Detection and Characterization of Cold Interstellar Dust and Polycyclic Aromatic Hydrocarbon Emission, from<i>COBE</i>Observations

Dwek, Eli; Arendt, Richard G.; Fixsen, D. J.; Sodroski, T. J.; Odegard, N.; Weiland, J. L.; Reach, W. T.; Hauser, M. G.; Kelsall, T.; Moseley, S. H.; Silverberg, R. F.; Shafer, R. A.; Ballester, Jorge; Bazell, D.; Isaacman, R.

doi:10.1086/303568

Cited by 263 publications

(309 citation statements)

References 48 publications

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“…We consider our success as a strong support for the absence of any significant systematics from our analysis. We thus complement the probably most comprehensive benchmark test for stellar atmosphere modelling of OB stars to date Sofia & Meyer (2001); ( f ) value determined from strong-line transitions (Sofia et al 2011), which is compatible with data from the analysis of the [C ii] 158 μm emission (Dwek et al 1997). Weak-line studies of C ii] λ2325 Å indicate a higher gas-phase abundance ε(C) = 8.11 ± 0.07 (Sofia 2004), which corresponds to 84 ± 28 ppm of carbon locked up in dust; (g) Meyer et al (1997), corrected accordingly to Jensen et al (2007); (h) Cartledge et al (2004); (i) Cartledge et al (2006).…”

Section: Global Spectrum Synthesissupporting

confidence: 68%

“…For carbon, a recent investigation by Sofia et al (2011) raises doubts about the precision of weak-line analyses based on the C ii] λ2325 Å transition (see Sofia 2004, for a discussion), possibly related to a systematically underestimated oscillator strength. We therefore adopt a mean abundance from five sightlines of the strong-line analysis of Sofia et al (2011), which is compatible with data from the [C ii] λ158 μm line by Dwek et al (1997).…”

Section: Dust Composition Of the Local Ismmentioning

confidence: 99%

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Present-day cosmic abundances

Nieva

Przybilla²

2012

A&A

430

506

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Context. Early B-type stars are ideal indicators for present-day cosmic abundances since they preserve their pristine abundances and typically do not migrate far beyond their birth environments over their short lifetimes, in contrast to older stars like the Sun. They are also unaffected by depletion onto dust grains, unlike the cold/warm interstellar medium (ISM) or H ii regions. Aims. A carefully selected sample of early B-type stars in OB associations and the field within the solar neighbourhood is studied comprehensively. Quantitative spectroscopy is used to characterise their atmospheric properties in a self-consistent way. Present-day abundances for the astrophysically most interesting chemical elements are derived in order to investigate whether a present-day cosmic abundance standard can be established. Methods. High-resolution and high-S/N FOCES, FEROS and ELODIE spectra of well-studied sharp-lined early B-type stars are analysed in non-LTE. Line-profile fits based on extensive model grids and an iterative analysis methodology are used to constrain stellar parameters and elemental abundances at high accuracy and precision. Atmospheric parameters are derived from the simultaneous establishment of independent indicators, from multiple ionization equilibria and the Stark-broadened hydrogen Balmer lines, and they are confirmed by reproduction of the stars' global spectral energy distributions. Results. Effective temperatures are constrained to 1-2% and surface gravities to less than 15% uncertainty, along with accurate rotational, micro-and macroturbulence velocities. Good agreement of the resulting spectroscopic parallaxes with those from the new reduction of the Hipparcos catalogue is obtained. Absolute values for abundances of He, C, N, O, Ne, Mg, Si and Fe are determined to better than 25% uncertainty. The synthetic spectra match the observations reliably over almost the entire visual spectral range. Three sample stars, γ Ori, o Per and θ 1 Ori D, are identified as double-lined, indicating the presence of an early/mid B-type companion. Conclusions. A present-day cosmic abundance standard is established from a sample of 29 early B-type stars, indicating abundance fluctuations of less than 10% around the mean. Our results (i) resolve the long-standing discrepancy between a chemical homogeneous gas-phase ISM and a chemically inhomogeneous young stellar component out to several hundred parsec from the Sun, (ii) facilitate the amount of heavy elements locked up in the interstellar dust to be constrained precisely -the results imply that carbonaceous dust is largely destroyed inside the Orion H ii region, unlike the silicates, and that graphite is only a minority species in interstellar dust -, (iii) show that the mixing of CNO-burning products in the course of massive star evolution follows tightly the predicted nuclear path, (iv) provide reliable present-day reference points for anchoring Galactic chemical evolution models to observation, and (v) imply that the Sun has migrated outwards from the inne...

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Section: Global Spectrum Synthesissupporting

confidence: 68%

Section: Dust Composition Of the Local Ismmentioning

confidence: 99%

Present-day cosmic abundances

Nieva

Przybilla²

2012

A&A

430

506

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“…Models of the dust in the diffuse ISM are therefore critical for an understanding of the dust in dense clouds (Draine 1985) and its evolution. These models generally contain several dust components of differing chemical composition, structure and size (Draine & Lee 1984;Mathis 1990;Désert et al 1990;Dwek et al 1997;Zubko et al 2004). In this work we have adopted the DustEM model (Compiègne et al 2011) which has three separate dust components and which is consistent with the diffuse ISM dust extinction and emission:…”

Section: Dust Model and Computational Methodsmentioning

confidence: 99%

Dust coagulation processes as constrained by far-infrared observations

Koehler

Stepnik

Jones

et al. 2012

A&A

111

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Aims. We develop a simple model of coagulated dust particles of two sizes (3.5 and 60 nm radius) to understand the nature and the effects of coagulation, which could explain the evolution of the far-infrared (FIR) dust opacity observed in the transition between the diffuse and the dense interstellar medium (ISM) (n H > 10 3 cm −3 ). Methods. Using the discrete-dipole approximation (DDA) method, we have calculated the absorption coefficient, directly proportional to the opacity, of coagulated grains with varying numbers of sub-grains and of different grain composition. Results. We show that, in the transition from diffuse to dense clouds, an increase in the FIR opacity by a factor of about 2.7 is possible and a decrease in the grain temperature by up to 3−4 K can be explained by the presence of coagulated aggregates composed of four big grains and 4000 very small grains (40% of the volume of the BGs). The coagulation of very small grains into the aggregates leads to a decrease in the 60 μm emission. Conclusions. This model can explain the observed increase in opacity at long wavelengths, the decrease in temperature from the diffuse ISM to denser regions with the coagulation of grains into aggregates and the absence of the 60 μm emission with the coagulation of very small grains onto the surface of the big grains.

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“…Obviously, in the area of galactic interstellar medium studies, this paper has achieved wide utility, and the methodology has been used as an essential element of diffuse interstellar cloud studies (e.g., van Dishoeck & Black 1986;Boulanger & Perault 1988); carbon and silicate dust thermal emission models (e.g. Draine & Lee 1984;Dwek et al 1997;Désert et al 1990;Draine & Li 2001b, online); small grain and "PAH" stochastic thermal emission (e.g. Puget & Léger 1989;Draine & Li 2001a, online); understanding the large-scale distribution of the extended red emission (ERE, e.g.…”

Section: Article Published By Edp Sciencesmentioning

confidence: 99%

Interstellar radiation and dust

Jones

2009

A&A

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The Sun shines down on the Earth breathing life into everything around us. A myriad of other stars likewise illuminate their own neighborhoods. However, those distant stars are often much less benevolent to their local environments than the Sun is to its own back yard. The sum of these stellar illuminations is the interstellar radiation field (ISRF), which is made up of photons originating from a large number of stars with very different colors, activity levels, and ages. One should, of course, add the extragalactic and cosmological contributions to this radiation.The photons of the ISRF are responsible for warming the cold interstellar medium through the heating of the gas and dust. They can, when particularly energetic, lead to the destruction of that gas and dust by "photo-dissociation". Some important effects of the ISRF on the interstellar medium include the heating of the gas by the energetic photo-electrons ejected from grains following ultraviolet photon absorption, the forces exerted on dust by photons that then drive mass movements, and the thermal energy re-radiated by dust at mid-infrared to millimeter wavelengths that can heat dust in the interiors of dense cores that are opaque to stellar visible and ultraviolet photons.A detailed knowledge of the combined contribution of the stars to the ISRF is one of the keys to interstellar medium studies of the gas and dust physics. Earlier ISRF studies mainly focused on the shorter wavelength, stellar part of the ISRF (e.g. Habing 1968; Draine 1978, online). John Mathis, Peter Mezger, and Nino Panagia built upon these foundations in their 1983 paper, which was itself based on the soon-to-be eclipsed companion paper (Mezger et al. 1982, with >200 citations), and laid out a four-component stellar radiation field model and an associated dust emission model to explain the existing observations of the ISRF from the ultraviolet to the mm wavelength domain. The utility of their approach has clearly been attested to over the years by the almost 600 SAO/NASA Astrophysics Data System (ADS) citations to the paper. This is a seminal piece of work in the many areas of interstellar medium physics that it tackles, including the stellar input to the ISRF, the dust heating in GMCs and dense cloud interiors, and radiative transfer effects in interstellar clouds. The scope of the paper couples some of the extremes of astrophysics, i.e., encompassing studies of the big (stars) and the small (dust grains), and leads the reader to a series of analytical equations that provide a complete and self-consistent description of the ISRF and the dust temperatures in the interstellar medium.An important element that this work brought to interstellar medium studies was the calculation of the three-dimensional variations in the Galactic ISRF, principally as a function of galacto-centric distance (D G ). This was based on a simple geometric model of the Galaxy, omitting spiral structure and the clumpiness of the ISM. In particular, Mathis, Mezger, and Panagia showed that the ISRF total energ...

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Detection and Characterization of Cold Interstellar Dust and Polycyclic Aromatic Hydrocarbon Emission, fromCOBEObservations

Cited by 263 publications

References 48 publications

Present-day cosmic abundances

Present-day cosmic abundances

Dust coagulation processes as constrained by far-infrared observations

Interstellar radiation and dust

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