65 research outputs found
The PAH Emission Characteristics of the Reflection Nebula NGC 2023
Interstellar matter and star formatio
The PAH Emission Characteristics of the Reflection Nebula NGC 2023
Interstellar matter and star formatio
Spectroscopy of large PAHs. Laboratory studies and comparison to the Diffuse Interstellar Bands
Grain Surface Models and Data for Astrochemistry
AbstractThe cross-disciplinary field of astrochemistry exists to understand the formation, destruction, and survival of molecules in astrophysical environments. Molecules in space are synthesized via a large variety of gas-phase reactions, and reactions on dust-grain surfaces, where the surface acts as a catalyst. A broad consensus has been reached in the astrochemistry community on how to suitably treat gas-phase processes in models, and also on how to present the necessary reaction data in databases; however, no such consensus has yet been reached for grain-surface processes. A team of âŒ25 experts covering observational, laboratory and theoretical (astro)chemistry met in summer of 2014 at the Lorentz Center in Leiden with the aim to provide solutions for this problem and to review the current state-of-the-art of grain surface models, both in terms of technical implementation into models as well as the most up-to-date information available from experiments and chemical computations. This review builds on the results of this workshop and gives an outlook for future directions
PDRs4All: A JWST Early Release Science Program on Radiative Feedback from Massive Stars
22 pags., 8 figs., 1 tab.Massive stars disrupt their natal molecular cloud material through radiative and mechanical feedback processes. These processes have profound effects on the evolution of interstellar matter in our Galaxy and throughout the universe, from the era of vigorous star formation at redshifts of 1-3 to the present day. The dominant feedback processes can be probed by observations of the Photo-Dissociation Regions (PDRs) where the far-ultraviolet photons of massive stars create warm regions of gas and dust in the neutral atomic and molecular gas. PDR emission provides a unique tool to study in detail the physical and chemical processes that are relevant for most of the mass in inter-and circumstellar media including diffuse clouds, proto-planetary disks, and molecular cloud surfaces, globules, planetary nebulae, and star-forming regions. PDR emission dominates the infrared (IR) spectra of star-forming galaxies. Most of the Galactic and extragalactic observations obtained with the James Webb Space Telescope (JWST) will therefore arise in PDR emission. In this paper we present an Early Release Science program using the MIRI, NIRSpec, and NIRCam instruments dedicated to the observations of an emblematic and nearby PDR: the Orion Bar. These early JWST observations will provide template data sets designed to identify key PDR characteristics in JWST observations. These data will serve to benchmark PDR models and extend them into the JWST era. We also present the Science-Enabling products that we will provide to the community. These template data sets and Science-Enabling products will guide the preparation of future proposals on star-forming regions in our Galaxy and beyond and will facilitate data analysis and interpretation of forthcoming JWST observations.Support for JWST-ERS program ID 1288 was provided through grants from the STScI under NASA contract NAS5-03127 to STScI (K.G., D.V.D.P., M.R.), Univ. of Maryland (M.W., M.P.), Univ. of Michigan (E.B., F.A.), and Univ. of Toledo (T.S.-Y.L.). O.B. and E.H. are supported by the Programme National âPhysique et Chimie du Milieu Interstellaireâ (PCMI) of CNRS/INSU with INC/INP co-funded by CEA and CNES, and through APR grants 6315 and 6410 provided by CNES. E. P. and J.C. acknowledge support from the National Science and
Engineering Council of Canada (NSERC) Discovery Grant program (RGPIN-2020-06434 and RGPIN-2021-04197 respectively). E.P. acknowledges support from a Western Strategic Support Accelerator Grant (ROLA ID 0000050636). J.R.G. and S.C. thank the Spanish MCINN for funding support under grant PID2019-106110GB-I00. Work by M.R. and Y.O. is carried out within the Collaborative Research Centre 956, subproject C1, funded by the Deutsche Forschungsgemeinschaft (DFG)âproject ID 184018867. T.O. acknowledges support from JSPS Bilateral Program, grant No. 120219939. M.P. and M.W. acknowledge support from NASA Astrophysics Data Analysis Program award #80NSSC19K0573. C.B. is grateful for an appointment at NASA Ames Research Center through the San JosĂ© State University Research Foundation (NNX17AJ88A) and acknowledges support from the Internal Scientist Funding Model (ISFM) Directed Work Package at
NASA Ames titled: âLaboratory AstrophysicsâThe NASA Ames PAH IR Spectroscopic Database.âPeer reviewe
Space as a Tool for Astrobiology: Review and Recommendations for Experimentations in Earth Orbit and Beyond
PAHS AND ASTROBIOLOGY
In dense molecular clouds, the birthplace of stars and planets, interstellar atoms and
molecules freeze onto extremely cold dust and ice particles. These ices are processed by
ultraviolet light and cosmic rays forming hundreds of far more complex species, some of
astrobiological interest. Eventually, these rain down on primordial planets where they
take part in the young chemistry on these new worlds.
Although the IR spectroscopy and energetic processing of interstellar ice analogs have
been studied for nearly 30 years, similar studies of PAH containing ices have only just
begun. This paper presents recent results from laboratory studies on the vacuum
ultraviolet (VUV) photochemistry of PAHs in water ice at low temperatures to assess the
roles they play in the photochemical evolution of interstellar ices and their relevance to
astrobiology. A number of âsurprisesâ were found in these studies on PAH containing
water-rich ices, indicating that PAHs likely play very important, unexpected roles in
cosmic ice chemistry, physics and astrobiology
Infra-red molecular line emission from grain surfaces in dense clouds
Wetensch. publicatieFaculteit der Wiskunde en Natuurwetenschappe
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