Discovery of a Cold Extended Condensation in the Orion A Complex

Ristorcelli, I.; Serra, G.; Lamarre, J.-M.; Giard, M.; Pajot, F.; Bernard, J.-P.; Torre, J. P.; Luca, A. De; Puget, J.

doi:10.1086/305360

Cited by 27 publications

(33 citation statements)

References 30 publications

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“…The flattening is interpreted as modifications of the population of small grains, due to ice mantle deposition and grain coagulation (e.g., Cardelli & Clayton 1991;Kim et al 1993). Evidence of a decreased population of small grains due to grain coagulation, as well as formation of large fluffy aggregates has also been found at FIR wavelengths in dense filaments in Taurus (Stepnik et al 2003), in the Polaris cirrus cloud (Bernard et al 1999;Cambrésy et al 2001), and in a condensation of the Orion complex ( Ristorcelli et al 1998), thanks to a combination of Infrared Astronomical Satellite (IRAS ) and Projet National d'Astronomie Submillimé-trique ( PRONAOS) data. Grain growth with increasing density in dark clouds has also been probed by the increase in the wavelength of maximum polarization by absorption, interpreted as the result of ice mantle deposition in Taurus (Whittet et al 2001) and grain coagulation in Ophiuchi (Vrba et al 1993).…”

Section: Grain Growth and Nir Extinction Efficiencymentioning

confidence: 91%

Can We Trust the Dust? Evidence of Dust Segregation in Molecular Clouds

Padoan

Cambrésy

Juvela

et al. 2006

ApJ

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Maps of estimated dust column density in molecular clouds are usually assumed to reliably trace the total gas column density structure. In this work we present results showing a clear discrepancy between the dust and the gas distribution in the Taurus molecular cloud complex. We compute the power spectrum of a 2MASS extinction map of the Taurus region and find that it is much shallower than the power spectrum of a 13 CO map of the same region that was previously analyzed. This discrepancy could be explained as the effect of grain growth on the grain extinction efficiency. However, this would require a wide range of maximum grain sizes, which is ruled out based on constraints from the extinction curve and the available grain models. We show that major effects due to CO formation and depletion are also ruled out. Our result may therefore suggest the existence of intrinsic spatial fluctuations of the dustto-gas ratio, with amplitude increasing toward smaller scales. Preliminary results of numerical simulations of trajectories of inertial particles in turbulent flows illustrate how the process of clustering of dust grains by the cloud turbulence may lead to observable effects. However, these results cannot be directly applied to large-scale supersonic and magnetized turbulence at present.

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Section: Grain Growth and Nir Extinction Efficiencymentioning

confidence: 91%

Can We Trust the Dust? Evidence of Dust Segregation in Molecular Clouds

Padoan

Cambrésy

Juvela

et al. 2006

ApJ

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“…Reach et al 1995;Lagache et al 1998), as well as in nearby star-forming regions (Ophiuchi, Orion), at about 20 K. Such large-scale investigations were clearly limited by the lack of angular resolution (typically 1 • for DIRBE). Balloon-borne experiments operating in the FIR have revealed the spatial distribution of dust temperature on arc-minute scales in several starforming regions (Dupac et al 2001;Ristorcelli et al 1998) and more diffuse environments (Bernard et al 1999). These observations showed apparent dust temperatures as low as T D 13 K towards molecular regions, going down to T D 11 K in dense regions, after subtraction of the emission from the surrounding warmer background.…”

Section: Previous Fir Observations Of the Diffuse Ism At High And Intmentioning

confidence: 99%

Dust temperature tracing the ISRF intensity in the Galaxy

Bernard

Paradis

Marshall

et al. 2010

A&A

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163

126

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New observations with Herschel allow accurate measurement of the equilibrium temperature of large dust grains heated by the interstellar radiation field (ISRF), which is critical in deriving dust column density and masses. We present temperature maps derived from the Herschel SPIRE and PACS data in two fields along the Galactic plane, obtained as part of the Hi-GAL survey during the Herschel science demonstration phase (SDP). We analyze the distribution of the dust temperature spatially, as well as along the two lines-of-sight (LOS) through the Galaxy. The zero-level offsets in the Herschel maps were established by comparison with the IRAS and Planck data at comparable wavelengths. We derive maps of the dust temperature and optical depth by adjusting a detailed model for dust emission at each pixel. The dust temperature maps show variations in the ISRF intensity and reveal the intricate mixture of the warm dust heated by massive stars and the cold filamentary structures of embedded molecular clouds. The dust optical depth at 250 μm is well correlated with the gas column density, but with a significantly higher dust emissivity than in the solar neighborhood. We correlate the optical depth with 3-D cubes of the dust extinction to investigate variations in the ISRF strength and dust abundance along the line of sight through the spiral structure of the Galaxy. We show that the warmest dust along the LOS is located in the spiral arms of the Galaxy, and we quantify their respective IR contribution.

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“…Cold interstellar grains should therefore manifest some of these properties in their long wavelength emission when their temperatures fall within the range of interest. Such effects have already been observed in the dust emission at FIR to submm wavelengths in a variety of galactic regions and indicate significant differences compared to the standard dust model results (e.g., Ristorcelli et al 1998;Bernard et al 1999;Stepnik et al 2003;Dupac et al 2001Dupac et al , 2002Dupac et al , 2003. These data show an enhancement in the dust emissivity index for dust temperatures less than about 30 K.…”

Section: Introductionmentioning

confidence: 69%

Microwave emission from dust revisited

Jones¹

2009

A&A

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Context. The origin of the anomalous microwave emission is not yet identified but it may be associated with (spinning) dust. Aims. We point out that the emission from low-energy, solid-state structural transitions, apparent over a range of dust temperatures, and particularly important at low dust temperatures (T d < 30 K), could provide an origin for the excess microwave emission. Methods. The physics of two-level systems (TLS) within amorphous materials is applied within the context of interstellar dust. Results. TLS systems, which are thought to be at the origin of the temperature-dependent emissivity of interstellar dust, should reveal their existence at long wavelengths in the emission from dust. Conclusions. Low-energy, structural transitions in amorphous interstellar grains could make a contribution to the anomalous microwave emission, which should correlate with the emission from dust components with temperatures less than about 30 K.

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Discovery of a Cold Extended Condensation in the Orion A Complex

Cited by 27 publications

References 30 publications

Can We Trust the Dust? Evidence of Dust Segregation in Molecular Clouds

Can We Trust the Dust? Evidence of Dust Segregation in Molecular Clouds

Dust temperature tracing the ISRF intensity in the Galaxy

Microwave emission from dust revisited

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