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Topanga, CA, United States

Harker D.E.,University of California at San Diego | Woodward C.E.,University of Minnesota | Kelley M.S.,University of Maryland University College | Sitko M.L.,Space Science Institute | And 3 more authors.
Astronomical Journal | Year: 2011

We present mid-infrared spectra and images from the Gemini-N (+ Michelle) observations of fragments SW3-[B] and SW3-[C] of the ecliptic (Jupiter family) comet 73P/Schwassmann-Wachmann 3 pre-perihelion. We observed fragment B soon after an outburst event (between 2006 April 16-26 UT) and detected crystalline silicates. The mineralogy of both fragments was dominated by amorphous carbon and amorphous pyroxene. The grain size distribution (assuming aHanner-modified power law) for fragment SW3-[B] has a peak grain radius of ap ∼ 0.5μm, and for fragment SW3-[C], ap ∼ 0.3μm; both values are larger than the peak grain radius of the size distribution for the dust ejected from ecliptic comet 9P/Tempel 1 during the Deep Impact event (a p = 0.2μm). The silicateto- carbon ratio and the silicate crystalline mass fraction for the submicron to micron-sized portion of the grain size distribution on the nucleus of fragment SW3-[B] were 1.341 -0.253+0.250 and 0.335+0.089 -0.112, respectively, while on the nucleus of fragment SW3-[C] they were 0.671 -0.076+0.076 and 0.257-0.043+0.039, respectively. The similarity in mineralogy and grain properties between the two fragments implies that 73P/Schwassmann-Wachmann 3 is homogeneous in composition. The slight differences in grain size distribution and silicate-to-carbon ratio between the two fragments likely arise because SW3-[B] was actively fragmenting throughout its passage while the activity in SW3-[C] was primarily driven by jets. The lack of diverse mineralogy in the fragments SW3-[B] and SW3-[C] of 73P/ Schwassmann-Wachmann 3 along with the relatively larger peak in the coma grain size distribution suggests that the parent body of this comet may have formed in a region of the solar nebulawith different environmental properties than the natal sites where comet C/1995 O1 (Hale-Bopp) and 9P/Tempel 1 nuclei aggregated. © 2011 The American Astronomical Society. All rights reserved. Source

Bernstein L.S.,Spectral Sciences, Inc. | Clark F.O.,Spectral Sciences, Inc. | Lynch D.K.,Thule Scientific | Galazutdinov G.A.,Catolica del Norte University
Astrophysical Journal | Year: 2015

We present an analysis of the diverse spectral profiles observed for the λ6614 diffuse interstellar band (DIB). This includes the anomalous Herschel 36 profile, exhibiting a prominent, broad red tail, and the typically observed narrow profiles, exhibiting much narrower, but noticeable red tails. This study was motivated by the inability of previous rotational contour modeling work to account for the narrow and broad red tails. We show that the full profiles, for all the observations, can consistently be modeled as a superposition of two overlapping DIBs, with peaks at 6613.6 and 6614.2 Å. Each DIB is plausibly fit using a prolate, parallel band, symmetric top spectral contour model. For λ6613.6, there are small differences in the rotational constants, less than 1%, between the upper and lower transition states; whereas, for λ6614.2, the differences are much larger,-5%. These results are consistent with λ6614.2 being the source of the narrow and broad red tails. The fit residuals are shown to be consistent with contributions from overlapping spectra, attributed to closely spaced vibrational sequences, originating from low frequency vibrations. We suggest that such sequences may be the source of the anomalous broadening needed to obtain good spectral fits to narrow DIB profiles. We discuss how λ6614.2 and the other Herschel 36 extended red tail DIBs help bridge the association gap between the narrow, absorption DIBs and the even broader and more redshifted emission features observed for the Red Rectangle. Finally, the broader implications of this study, in the context of identifying DIB molecular carriers, are discussed. © 2015. The American Astronomical Society. All rights reserved.. Source

Lynch D.K.,Thule Scientific | Dearborn D.S.P.,Lawrence Livermore National Laboratory | Lock J.A.,Cleveland State University
Applied Optics | Year: 2011

We present new observations of glitter and glints using short and long time exposure photographs and high frame rate videos. Using the sun and moon as light sources to illuminate the ocean and laboratory water basins, we found that (1) most glitter takes place on capillary waves rather than on gravity waves, (2) certain aspects of glitter morphology depend on the presence or absence of thin clouds between the light source and the water, and (3) bent glitter paths are caused by asymmetric wave slope distributions We present computer simulations that are able to reproduce the observations and make predictions about the brightness, polarization, and morphology of glitter and glints.We demonstrate that the optical catastrophe represented by creation and annihilation of a glint can be understood using both ray optics and diffraction theory. © 2011 Optical Society of America. Source

Bernstein L.S.,Spectral Sciences, Inc. | Clark F.O.,Spectral Sciences, Inc. | Lynch D.K.,Thule Scientific
Astrophysical Journal | Year: 2013

We suggest that the diffuse interstellar bands (DIBs) arise from absorption lines of electronic transitions in molecular clusters primarily composed of a single molecule, atom, or ion ("seed"), embedded in a single-layer shell of H2 molecules. Less abundant variants of the cluster, including two seed molecules and/or a two-layer shell of H2 molecules, may also occur. The lines are broadened, blended, and wavelength-shifted by interactions between the seed and surrounding H 2 shell. We refer to these clusters as contaminated H2 clusters (CHCs). We show that CHC spectroscopy matches the diversity of observed DIB spectral profiles and provides good fits to several DIB profiles based on a rotational temperature of 10 K. CHCs arise from ∼centimeter-sized, dirty H2 ice balls, called contaminated H2 ice macro-particles (CHIMPs), formed in cold, dense, giant molecular clouds (GMCs), and later released into the interstellar medium (ISM) upon GMC disruption. Attractive interactions, arising from Van der Waals and ion-induced dipole potentials, between the seeds and H2 molecules enable CHIMPs to attain centimeter-sized dimensions. When an ultraviolet (UV) photon is absorbed in the outer layer of a CHIMP, it heats the icy matrix and expels CHCs into the ISM. While CHCs are quickly destroyed by absorbing UV photons, they are replenished by the slowly eroding CHIMPs. Since CHCs require UV photons for their release, they are most abundant at, but not limited to, the edges of UV-opaque molecular clouds, consistent with the observed, preferred location of DIBs. An inherent property of CHCs, which can be characterized as nanometer size, spinning, dipolar dust grains, is that they emit in the radio-frequency region. We also show that the CHCs offer a natural explanation for the anomalous microwave emission feature in the ∼10-100 GHz spectral region. © 2013. The American Astronomical Society. All rights reserved. Source

Lynch D.K.,Thule Scientific
Applied Optics | Year: 2015

The angular diameter of Snell's window as a function of maximumwave slope is calculated. For flat water the diameter is 97° and increases up to about 122° when the wave slope is about 16°. Steeper waves break and disrupt the smooth surface used in the analysis. Breaking waves produce a window almost 180° wide. The brightness of the dark area around Snell's window is heavily influenced by turbidity and upwelling radiation, especially in shallow water. © 2014 Optical Society of America. Source

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