The Angular Momentum of the Solar Wind
TL;DR: Steady state model of solar wind flow in equatorial plane solved for radial and azimuthal motions, taking into account pressure gradient, magnetic field and gravitational effects as discussed by the authors.
Abstract: Steady state model of solar wind flow in equatorial plane solved for radial and azimuthal motions, taking into account pressure gradient, magnetic field and gravitational effects
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TL;DR: Modules for Experiments in Stellar Astrophysics (MESA) as discussed by the authors is an open source software package for modeling the evolution of stellar structures and composition. But it is not suitable for large-scale systems such as supernovae.
Abstract: We substantially update the capabilities of the open source software package Modules for Experiments in Stellar Astrophysics (MESA), and its one-dimensional stellar evolution module, MESA star. Improvements in MESA star's ability to model the evolution of giant planets now extends its applicability down to masses as low as one-tenth that of Jupiter. The dramatic improvement in asteroseismology enabled by the space-based Kepler and CoRoT missions motivates our full coupling of the ADIPLS adiabatic pulsation code with MESA star. This also motivates a numerical recasting of the Ledoux criterion that is more easily implemented when many nuclei are present at non-negligible abundances. This impacts the way in which MESA star calculates semi-convective and thermohaline mixing. We exhibit the evolution of 3-8 M ? stars through the end of core He burning, the onset of He thermal pulses, and arrival on the white dwarf cooling sequence. We implement diffusion of angular momentum and chemical abundances that enable calculations of rotating-star models, which we compare thoroughly with earlier work. We introduce a new treatment of radiation-dominated envelopes that allows the uninterrupted evolution of massive stars to core collapse. This enables the generation of new sets of supernovae, long gamma-ray burst, and pair-instability progenitor models. We substantially modify the way in which MESA star solves the fully coupled stellar structure and composition equations, and we show how this has improved the scaling of MESA's calculational speed on multi-core processors. Updates to the modules for equation of state, opacity, nuclear reaction rates, and atmospheric boundary conditions are also provided. We describe the MESA Software Development Kit that packages all the required components needed to form a unified, maintained, and well-validated build environment for MESA. We also highlight a few tools developed by the community for rapid visualization of MESA star results.
2,761 citations
Cites background from "The Angular Momentum of the Solar W..."
...Whatever the origin of surface magnetic fields, these are expected to couple to the wind mass-loss and, if strong enough, produce magnetic braking (e.g., Weber & Davis 1967; ud-Doula & Owocki 2002; Meynet et al. 2011)....
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TL;DR: In this paper, the properties of large amplitude microscale Alfven waves in interplanetary medium were investigated using plasma and magnetic field data from Mariner 5. But the results were limited to a single-dimensional image.
Abstract: Dynamic nonshock properties of large amplitude microscale Alfven waves in interplanetary medium, using plasma and magnetic field data from Mariner 5
1,714 citations
TL;DR: In this article, the authors derived an improved activity-age calibration for F7-K2 dwarfs (0:5 mag < B -V < 0.9 mag).
Abstract: While the strong anticorrelation between chromospheric activity and age has led to the common use of the Ca II H
and K emission index (R'_(HK) = L_(HK)/L_(bol)) as an empirical age estimator for solar-type dwarfs, existing activity-age relations
produce implausible ages at both high and low activity levels.We have compiled R'_(HK)
HK data from the literature
for young stellar clusters, richly populating for the first time the young end of the activity-age relation. Combining the
cluster activity data with modern cluster age estimates and analyzing the color dependence of the chromospheric activity
age index,we derive an improved activity-age calibration for F7-K2 dwarfs (0:5 mag < B - V < 0.9 mag). We
also present a more fundamentally motivated activity-age calibration that relies on conversion of R'_(HK) values through
the Rossby number to rotation periods and then makes use of improved gyrochronology relations. We demonstrate that
our new activity-age calibration has typical age precision of ~0.2 dex for normal solar-type dwarfs aged between the
Hyades and the Sun (~0.6-4.5 Gyr). Inferring ages through activity-rotation-age relations accounts for some color-dependent
effects and systematically improves the age estimates (albeit only slightly). We demonstrate that coronal
activity as measured through the fractional X-ray luminosity (R_X = L_X/L_(bol)) has nearly the same age- and rotation inferring
capability as chromospheric activity measured through R'_(HK). As a first application of our calibrations, we
provide new activity-derived age estimates for a volume-limited sample of the 108 solar-type field dwarfs within
16 pc.
1,325 citations
Cites background from "The Angular Momentum of the Solar W..."
...The an- gular momentum loss is theoretically understood as due to mass loss in a magnetized wind (Schatzman 1962; Weber & Davis 1967; Mestel 1968)....
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TL;DR: The Modules for Experiments in Stellar Astrophysics (MESA) Isochrones and Stellar Tracks (MIST) project as discussed by the authors provides a set of stellar evolutionary tracks and isochrones computed using MESA, a state-of-the-art 1D stellar evolution package.
Abstract: This is the first of a series of papers presenting the Modules for Experiments in Stellar Astrophysics (MESA) Isochrones and Stellar Tracks (MIST) project, a new comprehensive set of stellar evolutionary tracks and isochrones computed using MESA, a state-of-the-art open-source 1D stellar evolution package. In this work, we present models with solar-scaled abundance ratios covering a wide range of ages ($5 \leq \rm \log(Age)\;[yr] \leq 10.3$), masses ($0.1 \leq M/M_{\odot} \leq 300$), and metallicities ($-2.0 \leq \rm [Z/H] \leq 0.5$). The models are self-consistently and continuously evolved from the pre-main sequence to the end of hydrogen burning, the white dwarf cooling sequence, or the end of carbon burning, depending on the initial mass. We also provide a grid of models evolved from the pre-main sequence to the end of core helium burning for $-4.0 \leq \rm [Z/H] < -2.0$. We showcase extensive comparisons with observational constraints as well as with some of the most widely used existing models in the literature. The evolutionary tracks and isochrones can be downloaded from the project website at this http URL
1,301 citations
Cites background from "The Angular Momentum of the Solar W..."
...Currently, surface magnetic fields are not included in MESA calculations, which can couple to mass loss and give rise to magnetic braking (e.g., Weber & Davis 1967; Mestel 1968; ud-Doula & Owocki 2002; Meynet et al. 2011), a mechanism for winding down surface rotation over time in stars with…...
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TL;DR: Green function solution to the Maxwell equations for interplanetary and coronal magnetic fields above photosphere, considering field at source surface as discussed by the authors, considering magnetic field at the source surface.
Abstract: Green function solution to Maxwell equations for interplanetary and coronal magnetic fields above photosphere, considering field at source surface
1,135 citations