Nuclear Processing and Isotopes in the Galaxy

  title={Nuclear Processing and Isotopes in the Galaxy},
  author={A. Penzias},
  pages={663 - 669}
The galactic distributions of the stable isotopic species of hydrogen, carbon, nitrogen, oxygen, sulfur, and silicon have been derived from the study of interstellar molecules which contain them. The resulting observational framework appears consistent with our general understanding of stellar evolution and nuclear processing in the galaxy. The greater amount of star formation that has taken place near the center of our galaxy is reflected in an enhanced abundance of processed material, notably… Expand
Isotopes in the interstellar medium and circumstellar envelopes
Measurements of the present-day abundances of elements and isotopes, combined with model calculations, allow us to trace the history of nucleosynthesis in the universe. Throughout this review,Expand
Nitrogen isotopes in the solar system
Measurements of the isotopic composition of nitrogen in the solar system are summarized. We show that the 30% change, during the last 3 to 4 billion years, of 15N14N in solar-wind-bearing lunar soilsExpand
Carbon and oxygen isotope ratios in starburst galaxies: New data from NGC 253 and Mrk 231 and their implications
Carbon and oxygen isotope ratios are excellent measures of nuclear processing, but few such data have been taken toward extragalactic targets so far. Therefore, using the IRAM 30-m telescope, CN andExpand
Star formation and abundance gradients in the galaxy
Sect. I: Chemical Evolution of the Galaxy. The closed system model and its limitations. For a closed system, where the sum of gas and matter contained in stars is constant at any time, one derives aExpand
Abundances in the interstellar medium
SummaryRecent developments in the theory of element production and the chemical evolution of the galaxy are presented. Following this, observational data and their interpretation are given. A case byExpand
Photochemical fractionation of16O in the space medium modeled by resonance excitation of CO by H-Lyman α
Inferences about the formation of primordial matter in our solar system rest on analysis of the earliest preserved materials in meteorites, of the structure of the solar system today, and of matterExpand
MAST: a mass spectrometer telescope for studies of the isotopic composition of solar, anomalous, and galactic cosmic ray nuclei
The mass spectrometer telescope (MAST) on SAMPEX (Solar, Anomalous, and Magnetospheric Particle Explorer) is designed to provide high-resolution measurements of the isotopic composition of energeticExpand
Gas and Dust in the Inner Few Degrees of the Galaxy
This review discusses the complex morphology and perturbed kinematics, as well as the outstanding physical characteristics of the interstellar medium within a few 100 pc of the galactic center. AExpand
Stable isotope measurements of meteorites and cosmic dust grains
  • C. Pillinger
  • Physics
  • Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences
  • 1987
Although it was well known that a high 13C abundance was a common feature of the spectra of evolved stars, it took over 50 years to find evidence of carbonaceous instellar dust, which might have beenExpand
Stable Isotopic Compositions of Hydrogen, Carbon, Nitrogen, Oxygen and Sulfur in Meteoritic Low Temperature Condensates
The study of light element stable isotopes (D/H, 13C/12C, 15N/14N, 18O/17O/16O/ 36S/34S/33S/32S) in meteorites gives an insight into processes which occurred during, and indeed before, the formationExpand


On the origin and evolution of isotopes of carbon, nitrogen, and oxygen
New calculations of CNO processing in stellar envelopes and other results from nucleosynthesis theory have been used as input to models for chemical evolution in the solar neighborhood. In contrastExpand
Is deuterium of cosmological or of galactic origin
If deuterium is made primarily in stars, then according to current models of galactic evolution it should have a higher abundance in the metal-rich parts of the Galaxy. If it is produced only in theExpand
Deuterium in the Galaxy.
A survey of millimeter-wave line emission from the deuterated and carbon-13 isotopes of interstellar hydrocyanic acid (DCN and H/sup 13/CN) has been carried out. The results indicate that theExpand
Isotopic abundance variations in interstellar HCN
A study of the relative abundances of the rare isotopic species H/sup 12/C/sup 15/N and H/sup 13/C/sup 14/N has been made in six dense molecule clouds through observations of the 3.5 mm wavelengthExpand
Isotope abundance anomalies in IRC +10216
The isotope composition of material ejected from the carbon star IRC +10216 has been examined by means of isotopically substituted species of CO, CS, and HCN. The rare isotopes included in ourExpand
Evidence for isotropic fractionation of carbon monoxide in dark clouds
Chemical fractionation of the various isotopes of carbon mmonoxide has been studied in four isolated dark clouds. At positions away from the centers of three of the objects: B5, B335, and L1262: theExpand
The Evolution of the Universe
It is concluded first of all that the relative abundances of various atomic species must represent the most ancient archæological document pertaining to the history of the universe, and that it must have been established during the earliest stages of expansion. Expand
The isotopic composition of solar flare accelerated neon
The individual isotopes of neon in energetic solar flare particles have been clearly resolved with arms mass resolution of 0.20 amu. We find ^(20)Ne/^(22)Ne = 7.6 (+2.0, -1.8) and ^(21)Ne/^(22)Ne ≾Expand
Isotopic Abundances and Their Variations within the Galaxy.
Ihe relative abundances of isotopic species in parts of the Galaxy ouLtside the solar system represenlt an important record of the past, and one which is bccomiing increasingly available in interstellar clouLds and in stellar atmospheres. Expand
Energy production in stars.
It is shown that no elements heavier than He4 can be built up in ordinary stars, and the suggested mechanism of energy production is used to draw conclusions about astrophysical problems, such as the mass-luminosity relation, the stability against temperature changes, and stellar evolution. Expand