scholarly journals THESPITZERVIEW OF LOW-METALLICITY STAR FORMATION. III. FINE-STRUCTURE LINES, AROMATIC FEATURES, AND MOLECULES

2010 ◽  
Vol 712 (1) ◽  
pp. 164-187 ◽  
Author(s):  
Leslie K. Hunt ◽  
Trinh X. Thuan ◽  
Yuri I. Izotov ◽  
Marc Sauvage
2005 ◽  
Vol 13 ◽  
pp. 833-838
Author(s):  
R. Srianand ◽  
P. Petitjean ◽  
C. Ledoux ◽  
G. Ferland

AbstractThis review talk summarizes the main results obtained from the just completed survey of molecular hydrogen in damped Lyman-a systems (DLAs). Preliminary results based on modeling ionization conditions and chemical network is also presented. The presence of H2 and fine-structure lines of C 1 in 13-20% of DLAs allow one to investigate the physical conditions using the techniques that are commonly used in the studies of the Galactic ISM. It is shown that the DLAs with H2 trace regions with higher density, lower temperature, moderate to high dust depletion, and local star-formation. Absence of H2 in DLAs with moderate dust depletion could just be a simple consequence of lower densities in the systems.


Author(s):  
F. F. S. van der Tak ◽  
S. C. Madden ◽  
P. Roelfsema ◽  
L. Armus ◽  
M. Baes ◽  
...  

AbstractThe SPICA mid- and far-infrared telescope will address fundamental issues in our understanding of star formation and ISM physics in galaxies. A particular hallmark of SPICA is the outstanding sensitivity enabled by the cold telescope, optimised detectors, and wide instantaneous bandwidth throughout the mid- and far-infrared. The spectroscopic, imaging, and polarimetric observations that SPICA will be able to collect will help in clarifying the complex physical mechanisms which underlie the baryon cycle of galaxies. In particular, (i) the access to a large suite of atomic and ionic fine-structure lines for large samples of galaxies will shed light on the origin of the observed spread in star-formation rates within and between galaxies, (ii) observations of HD rotational lines (out to ~10 Mpc) and fine structure lines such as [C ii] 158 μm (out to ~100 Mpc) will clarify the main reservoirs of interstellar matter in galaxies, including phases where CO does not emit, (iii) far-infrared spectroscopy of dust and ice features will address uncertainties in the mass and composition of dust in galaxies, and the contributions of supernovae to the interstellar dust budget will be quantified by photometry and monitoring of supernova remnants in nearby galaxies, (iv) observations of far-infrared cooling lines such as [O i] 63 μm from star-forming molecular clouds in our Galaxy will evaluate the importance of shocks to dissipate turbulent energy. The paper concludes with requirements for the telescope and instruments, and recommendations for the observing strategy.


2014 ◽  
Vol 568 ◽  
pp. A62 ◽  
Author(s):  
Ilse De Looze ◽  
Diane Cormier ◽  
Vianney Lebouteiller ◽  
Suzanne Madden ◽  
Maarten Baes ◽  
...  

2019 ◽  
Vol 882 (1) ◽  
pp. 1 ◽  
Author(s):  
C. Lamarche ◽  
G. J. Stacey ◽  
A. Vishwas ◽  
D. Brisbin ◽  
C. Ferkinhoff ◽  
...  

1997 ◽  
Vol 159 ◽  
pp. 333-336
Author(s):  
D. Lutz ◽  
R. Genzel ◽  
E. Sturm ◽  
A.F.M. Moorwood ◽  
E. Oliva ◽  
...  

AbstractWe discuss 2.5–45 µm spectra of the Circinus galaxy and of Cen A, obtained with the Short Wavelength Spectrometer (SWS) on board the Infrared Space Observatory. The large number of detected ionic fine structure lines, observable also in visually obscured sources, provides strong constraints on the shape of the ionizing spectrum, which is found to exhibit a UV bump peaking at ~ 70 eV in the case of Circinus. Pure rotational emission of molecular hydrogen, directly probing warm molecular gas, can for the first time be detected in external galaxies.


2006 ◽  
Vol 643 (2) ◽  
pp. L107-L110 ◽  
Author(s):  
N. Mizuno ◽  
E. Muller ◽  
H. Maeda ◽  
A. Kawamura ◽  
T. Minamidani ◽  
...  

Model theoretical calculations have been made of the fine structure associated with the perpendicular vibrations of a ‘light’ symmetric top group (such as CH 3 , SiH 3 , etc.) resulting from its internal rotation with respect to an infinitely heavy planar framework. Investigations have been made of the effects on the internal rotational fine structure of the removal of the degeneracy of the perpendicular vibrations as required by the lower site symmetry. Separate calculations have been made for the cases where the removal of degeneracy is caused ( a ) by electronic effects which result in an angular variation of the appropriate force constant, or ( b ) by interaction with another vibration in the framework part of the molecule. It is found that no fine structure lines occur between the non-degenerate frequencies, but that the effect of internal rotation is to generate rotational wings outside this frequency range. The effects of a finite sixfold barrier to internal rotation on the vibrational/internal-rotational absorption band have been calculated for the degenerate and non-degenerate cases. It is shown that certain lines are split by amounts comparable to the barrier height, V 6 , which should therefore be experimentally obtainable from this type of spectrum in favourable cases. The effect of an increasing barrier is to cause more of the intensity within the overall band contour to occur in the vicinity of the vibrational frequency or frequencies, and less in the internal rotational wings, as expected on physical grounds.


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