(C-12)/(C-13) isotope ratio in the local interstellar medium from observations of (C-13)(O-18) in molecular clouds

1993 ◽  
Vol 408 ◽  
pp. 539 ◽  
Author(s):  
William D. Langer ◽  
Arno A. Penzias
Keyword(s):  
Interstellar Medium ◽  
Isotope Ratio ◽  
Molecular Clouds ◽  
Local Interstellar Medium ◽  
O 18

A reassessment of the double isotope ratio (C-13)O/C(O-18) in molecular clouds

1989 ◽  
Vol 341 ◽  
pp. 293 ◽  
Author(s):  
David K. Taylor ◽  
R. L. Dickman
Keyword(s):  
Isotope Ratio ◽  
Molecular Clouds ◽  
O 18 ◽  
Double Isotope

scholarly journals 7. Carbon Isotope Ratio in Comets and Interstellar Matter

1977 ◽  
Vol 39 ◽  
pp. 499-503 ◽  
Author(s):  
V. Vanysek
Keyword(s):  
Solar System ◽  
Interstellar Medium ◽  
Carbon Isotope ◽  
Isotope Ratio ◽  
Molecular Clouds ◽  
Carbon Isotope Ratio ◽  
Stellar Atmospheres ◽  
Interstellar Matter ◽  
Interstellar Molecular Clouds

The 12C/13C isotope ratio in the interstellar medium and in stellar atmospheres is discussed and compared to the value found in the solar system and especially in comets. The cometary value (≥ 100) tends to be slightly above the terrestrial value (89) and is definitively higher than that for interstellar molecular clouds (about 30 to 50). This result implies that comets are not of interstellar origin.

scholarly journals Molecular Clouds Within 100 pc

1984 ◽  
Vol 81 ◽  
pp. 229-234
Author(s):  
Leo Blitz ◽  
Loris Magnani ◽  
Lee Mundy
Keyword(s):  
Interstellar Medium ◽  
Molecular Hydrogen ◽  
Molecular Clouds ◽  
Milky Way ◽  
Velocity Dispersion ◽  
Scale Height ◽  
Galactic Latitude ◽  
Local Interstellar Medium ◽  
High Galactic Latitude ◽  
The Mean

AbstractObservations at the 2.6 mm line of CO reveal the presence of a large number of molecular clouds at high galactic latitude. If the velocity dispersion of the clouds is a measure of their scale height, the mean distance of the ensemble we have detected is 100 pc. The clouds are unusual in that either they are not gravitationally bound or they are very deficient in CO relative to molecular hydrogen. These clouds represent a heretofore unrecognized component of the local interstellar medium. If they are pervasive in the Milky Way, they probably represent the small molecular cloud component of the interstellar medium.

scholarly journals A Wide Latitiude CO Survey of Molecular Clouds in the Northern Milky Way

1984 ◽  
Vol 81 ◽  
pp. 235-238 ◽  
Author(s):  
T.M. Dame ◽  
P. Thaddeus
Keyword(s):  
Interstellar Medium ◽  
Molecular Clouds ◽  
Milky Way ◽  
Angular Resolution ◽  
Local Interstellar Medium ◽  
Large Area ◽  
Interstellar Molecule ◽  
Dark Clouds ◽  
Cold Component ◽  
Galactic Longitude

It is now well established that molecular clouds are an important part of the interstellar medium, containing much or most of the dense, cold component of the gas, and producing the massive stars and supernovae responsible for the diffuse, hot component. It would therefore appear essential in formulating a complete picture of the local interstellar medium to have some knowledge of the distribution and properties of nearby molecular clouds. To this end we have used the Goddard-Columbia 1.2-meter telescope to carry out a wide latitude, low angular resolution survey of CO along most of the first galactic quadrant and a small part of the second. The survey is uniform and fully sampled in galactic longitude from 12° to 100°, and in latitude from -5° to +6°, with extensions to as high as +11° to include specific dark clouds; the total area surveyed, 1128 deg2, is much larger than any region previously studied in CO or any other interstellar molecule. In order to fully sample such a large area in a reasonable amount of time, angular resolution has been sacrificed to coverage and speed; an angular resolution of 1° was obtained synthetically by simply scanning a square 8 x 8 raster of points separated by 1/8°, the size of the primary beam, and summing the resulting 64 spectra at the end of an observation.

Kinematical Structure of the Local Interstellar Medium: The Galactic Center Hemisphere

1997 ◽  
Vol 484 (2) ◽  
pp. 761-778 ◽  
Author(s):  
Ricardo Genova ◽  
John E. Beckman ◽  
Stuart Bowyer ◽  
Thomas Spicer
Keyword(s):  
Interstellar Medium ◽  
Galactic Center ◽  
Local Interstellar Medium

scholarly journals Abundances in the Gaseous Galactic Halo

1998 ◽  
Vol 11 (1) ◽  
pp. 86-89
Author(s):  
Ulysses J. Sofia
Keyword(s):  
Interstellar Medium ◽  
Gas Phase ◽  
High Velocity ◽  
Galactic Halo ◽  
Solar Neighborhood ◽  
Local Interstellar Medium ◽  
The Galaxy ◽  
Metal Abundances ◽  
High Velocity Clouds

Abstract The well measured gas-phase abundances in the low halo suggest that this region of the Galaxy has total (gas plus dust) metal abundances which are close to those in the solar neighborhood. The gas-phase abundances in the halo are generally higher than those seen in the disk, however, this affect is likely due to the destruction of dust in the halo clouds. Observations of high velocity clouds (HVCs) in the halo suggest that these clouds have metal abundances which are substantially lower than those measured for the local interstellar medium. These determinations, however, are often of lower quality than those for the low halo because of uncertainties in the hydrogen abundances along the sightlines, in the incorporation of elements into dust, and in the partial ionization of the clouds.

The HRS GTO program to study the neutral hydrogen column density and D/H ratio in the local interstellar medium

1986 ◽  
Vol 6 (2) ◽  
pp. 91-94
Author(s):  
J.L. Linsky, ◽  
W.B. Landsman ◽  
B.D. Savage ◽  
S.R. Heap ◽  
A.M. Smith ◽  
...  
Keyword(s):  
Interstellar Medium ◽  
Column Density ◽  
Neutral Hydrogen ◽  
Local Interstellar Medium ◽  
Hydrogen Column Density

Magnetic Field Draping of the Heliopause and Its Consequences for Radio Emission in the Very Local Interstellar Medium

2021 ◽  
Vol 917 (2) ◽  
pp. L20
Author(s):  
N. V. Pogorelov ◽  
F. Fraternale ◽  
T. K. Kim ◽  
L. F. Burlaga ◽  
D. A. Gurnett
Keyword(s):  
Magnetic Field ◽  
Radio Emission ◽  
Interstellar Medium ◽  
Local Interstellar Medium
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