The carbon abundance in diffuse interstellar clouds

1981 ◽  
Vol 246 ◽  
pp. L147 ◽  
Author(s):  
H. S. Liszt
Keyword(s):  
Interstellar Clouds ◽  
Carbon Abundance

Dynamics of comets in the collapsing protosolar nebula

1999 ◽  
Vol 173 ◽  
pp. 45-50
Author(s):  
L. Neslušan
Keyword(s):  
Solar System ◽  
Velocity Distribution ◽  
Oort Cloud ◽  
Interstellar Clouds ◽  
Protosolar Nebula ◽  
Moving Bodies

AbstractComets are created in the cool, dense regions of interstellar clouds. These macroscopic bodies take place in the collapse of protostar cloud as mechanically moving bodies in contrast to the gas and miscroscopic dust holding the laws of hydrodynamics. In the presented contribution, there is given an evidence concerning the Solar system comets: if the velocity distribution of comets before the collapse was similar to that in the Oort cloud at the present, then the comets remained at large cloud-centric distances. Hence, the comets in the solar Oort cloud represent a relict of the nebular stage of the Solar system.

Modelling polarized radiation from interstellar clouds

2008 ◽  
Vol 31 ◽  
pp. 179-180
Author(s):  
M. Juvela ◽  
J. Goncalves ◽  
V.-M. Pelkonen ◽  
T. Lunttila
Keyword(s):  
Interstellar Clouds ◽  
Polarized Radiation

Preliminary Observations of Interstellar Sodium D-Line Absorption towards the Carina Nebula

1980 ◽  
Vol 4 (1) ◽  
pp. 95-97 ◽  
Author(s):  
J. B. Whiteoak ◽  
F. F. Gardner
Keyword(s):  
High Resolution ◽  
Hii Regions ◽  
Early Type ◽  
Interstellar Clouds ◽  
Carina Nebula ◽  
Line Absorption ◽  
General Investigation ◽  
Early Type Stars ◽  
Resolution Study

As part of a general investigation of interstellar clouds associated with southern HII regions we have begun a high-resolution study of the sodium D-line absorption in the directions of early-type stars that are likely to be associated with or located behind the clouds.

scholarly journals Insights into the physics when modelling cold gas clouds in a hot plasma

2019 ◽  
Vol 490 (1) ◽  
pp. L52-L56
Author(s):  
Bastian Sander ◽  
Gerhard Hensler
Keyword(s):  
Adaptive Mesh Refinement ◽  
Adaptive Mesh ◽  
Careful Consideration ◽  
Necessary Condition ◽  
Interstellar Clouds ◽  
Hot Plasma ◽  
Magnetic Dipole Field ◽  
Set Up ◽  
Self Gravity ◽  
Cold Gas

ABSTRACT This paper aims at studying the reliability of a few frequently raised, but not proven, arguments for the modelling of cold gas clouds embedded in or moving through a hot plasma and at sensitizing modellers to a more careful consideration of unavoidable acting physical processes and their relevance. At first, by numerical simulations we demonstrate the growing effect of self-gravity on interstellar clouds and, by this, moreover argue against their initial set-up as homogeneous. We apply the adaptive-mesh refinement code flash with extensions to metal-dependent radiative cooling and external heating of the gas, self-gravity, mass diffusion, and semi-analytic dissociation of molecules, and ionization of atoms. We show that the criterion of Jeans mass or Bonnor–Ebert mass, respectively, provides only a sufficient but not a necessary condition for self-gravity to be effective, because even low-mass clouds are affected on reasonable dynamical time-scales. The second part of this paper is dedicated to analytically study the reduction of heat conduction by a magnetic dipole field. We demonstrate that in this configuration, the effective heat flow, i.e. integrated over the cloud surface, is suppressed by only 32 per cent by magnetic fields in energy equipartition and still insignificantly for even higher field strengths.

scholarly journals The role of faint population III supernovae in forming CEMP stars in ultra-faint dwarf galaxies

2021 ◽  
Author(s):  
Myoungwon Jeon ◽  
Volker Bromm ◽  
Gurtina Besla ◽  
Jinmi Yoon ◽  
Yumi Choi
Keyword(s):  
Milky Way ◽  
Dwarf Galaxies ◽  
Mass Resolution ◽  
Explosion Energy ◽  
High Carbon ◽  
Cosmological Simulations ◽  
Carbon Abundance ◽  
The Absolute ◽  
Zoom In

Abstract CEMP-no stars, a subset of carbon enhanced metal poor (CEMP) stars ($\rm [C/Fe]\ge 0.7$ and $\rm [Fe/H]\lesssim -1$) have been discovered in ultra-faint dwarf (UFD) galaxies, with Mvir ≈ 108 M⊙ and M* ≈ 103 − 104 M⊙ at z = 0, as well as in the halo of the Milky Way (MW). These CEMP-no stars are local fossils that may reflect the properties of the first (Pop III) and second (Pop II) generation of stars. However, cosmological simulations have struggled to reproduce the observed level of carbon enhancement of the known CEMP-no stars. Here we present new cosmological hydrodynamic zoom-in simulations of isolated UFDs that achieve a gas mass resolution of mgas ≈ 60 M⊙. We include enrichment from Pop III faint supernovae (SNe), with ESN = 0.6 × 1051 erg, to understand the origin of CEMP-no stars. We confirm that Pop III and Pop II stars are mainly responsible for the formation of CEMP and C-normal stars respectively. New to this study, we find that a majority of CEMP-no stars in the observed UFDs and the MW halo can be explained by Pop III SNe with normal explosion energy (ESN = 1.2 × 1051 erg) and Pop II enrichment, but faint SNe might also be needed to produce CEMP-no stars with $\rm [C/Fe]\gtrsim 2$, corresponding to the absolute carbon abundance of $\rm A(C)\gtrsim 6.0$. Furthermore, we find that while we create CEMP-no stars with high carbon ratio $\rm [C/Fe]\approx 3-4$, by adopting faint SNe, it is still challenging to reproduce CEMP-no stars with extreme level of carbon abundance of $\rm A(C)\approx 7.0-7.5$, observed both in the MW halo and UFDs.

scholarly journals On the Mechanism of H2 Formation in the Interstellar Medium

1987 ◽  
Vol 120 ◽  
pp. 167-169
Author(s):  
Valerio Pirronello
Keyword(s):  
Interstellar Medium ◽  
Molecular Hydrogen ◽  
Formation Rate ◽  
Cosmic Ray ◽  
Interstellar Clouds ◽  
H2 Formation ◽  
Reduced Mobility

The problem of the formation of molecular hydrogen in interstellar clouds is revisited. the role played by cosmic ray bombardment under certain circumstances is considered mainly in the light of the low formation rate of H2 on grains due to the reduced mobility of adsorbed H atoms on their amorphous surfaces at interstellar temperatures.

EXCITATION OF C2IN DIFFUSE INTERSTELLAR CLOUDS

2012 ◽  
Vol 749 (1) ◽  
pp. 48 ◽  
Author(s):  
Silvia Casu ◽  
Cesare Cecchi-Pestellini
Keyword(s):  
Interstellar Clouds

scholarly journals TheSpitzerc2d Survey of Large, Nearby, Interstellar Clouds. I. Chamaeleon II Observed with MIPS

2005 ◽  
Vol 628 (1) ◽  
pp. 283-297 ◽  
Author(s):  
Kaisa E. Young ◽  
Paul M. Harvey ◽  
Timothy Y. Brooke ◽  
Nicholas Chapman ◽  
Jens Kauffmann ◽  
...  
Keyword(s):  
Interstellar Clouds
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