scholarly journals Exoplanet transits observed at UNI's Astronomical Observatory

2019 ◽  
Vol 29 (1) ◽  
Author(s):  
Antonio Pereyra ◽  
José Ricra
Keyword(s):  
Astronomical Observatory ◽  
Light Curves ◽  
Physical Parameters ◽  
Astronomical Facility

This work present the exoplanet transit program developed at OAUNI on the 2016 and 2017 campaigns. Seventeen exoplanet transits were observed and in six of them more than one event was registered. In a couple of cases the same transit were gathered four times. Preliminary reductions are shown in three transits (WASP-80 b, WASP-52 b, and WASP-77 A b). The associated light curves show well-defined events and their modeling let to infer physical parameters of each system. These measurements are the first ones of their kind collected by a peruvian astronomical facility.

scholarly journals An extensive photometric study of the Blazhko RR Lyrae star RZ Lyr*

2012 ◽  
Vol 423 (2) ◽  
pp. 993-1005 ◽  
Author(s):  
J. Jurcsik ◽  
Á. Sódor ◽  
G. Hajdu ◽  
B. Szeidl ◽  
Á. Dózsa ◽  
...  
Keyword(s):  
Light Curve ◽  
Light Curves ◽  
Stellar Structure ◽  
Time Base ◽  
Photometric Method ◽  
Physical Parameters ◽  
Component Solution ◽  
Rr Lyrae ◽  
Curve Variation ◽  
Type Variable

Abstract The analysis of recent, extended multicolour CCD and archive photoelectric, photographic and visual observations has revealed several important properties of RZ Lyr, an RRab-type variable exhibiting large-amplitude Blazhko modulation. On the time base of ∼110 yr, a strict anticorrelation between the pulsation- and modulation-period changes is established. The light curve of RZ Lyr shows a remarkable bump on the descending branch in the small-amplitude phase of the modulation, similarly to the light curves of bump Cepheids. We speculate that the stellar structure temporally suits a 4:1 resonance between the periods of the fundamental and one of the higher order radial modes in this modulation phase. The light-curve variation of RZ Lyr can be correctly fitted with a two-modulation-component solution; the 121-d period of the main modulation is nearly but not exactly four times longer than the period of the secondary modulation component. Using the inverse photometric method, the variations in the pulsation-averaged values of the physical parameters in different phases of both modulation components are determined.

scholarly journals New Data on the Eclipsing Binary V1848 Ori and Improved Orbital and Light Curve Solutions

2020 ◽  
Vol 29 (1) ◽  
pp. 72-80 ◽  
Author(s):  
Fatemeh Davoudi ◽  
Atila Poro ◽  
Fahri Alicavus ◽  
Afshin Halavati ◽  
Saeed Doostmohammadi ◽  
...  
Keyword(s):  
Binary System ◽  
Light Curve ◽  
Mass Function ◽  
Light Curves ◽  
Complete Analysis ◽  
Physical Parameters ◽  
Mass Ratio ◽  
Third Body ◽  
Eclipsing Binary

AbstractNew observations of the eclipsing binary system V1848 Ori were carried out using the V filter resulting in a determination of new times of minima and new ephemeris were obtained. We presented the first complete analysis of the system’s orbital period behavior and analysis of O-C diagram done by the GA and MCMC approaches in OCFit code. The O-C diagram demonstrates a sinusoidal trend in the data; this trend suggests a cyclic change caused by the LITE effect with a period of 10.57 years and an amplitude of 7.182 minutes. It appears that there is a third body with mass function of f (m3) = 0.0058 M⊙ in this binary system. The light curves were analyzed using the Wilson-Devinney code to determine some geometrical and physical parameters of the system. These results show that V1848 Ori is a contact W UMa binary system with the mass ratio of q = 0.76 and a weak fillout factor of 5.8%. The O’Connell effect was not seen in the light curve and there is no need to add spot.

scholarly journals Understanding Type II Supernovae

2005 ◽  
Vol 192 ◽  
pp. 275-280 ◽  
Author(s):  
L. Zampieri ◽  
M. Ramina ◽  
A. Pastorello
Keyword(s):  
Physical Properties ◽  
Large Range ◽  
Simultaneous Analysis ◽  
Light Curves ◽  
Physical Parameters ◽  
Expansion Velocity ◽  
Type Ii ◽  
Strong Correlations ◽  
Systematic Analysis ◽  
Robust Estimates

SummaryWe present the results of a systematic analysis of a group of Type II plateau supernovae that span a large range in luminosities, from faint objects like SN 1997D and 1999br to very luminous events like SN 1992am. The physical properties of the supernovae appear to be related to the plateau luminosity or the expansion velocity. The simultaneous analysis of the observed light curves, line velocities and continuum temperatures leads us to robust estimates of the physical parameters of the ejected envelope. We find strong correlations among several parameters. The implications of these results regarding the nature of the progenitor, the central remnant and the Ni yield are also addressed.

scholarly journals Hydrodynamic Models of Solar and Stellar Flares

1989 ◽  
Vol 104 (1) ◽  
pp. 289-298
Author(s):  
Giovanni Peres
Keyword(s):  
High Resolution ◽  
Light Curve ◽  
Solar Flares ◽  
Impulsive Phase ◽  
Light Curves ◽  
Physical Parameters ◽  
The Sun ◽  
Hydrodynamic Models ◽  
X Ray ◽  
Stellar Flares

AbstractThis paper discusses the hydrodynamic modeling of flaring plasma confined in magnetic loops and its objectives within the broader scope of flare physics. In particular, the Palermo-Harvard model is discussed along with its applications to the detailed fitting of X-ray light curves of solar flares and to the simulation of high-resolution Caxix spectra in the impulsive phase. These two approaches provide complementary constraints on the relevant features of solar flares. The extension to the stellar case, with the fitting of the light curve of an X-ray flare which occurred on Proxima Centauri, demonstrates the feasibility of using this kind of model for stars too. Although the stellar observations do not provide the wealth of details available for the Sun, and, therefore, constrain the model more loosely, there are strong motivations to pursue this line of research: the wider range of physical parameters in stellar flares and the possibility of studying further the solar-stellar connection.

scholarly journals Interacting Binary White Dwarf Stars

1992 ◽  
Vol 151 ◽  
pp. 461-464
Author(s):  
J.-E. Solheim
Keyword(s):  
White Dwarf ◽  
Structural Changes ◽  
Light Curves ◽  
Physical Parameters ◽  
Dwarf Stars ◽  
White Dwarf Stars ◽  
Test Models ◽  
Radial Pulsations ◽  
Whole Earth

This group of stars consists of 4 systems, also called helium cataclysmics. Three of them show photometric variations and have been studied by the Whole Earth Telescope (WET), which have revealed multiperiodic light curves showing the signature of g-mode non-radial pulsations on the accreting star. The combination of accretion and g-mode pulsations gives a unique opportunity to test models for the accreator's structural changes in response to accretion. IUE-spectra provide additional physical parameters.

The High-Cadence Transient Survey (HiTS): Early Supernova Light-Curves

2017 ◽  
Vol 14 (S339) ◽  
pp. 66-66
Author(s):  
F. Förster
Keyword(s):  
Interdisciplinary Approach ◽  
Early Time ◽  
Small Region ◽  
Variable Stars ◽  
Machine Learning Algorithms ◽  
Light Curves ◽  
Physical Parameters ◽  
Physical Mechanisms ◽  
Cosmic Explosions ◽  
High Cadence

AbstractSupernovae (SNe) are cosmic explosions which are usually represented in a small region of the luminosity–time-scale diagram when discussing the variable sky. However, there are different time-scales involved in the evolution of SNe that are not reflected by that representation. This talk reviewed some of the physical mechanisms driving the SN light-curve diversity, especially at early times. It then discussed our efforts in the astroinformatics laboratory at CMM and at MAS to discover very young SNe using large etendue telescopes such as Blanco/DECam; those efforts led to the real-time discovery of more than one hundred SNe, some of them very young, under the High cadence Transient Survey (HiTS). We showed that, by comparing hydrodynamical models in the literature with HiTS SNe using Markov Chain Monte Carlo to sample from the posterior in a Bayesian approach, we can constrain the physical parameters that are driving the early time-evolution of these events. We also discussed how these data are being used for different projects, such as the discovery of asteroids and variable stars, and for testing different machine-learning algorithms in an interdisciplinary approach.

scholarly journals Magnetic Activity of Two Similar Subgiants in Binaries with Very Different Mass Ratios: EI Eri and V711 Tau

2011 ◽  
Vol 7 (S282) ◽  
pp. 478-479 ◽  
Author(s):  
Katalin Oláh ◽  
Zsolt Kővári ◽  
Krisztián Vida ◽  
Klaus G. Strassmeier
Keyword(s):  
Differential Rotation ◽  
Activity Patterns ◽  
Magnetic Activity ◽  
Light Curves ◽  
Physical Parameters ◽  
Remarkable Difference ◽  
High Latitudes ◽  
Solar Type ◽  
Low Mass ◽  
Fast Rotating

AbstractWe use more than three decades-long photometry to study the activity patterns on the two fast-rotating subgiant components in EI Eri (G5IV) and V711 Tau (K1IV). From yearly mean rotational periods from the light curves, we find that EI Eri, with well-measured solar-type differential rotation, always has spots from the equator to high latitudes. The measured differential rotation of V711 Tau is controversial, and in any case is very small. The spots on the K1IV star in V711 Tau seem to be tidally locked. The physical parameters of the two systems are similar, with one remarkable difference: EI Eri has a low mass M4-5 dwarf companion, whereas V711 Tau has a G5V star in the system, thus their mass centers are in very different positions. This may modify the whole internal structure of the active stars, causing marked differences in their surface features.

scholarly journals Light Curve Modeling of Superluminous Supernovae

2013 ◽  
Vol 9 (S296) ◽  
pp. 86-89
Author(s):  
Takashi Moriya ◽  
Sergei I. Blinnikov ◽  
Nozomu Tominaga ◽  
Naoki Yoshida ◽  
Masaomi Tanaka ◽  
...  
Keyword(s):  
Kinetic Energy ◽  
Light Curve ◽  
Mass Loss ◽  
Numerical Simulations ◽  
Radiation Energy ◽  
Light Curves ◽  
Physical Parameters ◽  
Radiation Hydrodynamics ◽  
One Dimensional ◽  
Curve Modeling

AbstractOrigins of superluminous supernovae (SLSNe) discovered by recent SN surveys are still not known well. One idea to explain the huge luminosity is the collision of dense CSM and SN ejecta. If SN ejecta is surrounded by dense CSM, the kinetic energy of SN ejecta is efficiently converted to radiation energy, making them very bright. To see how well this idea works quantitatively, we performed numerical simulations of collisions of SN ejecta and dense CSM by using one-dimensional radiation hydrodynamics code STELLA and obtained light curves (LCs) resulting from the collision. First, we show the results of our LC modeling of SLSN 2006gy. We find that physical parameters of dense CSM estimated by using the idea of shock breakout in dense CSM (e.g., Chevalier & Irwin 2011, Moriya & Tominaga 2012) can explain the LC properties of SN 2006gy well. The dense CSM's radius is about 1016 cm and its mass about 15 M⊙. It should be ejected within a few decades before the explosion of the progenitor. We also discuss how LCs change with different CSM and SN ejecta properties and origins of the diversity of H-rich SLSNe. This can potentially be a probe to see diversities in mass-loss properties of the progenitors. Finally, we also discuss a possible signature of SN ejecta-CSM interaction which can be found in H-poor SLSN.

scholarly journals 4 Years of Radio to X-ray Observations of 3C 273

1989 ◽  
Vol 134 ◽  
pp. 112-113
Author(s):  
T.J.-L. Courvoisier ◽  
E. I. Robson ◽  
A. Blecha ◽  
P. Bouchet
Keyword(s):  
Near Infrared ◽  
Optical Emission ◽  
Light Curves ◽  
Physical Parameters ◽  
List Type ◽  
Type Number ◽  
Rapid Variability ◽  
X Ray ◽  
Model Independent ◽  
Ir Emission

The quasar 3C273 has been repeatedly observed at radio, mm, IR, optical, UV and X-ray frequencies since December 1983. A complex pattern of continuum variations has been discovered, which can be used to provide model independent physical parameters, and to constrain different models. The main features revealed by our set of observations are: (i)A flux decrease by 40% in the 2–10 kev flux in 20 days in early 1984 (Courvoisier et al. 1987).(ii)Differences between the X-ray light curves at 0.5 keV and 2–10 keV.(iii)A drop in the mm to mid-IR emission by factors 2–4 in early 1986, while the near infrared flux remained stable (Robson et al. 1986).(iv)A decrease in the ultraviolet intensity of ∼40% in about 6 months in 1987 (Ulrich, Courvoisier and Wamsteker 1988).(v)Rapid variability in the infrared and optical emission on timescales as short as one day in 1988 (Courvoisier et al. 1988 and Robson, Courvoisier and Bouchet this conference).

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