A5016662920- Astrophysical Phenomena and Observations
- Stellar, planetary, and galactic studies
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- High-pressure geophysics and materials
- Pulsars and Gravitational Waves Research
- Particle Accelerators and Free-Electron Lasers
- Astronomy and Astrophysical Research
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Astrophysics and Cosmic Phenomena
- Solar and Space Plasma Dynamics
- Laser-Plasma Interactions and Diagnostics
- Quantum Chromodynamics and Particle Interactions
- Advanced X-ray Imaging Techniques
- Geophysics and Gravity Measurements
- History and Developments in Astronomy
- X-ray Spectroscopy and Fluorescence Analysis
- Atomic and Molecular Physics
- Nuclear Physics and Applications
- Mechanics and Biomechanics Studies
- Particle accelerators and beam dynamics
- Adaptive optics and wavefront sensing
- Scientific Measurement and Uncertainty Evaluation
- Black Holes and Theoretical Physics
ExxonMobil (United States)
2023
Columbia University
2012-2022
Ford Motor Company (Canada)
2013
The University of Texas at Austin
1978-2010
University of Warwick
2010
University of Washington
2010
University of Arizona
2010
Environmental Education Exchange
2010
University of Hawaii at Hilo
2010
University of Alabama
2010
We review the properties of DQ Herculis stars: cataclysmic variables containting an accreting, magnetic, rapidly rotating white dwarf. These stars are characterized by strong X-ray emission, high-excitation spectra, and very stable optical pulsations in their light curves. There is considerable resemblance to more famous cousins, AM stars, but hte latter class additionally spin-orbit synchronism presence circular polarization. list eighteen passing muster as certain or likely Her stars. The...
ABSTRACT We present an attempt to reconstruct the complete evolutionary path followed by cataclysmic variables (CVs), based on observed mass–radius relationship of their donor stars. Along way, we update semi-empirical CV sequence presented previously one us, a comprehensive review connection between evolution and secondary stars in these systems, reexamine most commonly used magnetic braking (MB) recipes, finding that even conceptually similar ones can differ greatly both magnitude...
We report on successes and failures in searching for positive superhumps cataclysmic variables, show the superhumping fraction as a function of orbital period. Basically, all short-period systems do, long-period don't, 50% success rate is found at P_orb=3.1+-0.2 hr. can use this to measure critical mass ratio creation superhumps. With mass-radius relation appropriate an assumed mean white-dwarf 0.75 M_sol, we find q_crit=0.35+-0.02. also superhump studies several stars independently known...
We study the evolution of hydrogen-rich cataclysmic variables (CVs) near minimum orbital period at ~78 minutes. As has been known for many years, these are among most intrinsically common CVs, but they hide fairly well because their faintness and low incidence eruptions. discuss number observational signatures, paying special attention to those that may have passed period—the bouncers. The status binaries is best determined by mass ratio, this constrained measuring accretion disk precession...
view Abstract Citations (279) References (99) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS X-ray emission from cataclysmic variables with accretion disks. I. Hard X-rays. Patterson, J. ; Raymond, C. Theoretical models explaining the hard-X-ray, soft-X-ray, and EUV of accretion-disk in terms disk boundary layer (DBL) are developed on basis a survey published observational data. The data compared model predictions graphs for systems high or low (greater than...
view Abstract Citations (217) References (36) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Rapid oscillations in cataclysmic variables. III. an oblique rotator AE Aqr. Patterson, J. A rapid, strictly periodic oscillation has been discovered the light curve of novalike variable Aquarii. The fundamental period is 33.076737 s, with comparable power at first harmonic. amplitude averages 0.2 - 0.3% but can exceed 1% flares. Pulse timings around binary orbit...
view Abstract Citations (209) References (41) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Rapid oscillations in cataclysmic variables. VI. Periodicities erupting dwarf novae. Patterson, J. A comprehensive account is presented of the optical observations coherent associated with eruptions novae, and a critical evaluation current theoretical situation conducted. Detailed studies AH Herculis SY Cancri are described, report discovery an eclipse-related phase...
view Abstract Citations (163) References (33) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS X-ray emission from cataclysmic variables with accretion disks. II. EUV/soft radiation. Patterson, J. ; Raymond, C. About half of the gravitational luminosity released by gas accreting onto a white dwarf through disk should emerge star/disk boundary layer. For rates present in many variables, theory predicts that this be form an optically thick component, Te ≈ (1-3)...
We redetermine the relationship between absolute magnitude and orbital period for dwarf novae, based on 46 stars with good distance estimates. This improves upon Warner's previous relation, building today's improved estimates of binary inclination, greater wavelength coverage. Together other dynamical constraints, this calibration is then applied to a set ∼300 known or likely novae short period, study dependence quiescent Mv, time-averaged mass ratio q white-dwarf temperature TWD, Porb....
We summarize the results of a 20-yr campaign to study light curves BK Lyn, nova-like star strangely located below 2 3 h orbital-period gap in family cataclysmic variables (CVs). Two apparent superhumps dominate nightly curves, with periods 4.6 per cent longer, and 3.0 shorter, than orbital period. The first appears be associated star's brighter states (V ∼ 14), while second present throughout becomes very dominant low state 15.7). It is plausible that these arise, respectively, from prograde...
We report the results of a worldwide campaign to observe WZ Sagittae during its 2001 superoutburst. After 23 yr slumber at V = 15.5, star rose within 2 days peak brightness 8.2, and showed main eruption lasting 25 days. The return quiescence was punctuated by 12 small eruptions, ∼1 mag amplitude day recurrence time; these "echo outbursts" are uncertain origin, but somewhat resemble normal outbursts dwarf novae. 52 days, began slow decline quiescence.
The transient black-hole binary XTE J1118+480 exhibited dramatic rapid variability at all wavelengths which were suitably observed during its 2000 April–July outburst. We examine time-resolved X-ray, ultraviolet, optical and infrared data spanning the plateau phase of find that both X-ray bands show large amplitude variability. ultraviolet is more subdued, but clearly correlated with seen in X-rays. least, appears to be dominated by continuum, although lines are also variable. Using...
view Abstract Citations (131) References (15) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Magnetic Activity, Tides, and Orbital Period Changes in Close Binaries Applegate, James H. ; Patterson, Joseph It is proposed that a variable quadrupole moment produced by magnetic activity the outer convection zone of one stars close binary responsible for orbital period changes which occur on time scale order 10 yr. In model, modulates period, superposed any...
view Abstract Citations (127) References (30) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A photometric study of the dwarf nova WZ SGE in outburst. Patterson, J. ; McGraw, T. Coleman, L. Africano, Periodic light curve humps are seen at all times high-speed photometry results Sagittae during its 1978 eruption, with a variation orbital period appearing to be present throughout eruption. If this arises from mass-transfer bright spot, then spot must have...
We present ultraviolet (UV) spectroscopic observations covering three distinct accretion states of the low-mass X-ray binary (LMXB) MAXI J1820+070: luminous hard state, a hard-intermediate state and soft state. Our were obtained during 2018 eruption J1820+070 with Hubble Space Telescope (HST) AstroSat observatory. The extinction towards source turns out to be low - $\rm E_{B-V} = 0.2 \pm 0.05$ making it one best UV laboratories among LMXBs. Remarkably, we observe only moderate differences...
The mass‐losing secondaries in cataclysmic binaries are progressively whittled away by the ongoing loss of angular momentum. expected rate evolution implies that should spend most their lives at very short orbital period, with light (<0.08 M⊙). But compared to nearby white dwarf and accretion disk, these effectively dark, so it has been quite difficult learn anything about them from observation. Here we show for novae, majority species, mass ratios can be measured simple photometric...
We report a radial-velocity study of the dwarf nova V503 Cygni at quiescence, revealing motion emission lines with period 111.9 ± 0.4 min. This is almost certainly underlying orbital binary. also photometry all stages outburst cycle, which demonstrates complex pattern signals. In superoutburst, star shows periodic signal 116.7 0.1 min, bears earmarks "superhump," normal trait SU UMa-type nova. During quiescence and short eruptions, large-amplitude wave 109.00 0.02 min--a "negative superhump"...
We report photometry and spectroscopy of the dwarf nova EG Cancri in its 1996/1997 episode eruptions. The main eruption was clearly a superoutburst featuring common superhumps with period 0.06036(2) days, establishing star as new member SU UMa class novae. At end eruption, were replaced by another wave slightly longer (0.06045 days), which endured for at least 90 days. properties latter suggest identification "late superhump." recurrence time superoutbursts is long, probably range 7–20 yr....
view Abstract Citations (93) References (14) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS 33 second X-ray pulsations in AE Aquarii. Patterson, J. ; Branch, D. Chincarini, G. Robinson, E. L. The discovery of 33-s the 0.1-4.0 keV light curve nova-like variable Aquarii is reported. These agree period and phase with optical pulsations. periodicity probably originated from an accretion-induced hot spot on a rapidly rotating, magnetized white dwarf. It possible...
view Abstract Citations (132) References (35) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A photometric study of the recurrent nova WZ Sagittae at minimum light. Robinson, E. L. ; Nather, R. Patterson, J. We have acquired a new set high-speed observations Sge; using these observations, we develop quantitative model for system. Sge is binary system with an orbital period and separation 3.2 x 1010 cm consisting unevolved star mass 0.019 M0 orbiting white...
After a decade of near stability at P=0.146 d, the photometric "superhump" periodicity old nova V603 Aquilae experienced remarkable change between 1991 and 1992. Observation in 1992--1994 indicates that dominant signal was then period range 0.1338-0.1345 3% shorter than orbital period. Like its predecessor, new also wanders on timescale few months. The full amplitude 1994 0.20 mag, more twice as great superhump displayed during 1980--1991. An intensive observing campaign revealed 0.146 d...
We discuss the nature of V Sagittae and T Pyxidis, two enigmatic blue variable stars commonly classed among cataclysmic variables. These have bolometric luminosities in range (1–50) × 1036 ergs s−1, far exceeding that any accretion‐powered variable. They also show extremely colors (B - = -0.3 U B -1.3 after dereddening) orbital light curves are quite similar yet not seen normal But all these respects, as well rich highly excited emission‐line spectrum, provide a good match for newly...
We report photometry of the cataclysmic variable V1159 Orionis for ~400 hours over 168 nights during 1992-4. The long-term light curves show that this is a dwarf nova SU UMa class, with normal outbursts recurring on mean period 4.0 days, and superoutbursts 47.6 days. These periods wander slightly, as typical class. High-speed at minimum light, far from superoutbursts, reveals weak photometric signal 89.83 ± 0.10 min, which presumably underlying orbital binary. During superoutburst,...