The temperature of large dust grains in molecular clouds

1991 ◽  
Vol 371 ◽  
pp. 602 ◽  
Author(s):  
F. O. Clark ◽  
R. J. Laureijs ◽  
T. Prusti
Keyword(s):  
Molecular Clouds ◽  
Dust Grains

Transport of Dust Grains in Turbulent Molecular Clouds

1998 ◽  
Vol 498 (2) ◽  
pp. 757-762 ◽  
Author(s):  
B. R. Ragot
Keyword(s):  
Molecular Clouds ◽  
Dust Grains

scholarly journals Clustering and dynamic decoupling of dust grains in turbulent molecular clouds

2018 ◽  
Vol 483 (4) ◽  
pp. 5623-5641 ◽  
Author(s):  
Lars Mattsson ◽  
Akshay Bhatnagar ◽  
Fred A Gent ◽  
Beatriz Villarroel
Keyword(s):  
Molecular Clouds ◽  
Dust Grains ◽  
Dynamic Decoupling

scholarly journals The Magnetic Field in the Perseus Molecular Cloud Complex

1990 ◽  
Vol 140 ◽  
pp. 319-320
Author(s):  
A.A. Goodman ◽  
P.C. Myers ◽  
P. Bastien ◽  
R.M. Crutcher ◽  
C. Heiles ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Molecular Cloud ◽  
Molecular Clouds ◽  
Dust Grains ◽  
Magnetically Aligned ◽  
Cloud Complex ◽  
The Magnetic Field ◽  
Co Emission ◽  
Selective Extinction

In Figure 1, we present a map of the polarization of background starlight in the Perseus region (Goodman, Bastien, Myers, and Menard 1989) superposed on contours of integrated 13CO emission (Bachiller and Cernicharo 1986). The polarization vectors map the plane-of-the-sky field (B⊥), assuming as usual that the observed polarization is the result of selective extinction by magnetically aligned dust grains associated with the molecular clouds between the observer and background stars (e.g. Dolginov 1989).

Laboratory experiments on cosmic dust and ices

2019 ◽  
Vol 15 (S350) ◽  
pp. 27-34
Author(s):  
Cornelia Jäger ◽  
Alexey Potapov ◽  
Gaël Rouillé ◽  
Thomas Henning
Keyword(s):  
Molecular Clouds ◽  
Laboratory Experiments ◽  
Recent Progress ◽  
Protoplanetary Disks ◽  
Interstellar Extinction ◽  
Cosmic Dust ◽  
Dust Grains ◽  
Emission And Absorption Spectra ◽  
Ir Emission ◽  
Elemental Depletion

AbstractThe existence of cosmic dust is attested by the interstellar extinction and polarization, IR emission and absorption spectra, and elemental depletion patterns. Dust grains are efficiently processed or even destroyed in shocks, molecular clouds, or protoplanetary disks. A considerable amount of dust has to be re-formed in the ISM. In various astrophysical environments, dust grains are covered by molecular ices and therefore contribute or catalytically influence the chemical reactions in these layers. Laboratory experiments are desperately required to understand the evolution of grains and grain/ice mixtures in molecular clouds and early planetary disks. This review considers recent progress in laboratory approaches to dust/ice experiments.

scholarly journals Variations in the abundance of small particles

1991 ◽  
Vol 147 ◽  
pp. 151-160
Author(s):  
F. Boulanger
Keyword(s):  
Gas Phase ◽  
Large Amplitude ◽  
Molecular Clouds ◽  
Velocity Structure ◽  
Size Range ◽  
Interstellar Matter ◽  
Dust Grains ◽  
Small Particles ◽  
Order Of Magnitude ◽  
Ir Emission

IRAS images of nearby molecular clouds show that the mid-IR emission from small particles in the size range 102 to 105 atoms is distributed very differently from the 100 μm emission from large dust grains. Variations in color ratios by as much as one order of magnitude are seen on all angular scales. We summarize observational properties of the color variations and argue that neither their large amplitude nor their morphology can be explained by changes of the excitation by the UV radiation field only. The color variations reflect considerable inhomogeneities in the abundance of small particles. We suggest that the abundance variations are related to the cycling of interstellar matter between the gas phase and dust grains. This interpretation entails that clouds with distinct IR colors differ in their density and velocity structure and that cycling of matter between gas phase and dust grains is more ubiquitous and rapid that generally thought.

Detection of submillimeter-wave [C I]emission in gaseous debris disks of 49 Ceti and β Pictoris

2017 ◽  
Vol 13 (S332) ◽  
pp. 81-87
Author(s):  
Aya E. Higuchi ◽  
Aki Sato ◽  
Takashi Tsukagoshi ◽  
Nami Sakai ◽  
Kazunari Iwasaki ◽  
...  
Keyword(s):  
Molecular Clouds ◽  
Column Density ◽  
Density Ratio ◽  
Submillimeter Wave ◽  
Debris Disks ◽  
Excitation Temperature ◽  
Dust Grains ◽  
Line Profiles ◽  
Order Of Magnitude ◽  
Diffuse Clouds

AbstractWe have detected [C I] 3P1–3P0 emissions in the gaseous debris disks of 49 Ceti and β Pictoris with the 10 m telescope of the Atacama Submillimeter Telescope Experiment, which is the first detection of such emissions. The line profiles of [C I] are found to resemble those of CO(J=3–2) observed with the same telescope and the Atacama Large Millimeter/submillimeter Array. This result suggests that atomic carbon (C) coexists with CO in the debris disks, and is likely formed by the photodissociation of CO. Assuming an optically thin [C I] emission with the excitation temperature ranging from 30 to 100 K, the column density of C is evaluated to be (2.2 ± 0.2) × 1017 and (2.5 ± 0.7) × 1016 cm−2 for 49 Ceti and β Pictoris, respectively. The C/CO column density ratio is thus derived to be 54 ± 19 and 69 ± 42 for 49 Ceti and β Pictoris, respectively. These ratios are higher than those of molecular clouds and diffuse clouds by an order of magnitude. The unusually high ratios of C to CO are likely attributed to a lack of H2 molecules needed to reproduce CO molecules efficiently from C. This result implies a small number of H2 molecules in the gas disk; i.e., there is an appreciable contribution of secondary gas from dust grains.

scholarly journals Variations in the abundance of small particles

1991 ◽  
Vol 147 ◽  
pp. 151-160
Author(s):  
F. Boulanger
Keyword(s):  
Gas Phase ◽  
Large Amplitude ◽  
Molecular Clouds ◽  
Velocity Structure ◽  
Size Range ◽  
Interstellar Matter ◽  
Dust Grains ◽  
Small Particles ◽  
Order Of Magnitude ◽  
Ir Emission

IRAS images of nearby molecular clouds show that the mid-IR emission from small particles in the size range 102 to 105 atoms is distributed very differently from the 100 μm emission from large dust grains. Variations in color ratios by as much as one order of magnitude are seen on all angular scales. We summarize observational properties of the color variations and argue that neither their large amplitude nor their morphology can be explained by changes of the excitation by the UV radiation field only. The color variations reflect considerable inhomogeneities in the abundance of small particles. We suggest that the abundance variations are related to the cycling of interstellar matter between the gas phase and dust grains. This interpretation entails that clouds with distinct IR colors differ in their density and velocity structure and that cycling of matter between gas phase and dust grains is more ubiquitous and rapid that generally thought.

Molecular Ices as Temperature Indicators in the ISM

1993 ◽  
Vol 10 (3) ◽  
pp. 241-246
Author(s):  
R. G. Smith ◽  
G. Robinson ◽  
A. R. Hyland
Keyword(s):  
Molecular Clouds ◽  
Interstellar Dust ◽  
Spectral Features ◽  
Dust Grains ◽  
Temperature Dependent ◽  
Common Component ◽  
Interstellar Dust Grains ◽  
Infrared Spectral ◽  
Circumstellar Shells

AbstractMolecular ices are a common component of the dust in many molecular clouds and circumstellar shells. The most abundant molecule, H2O, has several infrared spectral features which have strongly temperature dependent shapes (FWHM) and peak wavelengths. This paper describes how a study of these features, both astronomically and in the laboratory, can lead to constraints on the temperatures of interstellar dust grains. This is demonstrated in part by comparing several astronomical spectra with laboratory spectra of H2O ice.

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