Open Access. Powered by Scholars. Published by Universities.®
- Institution
- Publication
- Publication Type
Articles 1 - 12 of 12
Full-Text Articles in Astrophysics and Astronomy
Expanding Band Parameter Analysis Methods For Hed Meteorites And V-Type Asteroids, Noah Adm Haverkamp Frere
Expanding Band Parameter Analysis Methods For Hed Meteorites And V-Type Asteroids, Noah Adm Haverkamp Frere
Masters Theses
Vesta and Vesta-like asteroids have been convincingly linked, through visible and near-infrared (VNIR; 0.7 - 2.5 µm [micron]) spectral analysis, to a clan of basaltic achondritic meteorites – howardites, eucrites, and diogenites (HEDs). VNIR reflectance spectra of V-type asteroids and HED meteorites have two absorption features centered near 1 µm (Band I) and 2 µm (Band II) caused primarily by Fe2+ [iron] and Ca2+ [calcium] cations in pyroxene. Previous studies have shown a correlation between the mol% Fs and Wo with the central wavelengths of Band I and Band II, hereafter called Band I Center (BIC) and Band …
Exploring The Possibility Of O And Ne Contamination In Ulysses Observations Of Interstellar Helium, Brian E. Wood, Hans-Reinhard Müller, Maciej Bzowski, Justyna M. Sokół
Exploring The Possibility Of O And Ne Contamination In Ulysses Observations Of Interstellar Helium, Brian E. Wood, Hans-Reinhard Müller, Maciej Bzowski, Justyna M. Sokół
Dartmouth Scholarship
We explore the possibility that interstellar O and Ne may be contributing to the particle signal from the GAS instrument on Ulysses, which is generally assumed to be entirely He. Motivating this study is the recognition that an interstellar temperature higher than any previously estimated from Ulysses data could potentially resolve a discrepancy between Ulysses He measurements and those from the Interstellar Boundary Explorer (IBEX). Contamination by O and Ne could lead to Ulysses temperature measurements that are too low. We estimate the degree of O and Ne contamination necessary to increase the inferred Ulysses temperature to …
Investigating The Correlation Between Inclination Of Coronal Loops And Solar Flare Activity, John-Paul Mann
Investigating The Correlation Between Inclination Of Coronal Loops And Solar Flare Activity, John-Paul Mann
Symposium Of University Research and Creative Expression (SOURCE)
The purpose of this research is to investigate changes in the coronal loop structures during the life cycle of a solar flare. Coronal loops are intricate and complicated magnetic features on the solar surface that are the source of large solar flares. Understanding the dynamics of these coronal loops provides better models for predicting solar flare activity. By obtaining the magnetogram, or magnetic field strength, along with the inclination of these coronal loops, the full structure of the coronal loop can be obtained. Therefore, we studied how the coronal loops inclination angle, as it emerges from the photosphere, changes in …
Revisiting Ulysses Observations Of Interstellar Helium, Brian E. Wood, Hans-Reinhard Müller, Manfred Witte
Revisiting Ulysses Observations Of Interstellar Helium, Brian E. Wood, Hans-Reinhard Müller, Manfred Witte
Dartmouth Scholarship
We report the results of a comprehensive reanalysis of Ulysses observations of interstellar He atoms flowing through the solar system, the goal being to reassess the interstellar He flow vector and to search for evidence of variability in this vector. We find no evidence that the He beam seen by Ulysses changes at all from 1994-2007. The direction of flow changes by no more than ~03 and the speed by no more than ~0.3 km s–1. A global fit to all acceptable He beam maps from 1994-2007 yields the following He flow parameters: V ISM = 26.08 ± …
Evidence For A Weak Wind From The Young Sun, Brian E. Wood, Hans-Reinhard Müller, Seth Redfield, Eric Edelman
Evidence For A Weak Wind From The Young Sun, Brian E. Wood, Hans-Reinhard Müller, Seth Redfield, Eric Edelman
Dartmouth Scholarship
The early history of the solar wind has remained largely a mystery due to the difficulty of detecting winds around young stars that can serve as analogs for the young Sun. Here we report on the detection of a wind from the 500 Myr old solar analog π1 UMa (G1.5 V), using spectroscopic observations from the Hubble Space Telescope. We detect H I Lyα absorption from the interaction region between the stellar wind and interstellar medium, i.e., the stellar astrosphere. With the assistance of hydrodynamic models of the π1 UMa astrosphere, we infer a wind only half as strong as …
A Journey Into Quantization In Astrophysics, Florentin Smarandache, Victor Christianto
A Journey Into Quantization In Astrophysics, Florentin Smarandache, Victor Christianto
Branch Mathematics and Statistics Faculty and Staff Publications
The present book consists of 17 select scientific papers from ten years of work around 2003-2013. The topic covered here is quantization in Astrophysics. We also discuss other topics for instance Pioneer spacecraft anomaly. We discuss a number of sub-topics, for instance the use of Schrödinger equation to describe celestial quantization. Our basic proposition here is that the quantization of planetary systems corresponds to quantization of circulation as observed in superfluidity. And then we extend it further to the use of (complex) Ginzburg-Landau equation to describe possible nonlinearity of planetary quantization. Some of these papers have been published in journal …
Distribution Of Plasmoids In Post-Coronal Mass Ejection Current Sheets, L.-J. Guo, A. Bhattacharjee, Y.-M. Huang
Distribution Of Plasmoids In Post-Coronal Mass Ejection Current Sheets, L.-J. Guo, A. Bhattacharjee, Y.-M. Huang
Dartmouth Scholarship
Recently, the fragmentation of a current sheet in the high-Lundquist-number regime caused by the plasmoid instability has been proposed as a possible mechanism for fast reconnection. In this work, we investigate this scenario by comparing the distribution of plasmoids obtained from Large Angle and Spectrometric Coronagraph (LASCO) observational data of a coronal mass ejection event with a resistive magnetohydrodynamic simulation of a similar event. The LASCO/C2 data are analyzed using visual inspection, whereas the numerical data are analyzed using both visual inspection and a more precise topological method. Contrasting the observational data with numerical data analyzed with both methods, we …
Trajectories And Distribution Of Interstellar Dust Grains In The Heliosphere, Jonathan D. Slavin, Priscilla C. Frisch, Hans-Reinhard Müller, Jacob Heerikhuisen
Trajectories And Distribution Of Interstellar Dust Grains In The Heliosphere, Jonathan D. Slavin, Priscilla C. Frisch, Hans-Reinhard Müller, Jacob Heerikhuisen
Dartmouth Scholarship
The solar wind carves a bubble in the surrounding interstellar medium (ISM) known as the heliosphere. Charged interstellar dust grains (ISDG) encountering the heliosphere may be diverted around the heliopause or penetrate it depending on their charge-to-mass ratio. We present new calculations of trajectories of ISDG in the heliosphere, and the dust density distributions that result. We include up-to-date grain charging calculations using a realistic UV radiation field and full three-dimensional magnetohydrodynamic fluid + kinetic models for the heliosphere. Models with two different (constant) polarities for the solar wind magnetic field (SWMF) are used, with the grain trajectory calculations done …
The Ages And Metallicities Of Type Ia Supernova Host Galaxies From The Nearby Galaxies Supernova Search Program, Suzanna Sadler
The Ages And Metallicities Of Type Ia Supernova Host Galaxies From The Nearby Galaxies Supernova Search Program, Suzanna Sadler
Mahurin Honors College Capstone Experience/Thesis Projects
We seek to better understand the physical constraints under which White Dwarf stars ultimately become Type Ia supernovae (SNe Ia), an important test of the robustness of these tools in precisely measuring Dark Energy, as the definite progenitor system still remains elusive. The host galaxy environments of Type Ia supernovae provide our best opportunity for constraining the mechanism(s) of SN Ia production, i.e., the stars involved and the incubation times (tied to stellar ages), and the sensitivity of SNe Ia to changes in the local metallicity. We have measured the ages and metallicities of approximately 60 galaxies from a sample …
Perpendicular Ion Heating By Low-Frequency Alfvén-Wave Turbulence In The Solar Wind, Benjamin D. G. Chandran, Bo Li, Barrett N. Rogers, Eliot Quataert, Kai Germaschewski
Perpendicular Ion Heating By Low-Frequency Alfvén-Wave Turbulence In The Solar Wind, Benjamin D. G. Chandran, Bo Li, Barrett N. Rogers, Eliot Quataert, Kai Germaschewski
Dartmouth Scholarship
We consider ion heating by turbulent Alfvén waves (AWs) and kinetic Alfvén waves (KAWs) with wavelengths (measured perpendicular to the magnetic field) that are comparable to the ion gyroradius and frequencies ω smaller than the ion cyclotron frequency Ω. We focus on plasmas in which β < 1, where β is the ratio of plasma pressure to magnetic pressure. As in previous studies, we find that when the turbulence amplitude exceeds a certain threshold, an ion's orbit becomes chaotic. The ion then interacts stochastically with the time-varying electrostatic potential, and the ion's energy undergoes a random walk. Using phenomenological arguments, we derive an analytic expression for the rates at which different ion species are heated, which we test by simulating test particles interacting with a spectrum of randomly phased AWs and KAWs. We find that the stochastic heating rate depends sensitively on the quantity ε = δv ρ/v ⊥, where v ⊥ (v ∥) is the component of the ion velocity perpendicular (parallel) to the background magnetic field B 0, and δv ρ (δB ρ) is the rms amplitude of the velocity (magnetic-field) fluctuations at the gyroradius scale. In the case …
On Using The Color-Magnitude Diagram Morphology Of M67 To Test Solar Abundances, Z. Magic, A. Serenelli, A. Weiss, B. Chaboyer
On Using The Color-Magnitude Diagram Morphology Of M67 To Test Solar Abundances, Z. Magic, A. Serenelli, A. Weiss, B. Chaboyer
Dartmouth Scholarship
The open cluster M67 has solar metallicity and an age of about 4 Gyr. The turnoff (TO) mass is close to the minimum mass for which solar metallicity stars develop a convective core during main sequence evolution as a result of the development of hydrogen burning through the CNO cycle. The morphology of the color-magnitude diagram (CMD) of M67 around the TO shows a clear hook-like feature, a direct sign that stars close to the TO have convective cores. VandenBerg et al. investigated the possibility of using the morphology of the M67 TO to put constraints on the solar metallicity, …
Neutrosophic Logic, Wave Mechanics, And Other Stories: Selected Works 2005-2008, Florentin Smarandache, Victor Christianto
Neutrosophic Logic, Wave Mechanics, And Other Stories: Selected Works 2005-2008, Florentin Smarandache, Victor Christianto
Branch Mathematics and Statistics Faculty and Staff Publications
There is beginning for anything; we used to hear that phrase. The same wisdom word applies to us too. What began in 2005 as a short email on some ideas related to interpretation of the Wave Mechanics results in a number of papers and books up to now. Some of these papers can be found in Progress in Physics or elsewhere. It is often recognized that when a mathematician meets a physics-inclined mind then the result is either a series of endless debates or publication. In our story, we prefer to publish rather than perish. Therefore, our purpose with this …