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Physical Sciences and Mathematics Commons™

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The Sun and the Solar System

Physics and Astronomy Faculty Publications

Series

Articles 1 - 9 of 9

Full-Text Articles in Physical Sciences and Mathematics

The Limited Reign Of Saturn's Rings, Laurence A. Marschall Mar 2019

The Limited Reign Of Saturn's Rings, Laurence A. Marschall

Physics and Astronomy Faculty Publications

Saturn’s rings—stretching tens of thousands of miles above its equator but no more than a few hundred yards thick—mark an ancient debris field of orbiting ice shards, the remains of a moon-sized object that strayed too close and was torn to pieces by Saturn’s intense gravitation. Astronomers have debated when the rings formed and how long they will stay in orbit. Recent observations from large, land-based telescopes and orbiting spacecraft reveal that Saturn’s rings are remarkably young and are dissipating at a rapid rate. [excerpt]

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Catching Shadow Bands, Laurence A. Marschall May 2017

Catching Shadow Bands, Laurence A. Marschall

Physics and Astronomy Faculty Publications

Even though shadow bands are only visible for a few fleeting minutes, it is possible to catch them if you prepare in advance. Get a large piece of white cardboard or white-painted plywood to act as a screen--the bands are subtle and can be more easily seen against a clean, white surface. (excerpt)

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Back Half Of The Year, Ian R. Clarke Jul 2016

Back Half Of The Year, Ian R. Clarke

Physics and Astronomy Faculty Publications

Here we are in the back half of 2016, and the days are getting shorter. We have, as of today, lost 18 minutes since the solstice on June 20, and the speed of that change is quickening. You may wonder why it is that we have our hottest weather after our longest day is behind us. The simple answer is that it takes time for land and water masses to warm up. That’s the reason that Sept. 21 is likely to be a lot warmer than March 21, even though they have the same amount of daylight. [excerpt]

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Living In The Milky Way, Ian R. Clarke Jun 2016

Living In The Milky Way, Ian R. Clarke

Physics and Astronomy Faculty Publications

It’s finally here. Today, June 20 at 6:34 p.m., is the the summer solstice, also known as the first day of summer and, confusingly enough, midsummer’s eve. From a scientific perspective, it marks the moment the sun reaches its northernmost point in our sky. As a result of that position, it’s the shortest night and longest day if you live north of the equator. [excerpt]

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Variations In Solar Wind Fractionation As Seen By Ace/Swics And The Implications For Genesis Mission Results, P. Pilleri, Daniel B. Reisenfeld, T. H. Zurbuchen, S. T. Lepri, P. Shearer, J. A. Gilbert, R. Von Steiger, R. C. Wiens Oct 2015

Variations In Solar Wind Fractionation As Seen By Ace/Swics And The Implications For Genesis Mission Results, P. Pilleri, Daniel B. Reisenfeld, T. H. Zurbuchen, S. T. Lepri, P. Shearer, J. A. Gilbert, R. Von Steiger, R. C. Wiens

Physics and Astronomy Faculty Publications

We use Advanced Composition Explorer (ACE)/Solar Wind Ion Composition Spectrometer (SWICS) elemental composition data to compare the variations in solar wind (SW) fractionation as measured by SWICS during the last solar maximum (1999-2001), the solar minimum (2006-2009), and the period in which the Genesis spacecraft was collecting SW (late 2001-early 2004). We differentiate our analysis in terms in SW regimes (i.e., originating from interstream or coronal hole flows, or coronal mass ejecta). Abundances are normalized to the low-first ionization potential (low-FIP) ion magnesium to uncover correlations that are not apparent when normalizing to high-FIP ions. We find that relative …

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Spectral Evolution Of Energetic Neutral Atom Emissions At The Heliospheric Poles As Measured By Ibex During Its First Three Yeras, M. Dayeh, F. Allegrini, R. Demajistre, M. I. Desai, R. W. Ebert, S. A. Fuselier, Paul H. Janzen, G. Livadiotis, D. J. Mccomas, Daniel B. Reisenfeld, N. A. Schwadron, M. Siewert Dec 2014

Spectral Evolution Of Energetic Neutral Atom Emissions At The Heliospheric Poles As Measured By Ibex During Its First Three Yeras, M. Dayeh, F. Allegrini, R. Demajistre, M. I. Desai, R. W. Ebert, S. A. Fuselier, Paul H. Janzen, G. Livadiotis, D. J. Mccomas, Daniel B. Reisenfeld, N. A. Schwadron, M. Siewert

Physics and Astronomy Faculty Publications

The Interstellar Boundary Explorer (IBEX) mission continues to measure energetic neutral atom (ENA) emissions produced by charge exchange between solar wind (SW) protons and interstellar neutrals at the edge of our heliosphere. Using the first 3 yr of IBEX-Hi ENA measurements (2009-2011), we examined the spectral evolution of ~0.5-6 keV ENAs at the polar regions (above 60°). We found the following: (1) pixels with a characteristic "ankle" spectra (lower spectral index at higher energies) increase by ~5% in 2010 and ~10% in 2011 compared to 2009. (2) The averaged spectral index in 2011 is smaller than that of 2009. (3) …

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Separation Of The Ribbon From Globally Distributed Energetic Neutral Atom Flux Using The First Five Years Of Ibex Observations, N. A. Schwadron, E. Moebius, S. A. Fuselier, D. J. Mccomas, H. O. Funsten, Paul H. Janzen, Daniel B. Reisenfeld, H. Kucharek, M. A. Lee, K. Fairchild, F. Allegrini, M. Dayeh, G. Livadiotis, M. Reno, M. Bzowski, J. M. Sokol, M. A. Kubiak, E. R. Christian, R. Demajistre, P. Frisch, A. Galli, P. Wurz, M. Gruntman Nov 2014

Separation Of The Ribbon From Globally Distributed Energetic Neutral Atom Flux Using The First Five Years Of Ibex Observations, N. A. Schwadron, E. Moebius, S. A. Fuselier, D. J. Mccomas, H. O. Funsten, Paul H. Janzen, Daniel B. Reisenfeld, H. Kucharek, M. A. Lee, K. Fairchild, F. Allegrini, M. Dayeh, G. Livadiotis, M. Reno, M. Bzowski, J. M. Sokol, M. A. Kubiak, E. R. Christian, R. Demajistre, P. Frisch, A. Galli, P. Wurz, M. Gruntman

Physics and Astronomy Faculty Publications

The Interstellar Boundary Explorer (IBEX) observes the IBEX ribbon, which stretches across much of the sky observed in energetic neutral atoms (ENAs). The ribbon covers a narrow (∼20◦–50◦) region that is believed to be roughly perpendicular to the interstellar magnetic field. Superimposed on the IBEX ribbon is the globally distributed flux that is controlled by the processes and properties of the heliosheath. This is a second study that utilizes a previously developed technique to separate ENA emissions in the ribbon from the globally distributed flux. A transparency mask is applied over the ribbon and …

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Ibex: The First Five Years (2009-2013), D. J. Mccomas, F. Allegrini, M. Bzowski, M. A. Dayeh, R. Demajistre, H. O. Funsten, S. A. Fuselier, M. Gruntman, Paul H. Janzen, M. A. Kubiak, H. Kucharek, E. Möbius, Daniel B. Reisenfeld, N. A. Schwadron, J. M. Sokol, M. Tokumaru Aug 2014

Ibex: The First Five Years (2009-2013), D. J. Mccomas, F. Allegrini, M. Bzowski, M. A. Dayeh, R. Demajistre, H. O. Funsten, S. A. Fuselier, M. Gruntman, Paul H. Janzen, M. A. Kubiak, H. Kucharek, E. Möbius, Daniel B. Reisenfeld, N. A. Schwadron, J. M. Sokol, M. Tokumaru

Physics and Astronomy Faculty Publications

The Interstellar Boundary Explorer (IBEX) returned its first five years of scientific observations from 2009 to 2013. In this study, we examine, validate, initially analyze, and provide to the broad scientific community this complete set of energetic neutral atom (ENA) observations for the first time. IBEX measures the fluxes of ENAs reaching 1 AU from sources in the outer heliosphere and most likely the very nearby interstellar space beyond the heliopause. The data, maps, and documentation provided in this study represent the fourth major release of the IBEX data, incorporate important improvements, and should be used for future studies and …

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Observations Of Shadow Bands At The Total Solar Eclipse Of 16 February 1980, Laurence A. Marschall, Rita Mahon, Richard C. Henry Dec 1984

Observations Of Shadow Bands At The Total Solar Eclipse Of 16 February 1980, Laurence A. Marschall, Rita Mahon, Richard C. Henry

Physics and Astronomy Faculty Publications

Photoelectric observations of short term light variations (shadow bands) at the 16 Feb. 1980 total solar eclipse have been made using a set of spatially separated PIN diodes. Light variations in a bandpass of 1-500 Hz were detected during the half-minutes preceding and following the total phase. Fourier analysis of the noise spectrum of the variations reveals a sharp drop-off for frequencies about 50 Hz and an overall spectrum quite similar to previously reported power spectra of stellar scintillation. This is consistent with an atmospheric origin for the shadow bands. Cross-correlations between the detector outputs are low, suggesting a short …

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