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Non-detection of the OH Meinel system in comet P/Swift-Tuttle

We report a search for emissions from the OH Meinel system in high-resolution near-infrared spectra of comet P/Swift-Tuttle. Because of the large cometary heliocentric velocity and high resolution of the spectrograph, the cometary lines should be well separated from the bright OH sky lines. Contrary to the findings of Tozzi et al. (1994) - who report seeing cometary OH at intensities comparable to the sky emissions in their low-resolution spectra - we find no OH in these spectra with an upper limit of 5% the value of the night sky lines. The non-detection of these cometary lines is consistent with theoretical calculations of expected emission strengths from prompt and fluorescent emission from cometary OH

A high-Resolution Catalog of Cometary Emission Lines

Using high-resolution spectra obtained with the Hamilton echelle spectrograph at Lick Observatory, we have constructed a catalog of emission lines observed in comets Swift-Tuttle and Brorsen-Metcalf. The spectra cover the range between 3800 Å and 9900 Å with a spectral resolution of λ/Δλ~42000. In the spectra, we catalog 2997 emission lines of which we identify 2438. We find cometary lines due to H, O, C_2, CN, NH_2, C_3, H_2O^+, CH, and CH^+. We list 559 unidentified lines compiled from the two spectra and comment on possibilities for their origins

Simultaneous Multi-Wavelength Observations of Magnetic Activity in Ultracool Dwarfs. I. The Complex Behavior of the M8.5 Dwarf TVLM513-46546

[Abridged] We present the first simultaneous radio, X-ray, ultraviolet, and optical spectroscopic observations of the M8.5 dwarf TVLM513-46546, with a duration of 9 hours. These observations are part of a program to study the origin of magnetic activity in ultracool dwarfs, and its impact on chromospheric and coronal emission. Here we detect steady quiescent radio emission superposed with multiple short-duration, highly polarized flares; there is no evidence for periodic bursts previously reported for this object, indicating their transient nature. We also detect soft X-ray emission, with L_X/L_bol~10^-4.9, the faintest to date for any object later than M5, and a possible weak X-ray flare. TVLM513-46546 continues the trend of severe violation of the radio/X-ray correlation in ultracool dwarfs, by nearly 4 orders of magnitude. From the optical spectroscopy we find that the Balmer line luminosity exceeds the X-ray luminosity by a factor of a few, suggesting that, unlike in early M dwarfs, chromospheric heating may not be due to coronal X-ray emission. More importantly, we detect a sinusoidal H-alpha light curve with a period of 2 hr, matching the rotation period of TVLM513-46546. This is the first known example of such Balmer line behavior, which points to a co-rotating chromospheric hot spot or an extended magnetic structure, with a covering fraction of about 50%. This feature may be transitory based on the apparent decline in light curve peak during the four observed maxima. From the radio data we infer a large scale steady magnetic field of ~100 G, in good agreement with the value required for confinement of the X-ray emitting plasma. The radio flares, on the other hand, are produced in a component of the field with a strength of ~3 kG and a likely multi-polar configuration.Comment: 13 pages, 4 figure

Accretion-powered Stellar Winds as a Solution to the Stellar Angular Momentum Problem

We compare the angular momentum extracted by a wind from a pre-main-sequence star to the torques arising from the interaction between the star and its Keplerian accretion disk. We find that the wind alone can counteract the spin-up torque from mass accretion, solving the mystery of why accreting pre-main-sequence stars are observed to spin at less than 10% of break-up speed, provided that the mass outflow rate in the stellar winds is ~10% of the accretion rate. We suggest that such massive winds will be driven by some fraction $\epsilon$ of the accretion power. For observationally constrained typical parameters of classical T-Tauri stars, $\epsilon$ needs to be between a few and a few tens of percent. In this scenario, efficient braking of the star will terminate simultaneously with accretion, as is usually assumed to explain the rotation velocities of stars in young clusters.Comment: Accepted by ApJ Letter

Frequency distribution of conception dates in a white-tailed deer herd

Conception dates of white-tailed deer, Odocoi/eus virginia1111s (Zinunennann, 1780) were estimated for the breeding periods of 1974 - 76 and 1984 using fall and winter- spring fetal data. Conception dates estimated from data collected in the fall were biased. This bias resulted in an earlier mean conception date than that based on information which included data from later breeding females. Mean breeding dates differed significantly between female age classes due to delayed conception in fawns which also resulted in a skewed frequency distribution of conception dates. The frequency distribution of conception dates was leptokurtotic, suggesting that the distribution is constrnincd in time by some factor(s). Conception date estimates did not differ by habitat type but were influenced significantly by period of data collection. Mean breeding date for deer on Lhe Savannah River Site, corrected for age class sampling bias, is 20 November± 27 days (adults plus fawns) and 13 November± 15 days (only adults)

Frequency distribution of conception dates in a white-tailed deer herd

Conception dates of white-tailed deer, Odocoi/eus virginia1111s (Zinunennann, 1780) were estimated for the breeding periods of 1974 - 76 and 1984 using fall and winter- spring fetal data. Conception dates estimated from data collected in the fall were biased. This bias resulted in an earlier mean conception date than that based on information which included data from later breeding females. Mean breeding dates differed significantly between female age classes due to delayed conception in fawns which also resulted in a skewed frequency distribution of conception dates. The frequency distribution of conception dates was leptokurtotic, suggesting that the distribution is constrnincd in time by some factor(s). Conception date estimates did not differ by habitat type but were influenced significantly by period of data collection. Mean breeding date for deer on Lhe Savannah River Site, corrected for age class sampling bias, is 20 November± 27 days (adults plus fawns) and 13 November± 15 days (only adults)