Orbit-resolved photometry and echelle spectroscopy of the cataclysmic variable ST LMi during a 2007 high state

We present high-resolution echelle spectra and contemporaneous photometry of the polar ST LMi during a high state in 2007 March. Emission lines at Hα, He I λ5876, and He I λ7065 show similar line profiles over orbital phase and have narrow and broad components. These profile changes with phase are very similar to those reported in earlier high-state studies of ST LMi. The radial velocity curves from double Gaussian fits to the line profiles are interpreted as two crossing curves, neither of which is coincident with the orbital motion of the secondary star. We attribute one component to infall motions near the white dwarf and the other to a gas streaming along magnetic field lines connecting the two stars

Spectroscopic and Photometric Analysis of the Nova-Like Cataclysmic Variable PG 1000+667: A New VY Sculptoris Star

Multiyear photometry and orbit-resolved spectroscopy of the nova-like cataclysmic variable PG 1000+667 show behavior associated with the VY Sculptoris subclass of nova-like cataclysmic variables. Photometric observations over a 35 month interval from Indiana University\u27s robotic telescope Robo-Scope show two drops of 3 mag to a low state. Spectroscopy shows a periodic velocity variation in the Hβ emission line with P = 3.47 hr. This places the star just above the 2-3 hour period gap, which supports the VY Sculptoris classification

The 1991-2012 Light Curve of the Old Nova HR LYRAE

The 22 yr light curve of HR Lyr, acquired with a typical cadence of 2-6 days, is examined for periodic and quasi-periodic variations. No persistent periodicities are revealed. Rather, the light curve variations often take the form of nearly linear rises and falls having typical e-folding times of about 100 days. Occasional ~0.6 mag outbursts are also seen, with properties similar to those of small outbursts found in some nova-like cataclysmic variables. When the photometry is formed into yearly averages, a decline of 0.012 ± 0.005 mag yr–1 is apparent, consistent with the fading of irradiation-induced $\dot{M}$ following the nova. The equivalent width of Hα is tabulated at three epochs over the interval 1986-2008 in order to compare with a recent result for DK Lac in which Hα was found to be fading 50 yr after the nova. However, our results for such a fading in HR Lyr are inconclusive. © 2014. The American Astronomical Society. All rights reserved

Reconnaissance of Suspected Old Novae

Several of the \ blank fields\ in the novae atlas by Duerbeck were imaged at the WIYN 3.5 m telescope during technical engineering and commissioning activities in 1994-1995. Several old novae have been recovered utilizing CCD photometry. Multiobject spectroscopy with the Hydra/MOS instrumentation at WIYN was also used on random stars in the fields to search for a cataclysmic variable. The old novae candidates identified include SV Ari, V465 Cyg, SS LMi, V2104 Oph, GR Ori, V529 Ori, UW Per, and UW Tri

The Chromospheric Activity of [HH97 FS Aur-79: a Close Binary With Late-Type Active (Dk7E+Dm3E) Components

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 Hα and Hβ 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 λ6708 in the spectra lets us put a lower limit on the age of this system to at least 500 Myr. © 2011. The American Astronomical Society. All rights reserved

Dissemination of Goss’s Wilt of Corn and Epiphytic Clavibacter michiganensis subsp. nebraskensis from Inoculum Point Sources

Goss’s wilt of corn, caused by Clavibacter michiganensis subsp. nebraskensis, has reemerged since 2006 as an economically important disease of corn in in the Midwestern United States. In 2012 and 2013, field plot studies were conducted with a pathogenic, rifampicin-resistant C. michiganensis subsp. nebraskensis isolate and a Goss’s wilt-susceptible corn hybrid to monitor epiphytic C. michiganensis subsp. nebraskensis population densities and the temporal and spatial spread of Goss’s wilt incidence originating from inoculum point sources. The randomized complete block trial included three treatments: noninoculated control, inoculum point sources established by wound inoculation, and inoculum point sources consisting of C. michiganensis subsp. nebraskensis-infested corn residue. Epiphytic C. michiganensissubsp. nebraskensis was detected on asymptomatic corn leaves collected up to 2.5 m away from inoculum sources at 15 days after inoculation in both years. The percentage of asymptomatic leaf samples on which epiphytic C. michiganensis subsp. nebraskensis was detected increased until mid-August in both years, and reached 90, 55, and 35% in wound-, residue-, and noninoculated plots, respectively, in 2012; and 50, 11, and 2%, respectively, in 2013. Although both growing seasons were drier than normal, Goss’s wilt incidence increased over time and space from all C. michiganensissubsp. nebraskensis point sources. Plots infested with C. michiganensis subsp. nebraskensis residue had final Goss’s wilt incidence of 7.5 and 1.8% in 2012 and 2013, respectively; plots with a wound-inoculated source had final Goss’s wilt incidence of 16.6 and 14.0% in 2012 and 2013, respectively. Our findings suggest that relatively recent outbreaks of Goss’s wilt in new regions of the United States may be the result of a gradual, nondetected buildup of C. michiganensis subsp. nebraskensisinoculum in fields

Long-term optical and X-ray observations of the old novae DI Lacertae and V841 Ophiuchi

We present an analysis of ground-based optical photometry and spectroscopy, and Rossi X-ray Timing Explorer X-ray observations of the old novae DI Lacertae and V841 Ophiuchi. Our optical photometry data (obtained with the automated photometry telescope RoboScope) comprise an almost decade-long light curve for each star, while the contemporaneous spectroscopy and X-ray observations repeatedly sampled each nova during separate intervals of ~45-55 d in length. The long-term optical light curves of both novae reveal quasiperiodic variability on typical time scales of ~30-50 d with amplitudes of dV ~ 0.4-0.8 mag. V841 Oph also displays a long-term, sinusoidal modulation of its optical light on a time scale of 3.5-5 yr. The optical spectra of these novae display quite different characteristics from each other, with DI Lac showing narrow Balmer emission cores situated in broad absorption troughs while V841 Oph exhibits strong single-peaked Balmer, He I and He II emission lines. We find little change between spectra obtained during different optical brightness states. The X-ray count rates for both novae were very low (< ~1.5 ct/s) and there was no reliable correlation between X-ray and optical brightness. The combined X-ray spectrum of DI Lac is best fit by a bremsstrahlung emission model (with kT ~ 4 keV and N_H < 1.8x10^22 cm^-3); the X-ray spectrum of V841 Oph is too weak to allow model fitting. We discuss the possible origin of variability in these old novae in terms of magnetic activity on the secondary star, dwarf nova type disk instabilities, and the ``hibernation'' scenario for cataclysmic variable stars.Comment: 16 pages, 9 figures, 4 tables; accepted by PASP on 28 August 2000 for the December 2000 issu

Masses, radii, and orbits of small Kepler planets : The transition from gaseous to rocky planets

We report on the masses, sizes, and orbits of the planets orbiting 22 Kepler stars. There are 49 planet candidates around these stars, including 42 detected through transits and 7 revealed by precise Doppler measurements of the host stars. Based on an analysis of the Kepler brightness measurements, along with high-resolution imaging and spectroscopy, Doppler spectroscopy, and (for 11 stars) asteroseismology, we establish low false-positive probabilities (FPPs) for all of the transiting planets (41 of 42 have an FPP under 1%), and we constrain their sizes and masses. Most of the transiting planets are smaller than three times the size of Earth. For 16 planets, the Doppler signal was securely detected, providing a direct measurement of the planet's mass. For the other 26 planets we provide either marginal mass measurements or upper limits to their masses and densities; in many cases we can rule out a rocky composition. We identify six planets with densities above 5 g cm-3, suggesting a mostly rocky interior for them. Indeed, the only planets that are compatible with a purely rocky composition are smaller than 2 R ⊕. Larger planets evidently contain a larger fraction of low-density material (H, He, and H2O).Peer reviewedFinal Accepted Versio