Interstellar Molecules and Dense Clouds

  title={Interstellar Molecules and Dense Clouds},
  author={David M. Rank and Charles H. Townes and William J. Welch},
  pages={1083 - 1101}
Current knowledge of the interstellar medium is discussed on the basis of recent published studies. The subjects considered include optical identification of interstellar molecules, radio molecular lines, interstellar clouds, isotopic abundances, formation and disappearance of interstellar molecules, and interstellar probing techniques. Diagrams are plotted for the distribution of galactic sources exhibiting molecular lines, for hydrogen molecule, hydrogen atom and electron abundances due to… 

Molecules as Probes of the Interstellar Matter

  • P. G. Mezger
  • Physics
  • 1974
26 interstellar molecules have now been observed. Some of the observational problems pertaining to detection of molecules by radio spectroscopy are discussed in section II. Our present knowledge

Molecular Abundances in Interstellar Clouds

A brief historical overview is given of the development of our understanding of the abundances of interstellar molecules. The events leading to the detections of interstellar molecules at optical and

Spectroscopy among the stars

Detailed high spectral and spatial resolution spectroscopic measurements reveal physical and chemical processes of the intricate star formation process.

Interstellar molecules in the Galaxy

Absorption lines due to interstellar gas have been known since 1904, when the H and K lines of ionized calcium were found in the spectrum of the binary star 60rionis . These lines did not show the

Diffuse Atomic and Molecular Clouds

AbstractDiffuse interstellar clouds have long been thought to be relatively devoid of molecules, because of their low densities and high radiation fields. However, in the past ten years or so, a

Some Implications of the Distribution of Interstellar Molecules

It is suggested that molecular observations of interstellar clouds can be used to determine the stage of cloud evolution. However, before observational data can reliably be used to investigate the

Some Implications of the Distribution of Interstellar Molecules

It is suggested that molecular observations of interstellar clouds can be used to determine the stage of cloud evolution. However, before observational data can reliably be used to investigate the

The Spectra of Interstellar Molecules

Abstract This review considers the spectroscopic observations which have led to the identification of more than 50 molecules in the interstellar medium. Although it concentrates on the results of

Molecules in space.

Abstract The interstellar space of the spiral arms of our galaxy contains dust clouds in which some 20 kinds of molecule are now known to exist. Many of the molecules are polyatomic. Only five years

Line Absorption Studies of the Interstellar Gas Near 1015 Hz

The Copernicus satellite now opens up the ultraviolet region for inspection, and the number of resonance lines which may be studied has increased from 6, seen in the visible, to more than 30. The




At present, interstellar molecular hydrogen is incapable of detection, although a high abundance has been suspected for almost two decades. An analysis is given of the various processes which

Detection of Interstellar OH in Two External Galaxies

Abstract : Molecular OH lines at 1665 and 1667 MHz have been detected in absorption in the spiral galaxy NGC 253 and the irregular galaxy M82. This is the first time interstellar molecular lines,

Unidentified Interstellar Microwave Line

During a search for H12C14N (hydrogen cyanide) and its molecular isotope H13C 14N, a new molecular line is detected using the 36-foot telescope of the National Radio Astronomy Observatory in Tucson, Arizona.

Detection of NH sub 3 molecules in the interstellar medium by their microwave emission.

Ammonia has been found in the direction of the galactic center by detection of its $J=1$, $K=1$ inversion transition. The region of emission closely corresponds to the position, velocity, and size of

Hydrogen Emission Line n110 → n109: Detection at 5009 Megahertz in Galactic H II Regions

The hydrogen emission line n1l0 → n109 at the frequency 5009 megahertz which was predicted by Kardashev has been detected in M 17, Orion, and nine other galactic H II regions with the 42.7-m

Molecular Spectroscopy and Astrophysical Problems

Molecular problems of astrophysics, such as the question of the presence of molecular hydrogen in planets and in the interstellar medium or the question of the composition of comets, have stimulated

Far-Infrared Observations of the Night Sky

A telescope cooled to liquid-helium temperatures and a gallium-doped germanium detector detected a minimum signal of 10-9 watt per square centimeter per steradian referred to 100 micrometers, which can place a firm upper limit on the color temperature of a dilute cosmic background flux.

Spectra, Variability, Size, and Polarization of H2O Microwave Emission Sources in the Galaxy

Radio spectral line radiation of water molecules at a wavelength of 1.35 centimeters has been measured from eight sources in the galaxy, which have extremely high brightness temperatures, and show many spectral features.


This review of infr·ared spectroscopy will be restricted to stars, and to wavelengths longer than 9000 A (0.9 p.). Infrared studies of the Sun will not be considered for their own sake but will


From observations of interstellar optical absorption lines of CN, CH, and C${\mathrm{H}}^{+}$ we are able to impose upper limits, at three wavelengths, on the intensity of background radiation in the