We present orbit-resolved spectroscopic and photometric observations of the polar ST LMi during its recent low and high states. In the low-state spectra, we report the presence of blue and red ...satellites in the Ha emission line; the velocities and visibility of the satellites vary with phase. This behavior is similar to emission-line profile variations recently reported in the low state of AM Her, which were interpreted as being due to magnetically confined gas motions in large loops near the secondary. Our low-state spectroscopy of ST LMi is discussed in terms of extreme chromospheric activity on the secondary star. Concurrent photometry indicates that occasional low-level accretion may be present, as well as cool regions on the secondary near the inner Lagrangian point, L1. Furthermore, we report a new 'extreme low state' of the system at V ~ 18.5 mag. Our orbital high-state spectroscopy reveals changes in the emission-line profiles with orbital phases that are similar to those reported by earlier high-state studies. The complicated emission-line profiles generally consist of two main components. The first has radial velocity variations identical to that of the major emission Ha component seen in the low state. The second is an additional redshifted component appearing at the phases of maximum visibility of the accreting column of the white dwarf; it is interpreted as being due to infall velocities on the accreting magnetic pole of the white dwarf. At the opposite phases, an extended blue emission wing appears on the emission-line profiles. We confirm the presence of a broad absorption feature near 6275 A, which has been previously identified as a Zeeman s- absorption component of Ha. This feature appears at just those phases when the accretion pole region is most directly visible and most nearly face-on to the observer.
Using Doppler tomography we show that FS Aur-79, a near-contact close binary system with late-type active dK7e+dM3e components, has chromospheric prominences in two distinct emission regions ...associated with the primary star and a larger amount of chromospheric activity associated with the cooler secondary star. The line profiles, equivalent widths, and equivalent width ratios of the H Delta *a and H Delta *b emission lines as a function of orbital phase further support that the majority of the chromospheric emission originates above the secondary star and near the neck region. Analysis of high-resolution spectra using the technique of broadening functions has enabled us to determine the radial velocity of the secondary star near quadratures to be approximately 224 km s--1. A Wilson-Devinney model of the system fitting the UBV light curves and radial velocities shows that there are star spots near the chromospherically active regions. Finally, the absence of Li I Delta *l6708 in the spectra lets us put a lower limit on the age of this system to at least 500 Myr.
The National Program structure of USDA-ARS provides an opportunity to coordinate research on problems of national and global significance. A team of USDA-ARS scientists is conducting nationally ...coordinated research to develop predictions of manure N availability to protect water quality and improve farm solvency. Experimental design and research protocols were developed and used in common across all participating locations. Laboratory incubations are conducted at each location with a minimum of three soils, three temperatures, two wetting/drying regimes, and two manure treatments. A soil from the central United States (Catlin silt loam, fine-silty, mixed, superactive, mesic Oxyaquic Argiudoll) is used as an internal reference across all locations. Incubation data are compiled across locations to develop generalized predictions of manure nitrogen mineralization (Nmin). Field validation data are then obtained by monitoring nitrogen (N) transformations in manure-amended soil cores equipped with anion exchange resin to capture leached nitrate. This field data will be used to compare laboratory-based predictions with field observations of Nmin in each soil, climatic zone, and manure type represented. A Decision Support System will then be developed for predicting manure N mineralization across ranges in soil, climate, and manure composition. Protocols used by this research team are provided to 1) document the procedures used and 2) offer others detailed information for conducting research on nutrient transformation processes involving collaboration across locations or complementary research between laboratory and field environments.
QU Carinae: Type Ia supernova in the making? Kafka, S.; Honeycutt, R. K.; Williams, R.
Monthly notices of the Royal Astronomical Society,
09/2012, Letnik:
425, Številka:
2
Journal Article
The QUEST (QUasar Equatorial Survey Team) Phase 1 camera has collected multibandpass photometry on a large strip of high Galactic latitude sky over a period of 26 months. This robust data set has ...been reduced and nightly catalogs compared to determine the photometric variability of the ensemble objects. Subsequent spectroscopic observations have confirmed a subset of the photometric variables as quasars, as previously reported. This paper reports on the details of the data reduction and analysis pipeline and presents multiple bandpass light curves for 198,213 QUEST1 objects, along with global variability information and matched Sloan photometry.
Aerobic incubation methods have been widely used to assess soil nitrogen (N) mineralization, but standardized protocols are lacking. A single silt loam soil (Catlin silt loam; fine-silty, mixed, ...superactive, mesic, Oxyaquic Arguidoll) was subjected to aerobic incubation at six USDA-ARS locations using a standardized protocol. Incubations were conducted at multiple temperatures, which were combined based on degree days (DD). Soil water was maintained at 60% water-filled pore space (WFPS; constant) or allowed to fluctuate between 60 and 30% WFPS (cycle). Soil subsamples were removed periodically and extracted in 2 M potassium chloride (KCl); nitrate (NO3) and ammonium (NH4) concentrations in extracts were determined colorimetrically. For each location, the rate of soil organic-matter N (SOMN) mineralization was estimated by regressing soil inorganic N (Ni) concentration on DD, using a linear (zero-order) model. When all data were included, the mineralization rate from four datasets was not statistically different, with a rate equivalent to 0.5 mg N kg-1 soil day-1. Soil incubated at two locations exhibited significantly higher SOMN mineralization rates. To assess whether this may have been due to pre-incubation conditions, time-zero data were excluded and regression analysis was conducted again. Using this data subset, SOMN mineralization from five (of six) datasets was not significantly different. Fluctuating soil water reduced N-mineralization rate at two (of four) locations by an average of 50%; fluctuating soil water content also substantially increased variability. This composite dataset demonstrates that standardization of aerobic incubation methodology is possible. Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture.
The secondary photometric standard star number 79 for the FS Aur field (Henden & Honeycutt 1997), designated as HH97 FS Aur-79 (GSC 1874-399), is a short-period (0.2508 days) eclipsing binary whose ...light curve is a combination of the b Lyr and BY Dra type variables. High signal-to-noise ratio multicolor photometry was obtained using the US Naval Observatory 1 m telescope. These light curves show asymmetry at quadrature phases (the O'Connell effect), which can be modeled with the presence of starspots. A low-resolution spectrum obtained with the 3.5 m Wisconsin-Indiana-Yale-NOAO telescope at orbital phase 0.76 is consistent with a spectral type of dK7e and dM3e. A radial velocity curve for the primary star was constructed using 24 high-resolution spectra from the 9.2 m Hobby-Eberly Telescope. Spectra show Ha and Hb in emission confirming chromospheric activity and possibly the presence of circumstellar material. Binary star models that simultaneously fit the U, B, V, R, and radial velocity curves are those with a primary star of mass 0.59 ± 0.02 M, temperature 4100 ± 25 K, and mean radius 0.67 R, just filling its Roche lobe, and a secondary star of mass 0.31 ± 0.09 M, temperature 3425 ± 25 K, and mean radius 0.48 R, just within its Roche lobe. An inclination angle of 83° ± 2° with a center-of-mass separation of 1.62 R is also derived. Starspots, expected for a rotation period of less than 1 day, had to be included in the modeling to fit the O'Connell effect.
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