the direct detection of extra-solar planets. Achromatic four-quadrant phase mask is currently being developed for broadband IR applications.

Published
2007
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15. First sky validation of an optical polarimetric interferometer

Author

Rousselet-Perraut, K., Le Bouquin, J. B., Mourard, D., Vakili, F., Chesneau, O., Bonneau, D., Chevassut, J. L., Crocherie, A., Glentzlin, A., Jankov, S., Ménardi, S., Petrov, R., Stehlé, C., Rousselet-Perraut, K., Le Bouquin, J. B., Mourard, D., Vakili, F., Chesneau, O., Bonneau, D., Chevassut, J. L., Crocherie, A., Glentzlin, A., Jankov, S., Ménardi, S., Petrov, R., and Stehlé, C.

Abstract

Aims.We present the first lab and sky validation of spectro-polarimetric equipment put at the combined focus of an optical long-baseline interferometer. We tested the polarimetric mode designed for the visible GI2T Interferometer to offer spectropolarimetric diagnosis at the milliarcsecond scale.

Published
2006
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16. Interferometric Remapped Array Nulling

Author

Vakili, F., Aristidi, E., Abe, L., Lopez, B., Vakili, F., Aristidi, E., Abe, L., and Lopez, B.

Abstract

This paper describes a method of beam-combination in the so-called hypertelescope imaging technique recently introduced by Labeyrie in optical interferometry. The method we propose is an alternative to the Michelson pupil reconfiguration that suffers from the loss of the classical object-image convolution relation. From elementary theory of Fourier optics we demonstrate that this problem can be solved by reconfiguring images instead of pupils. Imaging is performed in a combined pupil-plane where the point-source intensity distribution (PSID by comparison to the more commonly quoted point-spread function, PSF) tends towards a pseudo Airy disc for a sufficiently large number of telescopes. Our method is applicable to snap-shot imaging of extended sources with a field limited to the Airy pattern of single telescopes operated in a co-phased multi-aperture interferometric array. It thus allows to apply conveniently pupil plane coronagraphy. Our technique called Interferometric Remapped Array Nulling (IRAN) is particularly suitable for high dynamic imaging of extra-solar planetary companions or extra-galactic objects where long baseline interferometry would closely probe the central regions of AGNs for instance. We also discuss the application of IRAN to improve the performances of imaging and/or nulling interferometers like the full-fledged VLTI array or the DARWIN space-borne mission.

Published
2004
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17. Stellar differential rotation and inclination angle from spectro-interferometry

Author

Souza, A. Domiciano de, Zorec, J., Jankov, S., Vakili, F., Abe, L., Janot-Pacheco, E., Souza, A. Domiciano de, Zorec, J., Jankov, S., Vakili, F., Abe, L., and Janot-Pacheco, E.

Abstract

Differential interferometry (DI) is a technique that combines high spectral resolution with high spatial resolution. It is particularly suited to probe mechanisms that induce chromatic signatures, such as large scale mass motions. We thus investigate the use of DI combined with the Fourier transform method to study the stellar surface differential rotation. We show that, compared to spectroscopy, DI has the double advantage of allowing the use of all available Fourier frequencies as well as of disentangling the stellar differential rotation rate and the inclination angle. We derive some reference analytical expressions of DI observables. It is shown that the foreseen instrumental performances of the spectro-interferometer VLTI/AMBER are high enough to study the stellar differential rotation.

Published
2004
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18. The spinning-top Be star Achernar from VLTI-VINCI

Author

Souza, A. Domiciano de, Kervella, P., Jankov, S., Abe, L., Vakili, F., di Folco, E., Paresce, F., Souza, A. Domiciano de, Kervella, P., Jankov, S., Abe, L., Vakili, F., di Folco, E., and Paresce, F.

Abstract

We report here the first observations of a rapidly rotating Be star, αEridani, using Earth-rotation synthesis on the Very Large Telescope (VLT) Interferometer. Our measures correspond to a $2a/2b = 1.56\pm0.05$apparent oblate star, $2a$and $2b$being the equivalent uniform disc angular diameters in the equatorial and polar direction. Considering the presence of a circumstellar envelope (CSE) we argue that our measurement corresponds to a truly distorted star since αEridani exhibited negligible Hαemission during the interferometric observations. In this framework we conclude that the commonly adopted Roche approximation (uniform rotation and centrally condensed mass) should not apply to αEridani. This result opens new perspectives to basic astrophysical problems, such as rotationally enhanced mass loss and internal angular momentum distribution. In addition to its intimate relation with magnetism and pulsation, rapid rotation thus provides a key to the Be phenomenon: one of the outstanding non-resolved problems in stellar physics.

Published
2003
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19. Phase Knife Coronagraph

Author

Abe, L., Domiciano de Souza, A., Vakili, F., Gay, J., Abe, L., Domiciano de Souza, A., Vakili, F., and Gay, J.

Abstract

We report laboratory results from a monochromatic prototype of the Phase Knife Coronagraph which validate our previous theoretical and numerical simulations, prove the physical principle of it and set realistic limitations to the nulling properties of the coronagraph. The optical set-up, phase knife manufacturing technique and different aspects of the instrumental limitations are given. The first results attain easily a 3000 nulling effect obtained both on single and simulated double stars. Optical and mechanical stabilities are discussed and future steps to be carried out for a wide band version of this coronagraph are outlined.

Published
2003
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20. Modelling rapid rotators for stellar interferometry

Author

Souza, A. Domiciano de, Vakili, F., Jankov, S., Janot-Pacheco, E., Abe, L., Souza, A. Domiciano de, Vakili, F., Jankov, S., Janot-Pacheco, E., and Abe, L.

Abstract

Optical long baseline interferometry is a powerful tool to study detailed stellar structures. In particular, rapid rotation induces interferometric signatures requiring a detailed modelling for correctly interpreting high angular resolution data. In the present paper we study the effects of uniform stellar rotation on interferometric observables using a physically coherent model that includes gravity darkening and geometrical deformation, as well as a radiation transfer code. We investigate the use of multi-baseline and/or multi-channel observations, both in the continuum and spectral lines, in order to obtain the unique solutions for relevant model parameters. We show that this is possible and we provide a guide for observers in order to perform this task. However, this turns out to be quite demanding in terms of sensitivity requiring the use of new generation interferometers.

Published
2002
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21. Interferometric-Doppler imaging of stellar surface structure

Author

Jankov, S., Vakili, F., Domiciano de Souza, A., Janot-Pacheco, E., Jankov, S., Vakili, F., Domiciano de Souza, A., and Janot-Pacheco, E.

Abstract

In this paper we discuss the combination of two basic approaches which should potentially generate images of spatially unresolved stars: differential interferometry and classical spectroscopy. Doppler Imaging provides indirect observational information on stellar surface structures by modeling the rotational modulation of the observed flux distribution across spectral lines. Similarly, differential interferometry makes it possible to measure the disturbances of photocentroid location of an unresolved star as a function of wavelength and to deduce the corresponding stellar map. We present the general formalism to reconstruct images from spectroscopy and differential interferometry data for sources with spatially unresolved structures, and we discuss how their combination improves the image reconstructions. This technique, that we call Interferometric-Doppler Imaging (IDI), leads to significant progress in solving some long-standing problems of Doppler Imaging, such as latitude smearing and bias as well as the non-uniqueness of the solution in the special case of an equator-on star. We treat explicitly the most delicate case of non-radial stellar pulsations, for which the cancellation of opposite sign temperature or velocity fields introduces additional difficulties. The performance of the method is demonstrated, using the indirect imaging code built on the basis of the developed approach to reconstruct an input image from a series of generated noisy spectra. The problem of image reconstruction from two-aperture interferometry data has been particularly addressed since it represents the case of most presently operating interferometers.

Published
2001
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22. The achromatic phase knife coronagraph

Author

Abe, L., Vakili, F., Boccaletti, A., Abe, L., Vakili, F., and Boccaletti, A.

Abstract

We present the concept of a nulling coronagraph which theoretically attains the brightness ratio of 108suitable to directly detect exo-Earths in the vicinity of their parent stars. The concept is derived from the classical Foucault's optics test and Zernike's self-destructive phase contrast principle. We propose an achromatic set-up which should dramatically improve its wide band efficiency. The whole system is simulated against a numerical model which validates a formal analytical approach. The coronagraph is then compared to other concepts and its advantages and shortcomings are outlined, suggesting future laboratory developments and tests on the sky.

Published
2001
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23. A binary engine fuelling HD?87643's complex circumstellar environment

Author

Millour, F., Chesneau, O., Borges Fernandes, M., Meilland, A., Mars, G., Benoist, C., Thi?baut, E., Stee, P., Hofmann, K.-H., Baron, F., Young, J., Bendjoya, P., Carciofi, A., Domiciano de Souza, A., Driebe, T., Jankov, S., Kervella, P., Petrov, R., Robbe-Dubois, S., Vakili, F., Waters, L., and Weigelt, G.

Abstract

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 resolution 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, and 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 suggesting past violent ejections.

Published
2009

24. Spatially resolving the inhomogeneous structure of the dynamical atmosphere of Betelgeuse with VLTI/AMBER

Author

Ohnaka, K., Hofmann, K.-H., Benisty, M., Chelli, A., Driebe, T., Millour, F., Petrov, R., Schertl, D., Stee, Ph., Vakili, F., and Weigelt, G.

Abstract

Aims. We present spatially resolved, high-spectral resolution K-band observations of the red supergiant Betelgeuse (??Ori) using AMBER at the Very Large Telescope Interferometer (VLTI). Our aim is to probe inhomogeneous structures in the dynamical atmosphere of Betelgeuse. Methods. Betelgeuse was observed in the wavelength range between 2.28 and 2.31??m?with VLTI/AMBER using baselines of 16, 32, and 48?m. The spectral resolutions of 4800-12?000 allow us to study inhomogeneities seen in the individual CO?first overtone lines. Results. Spectrally dispersed interferograms have been successfully obtained in the second, third, and fifth lobes, which represents the highest spatial resolution (9?mas) achieved for Betelgeuse. This corresponds to five resolution elements over its stellar disk. The AMBER visibilities and closure phases in the K-band 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 and a limb-darkening parameter of (1.2 ? 0.07) ? 10-1. These AMBER data and the previous K-band interferometric data taken at various epochs suggest that Betelgeuse seen in the K-band continuum shows much smaller deviations from the above uniform disk or limb-darkened disk than predicted by recent 3-D convection simulations for red supergiants. On the other hand, our AMBER data in the CO?lines reveal salient inhomogeneous structures. The visibilities and phases (closure phases, as well as differential phases representing asymmetry in lines with respect to the continuum) measured within the CO?lines show that the blue and red wings originate in spatially distinct regions over the stellar disk, indicating an inhomogeneous velocity field that makes the star appear different in the blue and red wings. 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 with 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. Also, the AMBER data are consistent with the presence of warm molecular layers (so-called MOLsphere) extending to ~1.4-1.5?R*?with a CO?column density of ~1 ? 1020?cm-2. Conclusions. Our AMBER observations of Betelgeuse are the first spatially resolved study of the so-called macroturbulence in a stellar atmosphere (photosphere and possibly MOLsphere as well) other than the Sun. The spatially resolved CO?gas motion is likely to be related to convective motion in the upper atmosphere or intermittent mass ejections in clumps or arcs.

Published
2009

25. Diameter and photospheric structures of Canopus from?AMBER/VLTI interferometry

Author

Domiciano de Souza, A., Bendjoya, P., Vakili, F., Millour, F., and Petrov, R.

Abstract

Context. Direct measurements of fundamental parameters and photospheric structures of post-main-sequence intermediate-mass stars are required for a deeper understanding of their evolution. Aims. Based on near-IR long-baseline interferometry we aim to resolve the stellar surface of the F0 supergiant star Canopus, and to precisely measure its angular diameter and related physical parameters.Methods. We used the AMBER/VLTI instrument to record interferometric data on Canopus: visibilities and closure phases in the H and?K?bands with a spectral resolution of 35. The available baselines (?60-110?m) and the high quality of the AMBER/VLTI observations allowed us to measure fringe visibilities as far as in the third visibility lobe.Results. We determined an angular diameter of [Formula: see text][Formula: see text]?mas by adopting a linearly limb-darkened disk model. From this angular diameter and Hipparcos distance we derived a stellar radius R=71.4?4.0?R?. Depending on bolometric fluxes existing in the literature, the measured [Formula: see text][Formula: see text] provides two estimates of the effective temperature: Teff= 7284?107?K and Teff= 7582?252 ?K.Conclusions. In addition to providing the most precise angular diameter obtained to date, the AMBER interferometric data point towards additional photospheric structures on Canopus beyond the limb-darkened model alone. A promising explanation for such surface structures is the presence of convection cells. We checked such a hypothesis using first order star-cell models and concluded that the AMBER observations are compatible with the presence of surface convective structures. This direct detection of convective cells on Canopus from interferometry can provide strong constraints to radiation-hydrodynamics models of photospheres of F-type supergiants.

Published
2008

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