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Full-Text Articles in Physical Sciences and Mathematics
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 …
The Broad-Lined Type Ic Sn 2012ap And The Nature Of Relativistic Supernovae Lacking A Gamma-Ray Burst Detection, D. Milisavljevic, R. Margutti, J. T. Parrent, A. M. Soderberg, R. A. Fesen
The Broad-Lined Type Ic Sn 2012ap And The Nature Of Relativistic Supernovae Lacking A Gamma-Ray Burst Detection, D. Milisavljevic, R. Margutti, J. T. Parrent, A. M. Soderberg, R. A. Fesen
Dartmouth Scholarship
We present ultraviolet, optical, and near-infrared observations of SN 2012ap, a broad-lined Type Ic supernova in the galaxy NGC 1729 that produced a relativistic and rapidly decelerating outflow without a gamma-ray burst signature. Photometry and spectroscopy follow the flux evolution from –13 to +272 days past the B-band maximum of –17.4 ± 0.5 mag. The spectra are dominated by Fe II, O I, and Ca II absorption lines at ejecta velocities of v ≈ 20,000 km s–1 that change slowly over time. Other spectral absorption lines are consistent with contributions from photospheric He I, and hydrogen may also …
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 …
Optical Discovery Of An Apparent Galactic Supernova Remnant G159.6+7.3, Robert A. Fesen, Dan Milisavljevic
Optical Discovery Of An Apparent Galactic Supernova Remnant G159.6+7.3, Robert A. Fesen, Dan Milisavljevic
Dartmouth Scholarship
Deep Hα images of portions of a faint 3° × 4° Hα shell centered at l = 1596, b = 73 seen on the Virginia Tech Spectral Line Survey images revealed the presence of several thin emission filaments along its eastern limb. Low-dispersion optical spectra of two of these filaments covering the wavelength range of 4500-7500 Å show narrow Hα line emissions with velocities around –170 ± 30 km s–1. Both the morphology and spectra of these filaments are consistent with a Balmer-dominated shock interpretation and we propose that these optical filaments indicate that the large Hα emission …
Non-Gaussianity From Self-Ordering Scalar Fields, Daniel G. Figueroa, Robert R. Caldwell, Marc Kamionkowski
Non-Gaussianity From Self-Ordering Scalar Fields, Daniel G. Figueroa, Robert R. Caldwell, Marc Kamionkowski
Dartmouth Scholarship
The Universe may harbor relics of the post-inflationary epoch in the form of a network of self-ordered scalar fields. Such fossils, while consistent with current cosmological data at trace levels, may leave too weak an imprint on the cosmic microwave background and the large-scale distribution of matter to allow for direct detection. The non-Gaussian statistics of the density perturbations induced by these fields, however, permit a direct means to probe for these relics. Here we calculate the bispectrum that arises in models of self-ordered scalar fields. We find a compact analytic expression for the bispectrum, evaluate it numerically, and provide …
Detection Of Co And Dust Emission In Near-Infrared Spectra Of Sn 1998s, Christopher L. Gerardy, Robert A. Fesen, Peter Höflich, J. Craig Wheeler
Detection Of Co And Dust Emission In Near-Infrared Spectra Of Sn 1998s, Christopher L. Gerardy, Robert A. Fesen, Peter Höflich, J. Craig Wheeler
Dartmouth Scholarship
Near-infrared spectra (0.95 – 2.4 μ m) of the peculiar Type IIn supernova 1998S in NGC 3877 from 95 to 355 days after maximum light are presented. K -band data taken at days 95 and 225 show the presence of the first overtone of CO emission near 2.3 μ m, which is gone by day 355. An apparent extended blue wing on the CO profile in the day 95 spectrum could indicate a large CO expansion velocity (≈ 2000 – 3000 km s − 1). This is the third detection of infrared CO emission in nearly as many Type II …