Gamma-Ray Emission from X-Ray Binaries

We summarize the current observational picture regarding high-energy emission from Galactic X-ray binaries, reviewing the results of the Compton Gamma Ray Observatory mission. We speculate on the prospects for the GLAST era

The Hard X-Ray Emission from Scorpius X-1 Seen by INTEGRAL

We present the results of our hard X-ray and gamma-ray study of the LMXB Sco X-1 utilizing INTEGRAL data as well as contemporaneous RXTE PCA data. We have investigated the hard X-ray spectral properties of Sco X-1 including the nature of the high-energy, nonthermal component and its possible correlations with the location of the source on the soft X-ray color-color diagram. We find that Sco X-1 follows two distinct spectral tracks when the 20-40 keV count rate is greater than 130 counts/second. One state is a hard state which exhibits a significant high-energy, powerlaw tail to the lower energy thermal spectrum. The other state shows a much less significant high-energy component. We found suggestive evidence for a correlation of these hard and soft high-energy states with the position of Sco X-1 on the low-energy X-ray color-color diagram. We have searched for similar behavior in 2 other Z sources: GX 17+2 and GX 5-1 with negative results

Mass Determination of Black Holes in LMC X-1 and Nova Muscae 1991 from their High-Energy Spectra

We offer a brief description of the bulk-motion Comptonization (BMC) model for accretion onto black holes, illustrated by its application to observational data for LMC X-1, and Nova Muscae 1991. We then extract some physical parameters of these systems from observables (within the context of the BMC model}, drawing from results on GRO J1655-40, for which we presented extensive analysis previously. We derive estimates of the mass, (16 +/- 1) solar masses and mass accretion rate in the disk in Eddington units around 2 for LMC X-1, and (24 +/- 1)d_{5.5} and the disk mass acretion rate around 3 for Nova Muscae 1991 [where d_{5.5} stands for the distance in 5.5 kpc units]. Differences between these estimates and previous estimates based on dynamical studies are discussed. It is further shown that the disk inner radius increases with the high-to-low state transition in Nova Muscae 1991. Specifically, our analysis suggests that the inner-disk radius increases to 17 Scwarzschild radii as the transition to the low-hard state occurs.Comment: 14 pages, 3 figures, The paper is accepted for publication in the Astrophysical Journal Letter

Productivity levels of some Iowa soils

This report presents crop yield estimates for corn, soybeans, oats, and hay on 290 selected soil types and phases. These yield estimates are believed attainable as a 5-year average with the technology available in 1971 and average weather conditions.https://lib.dr.iastate.edu/specialreports/1063/thumbnail.jp

Simultaneous IUE, EXOSAT and optical observations of the unusual AM Her type variable H058+608

Simultaneous observations of the AM Her type variable H0538+608 made with IUE, EXOSAT, and a 1.3 m ground based telescope, and subsequent optical spectrophotometry at high and low resolution are discussed. The X-ray and optical data show clear evidence of a 3.30 + or - 0.03 hr period. Three SWP spectra were taken outside of eclipse and during overlapping phase intervals. The UV spectra contain strong emission lines characteristic of this class of objects and a flat continuum which appears to be deficient, given the brightness of source at optical and X-ray wavelengths. There is evidence for intensity variations in emission lines, particularly C IV. The X-ray light curves for H0538+608 reveal behavior which may be related to irregularities in its accretion flow

The X-ray transient XTE J1118+480: Multiwavelength observations of a low-state mini-outburst

We present multiwavelength observations of the newly discovered X-ray transient XTE J1118+480 obtained in the rising phase of the 2000 April outburst. This source is located at unusually high Galactic latitude and in a very low absorption line of sight. This made the first EUVE spectroscopy of an X-ray transient outburst possible. Together with our HST, RXTE, and UKIRT data this gives unprecedented spectral coverage. We find the source in the low hard state. The flat IR-UV spectrum appears to be a combination of optically thick disk emission and flat spectrum emission, possibly synchrotron, while at higher energies, including EUV, a typical low hard state power-law is seen. EUVE observations reveal no periodic modulation, suggesting an inclination low enough that no obscuration by the disk rim occurs. We discuss the nature of the source and this outburst and conclude that it may be more akin to mini-outbursts seen in GRO J0422+32 than to a normal X-ray transient outburst.Comment: 4 pages, 3 figures, replaced with accepted version. Uses emulateapj5.st

Different Cropping Systems Require Different Amounts and Kinds of Fertilizers

With increasing concern about pollution, it is important that fertilizers not be used in excess. Results of a series of ISU studies provide guidelines for proper fertilizer rates