A5012757780- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- High-pressure geophysics and materials
- Astronomical Observations and Instrumentation
- Astrophysics and Star Formation Studies
- Stellar, planetary, and galactic studies
- Pulsars and Gravitational Waves Research
- Astronomy and Astrophysical Research
- Scientific Measurement and Uncertainty Evaluation
- Particle Accelerators and Free-Electron Lasers
- Astro and Planetary Science
- Astrophysics and Cosmic Phenomena
- SAS software applications and methods
- Atomic and Molecular Physics
- Geophysics and Gravity Measurements
- Superconducting Materials and Applications
- Solar and Space Plasma Dynamics
- Adaptive optics and wavefront sensing
- Laser-Plasma Interactions and Diagnostics
- Geological and Geophysical Studies
- Diamond and Carbon-based Materials Research
- Advanced Sensor Technologies Research
- Quantum Electrodynamics and Casimir Effect
- Black Holes and Theoretical Physics
- Magnetic confinement fusion research
Universidade Federal de Santa Catarina
2010-2024
University of Minho
2024
Polydoro Ernani de São Thiago University Hospital
2000-2011
Southern Astrophysical Research Telescope
2007
Universidad Nacional Autónoma de México
2004
Space Telescope Science Institute
1993-1998
University of St Andrews
1996-1998
Universidade do Estado de Santa Catarina
1998
Valongo Observatory
1997
National Observatory
1997
We report on V and R high-speed photometry of the dwarf nova EX Draconis (EX Dra) in quiescence outburst. The analysis outburst light curves indicates that outbursts do not start outer disc regions. expands during rise to maximum shrinks decline along following quiescent period. decrease brightness at later stages is due fading from inner At end two system was seen go through a phase lower brightness, characterized by an out-of-eclipse level ≃15 per cent than typical fairly symmetric eclipse...
view Abstract Citations (66) References (56) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Hubble Space Telescope and R-Band Eclipse Maps of the UX Ursae Majoris Accretion Disk Baptista, R. ; Horne, Keith Hilditch, W. Mason, K. O. Drew, J. E. time-resolved spectroscopic ground-based R-band photometric data UMa during eclipse are presented discussed. The spectroscopy covers C IV λ1550 He II λ1640 spectral regions. eclipses in UV continuum deep, nearly...
We report an eclipse-mapping analysis of ensemble light curves the dwarf nova V2051 Oph, with aim to study spatial distribution its steady-light and flickering sources. The data are combined derive orbital dependence components at two different brightness levels, named "faint" "bright" states. differences in caused by long-term variations mass transfer rate from secondary star. white is hardly affected changes; flux increases only 10% faint bright state, whereas disk raises a factor 2....
Aims.We report identification of cyclical changes in the orbital period eclipsing cataclysmic variable HT Cas.
view Abstract Citations (52) References (43) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Multicolor Eclipse Studies of UU Aquarii. I. Observations and System Parameters Baptista, R. ; Steiner, J. E. Cieslinski, D. A study the eclipses in Aqr from multicolor high-speed photometry is presented. revised ephemeris for times minimum an upper limit orbital period variations are obtained. We use measurements contact phases eclipse light curve to derive binary...
We report the identification of cyclical changes in orbital period eclipsing dwarf novae V2051 Ophiuchi and V4140 Sagitarii. used sets white mid-eclipse timings to construct observed-minus-calculated diagrams covering, respectively, 25 16 years observations. The Oph data present variations that can be fitted by a linear plus sinusoidal function with 22 +/- 2 yr amplitude 17 3 s. statistical significance this an F-test is larger than 99.9 per cent. Sgr similar 6.9 0.3 which are statistically...
We present and analyze Hubble Space Telescope observations of the eclipsing nova-like cataclysmic variable UX UMa obtained with Faint Object Spectrograph. Two eclipses each were observed G160L grating (covering ultraviolet waveband) in 1994 August PRISM near-ultraviolet to near-infrared) November same year. The system was ~50% brighter than August, which, if due a change accretion rate, indicates fairly substantial increase acc by ≳50%. eclipse light curves are qualitatively consistent...
Maximum-entropy eclipse mapping techniques are used to obtain maps of the surface brightness distribution UU Aqr accretion disc in its high (V ≃ 13.5 mag) and low 13.8 states. A two-colour diagram pixels reconstructed shows that inner is optically thick, with colours between blackbody main-sequence relationships. The angular scale distance estimated from a colour-magnitude by method similar cluster fitting. We find D = 200 ± 30 pc. Temperatures range ∼ 6000 K outer regions ∼16 000 near white...
We report on high-speed eclipse photometry of the dwarf nova V2051 Oph while it was in a low brightness state, at B ≃ 16.2 mag. In comparison with average IUE spectra, ultraviolet continuum and emission lines appear reduced by factors of, respectively, 4 5. Flickering activity is mostly suppressed light curve shows compact white disc centre which contributes 60 per cent total 3900–4300 Å. use measurements contact phases to derive binary geometry estimate masses relevant dimensions. find mass...
We report on the analysis of high-speed photometry dwarf nova EX Dra through its outburst cycle with eclipse mapping techniques.The maps show evidence formation a one-armed spiral structure in disc at early stages and reveal how expands during rise until it fills most primary Roche lobe maximum light.During decline phase becomes progressively fainter only small bright region around white is left minimum light.The also suggest presence an inward outward-moving heating wave inward-moving...
When accretion temporarily ceases in the polar AM Her, emission-line profiles are known to develop several distinct components, whose origin remains poorly understood. The new low-state spectra reported here have a more favorable combination of spectral resolution (R ∼ 4500), time (~3 minute exposures), and S/N than earlier work, revealing additional details orbital dependence line profiles. central strong feature Hα is found be composed two components similar strength, one having K 100 km...
We report the analysis of a uniform sample 31 light curves nova-like variable UU Aqr with eclipse mapping techniques. The data were combined to derive maps average steady-light component, long-term brightness changes, and low- high-frequency flickering components. variability responsible for 'low' 'high' states is explained in terms response viscous disk changes 20-50 per cent mass transfer rate from donor star. Low- are dominated by emission two asymmetric arcs reminiscent those seen...
Time-resolved eclipse spectroscopy of the nova-like variable UX UMa obtained with HST/FOS on 1994 August and November is analysed mapping techniques to produce spatially resolved spectra its accretion disc gas stream as a function distance from centre. The inner characterized by blue continuum filled absorption bands lines, which cross over emission increasing radius, similar that reported Rutten et al. at optical wavelengths. comparison different azimuths reveals significant asymmetry in...
Eclipse light curves of the dwarf nova IP Peg during 1996 November outburst are analysed with eclipse mapping techniques to constrain location and investigate spatial structure spiral shocks observed in Doppler tomograms Harlaftis et al. maps blue continuum C iii+N iiiλ4650 emission line show two asymmetric arcs ∼90° azimuth, extending from intermediate outer disc regions R≃(0.2–0.6)RL1, where RL1 is distance centre inner Lagrangian point], which interpreted as being seen tomograms. The He...
We follow the changes in structure of accretion disk dwarf nova V2051 Oph along two separate outbursts order to investigate causes its recurrent outbursts. apply eclipse-mapping techniques a set light curves covering normal (2000 July) and low-amplitude (2002 August) outburst derive maps surface brightness distribution at different phases cycles. The sequence eclipse 2000 July reveal that shrinks onset while an uneclipsed component 13% total develops. derived radial intensity distributions...
Abstract We report the results of a statistical study cyclical period changes in cataclysmic variables (CVs). Assuming third-body hypothesis as cause changes, we estimate mass, m 3 , and its separation from binary, for 21 CVs showing well-sampled observed-minus-calculated diagrams covering more than decade observations. The inferred values are independent binary orbital period, P orb whereas increase with by 1 order magnitude shortest (oldest) to longest (youngest) systems, implying...
In this paper, all the light-curves obtained during PHEMU91 campaign of observations mutual phenomena Galilean satellites are presented. These give accurate astrometric positions major interest for dynamical studies motion satellites. The aim work is to observational data directly usable theoretical studies. We made 374 111 events from 56 sites. corresponding given in paper. accuracy each observation has been deduced a comparison with predictions. For observation, information about...
We report the analysis of light curves eclipsing dwarf nova IP Peg in quiescence. The are dominated by ellipsoidal variation mass-donor star, with additional contributions from accretion disc and anisotropic emission bright spot. A secondary eclipse is visible J H curves, 2% 3% flux disappearing at minimum light, respectively. modeled observed star (including possible illumination effects on its inner face) to find a mass ratio q = 0.42 an inclination i 84.5°, consistent three bands within...
Time-resolved spectroscopy of the nova-like variable UU Aquarii is analysed with eclipse mapping techniques to produce spatially resolved spectra its accretion disc and gas stream as a function distance from centre in range 3600–6900 Å. The show that continuum emission becomes progressively fainter redder for increasing radius — reflecting radial temperature gradient reveal H i He lines appear deep, narrow absorption features inner regions, transitioning P Cyg profiles intermediate large...
We report a study of the spectra and structure accretion disk dwarf nova V2051 Ophiuchi while star was in an unusual faint brightness state during 1996. The differences between UV resonant lines continuum surface distributions indicate vertically extended with emission from these arising upper atmospheric layers. Distinct along stream trajectory suggests occurrence gas overflow. Spatially resolved show that are at all radii. Balmer decrement becomes shallower increasing radius. FWHMs respect...
We report the analysis of time-resolved spectroscopy IP Pegasi in outburst with eclipse mapping techniques to investigate location and geometry observed spiral structures. were able obtain an improved view structures aid light curves extracted velocity bins matching range velocities arms combined a double default map tailored for reconstruction asymmetric Two-armed are clearly seen all maps. The located at different distances from disc centre. “blue” arm is farther out () than “red” ()....
We report the analysis of 22 B-band light curves dwarf nova V4140 Sgr obtained with SOAR Optical Imager (SOI)/SOAR during two nights along decline a superoutburst in 2006 September 12–24 and quiescence over 50 d following superoutburst. 3D eclipse mapping outburst indicates that accretion disc is elliptical (eccentricity e = 0.13) superhump maximum occurs when mass donor star aligned bulge disc. The geometrically thin both quiescence; it fills primary Roche lobe shrinks to about half this...
We report on time series of CCD photometry V4140 Sgr between 1991 and 2001. The analysis reveals that the object was in decline from an outburst 1992 again historical light curve collected by amateur astronomers shows low amplitude ( mag) outbursts 5–10 days long, recurrent every 80–90 days, confirming its dwarf nova nature. derive scale 1.2 mag-1. orbital parameters are revised. find a mass ratio , inclination respectively for primary secondary star masses. predicted values semi-amplitude...
We report analysis of VRIJH photometry and phase-resolved optical spectroscopy the eclipsing DA white dwarf (WD) plus dMe binary QS Vir. Modeling photometric data yields an inclination i = 74.9 ± 0.6 a mass ratio q M2/M1 0.50 0.05. Our Doppler maps indicate presence material in Roche lobe WD, at location near M star, likely due to accretion from stellar wind star (as opposed Roche-lobe overflow accretion). also constructed images brightness distribution different epochs which reveal two...