Fred C. Adams

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This paper outlines astrophysical issues related to the long term fate of the universe. We consider the evolution of planets, stars, stellar populations, galaxies, and the universe itself over time scales which greatly exceed the current age of the universe. Our discussion starts with new stellar evolution calculations which follow the future evolution of(More)
A pseudo-Nambu-Goldstone boson, with a potential of the form V (φ) = Λ[1 ± cos(φ/f)], can naturally give rise to an epoch of inflation in the early universe, if f ∼ MPl and Λ ∼ MGUT . Such mass scales arise in particle physics models with a gauge group that becomes strongly interacting at the GUT scale. We explore the particle physics basis for these(More)
When stars form within small groups (with N⋆ ≈ 100 − 500 members), their circumstellar disks are exposed to relatively little EUV (hν > 13.6 eV) radiation but a great deal of FUV (6 eV < hν < 13.6 eV) radiation (∼ 10 times the local interstellar FUV field) from the most massive stars in the group. This paper calculates the mass loss rates and evaporation(More)
The favored theoretical explanation for giant planet formation – in both our solar system and others – is the core accretion model (although it still has some serious difficulties). In this scenario, planetesimals accumulate to build up planetary cores, which then accrete nebular gas. With current opacity estimates for protoplanetary envelopes, this model(More)
This paper studies the dynamical evolution of young groups/clusters, with N = 100 − 1000 members, from their embedded stage out to ages of ∼ 10 Myr. We use N -body simulations to explore how their evolution depends on the system size N and the initial conditions. Motivated by recent observations suggesting that stellar groups begin their evolution with(More)
This paper explores the stability of an Earth-like planet orbiting a solar mass star in the presence of an outer-lying intermediate mass companion. The overall goal is to estimate the fraction of binary systems that allow Earth-like planets to remain stable over long time scales. We numerically determine the planet’s ejection time τej over a range of(More)
We present a series of 2-dimensional hydrodynamic simulations of massive disks around protostars. We simulate the same physical problem using both a ‘Piecewise Parabolic Method’ (PPM) code and a ‘Smoothed Particle Hydrodynamic’ (SPH) code, and analyze their differences. The disks studied here range in mass from 0.05M∗ to 1.0M∗ and in initial minimum Toomre(More)
The quest for Earth-like planets is a major focus of current exoplanet research. Although planets that are Earth-sized and smaller have been detected, these planets reside in orbits that are too close to their host star to allow liquid water on their surfaces. We present the detection of Kepler-186f, a 1.11 ± 0.14 Earth-radius planet that is the outermost(More)