scholarly journals Diffuse interstellar bands in the Taurus dark clouds

1991 ◽  
Vol 252 (2) ◽  
pp. 234-245 ◽  
Author(s):  
A. J. Adamson ◽  
D. C. B. Whittet ◽  
W. W. Duley
Keyword(s):  
Dark Clouds ◽  
Diffuse Interstellar Bands

scholarly journals Solid State DIBs

2013 ◽  
Vol 9 (S297) ◽  
pp. 359-363
Author(s):  
H. Linnartz
Keyword(s):  
Solid State ◽  
Low Temperatures ◽  
Molecular Hydrogen ◽  
Experimental Approach ◽  
Amorphous Solid ◽  
Young Stellar Objects ◽  
Stellar Objects ◽  
Dark Clouds ◽  
Diffuse Interstellar Bands ◽  
Interstellar Ice

AbstractThe diffuse interstellar bands are not due to solid state species. However, under the explicit assumption that DIB carriers survive the transfer from translucent to dark clouds, it is expected that for the low temperatures in the dense interstellar medium also DIB carriers accrete onto dust grains. Like all other molecules, apart from molecular hydrogen, they will get embedded in an ice matrix that largely consists of amorphous solid water. This offers - in principle - a tool to search for DIBs in complete different environments, both in space (i.e., towards embedded young stellar objects) and in the laboratory, namely in the solid state simulating interstellar ice analogues. Currently experiments are ongoing in the Sackler Laboratory for Astrophysics at Leiden Observatory to record optical ice spectra of potential DIB carriers. For this a new experimental approach has been developed. Its performance and potential are discussed.

scholarly journals The Transition from Diffuse to Dense Clouds

1992 ◽  
Vol 45 (4) ◽  
pp. 543 ◽  
Author(s):  
Theodore P Snow
Keyword(s):  
Gas Phase ◽  
Open Cluster ◽  
Dust Particles ◽  
Interstellar Clouds ◽  
Dark Clouds ◽  
Diffuse Interstellar Bands ◽  
Cloud Characteristics ◽  
Wide Range ◽  
Diffuse Clouds ◽  
The Impact

Optical and ultraviolet spectroscopy have shown that diffuse interstellar clouds can have a wide range of properties, with especially large variations in the nature of the UV extinction curve and the abundances of molecular species. More subtle variations are found in the properties of the diffuse interstellar bands, and there have been suggestions that elemental depletions from the gas phase into solid dust particles also vary significantly. It is the purpose of this paper to review studies of the relatively diffuse interstellar clouds where these variations occur, and to explore the possible relationship between dust properties, as indicated by UV extinction, and other cloud characteristics. The focus is on relatively dense diffuse clouds, which may be viewed as transitional or intermediate between ordinary diffuse clouds and dark clouds, because in principle the greatest amount of information is available for the intermediate clouds, and because they serve as indicators of processes that may occur in the denser molecular clouds. The paper begins with a brief review of some results from the literature on transitional or intermediate clouds, and then provides a summary of some recent results on one particular cloud, in front of the star BD+31 �643, in the small open cluster IC348, which is part of the Perseus II complex of dark clouds and OB associations. The paper concludes with some tentative speculations about the possible status of the transitional clouds, along with a brief mention of the impact of upcoming instrumental developments on research in this area.

Polarimetric and photometric observations of CB54, with analysis of four other dark clouds

2021 ◽  
Vol 503 (4) ◽  
pp. 5274-5290
Author(s):  
A K Sen ◽  
V B Il’in ◽  
M S Prokopjeva ◽  
R Gupta
Keyword(s):  
Magnetic Field ◽  
Near Infrared ◽  
Galactic Plane ◽  
Photometric Data ◽  
Dust Particles ◽  
Dark Cloud ◽  
Dark Clouds ◽  
High Polarization ◽  
Field Parallel ◽  
Photometric Observations

ABSTRACT We present the results of our BVR-band photometric and R-band polarimetric observations of ∼40 stars in the periphery of the dark cloud CB54. From different photometric data, we estimate E(B − V) and E(J − H). After involving data from other sources, we discuss the extinction variations towards CB54. We reveal two main dust layers: a foreground, E(B − V) ≈ 0.1 mag, at ∼200 pc and an extended layer, $E(B-V) \gtrsim 0.3$ mag, at ∼1.5 kpc. CB54 belongs to the latter. Based on these results, we consider the reason for the random polarization map that we have observed for CB54. We find that the foreground is characterized by low polarization ($P \lesssim 0.5$ per cent) and a magnetic field parallel to the Galactic plane. The extended layer shows high polarization (P up to 5–7 per cent). We suggest that the field in this layer is nearly perpendicular to the Galactic plane and both layers are essentially inhomogeneous. This allows us to explain the randomness of polarization vectors around CB54 generally. The data – primarily observed by us in this work for CB54, by A. K. Sen and colleagues in previous works for three dark clouds CB3, CB25 and CB39, and by other authors for a region including the B1 cloud – are analysed to explore any correlation between polarization, the near-infrared, E(J − H), and optical, E(B − V), excesses, and the distance to the background stars. If polarization and extinction are caused by the same set of dust particles, we should expect good correlations. However, we find that, for all the clouds, the correlations are not strong.

scholarly journals The role of radiolysis in the modelling of C2H4O2 isomers and dimethyl ether in cold dark clouds

2020 ◽  
Vol 500 (3) ◽  
pp. 3414-3424
Author(s):  
Alec Paulive ◽  
Christopher N Shingledecker ◽  
Eric Herbst
Keyword(s):  
Gas Phase ◽  
Dimethyl Ether ◽  
Recent Observation ◽  
Cosmic Ray ◽  
Thermal Method ◽  
Dark Clouds ◽  
Ice Surface ◽  
Dust Grain ◽  
Complex Organic

ABSTRACT Complex organic molecules (COMs) have been detected in a variety of interstellar sources. The abundances of these COMs in warming sources can be explained by syntheses linked to increasing temperatures and densities, allowing quasi-thermal chemical reactions to occur rapidly enough to produce observable amounts of COMs, both in the gas phase, and upon dust grain ice mantles. The COMs produced on grains then become gaseous as the temperature increases sufficiently to allow their thermal desorption. The recent observation of gaseous COMs in cold sources has not been fully explained by these gas-phase and dust grain production routes. Radiolysis chemistry is a possible non-thermal method of producing COMs in cold dark clouds. This new method greatly increases the modelled abundance of selected COMs upon the ice surface and within the ice mantle due to excitation and ionization events from cosmic ray bombardment. We examine the effect of radiolysis on three C2H4O2 isomers – methyl formate (HCOOCH3), glycolaldehyde (HCOCH2OH), and acetic acid (CH3COOH) – and a chemically similar molecule, dimethyl ether (CH3OCH3), in cold dark clouds. We then compare our modelled gaseous abundances with observed abundances in TMC-1, L1689B, and B1-b.

HOT MOLECULAR CORES IN INFRARED DARK CLOUDS

2011 ◽  
Vol 741 (2) ◽  
pp. 120 ◽  
Author(s):  
J. M. Rathborne ◽  
G. Garay ◽  
J. M. Jackson ◽  
S. Longmore ◽  
Q. Zhang ◽  
...  
Keyword(s):  
Dark Clouds ◽  
Infrared Dark Clouds

Trends in scientific publishing: Dark clouds loom large

2016 ◽  
Vol 363 ◽  
pp. 119-120 ◽  
Author(s):  
Pulikottil Wilson Vinny ◽  
Venugopalan Y. Vishnu ◽  
Vivek Lal
Keyword(s):  
Scientific Publishing ◽  
Dark Clouds
Sign in / Sign up

Export Citation Format

Share Document