High-Resolution Spectroscopy of Ursa Major Moving Group Stars

We use new and extant literature spectroscopy to address abundances and membership for UMa moving group stars. We first compare the UMa, Coma, and Hyades H-R diagrams via a homogeneous set of isochrones, and find that these three aggregates are essentially coeval. Our spectroscopy of cool UMa dwarfs reveals striking abundance anomalies--trends with Teff, ionization state, and excitation potential--like those recently seen in young cool M34, Pleaides, and Hyades dwarfs. In particular, the trend of rising 7774 Ang-based OI abundance with declining Teff is markedly subdued in UMa compared to the Pleiades, suggesting a dependence on age or metallicity. Despite disparate sources of Li data,our homogeneous analysis indicates that UMa members evince remarkably small scatter in the Li-Teff plane for Teff>5200 K. Significant star-to-star scatter suggested by previous studies is seen for cooler stars. Comparison with the consistently determined Hyades Li-Teff trend reveals differences qualitatively consistent with this cluster's larger [Fe/H] (and perhaps slightly larger age). However, quantitative comparison with standard stellar models indicates the differences are smaller than expected, suggesting the action of a fourth parameter beyond age, mass, and [Fe/H] controlling Li depletion.Comment: To appear in Publ. Astron. Soc. Pacif. (September 2005

Study of theory and applicability of laser technique for measuring atmospheric parameters Interim scientific report

Theory and applicability of laser energy interactions for measuring atmospheric parameter

Jet Production by Virtual Photons

The production of jets is studied in collisions of virtual photons, gamma*-p and gamma*-gamma*, specifically for applications at HERA and LEP2. Photon flux factors are convoluted with matrix elements involving either direct or resolved photons and, for the latter, with parton distributions of the photon. Special emphasis is put on the range of uncertainty in the modeling of the resolved component. The resulting model is compared with existing data.Comment: 1+10 pages, LaTeX2e, 4 eps figures, to appear in the Proceedings of the International Conference on the Structure and Interactions of the Photon; PHOTON99, 23-27 May 1999, Freiburg im Breisgau, German

Atmospheric nitric oxide measurement techniques Final report

Optical radar technique for measuring vertical density distribution of neutral nitric oxide in earth atmospher

Fe I and Fe II Abundances of Solar-Type Dwarfs in the Pleiades Open Cluster

We have derived Fe abundances of 16 solar-type Pleiades dwarfs by means of an equivalent width analysis of Fe I and Fe II lines in high-resolution spectra obtained with the Hobby - Eberly Telescope and High Resolution Spectrograph. Abundances derived from Fe II lines are larger than those derived from Fe I lines (herein referred to as over-ionization) for stars with Teff < 5400 K, and the discrepancy (deltaFe = [Fe II/H] - [Fe I/H]) increases dramatically with decreasing Teff, reaching over 0.8 dex for the coolest stars of our sample. The Pleiades joins the open clusters M 34, the Hyades, IC 2602, and IC 2391, and the Ursa Major moving group, demonstrating ostensible over-ionization trends. The Pleiades deltaFe abundances are correlated with Ca II infrared triplet and Halpha chromospheric emission indicators and relative differences therein. Oxygen abundances of our Pleiades sample derived from the high-excitation O I triplet have been previously shown to increase with decreasing Teff, and a comparison with the deltaFe abundances suggests that the over-excitation (larger abundances derived from high excitation lines relative to low excitation lines) and over-ionization effects that have been observed in cool open cluster and disk field main sequence (MS) dwarfs share a common origin. Star-to-star Fe I abundances have low internal scatter, but the abundances of stars with Teff < 5400 K are systematically higher compared to the warmer stars. The cool star [Fe I/H] abundances cannot be connected directly to over-excitation effects, but similarities with the deltaFe and O I triplet trends suggest the abundances are dubious. Using the [Fe I/H] abundances of five stars with Teff > 5400 K, we derive a mean Pleiades cluster metallicity of [Fe/H] = +0.01 +/- 0.02.Comment: 32 pages, 7 figures, 7 tables; accepted by PAS

John Spaghotte

Author Peter Schuler discusses his thoughts on how ideas of creativity, literature, and pedagogy helped to develop into his first novel, John Spaghotte of Crumb. Schuler is a native of the Coachella Valley in Southern California and writes from a middle-class appreciation of working and living in an area where everything is catered to the wealthy class. Through personal injury and his experience in undergraduate and graduate studies he fought to develop a healthy critical mind and a grasp as to the true nature of identity. As a result, his riveting debut novel about a young, nerdy California version of Don Quixote becomes a cautionary tale about the dangers of failing to recognize oneself among a world full of materialistic pleasures and grandiose, fictional heroes. In the formulation of his novel Schuler argues that artistic creation, appreciation, study, and the development of a critical scope to see the world with lead to a better understand his own identity while his protagonist suffers from the lack of such a development

Li I and K I Scatter in Cool Pleiades Dwarfs

We utilize high-resolution (R~60,000), high S/N (~100) spectroscopy of 17 cool Pleiades dwarfs to examine the confounding star-to-star scatter in the 6707 Li I line strengths in this young cluster. Our Pleiads, selected for their small projected rotational velocity and modest chromospheric emission, evince substantial scatter in the linestrengths of 6707 Li I feature that is absent in the 7699 K I resonance line. The Li I scatter is not correlated with that in the high-excitation 7774 O I feature, and the magnitude of the former is greater than the latter despite the larger temperature sensitivity of the O I feature. These results suggest that systematic errors in linestrength measurements due to blending, color (or color-based T_eff) errors, or line formation effects related to an overlying chromosphere are not the principal source of Li I scatter in our stars. There do exist analytic spot models that can produce the observed Li scatter without introducing scatter in the K I line strengths or the color-magnitude diagram. However, these models predict factor of >3 differences in abundances derived from the subordinate 6104 and resonance 6707 Li I features; we find no difference in the abundances determined from these two features. These analytic spot models also predict CN line strengths significantly larger than we observe in our spectra. The simplest explanation of the Li, K, CN, and photometric data is that there must be a real abundance component to the Pleiades Li dispersion. We suggest that this real abundance component is the manifestation of relic differences in erstwhile pre-main-sequence Li burning caused by effects of surface activity on stellar structure. We discuss observational predictions of these effects.Comment: 35 pages, 7 figures; accepted by Ap