Farouqi, K., Mashonkina, L. I., Pfeiffer, B., Cowan, J. J, ...
While the high-entropy wind (HEW) of Type II supernovae remains one of the more promising sites for the rapid neutron-capture (r-) process, hydrodynamic simulations have yet to reproduce the...
Lawler, J. E., Sneden, C., Cowan, J. J., Ivans, I. I., Sobeck, J. S., ...
Recent radiative lifetime measurements accurate to +/- 5% (Stockett et al. 2007, J. Phys. B 40, 4529) using laser-induced fluorescence (LIF) on 8 even-parity and 62 odd-parity levels of Er II have...
A Primordial r-Process? (2008)
T. Rauscher, J.H. Applegate, J.J. Cowan, M. Wiescher
this paper we also introduced (beta delayed) fission of heavy nuclei, as calculated by Thielemann, Metzinger, and Klapdor (1983) [9] with the Howard and Moller (1980) [10] fission barriers and masses...
Roederer, I. U., Frebel, A., Shetrone, M. D., Prieto, C. A., Rhee, J., Gallino, R., ...
We present the first detailed abundance analysis of the metal-poor giant HKII 17435-00532. This star was observed as part of the University of Texas long-term project Chemical Abundances of Stars in...
Nucleosynthesis Modes in the High-Entropy-Wind Scenario of Type II Supernovae (2008)
Farouqi, K., Cowan, J. J., Mashonkina, L. I., Pfeiffer, B., Sneden, C., ...
Astrophysical and Nuclear Physics Aspects of the r-Process (2007)
C. Freiburghaus, T. Rauscher, B. Pfeiffer, ...
also follow the freeze-out of reactions with declining temperatures and densities explicitely. We compare the similarities and differences between the two approaches. Special emphasis is given to...
Explosive Nucleosynthesis and the Astrophysical r-Process (2007)
C. Freiburghaus, T. Rauscher, E. Kolbe, B. Pfeiffer, ...
. We give an overview of chemical equilibria in explosive burning and the role which neutron and/or proton separation energies play. We focus then on the rapid neutron-capture process (r-process)...
THE AGE OF THE GALAXY FROM THORIUM COSMOCHRONOMETRY (2007)
El torio, elemento radioactivo de larga duracion, puede sevir como un reloj sencillo y directo para determinar la edad de nuestra galaxia. Las investigaciones espectroscopicas de torio en estrellas...
RevMexAA (Serie de Conferencias), 10, 221--227 (2001) (2007)
The Age Of, C. Sneden, J. J. Cowan
The long--lived radioactive element thorium can potentially provide a simple and direct clock to determine the age of our Galaxy. Spectroscopic investigations of thorium in metal--poor stars have...
Maddox, L. A., Cowan, J. J., Kilgard, R. E., Schinnerer, E., Stockdale, C. J.
We report the analysis of deep radio observations of the interacting galaxy system M51 from the Very Large Array, with the goal of understanding the nature of the population of compact radio sources...
Maddox, L. A., Cowan, J. J., Kilgard, R. E., Schinnerer, E., Stockdale, C. J.
We report the analysis of deep radio observations of the interacting galaxy system M51 from the Very Large Array, with the goal of understanding the nature of the population of compact radio sources...
Hf Transition Probabilities and Abundances (2006)
Lawler, J. E., Hartog, E. A. Den, Labby, Z. E., Sneden, C., Cowan, J. J., Ivans, I. I.
Radiative lifetimes from laser-induced fluorescence measurements, accurate to about +/- 5 percent, are reported for 41 odd-parity levels of Hf II. The lifetimes are combined with branching fractions...
r-Process Enhanced Halo Stars (2006)
Cowan, J. J., Sneden, C., Lawler, J. E., Hartog, E. A. Den
Abundance observations indicate the presence of rapid-neutron capture (i.e., r-process) elements in old Galactic halo and globular cluster stars. These observations provide insight into the nature of...
Gd Transition Probabilities and Abundances (2006)
Hartog, E. A. Den, Lawler, J. E., Sneden, C., Cowan, J. J.
Radiative lifetimes, accurate to +/- 5%, have been measured for 49 even-parity and 14 odd-parity levels of Gd II using laser-induced fluorescence. The lifetimes are combined with branching fractions...
The Age of the Galaxy from Thorium Cosmochronometry (2006)
The Age of the Galaxy from Thorium Cosmochronometry
Maddox, L. A., Cowan, J. J., Kilgard, R. E., Lacey, C. K., Prestwich, A. H., Stockdale, C. J., ...
We present analyses of deep radio observations of M83 taken with the Very Large Array spanning fifteen years, including never before published observations from 1990 and 1998. We report on the...
A Radio and X-Ray Study of Historical Supernovae in M83 (2005)
Stockdale, C. J., Maddox, L. A., Cowan, J. J., Prestwich, A., Kilgard, R., Immler, S., ...
We report the results of 15 years of radio observations of the six historical supernovae (SNe) in M83 using the Very Large Array. We note the near linear decline in radio emission from SN 1957D, a...
Sm Transition Probabilities and Abundances (2005)
Lawler, J. E., Hartog, E. A. Den, Sneden, C., Cowan, J. J.
Radiative lifetimes, accurate to +/- 5%, have been measured for 212 odd-parity levels of Sm II using laser-induced fluorescence. The lifetimes are combined with branching fractions measured using...
The Rise of the s-Process in the Galaxy (2004)
Simmerer, J., Sneden, C., Cowan, J. J., Collier, J., Woolf, V. M., Lawler, J. E.
From newly-obtained high-resolution, high signal-to-noise ratio spectra the abundances of the elements La and Eu have been determined over the stellar metallicity range -3
Binary Blue Metal-Poor Stars: Evidence for AGB Mass Transfer (2003)
Sneden, C., Preston, G. W., Cowan, J. J.
We present new abundance analyses of six blue metal-poor (BMP) stars with very low iron abundances ([Fe/H] < -2), based on new high resolution echelle spectra. Three are spectroscopic binaries and...
Sneden, C., Cowan, J. J., Lawler, J. E., Ivans, I. I., Burles, S., Beers, T. C., ...
High-resolution spectra obtained with three ground-based facilities and the Hubble Space Telescope (HST) have been combined to produce a new abundance analysis of CS 22892-052, an extremely...
r-Process Abundance Signatures (2002)
Abundance observations indicate the presence of rapid-neutron capture (i.e., r-process) elements in old Galactic halo and globular cluster stars. These observations demonstrate that the earliest...
Observations of Neutron-Capture Elements in the Early Galaxy (2002)
Sneden, C., Cowan, J. J., Lawler, J. E.
Neutron-capture elements in low metallicity Galactic halo stars vary widely both in overall contents and detailed abundance patterns. This review discusses recent observational results on the...
Probing the Neutron-Capture Nucleosynthesis History of Galactic Matter (2002)
Truran, J. W., Cowan, J. J., Pilachowski, C. A., Sneden, C.
The heavy elements formed by neutron capture processes have an interesting history from which we can extract useful clues to and constraints upon both the characteristics of the processes themselves...
Nucleosynthesis Clocks and the Age of the Galaxy (2001)
Truran, J. W., Burles, S., Cowan, J. J., Sneden, C.
Nucleocosmochronology involves the use of the abundances of radioactive nuclear species and their radiogenic decay daughters to establish the finite age of the elements and the time scale for their...
Sneden, C., Lawler, J. E., Cowan, J. J.
In a short review of neutron-capture elemental abundances in Galactic halo stars, emphasis is placed on the use of these elements to estimate the age of the Galactic halo. Two prominent...
The Early Formation, Evolution and Age of the Neutron-Capture Elements in the Early Galaxy (2001)
Cowan, J. J., Sneden, C., Truran, J. W.
Abundance observations indicate the presence of rapid-neutron capture (i.e., r-process) elements in old Galactic halo and globular cluster stars. These observations demonstrate that the earliest...
Cowan, J. J., Sneden, C., Truran, J. W.
Observations of metal-poor Galactic halo stars indicate that the abundance pattern of the (heaviest) neutron-capture elements is consistent with the scaled solar system r-process abundances....
Neutron-Capture Element Trends in the Halo (2001)
Sneden, C., Cowan, J. J., Truran, J. W.
In a brief review of abundances neutron-capture elements (Z > ~30) in metal-poor halo stars, attention is called to their star-to-star scatter, the dominance of r-process synthesis at lowest...
Halo Star Abundances and r-Process Synthesis (2001)
Truran, J. W., Cowan, J. J., Fields, B. D.
We review recent observational studies of heavy element abundances in low metallicity stars and explore some implications of these results for nucleosynthesis and early Galactic chemical evolution.
The age of the galaxy from thorium cosmochronometry (2001)
The long{lived radioactive element thorium can potentially provide a simple and direct clock to determine the age of our Galaxy. Spectroscopic investigations of thorium in metal{poor stars have...
The Age of the Galaxy from Thorium Cosmochronometry (2000)
The long-lived radioactive element thorium can potentially provide a simple and direct clock to determine the age of our Galaxy. Spectroscopic investigations of thorium in metal-poor stars have...
R-process abundances and cosmochronometers in old metal-poor halo stars (1998)
Pfeiffer, B., Cowan, J. J., Sneden, C., Burles, S., ...
Proc. IX. Workshop on Nuclear Astrophysics, Ringberg Castle, Tegernsee, Bavaria; March 1998
The Probable Detection of SN 1923A: The Oldest Radio Supernova? (1998)
Eck, C. R., Cowan, J. J., Branch, D.
Based upon the results of VLA observations, we report the detection of two unresolved radio sources that are coincident with the reported optical position of SN 1923A in M83. For the source closest...