Measuring the Hubble Constant with the Hubble Space Telescope

Ten years ago our team completed the Hubble Space Telescope Key Project on the extragalactic distance scale. Cepheids were detected in some 25 galaxies and used to calibrate four secondary distance indicators that reach out into the expansion field beyond the noise of galaxy peculiar velocities. The result was H_0 = 72 +/- 8 km/sec/Mpc and put an end to galaxy distances uncertain by a factor of two. This work has been awarded the Gruber Prize in Cosmology for 2009.Comment: Gruber Prize Lecture to be published in Transactions of the IA

A Unified Theory for the Atmospheres of the Hot and Very Hot Jupiters: Two Classes of Irradiated Atmospheres

We highlight the importance of gaseous TiO and VO opacity on the highly irradiated close-in giant planets. The atmospheres of these planets naturally fall into two classes that are somewhat analogous to the M- and L-type dwarfs. Those that are warm enough to have appreciable opacity due to TiO and VO gases we term the ``pM Class'' planets, and those that are cooler we term ``pL Class'' planets. We calculate model atmospheres for these planets, including pressure-temperature profiles, spectra, and characteristic radiative time constants. We show that pM Class planets have hot stratospheres $\sim$2000 K and appear ``anomalously'' bright in the mid infrared secondary eclipse, as was recently found for planets HD 149026b and HD 209458b. This class of planets absorbs incident flux and emits thermal flux from high in their atmospheres. Consequently, they will have large day/night temperature contrasts and negligible phase shifts between orbital phase and thermal emission light curves, because radiative timescales are much shorter than possible dynamical timescales. The pL Class planets absorb incident flux deeper in the atmosphere where atmospheric dynamics will more readily redistribute absorbed energy. This will lead to cooler day sides, warmer night sides, and larger phase shifts in thermal emission light curves. Around a Sun-like primary this boundary occurs at $\sim$0.04-0.05 AU. The eccentric transiting planets HD 147506b and HD 17156b alternate between the classes. Thermal emission in the optical from pM Class planets is significant red-ward of 400 nm, making these planets attractive targets for optical detection. The difference in the observed day/night contrast between ups Andromeda b (pM Class) and HD 189733b (pL Class) is naturally explained in this scenario. (Abridged.)Comment: Accepted to the Astrophysical Journa

The Measure of Cosmological Parameters

New, large, ground and space telescopes are contributing to an exciting and rapid period of growth in observational cosmology. The subject is now far from its earlier days of being data-starved and unconstrained, and new data are fueling a healthy interplay between observations and experiment and theory. I briefly review here the status of measurements of a number of quantities of interest in cosmology: the Hubble constant, the total mass-energy density, the matter density, the cosmological constant or dark energy component, and the total optical background light.Comment: 12 pages, 4 figures, to be published in "2001: A Spacetime Odyssey: Proceedings of the Inaugural Conference of the Michigan Center for Theoretical Physics", Michael J. Duff & James T. Liu, eds., (World Scientific, Singapore), in pres

Three flavour Quark matter in chiral colour dielectric model

We investigate the properties of quark matter at finite density and temperature using the nonlinear chiral extension of Colour Dielectric Model (CCM). Assuming that the square of the meson fields devlop non- zero vacuum expectation value, the thermodynamic potential for interacting three flavour matter has been calculated. It is found that $$and$$ remain zero in the medium whereas $$ changes in the medium. As a result, $u$ and $d$ quark masses decrease monotonically as the temperature and density of the quark matter is increased.In the present model, the deconfinement density and temperature is found to be lower compared to lattice results. We also study the behaviour of pressure and energy density above critical temperature.Comment: Latex file. 5 figures available on request. To appear in Phys. Rev.

PC tools for project management: Programs and the state-of-the-practice

The use of microcomputer tools for NASA project management; which features are the most useful; the impact of these tools on job performance and individual style; and the prospects for new features in project management tools and related tools are addressed. High, mid, and low end PM tools are examined. The pro's and con's of the tools are assessed relative to various tasks. The strengths and weaknesses of the tools are presented through cases and demonstrations

Nonrelativistic Limit of the Scalar Chern-Simons Theory and the Aharonov-Bohm Scattering

We study the nonrelativistic limit of the quantum theory of a Chern-Simons field minimally coupled to a scalar field with quartic self-interaction. The renormalization of the relativistic model, in the Coulomb gauge, is discussed. We employ a procedure to calculate scattering amplitudes for low momenta that generates their $|p|/m$ expansion and separates the contributions coming from high and low energy intermediary states. The two body scattering amplitude is calculated up to order $p^2/m^2$. It is shown that the existence of a critical value of the self-interaction parameter for which the 2-particle scattering amplitude reduces to the Aharonov-Bohm one is a strictly nonrelativistic feature. The subdominant terms correspond to relativistic corrections to the Aharonov-Bohm scattering. A nonrelativistic reduction scheme and an effective nonrelativistic Lagrangian to account for the relativistic corrections are proposed.Comment: 22 pages, 8 figures, revtex, to be published in Int. J. Mod. Phys.

The 8^8B Neutrino Spectrum

Knowledge of the energy spectrum of $^8$B neutrinos is an important ingredient for interpreting experiments that detect energetic neutrinos from the Sun. The neutrino spectrum deviates from the allowed approximation because of the broad alpha-unstable $^8$Be final state and recoil order corrections to the beta decay. We have measured the total energy of the alpha particles emitted following the beta decay of $^8$B. The measured spectrum is inconsistent with some previous measurements, in particular with a recent experiment of comparable precision. The beta decay strength function for the transition from $^8$B to the accessible excitation energies in $^8$Be is fit to the alpha energy spectrum using the R-matrix approach. Both the positron and neutrino energy spectra, corrected for recoil order effects, are constructed from the strength function. The positron spectrum is in good agreement with a previous direct measurement. The neutrino spectrum disagrees with previous experiments, particularly for neutrino energies above 12 MeV.Comment: 15 pages, 13 figures, 4 tables, submitted to Phys. Rev. C, typos correcte

Atmosphere, Interior, and Evolution of the Metal-Rich Transiting Planet HD 149026b

We investigate the atmosphere and interior of the new transiting planet HD 149026b, which appears to be very rich in heavy elements. We first compute model atmospheres at metallicities ranging from solar to ten times solar, and show how for cases with high metallicity or inefficient redistribution of energy from the day side, the planet may develop a hot stratosphere due to absorption of stellar flux by TiO and VO. The spectra predicted by these models are very different than cooler atmosphere models without stratospheres. The spectral effects are potentially detectable with the Spitzer Space Telescope. In addition the models with hot stratospheres lead to a large limb brightening, rather than darkening. We compare the atmosphere of HD 149026b to other well-known transiting planets, including the recently discovered HD 189733b, which we show have planet-to-star flux ratios twice that of HD 209458 and TrES-1. The methane abundance in the atmosphere of HD 189733b is a sensitive indicator of atmospheric temperature and metallicity and can be constrained with Spitzer IRAC observations. We then turn to interior studies of HD 149026b and use a grid of self-consistent model atmospheres and high-pressure equations of state for all components to compute thermal evolution models of the planet. We estimate that the mass of heavy elements within the planet is in the range of 60 to 93 M_earth. Finally, we discuss trends in the radii of transiting planets with metallicity in light of this new member of the class.Comment: Accepted to the Astrophysical Journal. 18 pages, including 10 figures. New section on the atmosphere of planet HD 189733b. Enhanced discussion of atmospheric Ti chemistry and core mass for HD 149026