المؤلفون: Abergel, A., Misselt, K., Gordon, K. D., Noriega-Crespo, A., Guillard, P., Van De Putte, D., Witt, A. N., Ysard, N., Baes, M., Beuther, H., Bouchet, P., Brandl, B. R., Elyajouri, M., Kannavou, O., Kendrew, S., Klassen, P., Trahin, B.

مصطلحات موضوعية: Astrophysics - Astrophysics of Galaxies

الوصف: The JWST has captured the sharpest IR images ever taken of the Horsehead nebula, a prototypical moderately irradiated PDR that is fully representative of most of the UV-illuminated molecular gas in the Milky Way and star-forming galaxies. We investigate the impact of FUV radiation of a molecular cloud and constrain the structure of the edge of the PDR and its illumination conditions. We used NIRCam and MIRI to obtain 17 broadband and 6 narrowband maps from 0.7 to 28 $\mu$m. We mapped the dust emission, scattered light, and several gas phase lines. We also used HST-WFC3 maps at 1.1 and 1. 6 $\mu$m, along with HST-STIS spectroscopic observations of the H$\alpha$ line. We probed the structure of the edge of the Horsehead and resolved its spatial complexity. We detected a network of faint striated features extending perpendicularly to the PDR front into the H\,II region in filters sensitive to nano-grain emission and light scattered by larger grains. This may indeed figure as the first detection of the entrainment of dust particles in the evaporative flow. The map of the 1-0 S(1) line of H$_2$ presents sharp sub-structures on scales as small as 1.5 arcsec. The ionization and dissociation fronts appear at distances 1-2 arcsec behind the edge of the PDR and seem to spatially coincide, indicating a thickness of the neutral atomic layer below 100 au. All broadband maps present strong color variations which can be explained by dust attenuation. Deviations of the emissions in the H$\alpha$, Pa$\alpha,$ and Br$\alpha$ lines also indicate dust attenuation. With a very simple model, we derive the main features of the extinction curve. A small excess of extinction at 3 $\mu$m may be attributed to icy H$_2$O mantles onto grains. In all lines of sight crossing the inner regions of the Horsehead, it appears that dust attenuation is non-negligible over the entire spectral range.
Comment: 25 pages, 17 figures

الوصول الحر: http://arxiv.org/abs/2404.15816Test

المؤلفون: Fuente, Asunción, Roueff, Evelyne, Petit, Franck Le, Bourlot, Jacques Le, Bron, Emeric, Wolfire, Mark G., Babb, James F., Yan, Pei-Gen, Onaka, Takashi, Black, John H., Schroetter, Ilane, Van De Putte, Dries, Sidhu, Ameek, Canin, Amélie, Trahin, Boris, Alarcón, Felipe, Chown, Ryan, Kannavou, Olga, Berné, Olivier, Habart, Emilie, Peeters, Els, Goicoechea, Javier R., Zannese, Marion, Meshaka, Raphael, Okada, Yoko, Röllig, Markus, Gal, Romane Le, Sales, Dinalva A., Palumbo, Maria Elisabetta, Baratta, Giuseppe Antonio, Madden, Suzanne C., Neelamkodan, Naslim, Zhang, Ziwei E., Stancil, P. C.

مصطلحات موضوعية: Astrophysics - Astrophysics of Galaxies

الوصف: One of the main problems in astrochemistry is determining the amount of sulfur in volatiles and refractories in the interstellar medium. The detection of the main sulfur reservoirs (icy H$_2$S and atomic gas) has been challenging, and estimates are based on the reliability of models to account for the abundances of species containing less than 1% of the total sulfur. The high sensitivity of the James Webb Space Telescope provides an unprecedented opportunity to estimate the sulfur abundance through the observation of the [S I] 25.249 $\mu$m line. We used the [S III] 18.7 $\mu$m, [S IV] 10.5 $\mu$m, and [S l] 25.249 $\mu$m lines to estimate the amount of sulfur in the ionized and molecular gas along the Orion Bar. For the theoretical part, we used an upgraded version of the Meudon photodissociation region (PDR) code to model the observations. New inelastic collision rates of neutral atomic sulfur with ortho- and para- molecular hydrogen were calculated to predict the line intensities. The [S III] 18.7 $\mu$m and [S IV] 10.5 $\mu$m lines are detected over the imaged region with a shallow increase (by a factor of 4) toward the HII region. We estimate a moderate sulfur depletion, by a factor of $\sim$2, in the ionized gas. The corrugated interface between the molecular and atomic phases gives rise to several edge-on dissociation fronts we refer to as DF1, DF2, and DF3. The [S l] 25.249 $\mu$m line is only detected toward DF2 and DF3, the dissociation fronts located farthest from the HII region. The detailed modeling of DF3 using the Meudon PDR code shows that the emission of the [S l] 25.249 $\mu$m line is coming from warm ($>$ 40 K) molecular gas located at A$_{\rm V}$ $\sim$ 1$-$5 mag from the ionization front. Moreover, the intensity of the [S l] 25.249 $\mu$m line is only accounted for if we assume the presence of undepleted sulfur.
Comment: 16 pages, 6 figures. Accepted for publication in Astronomy and Astrophysics

الوصول الحر: http://arxiv.org/abs/2404.09235Test

المؤلفون: Van De Putte, Dries, Meshaka, Raphael, Trahin, Boris, Habart, Emilie, Peeters, Els, Berné, Olivier, Alarcón, Felipe, Canin, Amélie, Chown, Ryan, Schroetter, Ilane, Sidhu, Ameek, Boersma, Christiaan, Bron, Emeric, Dartois, Emmanuel, Goicoechea, Javier R., Gordon, Karl D., Onaka, Takashi, Tielens, Alexander G. G. M., Verstraete, Laurent, Wolfire, Mark G., Abergel, Alain, Bergin, Edwin A., Bernard-Salas, Jeronimo, Cami, Jan, Cuadrado, Sara, Dicken, Daniel, Elyajouri, Meriem, Fuente, Asunción, Joblin, Christine, Khan, Baria, Lacinbala, Ozan, Languignon, David, Gal, Romane Le, Maragkoudakis, Alexandros, Okada, Yoko, Pasquini, Sofia, Pound, Marc W., Robberto, Massimo, Röllig, Markus, Schefter, Bethany, Schirmer, Thiébaut, Tabone, Benoit, Vicente, Sílvia, Zannese, Marion, Colgan, Sean W. J., He, Jinhua, Rouillé, Gaël, Togi, Aditya, Aleman, Isabel, Auchettl, Rebecca, Baratta, Giuseppe Antonio, Bejaoui, Salma, Bera, Partha P., Black, John H., Boulanger, Francois, Bouwman, Jordy, Brandl, Bernhard, Brechignac, Philippe, Brünken, Sandra, Buragohain, Mridusmita, Burkhardt, Andrew, Candian, Alessandra, Cazaux, Stéphanie, Cernicharo, Jose, Chabot, Marin, Chakraborty, Shubhadip, Champion, Jason, Cooke, Ilsa R., Coutens, Audrey, Cox, Nick L. J., Demyk, Karine, Meyer, Jennifer Donovan, Foschino, Sacha, García-Lario, Pedro, Gerin, Maryvonne, Gottlieb, Carl A., Guillard, Pierre, Gusdorf, Antoine, Hartigan, Patrick, Herbst, Eric, Hornekaer, Liv, Issa, Lina, Jäger, Cornelia, Janot-Pacheco, Eduardo, Kannavou, Olga, Kaufman, Michael, Kemper, Francisca, Kendrew, Sarah, Kirsanova, Maria S., Klaassen, Pamela, Kwok, Sun, Labiano, Álvaro, Lai, Thomas S. -Y., Floch, Bertrand Le, Petit, Franck Le, Li, Aigen, Linz, Hendrik, Mackie, Cameron J., Madden, Suzanne C., Mascetti, Joëlle, McGuire, Brett A., Merino, Pablo, Micelotta, Elisabetta R., Morse, Jon A., Mulas, Giacomo, Neelamkodan, Naslim, Ohsawa, Ryou, Omont, Alain, Paladini, Roberta, Palumbo, Maria Elisabetta, Pathak, Amit, Pendleton, Yvonne J., Petrignani, Annemieke, Pino, Thomas, Puga, Elena, Rangwala, Naseem, Rapacioli, Mathias, Rho, Jeonghee, Ricca, Alessandra, Roman-Duval, Julia, Roser, Joseph, Roueff, Evelyne, Salama, Farid, Sales, Dinalva A., Sandstrom, Karin, Sarre, Peter, Sciamma-O'Brien, Ella, Sellgren, Kris, Shenoy, Sachindev S., Teyssier, David, Thomas, Richard D., Witt, Adolf N., Wootten, Alwyn, Ysard, Nathalie, Zettergren, Henning, Zhang, Yong, Zhang, Ziwei E., Zhen, Junfeng

المصدر: A&A 687, A86 (2024)

مصطلحات موضوعية: Astrophysics - Astrophysics of Galaxies

الوصف: Mid-infrared emission features probe the properties of ionized gas, and hot or warm molecular gas. The Orion Bar is a frequently studied photodissociation region (PDR) containing large amounts of gas under these conditions, and was observed with the MIRI IFU aboard JWST as part of the "PDRs4All" program. The resulting IR spectroscopic images of high angular resolution (0.2") reveal a rich observational inventory of mid-IR emission lines, and spatially resolve the substructure of the PDR, with a mosaic cutting perpendicularly across the ionization front and three dissociation fronts. We extracted five spectra that represent the ionized, atomic, and molecular gas layers, and measured the most prominent gas emission lines. An initial analysis summarizes the physical conditions of the gas and the potential of these data. We identified around 100 lines, report an additional 18 lines that remain unidentified, and measured the line intensities and central wavelengths. The H I recombination lines originating from the ionized gas layer bordering the PDR, have intensity ratios that are well matched by emissivity coefficients from H recombination theory, but deviate up to 10% due contamination by He I lines. We report the observed emission lines of various ionization stages of Ne, P, S, Cl, Ar, Fe, and Ni, and show how certain line ratios vary between the five regions. We observe the pure-rotational H$_2$ lines in the vibrational ground state from 0-0 S(1) to 0-0 S(8), and in the first vibrationally excited state from 1-1 S(5) to 1-1 S(9). We derive H$_2$ excitation diagrams, and approximate the excitation with one thermal (~700 K) component representative of an average gas temperature, and one non-thermal component (~2700 K) probing the effect of UV pumping. We compare these results to an existing model for the Orion Bar PDR and highlight the differences with the observations.
Comment: 26 pages, 12 figures, 3 tables. Submitted to A&A, under review (1st revision)

الوصول الحر: http://arxiv.org/abs/2404.03111Test

المؤلفون: Berné, Olivier, Habart, Emilie, Peeters, Els, Schroetter, Ilane, Canin, Amélie, Sidhu, Ameek, Chown, Ryan, Bron, Emeric, Haworth, Thomas J., Klaassen, Pamela, Trahin, Boris, Van De Putte, Dries, Alarcón, Felipe, Zannese, Marion, Abergel, Alain, Bergin, Edwin A., Bernard-Salas, Jeronimo, Boersma, Christiaan, Cami, Jan, Cuadrado, Sara, Dartois, Emmanuel, Dicken, Daniel, Elyajouri, Meriem, Fuente, Asunción, Goicoechea, Javier R., Gordon, Karl D., Issa, Lina, Joblin, Christine, Kannavou, Olga, Khan, Baria, Lacinbala, Ozan, Languignon, David, Gal, Romane Le, Maragkoudakis, Alexandros, Meshaka, Raphael, Okada, Yoko, Onaka, Takashi, Pasquini, Sofia, Pound, Marc W., Robberto, Massimo, Röllig, Markus, Schefter, Bethany, Schirmer, Thiébaut, Simmer, Thomas, Tabone, Benoit, Tielens, Alexander G. G. M., Vicente, Sílvia, Wolfire, Mark G., Aleman, Isabel, Allamandola, Louis, Auchettl, Rebecca, Baratta, Giuseppe Antonio, Baruteau, Clément, Bejaoui, Salma, Bera, Partha P., Black, John H., Boulanger, Francois, Bouwman, Jordy, Brandl, Bernhard, Brechignac, Philippe, Brünken, Sandra, Buragohain, Mridusmita, Burkhardt, Andrew, Candian, Alessandra, Cazaux, Stéphanie, Cernicharo, Jose, Chabot, Marin, Chakraborty, Shubhadip, Champion, Jason, Colgan, Sean W. J., Cooke, Ilsa R., Coutens, Audrey, Cox, Nick L. J., Demyk, Karine, Meyer, Jennifer Donovan, Engrand, Cécile, Foschino, Sacha, García-Lario, Pedro, Gavilan, Lisseth, Gerin, Maryvonne, Godard, Marie, Gottlieb, Carl A., Guillard, Pierre, Gusdorf, Antoine, Hartigan, Patrick, He, Jinhua, Herbst, Eric, Hornekaer, Liv, Jäger, Cornelia, Janot-Pacheco, Eduardo, Kaufman, Michael, Kemper, Francisca, Kendrew, Sarah, Kirsanova, Maria S., Knight, Collin, Kwok, Sun, Labiano, Álvaro, Lai, Thomas S. -Y., Lee, Timothy J., Lefloch, Bertrand, Petit, Franck Le, Li, Aigen, Linz, Hendrik, Mackie, Cameron J., Madden, Suzanne C., Mascetti, Joëlle, McGuire, Brett A., Merino, Pablo, Micelotta, Elisabetta R., Morse, Jon A., Mulas, Giacomo, Neelamkodan, Naslim, Ohsawa, Ryou, Paladini, Roberta, Palumbo, Maria Elisabetta, Pathak, Amit, Pendleton, Yvonne J., Petrignani, Annemieke, Pino, Thomas, Puga, Elena, Rangwala, Naseem, Rapacioli, Mathias, Ricca, Alessandra, Roman-Duval, Julia, Roueff, Evelyne, Rouillé, Gaël, Salama, Farid, Sales, Dinalva A., Sandstrom, Karin, Sarre, Peter, Sciamma-O'Brien, Ella, Sellgren, Kris, Shannon, Matthew J., Simonnin, Adrien, Shenoy, Sachindev S., Teyssier, David, Thomas, Richard D., Togi, Aditya, Verstraete, Laurent, Witt, Adolf N., Wootten, Alwyn, Ysard, Nathalie, Zettergren, Henning, Zhang, Yong, Zhang, Ziwei E., Zhen, Junfeng

المصدر: Science, 383, 6686, 2024

مصطلحات موضوعية: Astrophysics - Astrophysics of Galaxies

الوصف: Most low-mass stars form in stellar clusters that also contain massive stars, which are sources of far-ultraviolet (FUV) radiation. Theoretical models predict that this FUV radiation produces photo-dissociation regions (PDRs) on the surfaces of protoplanetary disks around low-mass stars, impacting planet formation within the disks. We report JWST and Atacama Large Millimetere Array observations of a FUV-irradiated protoplanetary disk in the Orion Nebula. Emission lines are detected from the PDR; modelling their kinematics and excitation allows us to constrain the physical conditions within the gas. We quantify the mass-loss rate induced by the FUV irradiation, finding it is sufficient to remove gas from the disk in less than a million years. This is rapid enough to affect giant planet formation in the disk.

الوصول الحر: http://arxiv.org/abs/2403.00160Test

المؤلفون: Grossi, Davide, Hahn, Ulrike, Mäs, Michael, Nitsche, Andreas, Behrens, Jan, Boehmer, Niclas, Brill, Markus, Endriss, Ulle, Grandi, Umberto, Haret, Adrian, Heitzig, Jobst, Janssens, Nicolien, Jonker, Catholijn M., Keijzer, Marijn A., Kistner, Axel, Lackner, Martin, Lieben, Alexandra, Mikhaylovskaya, Anna, Murukannaiah, Pradeep K., Proietti, Carlo, Revel, Manon, Rouméas, Élise, Shapiro, Ehud, Sreedurga, Gogulapati, Swierczek, Björn, Talmon, Nimrod, Turrini, Paolo, Terzopoulou, Zoi, Van De Putte, Frederik

مصطلحات موضوعية: Computer Science - Computers and Society

الوصف: This white paper outlines a long-term scientific vision for the development of digital-democracy technology. We contend that if digital democracy is to meet the ambition of enabling a participatory renewal in our societies, then a comprehensive multi-methods research effort is required that could, over the years, support its development in a democratically principled, empirically and computationally informed way. The paper is co-authored by an international and interdisciplinary team of researchers and arose from the Lorentz Center Workshop on ``Algorithmic Technology for Democracy'' (Leiden, October 2022).

الوصول الحر: http://arxiv.org/abs/2401.16863Test

المؤلفون: Berné, Olivier, Martin-Drumel, Marie-Aline, Schroetter, Ilane, Goicoechea, Javier R., Jacovella, Ugo, Gans, Bérenger, Dartois, Emmanuel, Coudert, Laurent, Bergin, Edwin, Alarcon, Felipe, Cami, Jan, Roueff, Evelyne, Black, John H., Asvany, Oskar, Habart, Emilie, Peeters, Els, Canin, Amelie, Trahin, Boris, Joblin, Christine, Schlemmer, Stephan, Thorwirth, Sven, Cernicharo, Jose, Gerin, Maryvonne, Tielens, Alexander, Zannese, Marion, Abergel, Alain, Bernard-Salas, Jeronimo, Boersma, Christiaan, Bron, Emeric, Chown, Ryan, Cuadrado, Sara, Dicken, Daniel, Elyajouri, Meriem, Fuente, Asunción, Gordon, Karl D., Issa, Lina, Kannavou, Olga, Khan, Baria, Lacinbala, Ozan, Languignon, David, Gal, Romane Le, Maragkoudakis, Alexandros, Meshaka, Raphael, Okada, Yoko, Onaka, Takashi, Pasquini, Sofia, Pound, Marc W., Robberto, Massimo, Röllig, Markus, Schefter, Bethany, Schirmer, Thiébaut, Sidhu, Ameek, Tabone, Benoit, Van De Putte, Dries, Vicente, Sílvia, Wolfire, Mark G.

المصدر: Nature 621, 56-59 (2023)

مصطلحات موضوعية: Astrophysics - Astrophysics of Galaxies, Physics - Chemical Physics

الوصف: Forty years ago it was proposed that gas phase organic chemistry in the interstellar medium was initiated by the methyl cation CH3+, but hitherto it has not been observed outside the Solar System. Alternative routes involving processes on grain surfaces have been invoked. Here we report JWST observations of CH3+ in a protoplanetary disk in the Orion star forming region. We find that gas-phase organic chemistry is activated by UV irradiation.
Comment: Published in Nature

الوصول الحر: http://arxiv.org/abs/2401.03296Test

المؤلفون: Elyajouri, M., Ysard, N., Abergel, A., Habart, E., Verstraete, L., Jones, A., Juvela, M., Schirmer, T., Meshaka, R., Dartois, E., Lebourlot, J., Rouille, G., Onaka, T., Peeters, E., Berne, O., Alarcon, F., Bernard-Salas, J., Buragohain, M., Cami, J., Canin, A., Chown, R., Demyk, K., Gordon, K., Kannavou, O., Kirsanova, M., Madden, S., Paladini, R., Pendleton, Y., Salama, F., Schroetter, I., Sidhu, A., Rollig, M., Trahin, B., Van De Putte, D.

المصدر: A&A 685, A76 (2024)

مصطلحات موضوعية: Astrophysics - Astrophysics of Galaxies

الوصف: We study the emission of dust grains within the Orion Bar - a well-known, highly far-UV (FUV)-irradiated PDR. The Orion Bar because of its edge-on geometry provides an exceptional benchmark for characterizing dust evolution and the associated driving processes under varying physical conditions. Our goal is to constrain the local properties of dust by comparing its emission to models. Taking advantage of the recent JWST PDRs4All data, we follow the dust emission as traced by JWST NIRCam (at 3.35 and 4.8 micron) and MIRI (at 7.7, 11.3, 15.0, and 25.5 micron), along with NIRSpec and MRS spectroscopic observations. First, we constrain the minimum size and hydrogen content of carbon nano-grains from a comparison between the observed dust emission spectra and the predictions of the THEMIS dust model coupled to the numerical code DustEM. Using this dust model, we then perform 3D radiative transfer simulations of dust emission with the SOC code and compare to data obtained along well chosen profiles across the Orion Bar. The JWST data allows us, for the first time, to spatially resolve the steep variation of dust emission at the illuminated edge of the Orion Bar PDR. By considering a dust model with carbonaceous nano-grains and submicronic coated silicate grains, we derive unprecedented constraints on the properties of across the Orion Bar. To explain the observed emission profiles with our simulations, we find that the nano-grains must be strongly depleted with an abundance (relative to the gas) 15 times less than in the diffuse ISM. The NIRSpec and MRS spectroscopic observations reveal variations in the hydrogenation of the carbon nano-grains. The lowest hydrogenation levels are found in the vicinity of the illuminating stars suggesting photo-processing while more hydrogenated nano-grains are found in the cold and dense molecular region, potentially indicative of larger grains.
Comment: 18 pages, 11 figures, accepted for publication in A&A

الوصول الحر: http://arxiv.org/abs/2401.01221Test

المؤلفون: Zannese, Marion, Tabone, Benoît, Habart, Emilie, Goicoechea, Javier R., Zanchet, Alexandre, van Dishoeck, Ewine F., van Hemert, Marc C., Black, John H., Tielens, Alexander G. G. M., Veselinova, A., Jambrina, P. G., Menendez, M., Verdasco, E., Aoiz, F. J., Gonzalez-Sanchez, L., Trahin, Boris, Dartois, Emmanuel, Berné, Olivier, Peeters, Els, He, Jinhua, Sidhu, Ameek, Chown, Ryan, Schroetter, Ilane, Van De Putte, Dries, Canin, Amélie, Alarcón, Felipe, Abergel, Alain, Bergin, Edwin A., Bernard-Salas, Jeronimo, Boersma, Christiaan, Bron, Emeric, Cami, Jan, Dicken, Daniel, Elyajouri, Meriem, Fuente, Asunción, Gordon, Karl D., Issa, Lina, Joblin, Christine, Kannavou, Olga, Khan, Baria, Lacinbala, Ozan, Languignon, David, Gal, Romane Le, Maragkoudakis, Alexandros, Meshaka, Raphael, Okada, Yoko, Onaka, Takashi, Pasquini, Sofia, Pound, Marc W., Robberto, Massimo, Röllig, Markus, Schefter, Bethany, Schirmer, Thiébaut, Vicente, Sílvia, Wolfire, Mark G.

مصطلحات موضوعية: Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Astrophysics of Galaxies, Astrophysics - Solar and Stellar Astrophysics

الوصف: Water is a key ingredient for the emergence of life as we know it. Yet, its destruction and reformation in space remains unprobed in warm gas. Here, we detect the hydroxyl radical (OH) emission from a planet-forming disk exposed to external far-ultraviolet (FUV) radiation with the James Webb Space Telescope. The observations are confronted with the results of quantum dynamical calculations. The highly excited OH infrared rotational lines are the tell-tale signs of H2O destruction by FUV. The OH infrared ro-vibrational lines are attributed to chemical excitation via the key reaction O+H=OH+H which seeds the formation of water in the gas-phase. We infer that the equivalent of the Earth ocean's worth of water is destroyed per month and replenished. These results show that under warm and irradiated conditions water is destroyed and efficiently reformed via gas-phase reactions. This process, assisted by diffusive transport, could reduce the HDO/H2O ratio in the warm regions of planet-forming disks.
Comment: Version submitted to Nature Astronomy

الوصول الحر: http://arxiv.org/abs/2312.14056Test

المؤلفون: Pasquini, S., Peeters, E., Schefter, B., Khan, B., Sidhu, A., Chown, R., Cami, J., Tielens, A., Alarcon, F., Canin, A., Schroetter, I., Trahin, B., Van De Putte, D., Boersma, C., Dartois, E., Onaka, T., Candian, A., Hartigan, P., Lai, T. S. -Y., Rouille, G., Sales, D. A., Zhang, Y., Habart, E., Berne, O.

المصدر: A&A 685, A77 (2024)

مصطلحات موضوعية: Astrophysics - Astrophysics of Galaxies

الوصف: [Abridged] JWST observations of the Orion Bar have shown the incredible richness of PAH bands and their variation on small scales. We aim to probe the photochemical evolution of PAHs across the key zones of the photodissociation region (PDR) that is the Orion Bar using unsupervised machine learning. We use NIRSpec and MIRI IFU data from the JWST ERS Program PDRs4All. We lever bisecting k-means clustering to generate detailed spatial maps of the spectral variability in several wavelength regions. We discuss the variations in the cluster profiles and connect them to the local physical conditions. We interpret these variations with respect to the key zones: the HII region, the atomic PDR zone, and the three dissociation fronts. The PAH emission exhibits spectral variation that depends strongly on spatial position in the PDR. We find the 8.6um band to behave differently than all other bands which vary systematically with one another. We find uniform variation in the 3.4-3.6um bands and 3.4/3.3 intensity ratio. We attribute the carrier of the 3.4-3.6um bands to a single side group attached to very similarly sized PAHs. Cluster profiles reveal a transition between characteristic profiles classes of the 11.2um feature from the atomic to the molecular PDR zone. We find the carriers of each of the profile classes to be independent, and reason the latter to be PAH clusters existing solely deep in the molecular PDR. Clustering also reveals a connection between the 11.2 and 6.2um bands; and that clusters generated from variation in the 10.9-11.63um region can be used to recover those in the 5.95-6.6um region. Clustering is a powerful tool for characterizing PAH variability on both spatial and spectral scales. For individual bands as well as global spectral behaviours, we find UV-processing to be the most important driver of the evolution of PAHs and their spectral signatures in the Orion Bar.
Comment: 28 pages, 20 figures, submitted to A&A

الوصول الحر: http://arxiv.org/abs/2311.01163Test

المؤلفون: Peeters, Els, Habart, Emilie, Berne, Olivier, Sidhu, Ameek, Chown, Ryan, Van De Putte, Dries, Trahin, Boris, Schroetter, Ilane, Canin, Amelie, Alarcon, Felipe, Schefter, Bethany, Khan, Baria, Pasquini, Sofia, Tielens, Alexander G. G. M., Wolfire, Mark G., Dartois, Emmanuel, Goicoechea, Javier R., Maragkoudakis, Alexandros, Onaka, Takashi, Pound, Marc W., Vicente, Silvia, Abergel, Alain, Bergin, Edwin A., Bernard-Salas, Jeronimo, Boersma, Christiaan, Bron, Emeric, Cami, Jan, Cuadrado, Sara, Dicken, Daniel, Elyajour, Meriem, Fuente, Asuncion, Gordon, Karl D., Issa, Lina, Joblin, Christine, Kannavou, Olga, Lacinbala, Ozan, Languignon, David, Gal, Romane Le, Meshaka, Raphael, Okada, Yoko, Robberto, Massimo, Roellig, Markus, Schirmer, Thiebaut, Tabone, Benoit, Zannese, Marion, Aleman, Isabel, Allamandola, Louis, Auchettl, Rebecca, Baratta, Giuseppe Antonio, Bejaoui, Salma, Bera, Partha P., Black, John H., Boulanger, Francois, Bouwman, Jordy, Brandl, Bernhard, Brechignac, Philippe, Brunken, Sandra, Buragohain, Mridusmita, Burkhardt, Andrew, Candian, Alessandra, Cazaux, Stephanie, Cernicharo, Jose, Chabot, Marin, Chakraborty, Shubhadip, Champion, Jason, Colgan, Sean W. J., Cooke, Ilsa R., Coutens, Audrey, Cox, Nick L. J., Demyk, Karine, Meyer, Jennifer Donovan, Foschino, Sacha, Garcia-Lario, Pedro, Gerin, Maryvonne, Gottlieb, Carl A., Guillard, Pierre, Gusdorf, Antoine, Hartigan, Patrick, He, Jinhua, Herbst, Eric, Hornekaer, Liv, Jager, Cornelia, Janot-Pacheco, Eduardo, Kaufman, Michael, Kendrew, Sarah, Kirsanova, Maria S., Klaassen, Pamela, Kwok, Sun, Labiano, Alvaro, Lai, Thomas S. -Y., Lee, Timothy J., Lefloch, Bertrand, Petit, Franck Le, Li, Aigen, Linz, Hendrik, Mackie, Cameron J., Madden, Suzanne C., Mascetti, Joelle, McGuire, Brett A., Merino, Pablo, Micelotta, Elisabetta R., Misselt, Karl, Morse, Jon A., Mulas, Giacomo, Neelamkodan, Naslim, Ohsawa, Ryou, Paladini, Roberta, Palumbo, Maria Elisabetta, Pathak, Amit, Pendleton, Yvonne J., Petrignani, Annemieke, Pino, Thomas, Puga, Elena, Rangwala, Naseem, Rapacioli, Mathias, Ricca, Alessandra, Roman-Duval, Julia, Roser, Joseph, Roueff, Evelyne, Rouille, Gael, Salama, Farid, Sales, Dinalva A., Sandstrom, Karin, Sarre, Peter, Sciamma-O'Brien, Ella, Sellgren, Kris, Shenoy, Sachindev S., Teyssier, David, Thomas, Richard D., Togi, Aditya, Verstraete, Laurent, Witt, Adolf N., Wootten, Alwyn, Ysard, Nathalie, Zettergren, Henning, Zhang, Yong, Zhang, Ziwei E., Zhen, Junfeng

المصدر: A&A 685, A74 (2024)

مصطلحات موضوعية: Astrophysics - Astrophysics of Galaxies

الوصف: (Abridged) We investigate the impact of radiative feedback from massive stars on their natal cloud and focus on the transition from the HII region to the atomic PDR (crossing the ionisation front (IF)), and the subsequent transition to the molecular PDR (crossing the dissociation front (DF)). We use high-resolution near-IR integral field spectroscopic data from NIRSpec on JWST to observe the Orion Bar PDR as part of the PDRs4All JWST Early Release Science Program. The NIRSpec data reveal a forest of lines including, but not limited to, HeI, HI, and CI recombination lines, ionic lines, OI and NI fluorescence lines, Aromatic Infrared Bands (AIBs including aromatic CH, aliphatic CH, and their CD counterparts), CO2 ice, pure rotational and ro-vibrational lines from H2, and ro-vibrational lines HD, CO, and CH+, most of them detected for the first time towards a PDR. Their spatial distribution resolves the H and He ionisation structure in the Huygens region, gives insight into the geometry of the Bar, and confirms the large-scale stratification of PDRs. We observe numerous smaller scale structures whose typical size decreases with distance from Ori C and IR lines from CI, if solely arising from radiative recombination and cascade, reveal very high gas temperatures consistent with the hot irradiated surface of small-scale dense clumps deep inside the PDR. The H2 lines reveal multiple, prominent filaments which exhibit different characteristics. This leaves the impression of a "terraced" transition from the predominantly atomic surface region to the CO-rich molecular zone deeper in. This study showcases the discovery space created by JWST to further our understanding of the impact radiation from young stars has on their natal molecular cloud and proto-planetary disk, which touches on star- and planet formation as well as galaxy evolution.
Comment: 52 pages, 30 figures, submitted to A&A

الوصول الحر: http://arxiv.org/abs/2310.08720Test