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Start Over Author "Riaz, B." Journal astronomy and astrophysics
8 results on '"Riaz, B."'

1. Herschel-PACS observation of the 10 Myr old T Tauri disk TW Hya

Author

Thi, W.-F., primary, Mathews, G., additional, Ménard, F., additional, Woitke, P., additional, Meeus, G., additional, Riviere-Marichalar, P., additional, Pinte, C., additional, Howard, C. D., additional, Roberge, A., additional, Sandell, G., additional, Pascucci, I., additional, Riaz, B., additional, Grady, C. A., additional, Dent, W. R. F., additional, Kamp, I., additional, Duchêne, G., additional, Augereau, J.-C., additional, Pantin, E., additional, Vandenbussche, B., additional, Tilling, I., additional, Williams, J. P., additional, Eiroa, C., additional, Barrado, D., additional, Alacid, J. M., additional, Andrews, S., additional, Ardila, D. R., additional, Aresu, G., additional, Brittain, S., additional, Ciardi, D. R., additional, Danchi, W., additional, Fedele, D., additional, de Gregorio-Monsalvo, I., additional, Heras, A., additional, Huelamo, N., additional, Krivov, A., additional, Lebreton, J., additional, Liseau, R., additional, Martin-Zaidi, C., additional, Mendigutía, I., additional, Montesinos, B., additional, Mora, A., additional, Morales-Calderon, M., additional, Nomura, H., additional, Phillips, N., additional, Podio, L., additional, Poelman, D. R., additional, Ramsay, S., additional, Rice, K., additional, Solano, E., additional, Walker, H., additional, White, G. J., additional, and Wright, G., additional

Published
2010
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2. GAS in Protoplanetary Systems (GASPS)

Author

Mathews, G. S., primary, Dent, W. R. F., additional, Williams, J. P., additional, Howard, C. D., additional, Meeus, G., additional, Riaz, B., additional, Roberge, A., additional, Sandell, G., additional, Vandenbussche, B., additional, Duchêne, G., additional, Kamp, I., additional, Ménard, F., additional, Montesinos, B., additional, Pinte, C., additional, Thi, W. F., additional, Woitke, P., additional, Alacid, J. M., additional, Andrews, S. M., additional, Ardila, D. R., additional, Aresu, G., additional, Augereau, J. C., additional, Barrado, D., additional, Brittain, S., additional, Ciardi, D. R., additional, Danchi, W., additional, Eiroa, C., additional, Fedele, D., additional, Grady, C. A., additional, de Gregorio-Monsalvo, I., additional, Heras, A., additional, Huelamo, N., additional, Krivov, A., additional, Lebreton, J., additional, Liseau, R., additional, Martin-Zaidi, C., additional, Mendigutía, I., additional, Mora, A., additional, Morales-Calderon, M., additional, Nomura, H., additional, Pantin, E., additional, Pascucci, I., additional, Phillips, N., additional, Podio, L., additional, Poelman, D. R., additional, Ramsay, S., additional, Rice, K., additional, Riviere-Marichalar, P., additional, Solano, E., additional, Tilling, I., additional, Walker, H., additional, White, G. J., additional, and Wright, G., additional

Published
2010
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3. TheHerschelview of GAS in Protoplanetary Systems (GASPS)

Author

Pinte, C., primary, Woitke, P., additional, Ménard, F., additional, Duchêne, G., additional, Kamp, I., additional, Meeus, G., additional, Mathews, G., additional, Howard, C. D., additional, Grady, C. A., additional, Thi, W.-F., additional, Tilling, I., additional, Augereau, J.-C., additional, Dent, W. R. F., additional, Alacid, J. M., additional, Andrews, S., additional, Ardila, D. R., additional, Aresu, G., additional, Barrado, D., additional, Brittain, S., additional, Ciardi, D. R., additional, Danchi, W., additional, Eiroa, C., additional, Fedele, D., additional, de Gregorio-Monsalvo, I., additional, Heras, A., additional, Huelamo, N., additional, Krivov, A., additional, Lebreton, J., additional, Liseau, R., additional, Martin-Zaïdi, C., additional, Mendigutía, I., additional, Montesinos, B., additional, Mora, A., additional, Morales-Calderon, M., additional, Nomura, H., additional, Pantin, E., additional, Pascucci, I., additional, Phillips, N., additional, Podio, L., additional, Poelman, D. R., additional, Ramsay, S., additional, Riaz, B., additional, Rice, K., additional, Riviere-Marichalar, P., additional, Roberge, A., additional, Sandell, G., additional, Solano, E., additional, Vandenbussche, B., additional, Walker, H., additional, Williams, J. P., additional, White, G. J., additional, and Wright, G., additional

Published
2010
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4. Gas in the protoplanetary disc of HD 169142:Herschel's view

Author

Meeus, G., primary, Pinte, C., additional, Woitke, P., additional, Montesinos, B., additional, Mendigutía, I., additional, Riviere-Marichalar, P., additional, Eiroa, C., additional, Mathews, G. S., additional, Vandenbussche, B., additional, Howard, C. D., additional, Roberge, A., additional, Sandell, G., additional, Duchêne, G., additional, Ménard, F., additional, Grady, C. A., additional, Dent, W. R. F., additional, Kamp, I., additional, Augereau, J. C., additional, Thi, W. F., additional, Tilling, I., additional, Alacid, J. M., additional, Andrews, S., additional, Ardila, D. R., additional, Aresu, G., additional, Barrado, D., additional, Brittain, S., additional, Ciardi, D. R., additional, Danchi, W., additional, Fedele, D., additional, de Gregorio-Monsalvo, I., additional, Heras, A., additional, Huelamo, N., additional, Krivov, A., additional, Lebreton, J., additional, Liseau, R., additional, Martin-Zaidi, C., additional, Mora, A., additional, Morales-Calderon, M., additional, Nomura, H., additional, Pantin, E., additional, Pascucci, I., additional, Phillips, N., additional, Podio, L., additional, Poelman, D. R., additional, Ramsay, S., additional, Riaz, B., additional, Rice, K., additional, Solano, E., additional, Walker, H., additional, White, G. J., additional, Williams, J. P., additional, and Wright, G., additional

Published
2010
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5. The unusual protoplanetary disk around the T Tauri star ET Chamaeleontis⋆

Author

Woitke, P., Riaz, B., Duchêne, G., Pascucci, I., Lyo, A.-R., Dent, W. R. F., Phillips, N., Thi, W.-F., Ménard, F., Herczeg, G. J., Bergin, E., Brown, A., Mora, A., Kamp, I., Aresu, G., Brittain, S., de Gregorio-Monsalvo, I., and Sandell, G.

Abstract

We present new continuum and line observations, along with modelling, of the faint (6−8) Myr old T Tauri star ET Cha belonging to the ηChamaeleontis cluster. We have acquired Herschel/PACS photometric fluxes at 70 μm and 160 μm, as well as a detection of the [OI] 63 μm fine-structure line in emission, and derived upper limits for some other far-IR OI, CII, CO and o-H2O lines. These observations were carried out in the frame of the open time key programme GASPS, where ET Cha was selected as one of the science demonstration phase targets. The Herschel data is complemented by new simultaneous ANDICAM B− Kphotometry, new HST/COS and HST/STIS UV-observations, a non-detection of CO J= 3 → 2 with APEX, re-analysis of a UCLES high-resolution optical spectrum showing forbidden emission lines like [OI] 6300 Å, [SII] 6731 Å and 6716 Å, and [NII] 6583 Å, and a compilation of existing broad-band photometric data. We used the thermo-chemical disk code ProDiMo and the Monte-Carlo radiative transfer code MCFOST to model the protoplanetary disk around ET Cha. The paper also introduces a number of physical improvements to the ProDiMo disk modelling code concerning the treatment of PAH ionisation balance and heating, the heating by exothermic chemical reactions, and several non-thermal pumping mechanisms for selected gas emission lines. By applying an evolutionary strategy to minimise the deviations between model predictions and observations, we find a variety of united gas and dust models that simultaneously fit all observed line and continuum fluxes about equally well. Based on these models we can determine the disk dustmass with confidence, Mdust≈ (2−5) × 10-8M⊙whereas the total disk gas mass is found to be only little constrained, Mgas≈ (5 × 10-5−3 × 10-3) M⊙. Both mass estimates are substantially lower than previously reported. In the models, the disk extends from 0.022 AU (just outside of the co-rotation radius) to only about 10 AU, remarkably small for single stars, whereas larger disks are found to be inconsistent with the CO J= 3 → 2 non-detection. The low velocity component of the [OI] 6300 Å emission line is centred on the stellar systematic velocity, and is consistent with being emitted from the inner disk. The model is also consistent with the line flux of H2v= 1 → 0 S(1) at 2.122 μm and with the [OI] 63 μm line as seen with Herschel/PACS. An additional high-velocity component of the [OI] 6300 Å emission line, however, points to the existence of an additional jet/outflow of low velocity 40−65 km s-1with mass loss rate  ≈ 10-9M⊙/yr. In relation to our low estimations of the disk mass, such a mass loss rate suggests a disk lifetime of only  ~0.05−3 Myr, substantially shorter than the cluster age. If a generic gas/dust ratio of 100 was assumed, the disk lifetime would be even shorter, only  ~3000 yrs. The evolutionary state of this unusual protoplanetary disk is discussed.

Published
2011
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6. Large-amplitude photometric variability of the candidate protoplanet TMR-1C

Author

Riaz, B. and Martín, E. L.

Abstract

Context.TMR-1C is a candidate protoplanet that lies at a separation of about 10″ (~1000 AU) from the Class I protobinary TMR-1 (IRAS 04361+2547) located in the Taurus molecular cloud. A narrow filament-like structure was observed in the discovery HST/NICMOS images, extending southeast from the central proto-binary system towards TMR-1C, suggesting a morphology in which the candidate protoplanet may have been ejected from the TMR-1 system. Follow-up low-resolution spectroscopy, however, could not confirm if this object is a protoplanet or a low-luminosity background star.

Published
2011
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7. The Herschelview of GAS in Protoplanetary Systems (GASPS)*

Author

Pinte, C., Woitke, P., Ménard, F., Duchêne, G., Kamp, I., Meeus, G., Mathews, G., Howard, C. D., Grady, C. A., Thi, W.-F., Tilling, I., Augereau, J.-C., Dent, W. R. F., Alacid, J. M., Andrews, S., Ardila, D. R., Aresu, G., Barrado, D., Brittain, S., Ciardi, D. R., Danchi, W., Eiroa, C., Fedele, D., de Gregorio-Monsalvo, I., Heras, A., Huelamo, N., Krivov, A., Lebreton, J., Liseau, R., Martin-Zaïdi, C., Mendigutía, I., Montesinos, B., Mora, A., Morales-Calderon, M., Nomura, H., Pantin, E., Pascucci, I., Phillips, N., Podio, L., Poelman, D. R., Ramsay, S., Riaz, B., Rice, K., Riviere-Marichalar, P., Roberge, A., Sandell, G., Solano, E., Vandenbussche, B., Walker, H., Williams, J. P., White, G. J., and Wright, G.

Abstract

The HerschelGASPS key program is a survey of the gas phase of protoplanetary discs, targeting 240 objects which cover a large range of ages, spectral types, and disc properties. To interpret this large quantity of data and initiate self-consistent analyses of the gas and dust properties of protoplanetary discs, we have combined the capabilities of the radiative transfer code MCFOST with the gas thermal balance and chemistry code ProDiMo to compute a grid of ≈300 000 disc models (DENT). We present a comparison of the first Herschel/GASPS line and continuum data with the predictions from the DENT grid of models. Our objective is to test some of the main trends already identified in the DENT grid, as well as to define better empirical diagnostics to estimate the total gas mass of protoplanetary discs. Photospheric UV radiation appears to be the dominant gas-heating mechanism for Herbig stars, whereas UV excess and/or X-rays emission dominates for T Tauri stars. The DENT grid reveals the complexity in the analysis of far-IR lines and the difficulty to invert these observations into physical quantities. The combination of Herschelline observations with continuum data and/or with rotational lines in the (sub-)millimetre regime, in particular CO lines, is required for a detailed characterisation of the physical and chemical properties of circumstellar discs.

Published
2010

8. Gas in the protoplanetary disc of HD 169142: Herschel's view *

Author

Meeus, G., Pinte, C., Woitke, P., Montesinos, B., Mendigutía, I., Riviere-Marichalar, P., Eiroa, C., Mathews, G. S., Vandenbussche, B., Howard, C. D., Roberge, A., Sandell, G., Duchêne, G., Ménard, F., Grady, C. A., Dent, W. R. F., Kamp, I., Augereau, J. C., Thi, W. F., Tilling, I., Alacid, J. M., Andrews, S., Ardila, D. R., Aresu, G., Barrado, D., Brittain, S., Ciardi, D. R., Danchi, W., Fedele, D., de Gregorio-Monsalvo, I., Heras, A., Huelamo, N., Krivov, A., Lebreton, J., Liseau, R., Martin-Zaidi, C., Mora, A., Morales-Calderon, M., Nomura, H., Pantin, E., Pascucci, I., Phillips, N., Podio, L., Poelman, D. R., Ramsay, S., Riaz, B., Rice, K., Solano, E., Walker, H., White, G. J., Williams, J. P., and Wright, G.

Abstract

In an effort to simultaneously study the gas and dust components of the disc surrounding the young Herbig Ae star HD 169142, we present far-IR observations obtained with the PACS instrument onboard the HerschelSpace Observatory. This work is part of the open time key program GASPS, which is aimed at studying the evolution of protoplanetary discs. To constrain the gas properties in the outer disc, we observed the star at several key gas-lines, including [OI] 63.2 and 145.5 μm, [CII] 157.7 μm, CO 72.8 and 90.2 μm, and o-H2O 78.7 and 179.5 μm. We only detect the [OI] 63.2 μm line in our spectra, and derive upper limits for the other lines. We complement our data set with PACS photometry and 12/13CO data obtained with the Submillimeter Array. Furthermore, we derive accurate stellar parameters from optical spectra and UV to mm photometry. We model the dust continuum with the 3D radiative transfer code MCFOST and use this model as an input to analyse the gas lines with the thermo-chemical code ProDiMo. Our dataset is consistent with a simple model in which the gas and dust are well-mixed in a disc with a continuous structure between 20 and 200 AU, but this is not a unique solution. Our modelling effort allows us to constrain the gas-to-dust mass ratio as well as the relative abundance of the PAHs in the disc by simultaneously fitting the lines of several species that originate in different regions. Our results are inconsistent with a gas-poor disc with a large UV excess; a gas mass of 5.0 ±2.0 × 10-3$M_{\odot}$is still present in this disc, in agreement with earlier CO observations.

Published
2010

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