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The formation and evolution of stars depends on various physical aspects of stellar matter, including the equation of state (EOS) and transport properties. Although often dismissed as `ideal gas-like' and therefore simple, states occurring in stellar matter are dense plasmas, and the EOS has not been established precisely. EOS constructed using multi-physics approaches found necessary for laboratory studies of warm dense matter give significant variations in stellar regimes, and vary from the EOS commonly used in simulations of the formation and evolution of stars. We have investigated the sensitivity of such simulations to variations in the EOS, for sun-like and low-mass stars, and found a strong sensitivity of the lifetime of the Sun and of the lower luminosity limit for red dwarfs. We also found a significant sensitivity in the lower mass limit for red dwarfs. Simulations of this type are also used for other purposes in astrophysics, including the interpretation of absolute magnitude as mass, the conversion of inferred mass distribution to the initial mass function using predicted lifetimes, simulations of star formation from nebulae, simulations of galactic evolution, and the baryon census used to bound the exotic contribution to dark matter. Although many of the sensitivities of stellar physics to the EOS are large, some of the inferred astrophysical quantities are also constrained by independent measurements, although the constraints may be indirect and non-trivial. However, it may be possible to use such measurements to constrain the EOS more than presently possible by established plasma theory.

Low-mass stars, ~1-2 solar masses, near the Main Sequence are efficient at producing 3He, which they mix into the convective envelope on the giant branch and distribute into the Galaxy by way of envelope loss. This process is so efficient that it is difficult to reconcile the observed cosmic abundance of 3He with the predictions of Big Bang nucleosynthesis. In this paper we find, by modeling a red giant with a fully three-dimensional hydrodynamic code and a full nucleosynthetic network, that mixing arises in the supposedly stable and radiative zone between the hydrogen-burning shell and the base of the convective envelope. This mixing is due to Rayleigh-Taylor instability within a zone just above the hydrogen-burning shell. In this zone the burning of the 3He left behind by the retreating convective envelope is predominantly by the reaction 3He + 3He -> 4He + 2p, a reaction which, untypically for stellar nuclear reactions, {\it lowers} the mean molecular weight, leading to a local minimum. This local minimum leads to Rayleigh-Taylor instability, and turbulent motion is generated which will continue ultimately up into the normal convective envelope. Consequently material from the envelope is dragged down sufficiently close to the burning shell that the 3He in it is progressively destroyed. Thus we are able to remove the threat that 3He production in low-mass stars poses to the Big Bang nucleosynthesis of 3He. Some slow mixing mechanism has long been suspected, that connects the convective envelope of a red giant to the burning shell. It appears to be necessary to account for progressive changes in the 12C/13C and 14N/12C ratios on the First Giant Branch. We suggest that these phenomena are also due to the Rayleigh-Taylor-unstable character of the 3He-burning region., Comment: Paper presented at IAU-GA, Prague, August 2006

Current practice in stellar evolution is to employ one-dimensional calculations that quantitatively apply only to a minority of the observed stars (single non-rotating stars, or well detached binaries). Even in these systems, astrophysicists are dependent on approximations to handle complex three-dimensional processes like convection. Understanding the structure of binary stars, like those that lead to the Type Ia supernovae used to measure the expansion of the universe, are grossly non-spherical and await a 3D treatment. To approach very large problems like multi-dimensional modeling of stars, the Lawrence Livermore National Laboratory has invested in massively parallel computers and invested even more in developing the algorithms to utilize them on complex physics problems. We have leveraged skills from across the lab to develop a 3D stellar evolution code, Djehuty (after the Egyptian god for writing and calculation) that operates efficiently on platforms with thousands of nodes, with the best available physical data (opacities, EOS, etc.). Djehuty has incorporated all basic physics for modeling stars including an accurate equation of state, radiation transport by diffusion, thermonuclear reaction rates, and hydrodynamics, and we have begun testing it in a number of applications., Comment: 14 pages, 8 figures. Proceedings of the 3D Stellar Evolution workshop held in Livermore, July 22-26 2002. ASP Conf. Series vol. 293

The DJEHUTY project is an intensive effort at the Lawrence Livermore National Laboratory (LLNL) to produce a general purpose 3-D stellar structure and evolution code to study dynamic processes in whole stars., Comment: 2 pages, IAU coll. 185

Without assuming any solar models and neutrino flavor conversions, $^8$B neutrinos seen by the Kamiokande experiment should contribute 2.6$\pm 0.45$ SNU to the chlorine experiment. When this rate is compared with the total event rate of 2.3$\pm 0.2$ SNU observed by the Homestake experiment which should inlude a 0.2 SNU contribution from uncertainty-free pep neutrinos, there may still be a possible evidence that $^7$Be neutrinos are more severely suppressed than the $^8$B neutrinos with respect to the predictions of standard solar models, which cannot be explained by any known astrophysics solution. Given a Kamiokande event rate of larger than 36$\%$ (2$\sigma$) of the prediciton of Bahcall and Pinsonneault's standard solar model, variations of standard solar models yield minimal rates of 3.6 SNU for the Homestake experiment and 114 SNU for GALLEX and SAGE. Therefore, variations of standard solar models as solutions to the solar neutrino problem are so far inconsistent with the Homestake experiment and only marginally allowed by the gallium experiments. If the gallium experiments confirm a flux significantly below 114 SNU, it would imply unconventional physics., Comment: revtex 17 pages, 3 figures upon request

The ages of globular clusters inferred from observations depends sensitively on assumptions like the initial helium abundance and the mass loss rate. A high helium abundance (e.g., $Y\approx$0.28) or a mass loss rate of $\sim$10$^{-11}M_\odot$ yr$^{-1}$ near the main sequence turn-off region lowers the current age estimate from 14 Gyr to about 10--12 Gyr, significantly relaxing the constraints on the Hubble constant, allowing values as high as 60km/sec/Mpc for a universe with the critical density and 90km/sec/Mpc for a baryon-only universe. Possible mechanisms for the helium enhancement in globular clusters are discussed, as are arguments for an instability strip induced mass loss near the turn-off. Ages lower than 10 Gyr are not possible even with the operation of both of these mechanisms unless the initial helium abundance in globular clusters is $>0.30$, which would conflict with indirect measurements of helium abundances in globular clusters., Comment: revtex 17 pages, 4 figures upon request, FERMILAB-PUB-94/060-A

The success of the Magnetospheric Multiscale mission depends on the accurate measurement of the magnetic field on all four spacecraft. To ensure this success, two independently designed and built fluxgate magnetometers were developed, avoiding single-point failures. The magnetometers were dubbed the digital fluxgate (DFG), which uses an ASIC implementation and was supplied by the Space Research Institute of the Austrian Academy of Sciences and the analogue magnetometer (AFG) with a more traditional circuit board design supplied by the University of California, Los Angeles. A stringent magnetic cleanliness program was executed under the supervision of the Johns Hopkins University,s Applied Physics Laboratory. To achieve mission objectives, the calibration determined on the ground will be refined in space to ensure all eight magnetometers are precisely inter-calibrated. Near real-time data plays a key role in the transmission of high-resolution observations stored onboard so rapid processing of the low-resolution data is required. This article describes these instruments, the magnetic cleanliness program, and the instrument pre-launch calibrations, the planned in-flight calibration program, and the information flow that provides the data on the rapid time scale needed for mission success.

Micrometeorites are constantly arriving at the Earth's surface, however, they are quickly diluted by the natural and anthropogenic back-ground dust. The successful collection of micromete-orites requires either the employment of a separation technique (e.g. using magnets to separate metal-bearing micrometeorites from deepsea sediments [e.g. 1,2] and dissolved pre-historic limestones and salts [e.g. 3,4]), or an approach that limits contamination by terrestrial dust (e.g. collecting from ice, snow and well water in polar regions - locations where the terrestrial dust flux is so low that micrometeorites repre-sent the major dust component [e.g. 5-7]). We have recently set up a micrometeorite collection station on Kwajalein Island in the Republic of the Marshall Is-lands in the Pacific Ocean, using high volume air samplers to collect particles directly from the atmosphere. Collecting at this location exploits the considerably reduced anthropogenic background; Kwajalein is >1000 miles from the nearest continent and for much of the year, trade winds blow from the northeast at 15 to 20 knots providing a continuous stream of oceanic aerosol for sampling. By collecting directly from the atmosphere, the terrestrial age of the particles, and hence weathering they experience, is minimal. We therefore anticipate that the Kwajalein col-lection may include particles that are highly susceptible to weathering and either not preserved well or not found at all in other collections. In addition, this collection method allows for particle arrival times to be constrained so that collections can be timed to correlate with celestial events (e.g. meteor showers). Here we describe the collections and their preparation and report on the initial results.

In the present study of astrometric, photometric, and spectrophotometric data for the low luminosity carbon star G77-61, radial velocity variations are detected which have a binary period of 245 days. The unseen companion is probably a cool white dwarf of much higher mass than the visible object. The most straightforward evolutionary hypothesis is that this star has an extremely metal-poor composition, and that it accreted a small amount of carbon-rich material when the now-unseen primary was at maximum radius. This may have inverted the C/O abundance of the secondary without achieving common envelope evolution and a sorter period.

The isotopic abundance ratio C-12/C-13 for the M supergiant alpha Orionis is derived from photoelectric high-resolution scans of the CN 2-0 red system and high-resolution interferometric spectra of the CO second-overtone bands. The two molecules yield consistent results and the final value for the C-12/C-13 ratio is 7.0 plus or minus 1.5. Rationale is offered for the causes contributing to an earlier suggestion that C-12/C-13 ratios from CO and CN were in disagreement.

Calculations of CNO processing in stellar envelopes, based on theoretical nucleosynthesis rather than empirical abundances in evolving stars, are presented and used in two models for the chemical evolution of the solar neighborhood. Seven stable isotopes are considered: C-12, C-13, N-14, N-15, O-16, O-17, and O-18. The two models ('infall' and 'initial-burst') represent extremes of types consistent with general constraints and include theoretical estimates of other nucleosynthesis sites and yields for CNO isotopes. The results obtained are found to predict that all CNO isotopes are produced mainly by stars with lifetimes much less than the age of the Galaxy (even at the present time when low-mass stars have the greatest death rate), so that isotopic ratios evolve very slowly after the first few billion years. Consequences of these slow changes are that the isotopic ratios cannot be employed to test between alternative hypotheses and that galactic evolution does not seem to be able to account for the apparent difference between the C-13/C-12 ratio in the solar system and in molecular clouds. The predicted envelope processing is shown to lead to approximately the solar-system values for the C-13/C-12 and O-17/O-16 abundance ratios but to a N-14/C-12 ratio that is too small by at least a factor of 2.