42 results on '"Acke, B."'
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2. Evidence for CO depletion in the inner regions of gas-rich protoplanetary disks*
- Author
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van der Plas, G., van den Ancker, M. E., Acke, B., Carmona, A., Dominik, C., Fedele, D., Waters, L. B. F. M., van der Plas, G., van den Ancker, M. E., Acke, B., Carmona, A., Dominik, C., Fedele, D., and Waters, L. B. F. M.
- Abstract
Aims. We investigate the physical properties and spatial distribution of Carbon Monoxide (CO) gas in the disks around the Herbig Ae/Be stars HD 97048 and HD 100546.
- Published
- 2009
- Full Text
- View/download PDF
3. Long-term photometric monitoring with the Mercator telescope***
- Author
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Cuypers, J., Aerts, C., De Cat, P., De Ridder, J., Goossens, K., Schoenaers, C., Uytterhoeven, K., Acke, B., Davignon, G., Debosscher, J., Decin, L., De Meester, W., Deroo, P., Drummond, R., Kolenberg, K., Lefever, K., Raskin, G., Reyniers, M., Saesen, S., Vandenbussche, B., Van Malderen, R., Verhoelst, T., Van Winckel, H., Waelkens, C., Cuypers, J., Aerts, C., De Cat, P., De Ridder, J., Goossens, K., Schoenaers, C., Uytterhoeven, K., Acke, B., Davignon, G., Debosscher, J., Decin, L., De Meester, W., Deroo, P., Drummond, R., Kolenberg, K., Lefever, K., Raskin, G., Reyniers, M., Saesen, S., Vandenbussche, B., Van Malderen, R., Verhoelst, T., Van Winckel, H., and Waelkens, C.
- Abstract
Context. γDor stars are excellent targets for asteroseismology since the gravity modes present in these stars probe the deep stellar interiors. Mode identification will improve the knowledge of these stars considerably.
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- 2009
- Full Text
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4. The structure of the protoplanetary disk surrounding three young intermediate mass stars *
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Fedele, D., van den Ancker, M. E., Acke, B., van der Plas, G., van Boekel, R., Wittkowski, M., Henning, Th., Bouwman, J., Meeus, G., Rafanelli, P., Fedele, D., van den Ancker, M. E., Acke, B., van der Plas, G., van Boekel, R., Wittkowski, M., Henning, Th., Bouwman, J., Meeus, G., and Rafanelli, P.
- Abstract
Aims. We present the first direct comparison of the distribution of the gas, as traced by the [O I] 6300 Å emission, and the dust, as traced by the 10 μm emission, in the planet-forming region of proto-planetary disks around three intermediate-mass stars: HD 101412, HD 135344 B and HD 179218.
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- 2008
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5. AMBER and MIDI interferometric observations of the post-AGB binary IRAS 08544-4431: the circumbinary disc resolved*
- Author
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Deroo, P., Acke, B., Verhoelst, T., Dominik, C., Tatulli, E., Van Winckel, H., Deroo, P., Acke, B., Verhoelst, T., Dominik, C., Tatulli, E., and Van Winckel, H.
- Abstract
Context.For a large group of post-AGB binaries, the presence of a stable reservoir of dust is postulated. Although this reservoir will influence the final evolution stages of these objects significantly, its actual geometry and structure remains largely unknown.
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- 2007
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6. Direct diameter measurement of a star filling its Roche lobe
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Verhoelst, T., van Aarle, E., Acke, B., Verhoelst, T., van Aarle, E., and Acke, B.
- Abstract
Context.Stellar evolution in close binary systems is strongly influenced by mass transfer from one star to the other when one component fills its zero-velocity surface or Roche Lobe. SS Lepis a fairly nearby close binary showing the Algolparadox and a shell spectrum, both indicative of (past) mass transfer.
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- 2007
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7. Direct constraint on the distance of γ2Velorum from AMBER/VLTI observations*
- Author
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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.
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- 2007
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8. AMBER, the near-infrared spectro-interferometric three-telescope VLTI instrument
- Author
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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).
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- 2007
- Full Text
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9. Constraining the wind launching region in Herbig Ae stars: AMBER/VLTI spectroscopy of HD 104237 *
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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.
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- 2007
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10. Disk and wind interaction in the young stellar object MWC 297spatially resolved with AMBER/VLTI *
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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
- Full Text
- View/download PDF
11. Near-infrared interferometry of ηCarinaewith spectral resolutions of 1 500 and 12 000 using AMBER/VLTI*
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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
- Full Text
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12. An asymmetry detected in the disk of κCanis Majoriswith AMBER/VLTI *
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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.
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- 2007
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13. Optical configuration and analysis of the AMBER/VLTI instrument
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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.
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- 2007
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14. Interferometric data reduction with AMBER/VLTI. Principle, estimators, and illustration *
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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.
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- 2007
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15. Long term photometric monitoring with the Mercator telescope***
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De Cat, P., Briquet, M., Aerts, C., Goossens, K., Saesen, S., Cuypers, J., Yakut, K., Scuflaire, R., Dupret, M.-A., Uytterhoeven, K., Van Winckel, H., Raskin, G., Davignon, G., Le Guillou, L., Van Malderen, R., Reyniers, M., Acke, B., De Meester, W., Vanautgaerden, J., Vandenbussche, B., Verhoelst, T., Waelkens, C., Deroo, P., Reyniers, K., Ausseloos, M., Broeders, E., Daszyńska-Daskiewicz, J., Debosscher, J., De Ruyter, S., Lefever, K., Decin, G., Kolenberg, K., Mazumdar, A., Van Kerckhoven, C., De Ridder, J., Drummond, R., Barban, C., Vanhollebeke, E., Maas, T., Decin, L., De Cat, P., Briquet, M., Aerts, C., Goossens, K., Saesen, S., Cuypers, J., Yakut, K., Scuflaire, R., Dupret, M.-A., Uytterhoeven, K., Van Winckel, H., Raskin, G., Davignon, G., Le Guillou, L., Van Malderen, R., Reyniers, M., Acke, B., De Meester, W., Vanautgaerden, J., Vandenbussche, B., Verhoelst, T., Waelkens, C., Deroo, P., Reyniers, K., Ausseloos, M., Broeders, E., Daszyńska-Daskiewicz, J., Debosscher, J., De Ruyter, S., Lefever, K., Decin, G., Kolenberg, K., Mazumdar, A., Van Kerckhoven, C., De Ridder, J., Drummond, R., Barban, C., Vanhollebeke, E., Maas, T., and Decin, L.
- Abstract
Aims.We selected a large sample of O-B stars that were considered as (candidate) slowly pulsating B, βCep, and Maia stars after the analysis of their hipparcosdata. We analysed our new seven passband genevadata collected for these stars during the first three years of scientific operations of the mercatortelescope. We performed a frequency analysis for 28 targets with more than 50 high-quality measurements to improve their variability classification. For the pulsating stars, we tried both to identify the modes and to search for rotationally split modes.
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- 2007
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16. A survey for nanodiamond features in the 3 micron spectra of Herbig Ae/Be stars
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Acke, B., van den Ancker, M. E., Acke, B., and van den Ancker, M. E.
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Aims.We have carried out a survey of 60 Herbig Ae/Be stars in the 3 micron wavelength region in search for the rare spectral features at 3.43 and 3.53 micron. These features have been attributed to the presence of large, hot, hydrogen-terminated nanodiamonds. Only two Herbig Ae/Be stars, HD 97048and Elias 3-1are known to display both these features.
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- 2006
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17. Resolving the disk rotation of HD 97048and HD 100546in the [O I] 6300 Å line: evidence for a giant planet orbiting HD 100546
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Acke, B., van den Ancker, M. E., Acke, B., and van den Ancker, M. E.
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Aims.We intend to spatially and spectrally resolve the [O i] emission region in two nearby Herbig stars.Methods.We present high-resolution ($\lambda/\Delta\lambda$= 80 000) VLT/UVES echelle spectra of the [O i] 6300 Å line in the Herbig Ae/Be stars HD 97048and HD 100546. Apart from the spectral signature, also the spatial extent of the [O i] emission region is investigated. For both stars, we have obtained spectra with the slit positioned at different position angles on the sky.Results.The [O i] emission region of HD 100546appears to be coinciding with the dust disk, its major axis located at $150\pm11$° east of north. The SE part of the disk moves towards the observer, while the NW side is redshifted. The [O i] emission region rotates counterclockwise around the central star. For HD 97048, the position angle of the emission region is $160\pm19$° east of north, which is the first determination of this angle in the literature. The southern parts of the disk are blueshifted, the northern side moves away from us. Our data support the idea that a gap is present at 10 AU in the disk of HD 100546. Such a gap is likely planet-induced. We estimate the mass and orbital radius of this hypothetical companion responsible for this gap to be $20~M_{\rm Jupiter}$and 6.5 AU respectively.Conclusions.Based on temporal changes in the [O i] line profile, we conclude that inhomogeneities are present in the [O i] emission region of HD 100546. These “clumps” could be in resonance with the suggested companion, orbiting the central star in about 11 yr. If confirmed, these observations could point to the existence of an object straddling the line between giant planet and brown dwarf in a system as young as 10 million years.
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- 2006
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18. [O I] 6300 Å emission in Herbig Ae/Be systems: Signature of Keplerian rotation
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Acke, B., van den Ancker, M. E., Dullemond, C. P., Acke, B., van den Ancker, M. E., and Dullemond, C. P.
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We present high spectral-resolution optical spectra of 49 Herbig Ae/Be stars in a search for the [O i] 6300 Å line. The vast majority of the stars in our sample show narrow (${\it FWHM} < 100$km s-1) emission lines, centered on the stellar radial velocity. In only three sources is the feature much broader (~400 km s-1), and strongly blueshifted (-200 km s-1) compared to the stellar radial velocity. Some stars in our sample show double-peaked line profiles, with peak-to-peak separations of ~10 km s-1. The presence and strength of the [O i] line emission appears to be correlated with the far-infrared energy distribution of each source: stars with a strong excess at 60 μm have in general stronger [O i] emission than stars with weaker 60 μm excesses. We interpret these narrow [O i] 6300 Å line profiles as arising in the surface layers of the protoplanetary disks surrounding Herbig Ae/Be stars. A simple model for [O i] 6300 Å line emission due to the photodissociation of OH molecules shows that our results are in quantitative agreement with that expected from the emission of a flared disk if the fractional OH abundance is ~$5 \times 10^{-7}$.
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- 2005
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19. Chemical analysis of 24 dusty (pre-)main-sequence stars*
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Acke, B., Waelkens, C., Acke, B., and Waelkens, C.
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We have analysed the chemical photospheric composition of 24 Herbig Ae/Be and Vega-type stars in search for the λBootis phenomenon. We present the results of the elemental abundances of the sample stars. Some of the stars were never before studied spectroscopically at optical wavelengths. We have determined the projected rotational velocities of our sample stars. Furthermore, we discuss stars that depict a (selective) depletion pattern in detail. HD 4881and HD 139614seem to display an overall deficiency. AB Aurand possibly HD 126367have subsolar values for the iron abundance, but are almost solar in silicon. HD 100546is the only clear λBootis star in our sample.
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- 2004
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20. ISO spectroscopy of disks around Herbig Ae/Be stars ***
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Acke, B., van den Ancker, M. E., Acke, B., and van den Ancker, M. E.
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We have investigated the infrared spectra of all 46 Herbig Ae/Be stars for which spectroscopic data are available in the ISO data archive. Our quantitative analysis of these spectra focuses on the emission bands at 3.3, 6.2, “7.7”, 8.6 and 11.2 micron, linked to polycyclic aromatic hydrocarbons (PAHs), the nanodiamond-related features at 3.4 and 3.5 micron, the amorphous 10 micron silicate band and the crystalline silicate band at 11.3 micron. We have detected PAH emission in 57% of the Herbig stars in our sample. Although for most of these sources the PAH spectra are similar, there are clear examples of differences in the PAH spectra within our sample which can be explained by differences in PAH size, chemistry and/or ionization. Amorphous silicate emission was detected in the spectra of 52% of the sample stars, amorphous silicate absorption in 13%. We have detected crystalline silicate emission in 11 stars (24% of our sample), of which four (9%) also display strong PAH emission. We have classified the sample sources according to the strength of their mid-IR energy distribution. The systems with stronger mid-infared (20–100 μm) excesses relative to their near-infrared (1–5 μm) excess display significantly more PAH emission than those with weaker mid-infrared excesses. There are no pronounced differences in the behaviour of the silicate feature between the two groups. This provides strong observational support for the disk models by [CITE], in which systems with a flaring disk geometry display a strong mid-infrared excess, whereas those with disks that are strongly shadowed by the puffed-up inner rim of the disk only display modest amounts of mid-infrared emission. Since the silicates are expected to be produced mainly in the warm inner disk regions, no large differences in silicate behaviour are expected between the two groups. In contrast to this, the PAH emission is expected to be produced mainly in the part of the disk atmosphere that is directly exposed to radiation from the central star. In this model, self-shadowed disks should display weaker PAH emission than flared disks, consistent with our observations.
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- 2004
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21. Correlation between grain growth and disk geometry in Herbig Ae/Be systems
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Acke, B., van den Ancker, M. E., Dullemond, C. P., van Boekel, R., Waters, L. B. F. M., Acke, B., van den Ancker, M. E., Dullemond, C. P., van Boekel, R., and Waters, L. B. F. M.
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We have calculated the (sub-)mm spectral indices of 26 Herbig Ae/Be stars, for which we can determine the infrared spectral energy distribution (SED). We find a clear correlation between the strength of the ratio of the near- to mid-infrared excess of these sources, and the slope of the (sub-)mm energy distribution. Based on earlier multi-dimensional modeling of disks around Herbig Ae stars, we interpret this as a correlation between the geometry of the disk (flared or self-shadowed) and the size of the grains: self-shadowed disks have, on average, larger grains than their flared counterparts. These data suggest that the geometry of a young stellar disk evolves from flared to self-shadowed.
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- 2004
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22. MWC?297: a young high-mass star rotating at critical velocity
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Acke, B., Verhoelst, T., van den Ancker, M., Deroo, P., Waelkens, C., Chesneau, O., Tatulli, E., Benisty, M., Puga, E., Waters, L., Verhoeff, A., and de Koter, A.
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Context. MWC 297 is a nearby young massive B[e] star. The central star is attenuated by 8?mag in the optical and has a high projected rotational velocity of 350?km?s-1. Despite the wealth of published observations, the nature of this object and its circumstellar environment is not understood very well.Aims. With the present paper, we intend to shed light on the geometrical structure of the circumstellar matter that is responsible for the near- to mid-infrared flux excess.Methods. The H-band (1.6-2.0??m), K-band (2.0-2.5??m), and N-band (8-13??m) brightness distribution of MWC?297 was probed with the ESO interferometric spectrographs AMBER and MIDI, mounted on the VLTI in Paranal, Chile. We obtained visibility measurements on 3?AMBER and 12?MIDI baselines, covering a wide range of spatial frequencies. Different models (parametrized circumstellar disks, a dusty halo) were invoked to fit the data, all of which fail to do so in a satisfying way. We approximated the brightness distribution in H, K, and N with a geometric model consisting of three Gaussian disks with different extents and brightness temperatures. This model can account for the entire near- to mid-IR emission of MWC?297.Results. The circumstellar matter around MWC?297 is resolved on all baselines. The near- and mid-IR emission, including the silicate emission at 10?micron, emanates from a very compact region (FWHM?< 1.5?AU) around the central star.Conclusions. We argue that the extinction towards the MWC?297 star+disk system is interstellar and most likely due to remnants of the natal cloud from which MWC?297 was formed. Furthermore, we argue that the circumstellar matter in the MWC?297 system is organized in a circumstellar disk, seen under moderate (i < 40?) inclination. The disk displays no inner emission-free gap at the resolution of our interferometric observations. The low inclination of the disk implies that the already high projected rotational velocity of the star corresponds to an actual rotational velocity that exceeds the critical velocity of the star. This result shows that stars can obtain such high rotation rates at birth. We discuss the impact of this result in terms of the formation of high-mass stars and the main-sequence evolution of classical Be?stars.
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- 2008
23. The structure of protoplanetary disks surrounding three young intermediate mass stars
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van der Plas, G., van den Ancker, M., Fedele, D., Acke, B., Dominik, C., Waters, L., and Bouwman, J.
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We present high-spectral-resolution, optical spectra of three young, intermediate-mass stars, in all of which we spectrally resolve the 6300??? [OI] emission?line. Two of these have a double-peaked line-profile. We attempt to fit these data using a simple model of [OI]?emission, which is generated by photo-dissociation of OH molecules, in the upper layer of a circumstellar disk, by stellar UV?radiation. We translate the Doppler-broadened [OI] emission?line profile, into a measure of emission, as a function of distance from the central star. The resulting spectra are in agreement with the expected disk shapes derived from their spectral energy distribution. We find evidence for shadowing by an inner rim in the disk surrounding HD?101412, and observe a flaring disk structure in HD?179218, while the [OI]?spectrum of HD?135344?B is more complex. The [OI]?emission starts for all three targets at velocities corresponding to their dust sublimation radius and extends up to radii of 10?90?AU. This shows that this method can be a valuable tool in the future investigation of circumstellar disks. ?
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- 2008
24. CoRoT’s view on variable B8/9 stars: spots versus pulsations
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Degroote, P., Acke, B., Samadi, R., Aerts, C., Kurtz, D. W., Noels, A., Miglio, A., Montalbán, J., Bloemen, S., Baglin, A., Baudin, F., Catala, C., Michel, E., and Auvergne, M.
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Context.There exist few variability studies of stars in the region in the Hertzsprung-Russell diagram between the A and B-star pulsational instability strips. With the aid of the high precision continuous measurements of the CoRoT space satellite, low amplitudes are more easily detected, making a study of this neglected region worthwhile.
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- 2011
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25. A survey for near-infrared H2emission in Herbig Ae/Be stars: emission from the outer disks of HD 97048 and HD 100546⋆⋆⋆
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Carmona, A., van der Plas, G., van den Ancker, M. E., Audard, M., Waters, L. B. F. M., Fedele, D., Acke, B., and Pantin, E.
- Abstract
We report on a sensitive search for H21-0 S(1), 1-0 S(0) and 2-1 S(1) ro-vibrational emission at 2.12, 2.22 and 2.25 μm in a sample of 15 Herbig Ae/Be stars employing CRIRES, the ESO-VLT near-infrared high-resolution spectrograph, at R~ 90 000. We report the detection of the H21-0 S(1) line toward HD 100546 and HD 97048. In the other 13 targets, the line is not detected. The H21-0 S(0) and 2-1 S(1) lines are undetected in all sources. These observations are the first detection of near-IR H2emission in HD 100546. The H21-0 S(1) lines observed in HD 100546 and HD 97048 are observed at a velocity consistent with the rest velocity of both stars, suggesting that they are produced in the circumstellar disk. In HD 97048 the emission is spatially resolved and it is observed to extend at least up to 200 AU from the star. We report an increase of one order of magnitude in the H21-0 S(1) line flux with respect to previous measurements taken in 2003 for this star, which suggests line variability. In HD 100546 the emission is tentatively spatially resolved and may extend at least up to 50 AU from the star. Modeling of the H21-0 S(1) line profiles and their spatial extent with flat Keplerian disks shows that most of the emission is produced at a radius larger than 5 AU. Upper limits to the H21-0 S(0)/1-0 S(1) and H22-1 S(1)/1-0 S(1) line ratios in HD 97048 are consistent with H2gas at T> 2000 K and suggest that the emission observed may be produced by X-ray excitation. The upper limits for the line ratios for HD 100546 are inconclusive. Because the H2emission is located at large radii, for both sources a thermal emission scenario (i.e., gas heated by collisions with dust) is implausible. We argue that the observation of H2emission at large radii may be indicative of an extended disk atmosphere at radii >5 AU. This may be explained by a hydrostatic disk in which gas and dust are thermally decoupled or by a disk wind caused by photoevaporation.
- Published
- 2011
- Full Text
- View/download PDF
26. Low abundance, strong features: window-dressing crystalline forsterite in the disk wall of HD 100546⋆
- Author
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Mulders, G. D., Waters, L. B. F. M., Dominik, C., Sturm, B., Bouwman, J., Min, M., Verhoeff, A. P., Acke, B., Augereau, J. C., Evans, N. J., Henning, Th., Meeus, G., and Olofsson, J.
- Abstract
Context.Forsterite is one of the crystalline dust species that is often observed in protoplanetary disks and solar system comets. Being absent in the interstellar medium, it must be produced during the disk lifetime. It can therefore serve as a tracer of dust processing and disk evolution, which can lead to a better understanding of the physical processes occurring in the disk, and possibly planet formation. However, the connection of these processes with the overall disk crystallinity remains unclear.
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- 2011
- Full Text
- View/download PDF
27. The βPictoris disk imaged by HerschelPACS and SPIRE ***
- Author
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Vandenbussche, B., Sibthorpe, B., Acke, B., Pantin, E., Olofsson, G., Waelkens, C., Dominik, C., Barlow, M. J., Blommaert, J. A. D. L., Bouwman, J., Brandeker, A., Cohen, M., De Meester, W., Dent, W. R. F., Exter, K., Di Francesco, J., Fridlund, M., Gear, W. K., Glauser, A. M., Gomez, H. L., Greaves, J. S., Hargrave, P. C., Harvey, P. M., Henning, Th., Heras, A. M., Hogerheijde, M. R., Holland, W. S., Huygen, R., Ivison, R. J., Jean, C., Leeks, S. J., Lim, T. L., Liseau, R., Matthews, B. C., Naylor, D. A., Pilbratt, G. L., Polehampton, E. T., Regibo, S., Royer, P., Sicilia-Aguilar, A., Swinyard, B. M., Walker, H. J., and Wesson, R.
- Abstract
We obtained HerschelPACS and SPIRE images of the thermal emission of the debris disk around the A5V star βPic. The disk is well resolved in the PACS filters at 70, 100, and 160 μm. The surface brightness profiles between 70 and 160 μm show no significant asymmetries along the disk, and are compatible with 90% of the emission between 70 and 160 μm originating in a region closer than 200 AU to the star. Although only marginally resolving the debris disk, the maps obtained in the SPIRE 250–500 μm filters provide full-disk photometry, completing the SED over a few octaves in wavelength that had been previously inaccessible. The small far-infrared spectral index (β= 0.34) indicates that the grain size distribution in the inner disk (<200 AU) is inconsistent with a local collisional equilibrium. The size distribution is either modified by non-equilibrium effects, or exhibits a wavy pattern, caused by an under-abundance of impactors which have been removed by radiation pressure.
- Published
- 2010
28. Dust, Ice, and Gas In Time (DIGIT) Herschelprogram first results*
- Author
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van Kempen, T. A., Green, J. D., Evans, N. J., van Dishoeck, E. F., Kristensen, L. E., Herczeg, G. J., Merín, B., Lee, J.-E., Jørgensen, J. K., Bouwman, J., Acke, B., Adamkovics, M., Augereau, J. C., Bergin, E., Blake, G. A., Brown, J. M., Carr, J. S., Chen, J.-H., Cieza, L., Dominik, C., Dullemond, C. P., Dunham, M. M., Glassgold, A., Güdel, M., Harvey, P. M., Henning, Th., Hogerheijde, M. R., Jaffe, D., Kim, H. J., Knez, C., Lacy, J. H., Maret, S., Meeus, G., Meijerink, R., Mulders, G. D., Mundy, L., Najita, J., Olofsson, J., Pontoppidan, K. M., Salyk, C., Sturm, B., Visser, R., Waters, L. B. F. M., Waelkens, C., and Yıldız, U. A.
- Abstract
Aims. We aim to study the composition and energetics of the circumstellar material of DK Cha, an intermediate-mass star in transition from an embedded configuration to a star plus disk stage, during this pivotal stage of its evolution.Methods. Using the range scan mode of PACS on the HerschelSpace Observatory, we obtained a spectrum of DK Cha from 55 to 210 μm as part of the DIGIT key program.Results. Almost 50 molecular and atomic lines were detected, many more than the 7 lines detected in ISO-LWS. Nearly the entire ladder of CO from J= 14–13 to 38–37 (Eu/k= 4080 K), water from levels as excited as $J_{K_{-1}K_{+1}}$= 707(Eu/k= 843 K), and OH lines up to Eu/k= 290 K were detected.Conclusions. The continuum emission in our PACS SED scan matches the flux expected by a model consisting of a star, a surrounding disk of 0.03 $M_\odot$, and an envelope of a similar mass, supporting the suggestion that the object is emerging from its main accretion stage. Molecular, atomic, and ionic emission lines in the far-infrared reveal the outflow's influence on the envelope. The inferred hot gas may be photon-heated, but some emission may be caused by C-shocks in the walls of the outflow cavity.
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- 2010
29. First results of the Herschelkey program “Dust, Ice and Gas In Time” (DIGIT): Dust and gas spectroscopy of HD 100546 *
- Author
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Sturm, B., Bouwman, J., Henning, Th., Evans, N. J., Acke, B., Mulders, G. D., Waters, L. B. F. M., van Dishoeck, E. F., Meeus, G., Green, J. D., Augereau, J. C., Olofsson, J., Salyk, C., Najita, J., Herczeg, G. J., van Kempen, T. A., Kristensen, L. E., Dominik, C., Carr, J. S., Waelkens, C., Bergin, E., Blake, G. A., Brown, J. M., Chen, J.-H., Cieza, L., Dunham, M. M., Glassgold, A., Güdel, M., Harvey, P. M., Hogerheijde, M. R., Jaffe, D., Jørgensen, J. K., Kim, H. J., Knez, C., Lacy, J. H., Lee, J.-E., Maret, S., Meijerink, R., Merín, B., Mundy, L., Pontoppidan, K. M., Visser, R., and Yıldız, U. A.
- Abstract
Context. We present far-infrared spectroscopic observations, taken with the Photodetector Array Camera and Spectrometer (PACS) on the HerschelSpace Observatory, of the protoplanetary disk around the pre-main-sequence star HD 100546. These observations are the first within the DIGIT Herschelkey program, which aims to follow the evolution of dust, ice, and gas from young stellar objects still embedded in their parental molecular cloud core, through the final pre-main-sequence phases when the circumstellar disks are dissipated.Aims. Our aim is to improve the constraints on temperature and chemical composition of the crystalline olivines in the disk of HD 100546 and to give an inventory of the gas lines present in its far-infrared spectrum. Methods. The 69 μm feature is analyzed in terms of position and shape to derive the dust temperature and composition. Furthermore, we detected 32 emission lines from five gaseous species and measured their line fluxes. Results. The 69 μm emission comes either from dust grains with ~70 K at radii larger than 50 AU, as suggested by blackbody fitting, or it arises from ~200 K dust at ~13 AU, close to the midplane, as supported by radiative transfer models. We also conclude that the forsterite crystals have few defects and contain at most a few percent iron by mass. Forbidden line emission from [C ii] at 157 μm and [O i] at 63 and 145 μm, most likely due to photodissociation by stellar photons, is detected. Furthermore, five H2O and several OH lines are detected. We also found high-J rotational transition lines of CO, with rotational temperatures of ~300 K for the transitions up to J= 22–21 and T~ 800 K for higher transitions.
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- 2010
30. The Vega debris disc: A view from Herschel*
- Author
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Sibthorpe, B., Vandenbussche, B., Greaves, J. S., Pantin, E., Olofsson, G., Acke, B., Barlow, M. J., Blommaert, J. A. D. L., Bouwman, J., Brandeker, A., Cohen, M., De Meester, W., Dent, W. R. F., Di Francesco, J., Dominik, C., Fridlund, M., Gear, W. K., Glauser, A. M., Gomez, H. L., Hargrave, P. C., Harvey, P. M., Henning, Th., Heras, A. M., Hogerheijde, M. R., Holland, W. S., Ivison, R. J., Leeks, S. J., Lim, T. L., Liseau, R., Matthews, B. C., Naylor, D. A., Pilbratt, G. L., Polehampton, E. T., Regibo, S., Royer, P., Sicilia-Aguilar, A., Swinyard, B. M., Waelkens, C., Walker, H. J., and Wesson, R.
- Abstract
We present five band imaging of the Vega debris disc obtained using the HerschelSpace Observatory. These data span a wavelength range of 70–500 μm with full-width half-maximum angular resolutions of 5.6–36.9”. The disc is well resolved in all bands, with the ring structure visible at 70 and 160 μm. Radial profiles of the disc surface brightness are produced, and a disc radius of 11” (~85 AU) is determined. The disc is seen to have a smooth structure thoughout the entire wavelength range, suggesting that the disc is in a steady state, rather than being an ephemeral structure caused by the recent collision of two large planetesimals.
- Published
- 2010
31. Dust, Ice, and Gas In Time (DIGIT) Herschelprogram first results*
- Author
-
van Kempen, T. A., Green, J. D., Evans, N. J., van Dishoeck, E. F., Kristensen, L. E., Herczeg, G. J., Merín, B., Lee, J.-E., Jørgensen, J. K., Bouwman, J., Acke, B., Adamkovics, M., Augereau, J. C., Bergin, E., Blake, G. A., Brown, J. M., Carr, J. S., Chen, J.-H., Cieza, L., Dominik, C., Dullemond, C. P., Dunham, M. M., Glassgold, A., Güdel, M., Harvey, P. M., Henning, Th., Hogerheijde, M. R., Jaffe, D., Kim, H. J., Knez, C., Lacy, J. H., Maret, S., Meeus, G., Meijerink, R., Mulders, G. D., Mundy, L., Najita, J., Olofsson, J., Pontoppidan, K. M., Salyk, C., Sturm, B., Visser, R., Waters, L. B. F. M., Waelkens, C., and Yıldız, U. A.
- Abstract
Aims. We aim to study the composition and energetics of the circumstellar material of DK Cha, an intermediate-mass star in transition from an embedded configuration to a star plus disk stage, during this pivotal stage of its evolution.
- Published
- 2010
- Full Text
- View/download PDF
32. First results of the Herschelkey program “Dust, Ice and Gas In Time” (DIGIT): Dust and gas spectroscopy of HD 100546 *
- Author
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Sturm, B., Bouwman, J., Henning, Th., Evans, N. J., Acke, B., Mulders, G. D., Waters, L. B. F. M., van Dishoeck, E. F., Meeus, G., Green, J. D., Augereau, J. C., Olofsson, J., Salyk, C., Najita, J., Herczeg, G. J., van Kempen, T. A., Kristensen, L. E., Dominik, C., Carr, J. S., Waelkens, C., Bergin, E., Blake, G. A., Brown, J. M., Chen, J.-H., Cieza, L., Dunham, M. M., Glassgold, A., Güdel, M., Harvey, P. M., Hogerheijde, M. R., Jaffe, D., Jørgensen, J. K., Kim, H. J., Knez, C., Lacy, J. H., Lee, J.-E., Maret, S., Meijerink, R., Merín, B., Mundy, L., Pontoppidan, K. M., Visser, R., and Yıldız, U. A.
- Abstract
Context. We present far-infrared spectroscopic observations, taken with the Photodetector Array Camera and Spectrometer (PACS) on the HerschelSpace Observatory, of the protoplanetary disk around the pre-main-sequence star HD 100546. These observations are the first within the DIGIT Herschelkey program, which aims to follow the evolution of dust, ice, and gas from young stellar objects still embedded in their parental molecular cloud core, through the final pre-main-sequence phases when the circumstellar disks are dissipated.
- Published
- 2010
- Full Text
- View/download PDF
33. The βPictoris disk imaged by HerschelPACS and SPIRE ***
- Author
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Vandenbussche, B., Sibthorpe, B., Acke, B., Pantin, E., Olofsson, G., Waelkens, C., Dominik, C., Barlow, M. J., Blommaert, J. A. D. L., Bouwman, J., Brandeker, A., Cohen, M., De Meester, W., Dent, W. R. F., Exter, K., Di Francesco, J., Fridlund, M., Gear, W. K., Glauser, A. M., Gomez, H. L., Greaves, J. S., Hargrave, P. C., Harvey, P. M., Henning, Th., Heras, A. M., Hogerheijde, M. R., Holland, W. S., Huygen, R., Ivison, R. J., Jean, C., Leeks, S. J., Lim, T. L., Liseau, R., Matthews, B. C., Naylor, D. A., Pilbratt, G. L., Polehampton, E. T., Regibo, S., Royer, P., Sicilia-Aguilar, A., Swinyard, B. M., Walker, H. J., and Wesson, R.
- Abstract
We obtained HerschelPACS and SPIRE images of the thermal emission of the debris disk around the A5V star βPic. The disk is well resolved in the PACS filters at 70, 100, and 160 μm. The surface brightness profiles between 70 and 160 μm show no significant asymmetries along the disk, and are compatible with 90% of the emission between 70 and 160 μm originating in a region closer than 200 AU to the star. Although only marginally resolving the debris disk, the maps obtained in the SPIRE 250–500 μm filters provide full-disk photometry, completing the SED over a few octaves in wavelength that had been previously inaccessible. The small far-infrared spectral index (β= 0.34) indicates that the grain size distribution in the inner disk (<200 AU) is inconsistent with a local collisional equilibrium. The size distribution is either modified by non-equilibrium effects, or exhibits a wavy pattern, caused by an under-abundance of impactors which have been removed by radiation pressure.
- Published
- 2010
- Full Text
- View/download PDF
34. The Vega debris disc: A view from Herschel*
- Author
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Sibthorpe, B., Vandenbussche, B., Greaves, J. S., Pantin, E., Olofsson, G., Acke, B., Barlow, M. J., Blommaert, J. A. D. L., Bouwman, J., Brandeker, A., Cohen, M., De Meester, W., Dent, W. R. F., Di Francesco, J., Dominik, C., Fridlund, M., Gear, W. K., Glauser, A. M., Gomez, H. L., Hargrave, P. C., Harvey, P. M., Henning, Th., Heras, A. M., Hogerheijde, M. R., Holland, W. S., Ivison, R. J., Leeks, S. J., Lim, T. L., Liseau, R., Matthews, B. C., Naylor, D. A., Pilbratt, G. L., Polehampton, E. T., Regibo, S., Royer, P., Sicilia-Aguilar, A., Swinyard, B. M., Waelkens, C., Walker, H. J., and Wesson, R.
- Abstract
We present five band imaging of the Vega debris disc obtained using the HerschelSpace Observatory. These data span a wavelength range of 70–500 μm with full-width half-maximum angular resolutions of 5.6–36.9”. The disc is well resolved in all bands, with the ring structure visible at 70 and 160 μm. Radial profiles of the disc surface brightness are produced, and a disc radius of 11” (~85 AU) is determined. The disc is seen to have a smooth structure thoughout the entire wavelength range, suggesting that the disc is in a steady state, rather than being an ephemeral structure caused by the recent collision of two large planetesimals.
- Published
- 2010
- Full Text
- View/download PDF
35. Photometric multi-site campaign on the open cluster NGC 884*
- Author
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Saesen, S., Carrier, F., Pigulski, A., Aerts, C., Handler, G., Narwid, A., Fu, J. N., Zhang, C., Jiang, X. J., Vanautgaerden, J., Kopacki, G., Stęślicki, M., Acke, B., Poretti, E., Uytterhoeven, K., Gielen, C., Østensen, R., De Meester, W., Reed, M. D., Kołaczkowski, Z., Michalska, G., Schmidt, E., Yakut, K., Leitner, A., Kalomeni, B., Cherix, M., Spano, M., Prins, S., Van Helshoecht, V., Zima, W., Huygen, R., Vandenbussche, B., Lenz, P., Ladjal, D., Puga Antolín, E., Verhoelst, T., De Ridder, J., Niarchos, P., Liakos, A., Lorenz, D., Dehaes, S., Reyniers, M., Davignon, G., Kim, S.-L., Kim, D. H., Lee, Y.-J., Lee, C.-U., Kwon, J.-H., Broeders, E., Van Winckel, H., Vanhollebeke, E., Waelkens, C., Raskin, G., Blom, Y., Eggen, J. R., Degroote, P., Beck, P., Puschnig, J., Schmitzberger, L., Gelven, G. A., Steininger, B., Blommaert, J., Drummond, R., Briquet, M., and Debosscher, J.
- Abstract
Context. Recent progress in the seismic interpretation of field βCep stars has resulted in improvements of the physics in the stellar structure and evolution models of massive stars. Further asteroseismic constraints can be obtained from studying ensembles of stars in a young open cluster, which all have similar age, distance and chemical composition.Aims. To improve our comprehension of the βCep stars, we studied the young open cluster NGC 884 to discover new B-type pulsators, besides the two known βCep stars, and other variable stars.Methods. An extensive multi-site campaign was set up to gather accurate CCD photometry time series in four filters (U, B, V, I) of a field of NGC 884. Fifteen different instruments collected almost 77 500 CCD images in 1286 h. The images were calibrated and reduced to transform the CCD frames into interpretable differential light curves. Various variability indicators and frequency analyses were applied to detect variable stars in the field. Absolute photometry was taken to deduce some general cluster and stellar properties.Results. We achieved an accuracy for the brightest stars of 5.7 mmag in V, 6.9 mmag in B, 5.0 mmag in Iand 5.3 mmag in U. The noise level in the amplitude spectra is 50 μmag in the Vband. Our campaign confirms the previously known pulsators, and we report more than one hundred new multi- and mono-periodic B-, A- and F-type stars. Their interpretation in terms of classical instability domains is not straightforward, pointing to imperfections in theoretical instability computations. In addition, we have discovered six new eclipsing binaries and four candidates as well as other irregular variable stars in the observed field.
- Published
- 2010
36. HD 95881: a gas rich to gas poor transition disk?*
- Author
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Verhoeff, A. P., Min, M., Acke, B., van Boekel, R., Pantin, E., Waters, L. B. F. M., Tielens, A. G. G. M., van den Ancker, M. E., Mulders, G. D., de Koter, A., and Bouwman, J.
- Abstract
Context. Based on the far infrared excess the Herbig class of stars is divided into a group with flaring circumstellar disks (group I) and a group with flat circumstellar disks (group II). Dust sedimentation is generally proposed as an evolution mechanism to transform flaring disks into flat disks. Theory predicts that during this process the disks preserve their gas content, however observations of group II Herbig Ae stars demonstrate a lack of gas.Aims. We map the spatial distribution of the gas and dust around the group II Herbig Ae star HD 95881.Methods. We analyze optical photometry, Q-band imaging, infrared spectroscopy, and Kand N-band interferometric spectroscopy. We use a Monte Carlo radiative transfer code to create a model for the density and temperature structure which quite accurately reproduces all the observables. Results. We derive a consistent picture in which the disk consists of a thick puffed up inner rim and an outer region which has a flaring gas surface and is relatively void of “visible” dust grains. Conclusions. HD 95881 is in a transition phase from a gas rich flaring disk to a gas poor self-shadowed disk.
- Published
- 2010
37. Photometric multi-site campaign on the open cluster NGC 884*
- Author
-
Saesen, S., Carrier, F., Pigulski, A., Aerts, C., Handler, G., Narwid, A., Fu, J. N., Zhang, C., Jiang, X. J., Vanautgaerden, J., Kopacki, G., Stęślicki, M., Acke, B., Poretti, E., Uytterhoeven, K., Gielen, C., Østensen, R., De Meester, W., Reed, M. D., Kołaczkowski, Z., Michalska, G., Schmidt, E., Yakut, K., Leitner, A., Kalomeni, B., Cherix, M., Spano, M., Prins, S., Van Helshoecht, V., Zima, W., Huygen, R., Vandenbussche, B., Lenz, P., Ladjal, D., Puga Antolín, E., Verhoelst, T., De Ridder, J., Niarchos, P., Liakos, A., Lorenz, D., Dehaes, S., Reyniers, M., Davignon, G., Kim, S.-L., Kim, D. H., Lee, Y.-J., Lee, C.-U., Kwon, J.-H., Broeders, E., Van Winckel, H., Vanhollebeke, E., Waelkens, C., Raskin, G., Blom, Y., Eggen, J. R., Degroote, P., Beck, P., Puschnig, J., Schmitzberger, L., Gelven, G. A., Steininger, B., Blommaert, J., Drummond, R., Briquet, M., and Debosscher, J.
- Abstract
Context. Recent progress in the seismic interpretation of field βCep stars has resulted in improvements of the physics in the stellar structure and evolution models of massive stars. Further asteroseismic constraints can be obtained from studying ensembles of stars in a young open cluster, which all have similar age, distance and chemical composition.
- Published
- 2010
- Full Text
- View/download PDF
38. HD 95881: a gas rich to gas poor transition disk?*
- Author
-
Verhoeff, A. P., Min, M., Acke, B., van Boekel, R., Pantin, E., Waters, L. B. F. M., Tielens, A. G. G. M., van den Ancker, M. E., Mulders, G. D., de Koter, A., and Bouwman, J.
- Abstract
Context. Based on the far infrared excess the Herbig class of stars is divided into a group with flaring circumstellar disks (group I) and a group with flat circumstellar disks (group II). Dust sedimentation is generally proposed as an evolution mechanism to transform flaring disks into flat disks. Theory predicts that during this process the disks preserve their gas content, however observations of group II Herbig Ae stars demonstrate a lack of gas.
- Published
- 2010
- Full Text
- View/download PDF
39. When an old star smolders
- Author
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Smolders, K., Acke, B., Verhoelst, T., Blommaert, J. A. D. L., Decin, L., Hony, S., Sloan, G. C., Neyskens, P., Van Eck, S., Zijlstra, A. A., and Van Winckel, H.
- Abstract
Polycyclic aromatic hydrocarbons (PAHs) produce characteristic infrared emission bands that have been observed in a wide range of astrophysical environments, where carbonaceous material is subjected to ultraviolet (UV) radiation. Although PAHs are expected to form in carbon-rich AGB stars, they have up to now only been observed in binary systems where a hot companion provides a hard radiation field. In this letter, we present low-resolution infrared spectra of four S-type AGB stars, selected from a sample of 90 S-type AGB stars observed with the infrared spectrograph aboard the Spitzersatellite. The spectra of these four stars show the typical infrared features of PAH molecules. We confirm the correlation between the temperature of the central star and the centroid wavelength of the 7.9 μm feature, present in a wide variety of stars spanning a temperature range from 3000 to 12 000 K. Three of four sources presented in this paper extend this relation towards lower temperatures. We argue that the mixture of hydrocarbons we see in these S-stars has a rich aliphatic component. The fourth star, BZ CMa, deviates from this correlation. Based on the similarity with the evolved binary TU Tau, we predict that BZ CMa has a hot companion as well.
- Published
- 2010
- Full Text
- View/download PDF
40. When an old star smolders*
- Author
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Smolders, K., Acke, B., Verhoelst, T., Blommaert, J. A. D. L., Decin, L., Hony, S., Sloan, G. C., Neyskens, P., Van Eck, S., Zijlstra, A. A., and Van Winckel, H.
- Abstract
Polycyclic aromatic hydrocarbons (PAHs) produce characteristic infrared emission bands that have been observed in a wide range of astrophysical environments, where carbonaceous material is subjected to ultraviolet (UV) radiation. Although PAHs are expected to form in carbon-rich AGB stars, they have up to now only been observed in binary systems where a hot companion provides a hard radiation field. In this letter, we present low-resolution infrared spectra of four S-type AGB stars, selected from a sample of 90 S-type AGB stars observed with the infrared spectrograph aboard the Spitzersatellite. The spectra of these four stars show the typical infrared features of PAH molecules. We confirm the correlation between the temperature of the central star and the centroid wavelength of the 7.9 μm feature, present in a wide variety of stars spanning a temperature range from 3000 to 12 000 K. Three of four sources presented in this paper extend this relation towards lower temperatures. We argue that the mixture of hydrocarbons we see in these S-stars has a rich aliphatic component. The fourth star, BZ CMa, deviates from this correlation. Based on the similarity with the evolved binary TU Tau, we predict that BZ CMa has a hot companion as well.
- Published
- 2010
41. Periodic mass-loss episodes due to an oscillation mode with variable amplitude in the hot supergiant HD 50064***
- Author
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Aerts, C., Lefever, K., Baglin, A., Degroote, P., Oreiro, R., Vučković, M., Smolders, K., Acke, B., Verhoelst, T., Desmet, M., Godart, M., Noels, A., Dupret, M.-A., Auvergne, M., Baudin, F., Catala, C., Michel, E., and Samadi, R.
- Abstract
Aims. We aim to interpret the photometric and spectroscopic variability of the luminous blue variable supergiant HD 50064 (V= 8.21).Methods. CoRoT space photometry and follow-up high-resolution spectroscopy with a time base of 137 d and 169 d, respectively, was gathered, analysed, and interpreted using standard time series analysis and light curve modelling methods, as well as spectral line diagnostics.Results. The space photometry reveals one period of 37 d, which undergoes a sudden amplitude change with a factor 1.6. The pulsation period is confirmed in the spectroscopy, which additionally reveals metal line radial velocity values differing by ~30 km s-1depending on the spectral line and on the epoch. We estimate Teff~ 13 500 K, log g~ 1.5 from the equivalent width of Si lines. The Balmer lines reveal that the star undergoes episodes of changing mass loss on a time scale similar to the changes in the photometric and spectroscopic variability, with an average value of log $\dot{M}$$\simeq$-5 (in M$_\odot$yr-1). We tentatively interpret the 37 d period as the result of a strange mode oscillation.
- Published
- 2010
42. Periodic mass-loss episodes due to an oscillation mode with variable amplitude in the hot supergiant HD 50064*
- Author
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Aerts, C., Lefever, K., Baglin, A., Degroote, P., Oreiro, R., Vučković, M., Smolders, K., Acke, B., Verhoelst, T., Desmet, M., Godart, M., Noels, A., Dupret, M.-A., Auvergne, M., Baudin, F., Catala, C., Michel, E., and Samadi, R.
- Abstract
Aims. We aim to interpret the photometric and spectroscopic variability of the luminous blue variable supergiant HD 50064 (V= 8.21).
- Published
- 2010
- Full Text
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