A5036252509- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Astronomy and Astrophysical Research
- Solar and Space Plasma Dynamics
- Astronomical Observations and Instrumentation
- Adaptive optics and wavefront sensing
- Astrophysics and Star Formation Studies
- Planetary Science and Exploration
- Solar Radiation and Photovoltaics
- History and Developments in Astronomy
- Isotope Analysis in Ecology
- Geophysics and Gravity Measurements
- Atmospheric Ozone and Climate
- Gamma-ray bursts and supernovae
- Calibration and Measurement Techniques
- Pulsars and Gravitational Waves Research
- Satellite Image Processing and Photogrammetry
- Space Exploration and Technology
- Geological and Geochemical Analysis
- Optical Systems and Laser Technology
- Inertial Sensor and Navigation
- Geophysics and Sensor Technology
- Spacecraft Design and Technology
- Mathematics and Applications
- Advanced Mathematical Theories and Applications
Universidade Estadual de Ponta Grossa
2015-2025
National Observatory
2019-2025
Ministry of Science, Technology and Innovation
2025
Universidade Tecnológica Federal do Paraná
2022-2024
Valongo Observatory
2019-2024
Universidad Nacional de Asunción
2023
Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati
2020
Istituto Nazionale di Fisica Nucleare
2020
University of Hawaii Maui College
2017-2019
University of Hawaii System
2000-2017
Quaoar is a classical Trans-Neptunian Object (TNO) with an area equivalent diameter of 1,100 km and orbital semi-major axis 43.3 astronomical units. Based on stellar occultations observed between 2018 2021, inhomogeneous ring (Q1R, Quaoar's first ring) was detected around this body. Aims. A new occultation by August 9th, 2022 aiming to improve shape models the physical parameters Q1R while searching for additional material Methods. The provided nine effective chords across Quaoar, pinning...
<i>Context. <i/>Be stars undergo outbursts producing a circumstellar disk from the ejected material. The beating of non-radial pulsations has been put forward as possible mechanism ejection.<i>Aims. <i/>We analyze pulsational behavior early B0.5IVe star HD 49330 observed during first CoRoT long run towards Galactical anticenter (LRA1). This Be is located close to lower edge <i>β<i/> Cephei instability strip in HR diagram and showed 0.03 mag outburst observations. It thus an ideal case for...
We present results derived from the first multi-chord stellar occultations by transneptunian object (50000) Quaoar, observed on 2011 May 4 and 2012 February 17, a single-chord occultation October 15. If timing of five chords obtained in were correct, then Quaoar would possess topographic features (crater or mountain) that be too large for body this mass. An alternative model consists applying time shifts to some account possible errors. Satisfactory elliptical fits are possible, yielding an...
The Michelson Doppler Imager instrument on board SOHO has operated for most of a solar cycle. Here we present careful analysis astrometric data obtained with it from above the Earth's turbulent atmosphere. These yield accurate direct constraint possible radius variations timescales minutes to years and first determination in absence atmospheric seeing.
Context. Be stars are rapidly rotating with a circumstellar decretion disk. They usually undergo pressure and/or gravity pulsation modes excited by the κ-mechanism, i.e. an effect of opacity iron-peak elements in envelope star. In Milky Way, p-modes observed that hotter than or equal to B3 spectral type, while g-modes at B2 type and cooler.
We analyze two multi-chord stellar occultations by Pluto observed on July 18th, 2012 and May 4th, 2013, monitored respectively from five six sites. They provide a total of fifteen light-curves, twelve them being used for simultaneous fit that uses unique temperature profile, assuming clear (no-haze) pure N_2 atmosphere, but allowing possible pressure variation between the dates. find solution fits satisfactorily (i.e. within noise level) all providing atmospheric constraints ~1,190 km...
Be stars are rapidly rotating B-type surrounded by circumstellar disks formed from self-ejected material. Understanding the mechanisms driving mass ejection and disk formation, known as phenomenon, requires a detailed investigation of their variability underlying physical processes. In this study, we analyze photometric, spectroscopic, seismic characteristics three stars—HD 212044, 28 Cyg, HD 174237—using high-cadence data TESS mission spectral BeSS database. Photometric was analyzed through...
Why does the solar luminosity vary and could it change on human timescales by enough to affect terrestrial climate? As important as these questions are, we lack answers because do not understand physical mechanisms responsible for irradiance cycle. Progress here depends discovering how changes in interior energy flow from radiative convection zones out through photosphere. Measurements of small radius are a critical probe Sun's stratification; they can tell us where is gated or stored. Here...
The Michelson Doppler Imager on board the Solar and Heliospheric Observatory satellite has operated for over a sunspot cycle. This instrument is now relatively well understood provides nearly continuous record of solar radius in combination with previously developed algorithms. Because these data are obtained from above Earth's atmosphere, they uniquely sensitive to possible long-term changes Sun's size. We report here first homogeneous, highly precise, complete solar-cycle measurement...
Our Constant Sun The exact shape of the provides information on its internal structure. Based data obtained by Helioseismic and Magnetic Imager aboard NASA's Solar Dynamics Observatory, Kuhn et al. (p. 1638 , published online 16 August; see Perspective Gough ) measured solar during a 2-year period in which evolved from minimum to maximum sunspot activity. Against expectations, Sun's oblate was found be constant not vary with 11-year cycle.
The Michelson Doppler Imager (MDI) aboard the Solar and Heliospheric Observatory observed transits of Mercury on 2003 May 7 2006 November 8. Contact times between solar limb have been used since 17th century to derive Sun's size but this is first time that high-quality imagery from space, above Earth's atmosphere, has available. Unlike other measurements technique largely independent optical distortion. true radius still a matter debate in literature as measured differences several tenths an...
After the discovery of rings around largest known Centaur object, (10199) Chariklo, we carried out observation campaigns stellar occultations produced by second-largest (2060) Chiron, to better characterize its physical properties and presence material on surroundings. We predicted successfully observed two Chiron. These observations were used constrain size shape fitting elliptical limbs with equivalent surface radii in agreement radiometric measurements. Constraints Chiron are reported for...
<i>Context. <i/>HD 181231 is a B5IVe star, which has been observed with the CoRoT satellite during ~5 consecutive months and simultaneously from ground in spectroscopy spectropolarimetry.<i>Aims. <i/>By analysing these data, we aim to detect characterize as many pulsation frequencies possible, search for presence of beating effects possibly at origin Be phenomenon. Our results will also provide basis seismic modelling.<i>Methods. <i/>The fundamental parameters star are determined spectral...
<i>Context. <i/>The origin of the short-term variability in Be stars remains a matter controversy. Pulsations and rotational modulation are components favored hypothesis.<i>Aims. <i/>We present our analysis CoRoT data B8IIIe star HD 175869 observed during first short run center direction (SRC1).<i>Methods. review both instrumental effects visible light curve methods used by team. We applied these to 175869. A search for line-profile variations spectroscopic was also performed. searched...
We present MCDA, a modification of the CoRoT detrend algorithm (CDA) suitable to chromatic light curves. By means robust statistics and better handling short term variability, implementation decreases systematic curve variations improves detection exoplanets when compared with original algorithm. All curves (a total 65,655) were analysed our Dozens new transit candidates all previously known rediscovered in those using box-fitting For three cases spectroscopic measurements candidates' host...
Context. The physical characterization of trans-Neptunian objects is essential for improving our understanding the formation and evolution Solar System. Stellar occultation a ground-based technique that can be successfully used to determine some TNOs’ fundamental properties with high precision, such as size shape. Aims. This work aimed at constraining size, shape, geometric albedo dwarf planet candidate (307261) 2002 MS 4 through analysis nine stellar events. Using multichord detection, we...
The Sun's shape is sensitive to the influence of gravity, rotation, and local turbulence magnetic fields in its outer atmosphere. A careful measurement this has long been sought better understand solar structure change during 11 yr cycle. Numerous disparate measurements oblateness or fractional difference between equatorial polar radii have difficult interpret, part because quantity much smaller than terrestrial atmospheric seeing most instrumental noise sources. In 1997 Michelson Doppler...
The presence of pulsations in late-type Be stars is still a matter controversy. It constitutes an important issue to establish the relationship between non-radial and mass-loss mechanism stars. To contribute this discussion, we analyse photometric time series B8IVe star HD 50209 observed by CoRoT mission seismology field. We use standard Fourier techniques linear non-linear least squares fitting methods light curve. In addition, applied detailed modelling high-resolution spectra obtain...
Aims. In this study, we analyze 122 B-type star candidates observed during Campaign 11 of the Kepler /K2 mission to investigate their variability and pulsation characteristics. A subset 45 B was mission’s between September December 2016. Our analyses aim gain a deeper understanding physical characteristics these massive stars. methods involve both spectroscopy seismology. The spectroscopic analysis performed through mediumresolution blue spectra, which also allowed us perform spectral...
Abstract A stellar occultation occurs when a Solar System object passes in front of star for an observer. This technique allows the sizes and shapes occulting body to be determined with kilometer precision. In addition, this constrains body’s positions, albedos, densities, so on. context Galilean moons, these events can provide their best ground-based astrometry, uncertainties order 1 mas (∼3 km at Jupiter’s distance during opposition). We organized campaigns successfully observed by Io (JI)...
ABSTRACT The Centaur (60558) Echeclus was discovered on 2000 March 03, orbiting between the orbits of Jupiter and Uranus. After exhibiting frequent outbursts, it also received a comet designation, 174P. If ejected material can be source debris to form additional structures, studying surroundings an active body like provide clues about formation scenarios rings, jets, or dusty shells around small bodies. Stellar occultation is handy technique for this kind investigation, as can, from...