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488 results on '"Cami, J."'

151. X-Shooter Survey of Near-Infrared DIBs

Author

Cox, N. L. J., primary, Cami, J., additional, Kaper, L., additional, Foing, B. H., additional, Ehrenfreund, P., additional, Ochsendorf, B. B., additional, van Hooff, S. H. M., additional, and Salama, F., additional

Published
2013
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155. XSHOOTER spectroscopy of the enigmatic planetary nebula Lin49 in the Small Magellanic Cloud.

Author

Masaaki Otsuka, Kemper, F., Leal-Ferreira, M. L., Aleman, I., Bernard-Salas, J., Cami, J., Ochsendorf, B. B., Peeters, E., and Scicluna, P.

Subjects
PLANETARY nebulae, STELLAR photospheres, VERY Large Telescope (Chile), INFRARED spectroscopy, COSMIC abundances, SMALL magellanic cloud
Abstract

We performed a detailed spectroscopic analysis of the fullerene C60-containing planetary nebula (PN) Lin49 in the Small Magellanic Cloud (SMC) using XSHOOTER at the European Southern Observatory Very Large Telescope and the Spitzer/Infrared Spectrograph instruments. We derived nebular abundances for nine elements. We used TLUSTY to derive photospheric parameters for the central star. Lin49 is C-rich and metal-deficient PN (Z ~ 0.0006). The nebular abundances are in good agreement with asymptotic giant branch nucleosynthesis models for stars with initial mass 1.25 M⊙ and metallicity Z = 0.001. Using the TLUSTY synthetic spectrum of the central star to define the heating and ionizing source, we constructed the photoionization model with CLOUDY that matches the observed spectral energy distribution (SED) and the line fluxes in the UV to far-IR wavelength ranges simultaneously. We could not fit the ~1-5 μm SED using a model with 0.005-0.1-μm-sized graphite grains and a constant hydrogen density shell owing to the prominent near-IR excess, while at other wavelengths the model fits the observed values reasonably well. We argue that the near-IR excess might indicate either (1) the presence of very small particles in the form of small carbon clusters, small graphite sheets, or fullerene precursors, or (2) the presence of a high-density structure surrounding the central star. We found that SMC C60 PNe show a near-IR excess component to lesser or greater degree. This suggests that these C60 PNe might maintain a structure nearby their central star. [ABSTRACT FROM AUTHOR]

Published
2016
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158. CO2V2V emission in O-rich AGB stars

Author

Cami, J., Justtanont, K., de Jong, T., Feuchtgruber, H., Tielens, A.G.G.M., Yamamura, I., Waters, L.B.F.M., Leech, K., Heras, A.M., Trams, N.R., Perry, M., and Low Energy Astrophysics (API, FNWI)

Published
1997

159. Amorphous alumina in the extended atmosphere of alpha Orionis

Author

Verhoelst, T., Decin, L., van Malderen, R., Hony, S., Cami, J., Eriksson, Kjell, Perrin, G., Deroo, P., Vandenbussche, B., Waters, L. B. F. M., Verhoelst, T., Decin, L., van Malderen, R., Hony, S., Cami, J., Eriksson, Kjell, Perrin, G., Deroo, P., Vandenbussche, B., and Waters, L. B. F. M.

Published
2006
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163. TheSpitzerspectroscopic survey of S-type stars

Author

Smolders, K., primary, Neyskens, P., additional, Blommaert, J. A. D. L., additional, Hony, S., additional, Van Winckel, H., additional, Decin, L., additional, Van Eck, S., additional, Sloan, G. C., additional, Cami, J., additional, Uttenthaler, S., additional, Degroote, P., additional, Barry, D., additional, Feast, M., additional, Groenewegen, M. A. T., additional, Matsuura, M., additional, Menzies, J., additional, Sahai, R., additional, van Loon, J. Th., additional, Zijlstra, A. A., additional, Acke, B., additional, Bloemen, S., additional, Cox, N., additional, de Cat, P., additional, Desmet, M., additional, Exter, K., additional, Ladjal, D., additional, Østensen, R., additional, Saesen, S., additional, van Wyk, F., additional, Verhoelst, T., additional, and Zima, W., additional

Published
2012
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171. The NASA Ames PAH IR Spectroscopic Database and the far-IR

Author

Boersma, C., primary, Allamandola, L.J., additional, Bauschlicher, C.W., additional, Ricca, A., additional, Cami, J., additional, Peeters, E., additional, Sánchez de Armas, F., additional, Puerta Saborido, G., additional, Mattioda, A.L., additional, and Hudgins, D.M., additional

Published
2011
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176. The dust disk of HR4049

Author

Dominik, C., Dullemond, C. P., Cami, J., van Winckel, H., Dominik, C., Dullemond, C. P., Cami, J., and van Winckel, H.

Abstract

We present the Spectral Energy Distribution of HR 4049 based on literature data and new continuum measurements at 850 micron. The SED shows variable absorption in the UV, and a large IR excess, both caused by circumstellar dust. The shape of the IR excess from 1 micron all the way down to 850 micron can be nearly perfectly fitted with a single blackbody function at T ~ 1150 K or alternatively with a sum of blackbodies in a narrow temperature range. The energy emitted in this IR continuum radiation is about one-third of the stellar luminosity. We show that this blackbody radiation must be due to the presence of a circumbinary disk with a large height. This disk must also be gas-rich, in agreement with the observations of molecular bands in the ISO-SWS spectrum. We present two possible scenario's for explaining the shape and the intensity of the IR excess. The first scenario involves large grains (a >1 mm) that each radiate like a blackbody. The second scenario argues that the blackbody radiation is due to a very optically thick circumbinary disk. We investigate if such a disk would indeed produce blackbody radiation by presenting results from radiative transfer calculations. We further quantify the properties of such a disk and its stability in the framework of (hydro)dynamics, grain settling, radiation pressure and grain drift. The virtues and shortcomings of both models for the origin of the IR blackbody are discussed by contrasting them with other observations and assessing them in the framework of (binary) (post-)AGB evolution., Comment: 16 pages, 12 figures, accepted for publication in A&A

Published
2002
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177. The time variation in infrared water-vapour bands in Mira variables

Author

Matsuura, M., Yamamura, I., Cami, J., Onaka, T., Murakami, H., Matsuura, M., Yamamura, I., Cami, J., Onaka, T., and Murakami, H.

Abstract

The time variation in the water-vapour bands in oxygen-rich Mira variables has been investigated using multi-epoch ISO/SWS spectra of four Mira variables in the 2.5-4.0 micron region. All four stars show H2O bands in absorption around minimum in the visual light curve. At maximum, H2O emission features appear in the ~3.5-4.0 micronm region, while the features at shorter wavelengths remain in absorption. These H2O bands in the 2.5-4.0 micron region originate from the extended atmosphere. The analysis has been carried out with a disk shape, slab geometry model. The observed H2O bands are reproduced by two layers; a `hot' layer with an excitation temperature of 2000 K and a `cool' layer with an excitation temperature of 1000-1400 K. The radii of the `hot' layer (R_hot) are ~1 R_* at visual minimum and 2 R_* at maximum, where R_* is a radius of background source of the model. The time variation of R_hot/R_* from 1 to 2 is attributed to the actual variation in the radius of the H2O layer. A high H2O density shell occurs near the surface of the star around minimum, and moves out with the stellar pulsation. This shell gradually fades away after maximum, and a new high H2O density shell is formed in the inner region again at the next minimum. Due to large optical depth of H2O, the near-infrared variability is dominated by the H2O layer, and the L'-band flux correlates with the area of the H2O shell. The infrared molecular bands trace the structure of the extended atmosphere and impose appreciable effects on near-infrared light curve of Mira variables., Comment: 15 pages, 16 figures, accepted by A&A

Published
2002
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181. The composition of circumstellar gas and dust in 51 Oph

Author

Ancker, M. E. van den, Meeus, G., Cami, J., Waters, L. B. F. M., Waelkens, C., Ancker, M. E. van den, Meeus, G., Cami, J., Waters, L. B. F. M., and Waelkens, C.

Abstract

We analyze ISO archive data of the nearby bright emission-line star 51 Oph, previously classified as a proto-planetary system similar to beta Pic. The infrared spectrum reveals the presence of gas-phase emission bands of hot (approx 850 K) CO, CO_2, H_2O and NO. In addition to this, partially crystalline silicate dust is present. The solid-state bands and the energy distribution are indicative of dust that has formed recently, rather than of debris dust. The presence of hot molecular gas and the composition of the circumstellar dust are highly unusual for a young star and are reminiscent of what is found around evolved (AGB) stars, although we exclude the possibility of 51 Oph belonging to this group. We suggest several explanations for the nature of 51 Oph, including a recent episode of mass loss from a Be star, and the recent destruction of a planet-sized body around a young star., Comment: 4 pages, 3 figures, accepted by A&A (letters)

Published
2001
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184. Interstellar gas, dust and diffuse bands in the SMC

Author

Cox, N. L. J., primary, Cordiner, M. A., additional, Ehrenfreund, P., additional, Kaper, L., additional, Sarre, P. J., additional, Foing, B. H., additional, Spaans, M., additional, Cami, J., additional, Sofia, U. J., additional, Clayton, G. C., additional, Gordon, K. D., additional, and Salama, F., additional

Published
2007
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185. Herschel* PACS and SPIRE spectroscopy of the photodissociation regions associated with S 106 and IRAS 23133+6050.

Author

Stock, D. J., Wolfire, M. G., Peeters, E., Tielens, A. G. G. M., Vandenbussche, B., Boersma, C., and Cami, J.

Subjects
PHOTODISSOCIATION, SUPERGIANT stars, MOLECULAR clouds, PHOTONS, INTERSTELLAR medium
Abstract

Context. Photodissociation regions (PDRs) contain a large portion of all of the interstellar matter in galaxies. Classical examples include the boundaries between ionized regions and molecular clouds in regions of massive star-formation, marking the point where all of the photons that are energetic enough to ionize hydrogen have been absorbed. Aims. To determine the physical properties of the PDRs associated with the star-forming regions IRAS 23133+6050 and S 106 and present them in the context of other Galactic PDRs associated with massive star-forming regions. Methods. We employ Herschel PACS and SPIRE spectroscopic observations to construct a full 55-650 μm spectrum of each object from which we measure the PDR cooling lines, other fine- structure lines, CO lines, and the total far-infrared flux. These measurements (and combinations thereof) are then compared to standard PDR models. Subsequently, detailed numerical PDR models are compared to these predictions, yielding additional insight into the dominant thermal processes in the PDRs and their structures. Results. We find that the PDRs of each object are very similar and can be characterized by a two-phase PDR model with a very dense, highly UV irradiated phase (n ∼ 106 cm-3, G0 ∼ 105) interspersed within a lower density, weaker radiation field phase (n ∼ 104 cm-3, G0 ∼ 104). We employed two different numerical models to investigate the data. We first used RADEX models to fit the peak of the 12CO ladder, which in conjunction with the properties derived, yielded a temperature of around 300 K. Subsequent numerical modeling with a full PDR model revealed that the dense phase has a filling factor of around 0.6 in both objects. The shape of the 12CO ladder was consistent with these components, with heating dominated by grain photoelectric heating. An extra excitation component for the heightest-J lines (J > 20) is required for S 106. [ABSTRACT FROM AUTHOR]

Published
2015
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187. ISO mid-infrared spectroscopy of Galactic Bulge AGB stars

Author

Blommaert, J. A. D. L., primary, Groenewegen, M. A. T., additional, Okumura, K., additional, Ganesh, S., additional, Omont, A., additional, Cami, J., additional, Glass, I. S., additional, Habing, H. J., additional, Schultheis, M., additional, Simon, G., additional, and van Loon, J. Th., additional

Published
2006
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191. Amorphous alumina in the extended atmosphere of α Orionis

Author

Verhoelst, T., primary, Decin, L., additional, Van Malderen, R., additional, Hony, S., additional, Cami, J., additional, Eriksson, K., additional, Perrin, G., additional, Deroo, P., additional, Vandenbussche, B., additional, and Waters, L. B. F. M., additional

Published
2006
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192. Magellanic Diffuse Interstellar Bands and Carbon Chemistry

Author

Ehrenfreund, P., primary, Cox, N., additional, Cami, J., additional, Foing, B.H., additional, Kaper, L., additional, d’Hendecourt, L., additional, Maier, J.P., additional, Salama, F., additional, Sarre, P., additional, Snow, T., additional, and Sonnentrucker, P., additional

Published
2005
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200. Determination of MDMA and its Metabolites in Blood and Urine by Gas Chromatography-Mass Spectrometry and Analysis of Enantiomers by Capillary Electrophoresis

Author

Pizarro, N., primary, Ortuno, J., additional, Farre, M., additional, Hernandez-Lopez, C., additional, Pujadas, M., additional, Llebaria, A., additional, Joglar, J., additional, Roset, P. N., additional, Mas, M., additional, Segura, J., additional, Cami, J., additional, and de la Torre, R., additional

Published
2002
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