We present spectral and photometric observations of 10 Type Ia supernovae (SNe Ia) in the redshift range 0.16 " z " 0.62. The luminosity distances of these objects are determined by methods that employ relations between SN Ia luminosity and light curve shape. Combined with previous data from our High-z Supernova Search Team and recent results by Riess et al., this expanded set of 16 high-redshift supernovae and a set of 34 nearby supernovae are used to place constraints on the following cosmo- logical parameters: the Hubble constant the mass density the cosmological constant (i.e., the (H 0 ), () M ), vacuum energy density, the deceleration parameter and the dynamical age of the universe ) " ), (q 0 ), ) M \ 1) methods. We estimate the dynamical age of the universe to be 14.2 ^ 1.7 Gyr including systematic uncer- tainties in the current Cepheid distance scale. We estimate the likely e†ect of several sources of system- atic error, including progenitor and metallicity evolution, extinction, sample selection bias, local perturbations in the expansion rate, gravitational lensing, and sample contamination. Presently, none of these e†ects appear to reconcile the data with and ) " \ 0 q 0 " 0.

/pdf/observational-evidence-from-supernovae-for-an-accelerating-2hxji77uix.pdf

Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant

https://biblio.ugent.be/publication/685594/file/1130605.pdf

Review of Particle Physics

We present spectral and photometric observations of 10 type Ia supernovae (SNe Ia) in the redshift range 0.16 � z � 0.62. The luminosity distances of these objects are determined by methods that employ relations between SN Ia luminosity and light curve shape. Combined with previous data from our High-Z Supernova Search Team (Garnavich et al. 1998; Schmidt et al. 1998) and Riess et al. (1998a), this expanded set of 16 high-redshift supernovae and a set of 34 nearby supernovae are used to place constraints on the following cosmological parameters: the Hubble constant (H0), the mass density (M), the cosmological constant (i.e., the vacuum energy density, �), the deceleration parameter (q0), and the dynamical age of the Universe (t0). The distances of the high-redshift SNe Ia are, on average, 10% to 15% farther than expected in a low mass density (M = 0.2) Universe without a cosmological constant. Different light curve fitting methods, SN Ia subsamples, and prior constraints unanimously favor eternally expanding models with positive cosmological constant (i.e., � > 0) and a current acceleration of the expansion (i.e., q0 < 0). With no prior constraint on mass density other than M � 0, the spectroscopically confirmed SNe Ia are statistically consistent with q0 < 0 at the 2.8�

Observational Evidence from Supernovae for an Accelerating Universe and a Cosmological Constant To Appear in the Astronomical Journal

http://earthscience.rice.edu/wp-content/uploads/2015/09/AndersGrevesse.pdf

Abundances of the elements: Meteoritic and solar

Stellar physics and evolution calculations enable a broad range of research in astrophysics. Modules for Experiments in Stellar Astrophysics (MESA) is a suite of open source, robust, efficient, thread-safe libraries for a wide range of applications in computational stellar astrophysics. A one-dimensional stellar evolution module, MESAstar, combines many of the numerical and physics modules for simulations of a wide range of stellar evolution scenarios ranging from very low mass to massive stars, including advanced evolutionary phases. MESAstar solves the fully coupled structure and composition equations simultaneously. It uses adaptive mesh refinement and sophisticated timestep controls, and supports shared memory parallelism based on OpenMP. State-of-the-art modules provide equation of state, opacity, nuclear reaction rates, element diffusion data, and atmosphere boundary conditions. Each module is constructed as a separate Fortran 95 library with its own explicitly defined public interface to facilitate independent development. Several detailed examples indicate the extensive verification and testing that is continuously performed and demonstrate the wide range of capabilities that MESA possesses. These examples include evolutionary tracks of very low mass stars, brown dwarfs, and gas giant planets to very old ages; the complete evolutionary track of a 1 M ☉ star from the pre-main sequence (PMS) to a cooling white dwarf; the solar sound speed profile; the evolution of intermediate-mass stars through the He-core burning phase and thermal pulses on the He-shell burning asymptotic giant branch phase; the interior structure of slowly pulsating B Stars and Beta Cepheids; the complete evolutionary tracks of massive stars from the PMS to the onset of core collapse; mass transfer from stars undergoing Roche lobe overflow; and the evolution of helium accretion onto a neutron star. MESA can be downloaded from the project Web site (http://mesa.sourceforge.net/).

https://iopscience.iop.org/article/10.1088/0067-0049/192/1/3/pdf

Modules for Experiments in Stellar Astrophysics (MESA)

Man inhabits a universe composed of a great variety of elements and their isotopes. In Table I,1 a count of the stable and radioactive elements and isotopes is listed. Ninety elements are found terrestrially and one more, technetium, is found in stars; only promethium has not been found in nature.

Synthesis of the Elements in Stars

Thermonuclear reaction rates V

Nucleosynthesis in Supernovae.

On the Synthesis of elements at very high temperatures

Modern computer technology has revolutionized theoretical calculations on stellar structure and stellar evolution. Physical information of great complexity, previously ignored or crudely treated, can now be introduced in detail into stellar computations and can be treated with great precision and completeness. In particular it is no longer necessary (Iben 1965, Wagoner,
Fowler & Hoyle 1967) to approximate hard-won laboratory results on nuclear reaction rates by crude power-law dependences on temperature.
In this article we review the available experimental data on cross sections for the nuclear interactions of neutrons, protons, and alpha particles with a
number of light and intermediate-mass nuclei and we present calculations on the resulting reaction rates, nuclear lifetimes, and energy generation rates
under astrophysical conditions. We restrict our considerations to nondegenerate, nonrelativistic circumstances for the interacting nuclei. Table I lists
the general nuclear processes discussed, along with the units used in presenting numerical results and the notation used in representing nuclear reactions.
Previous reviews of nuclear reaction rates, somewhat more limited in scope, have been given by Fowler (1954, 1960) , Burbidge, Burbidge, Fowler & Hoyle (1957) (hereafter referred to as B^2FH), Caughlan & Fowler (1962), and Parker, Bahcall & Fowler (1964). The last previous overall survey of nuclear reaction rates which has come to our attention is that of Reeves (1965).

William A. Fowler

Papers

Synthesis of the Elements in Stars

Thermonuclear reaction rates V

Nucleosynthesis in Supernovae.

On the Synthesis of elements at very high temperatures

Thermonuclear reaction rates. II