scholarly journals The High Cadence Transit Survey (HiTS): Compilation and Characterization of Light-curve Catalogs

2018 ◽  
Vol 156 (5) ◽  
pp. 186 ◽  
Author(s):  
Jorge Martínez-Palomera ◽  
Francisco Förster ◽  
Pavlos Protopapas ◽  
Juan Carlos Maureira ◽  
Paulina Lira ◽  
...  
Keyword(s):  
Light Curve ◽  
High Cadence

Characterization of stellar activity using transits and its impact on habitability

2019 ◽  
Vol 15 (S354) ◽  
pp. 461-466
Author(s):  
Raissa Estrela ◽  
Adriana Valio ◽  
Sourav Palit
Keyword(s):  
Magnetic Field ◽  
Light Curve ◽  
Physical Properties ◽  
Crucial Role ◽  
Coronal Plasma ◽  
Habitable Zone ◽  
Stellar Activity ◽  
Magnetic Cycles ◽  
Living Organisms

AbstractStellar magnetic field is the driver of activity in stars and can trigger spots, energetic flares, coronal plasma ejections and ionized winds. These phenomena play a crucial role in understanding the internal mechanisms of the star, but can also have potential effects in orbiting planets. During the transit of a planet, spots can be occulted producing features imprinted in the transit light curve. Here, we modelled these features to characterize the physical properties of the spots (radius, intensity, and location). In addition, we monitor spots signatures on multiple transits to estimate magnetic cycles length of Kepler stars. Flares have also been observed during transits in active stars. We derive the properties of the flares and analyse their UV impact on possible living organisms in planets orbiting in the habitable zone.

scholarly journals archi: pipeline for light curve extraction of CHEOPS background stars

2020 ◽  
Vol 496 (1) ◽  
pp. 282-294
Author(s):  
André M Silva ◽  
Sérgio G Sousa ◽  
Nuno Santos ◽  
Olivier D S Demangeon ◽  
Pedro Silva ◽  
...  
Keyword(s):  
Time Series ◽  
Light Curve ◽  
Central Star ◽  
Scientific Application ◽  
Exoplanetary Systems ◽  
Main Target ◽  
Precision Time ◽  
Simulated Images ◽  
Official Data

ABSTRACT High precision time-series photometry from space is being used for a number of scientific cases. In this context, the recently launched CHaracterizing ExOPlanet Satellite (CHEOPS) (ESA) mission promises to bring 20 ppm precision over an exposure time of 6 h, when targeting nearby bright stars, having in mind the detailed characterization of exoplanetary systems through transit measurements. However, the official CHEOPS (ESA) mission pipeline only provides photometry for the main target (the central star in the field). In order to explore the potential of CHEOPS photometry for all stars in the field, in this paper, we present archi, an additional open-source pipeline module1 to analyse the background stars present in the image. As archi uses the official data reduction pipeline data as input, it is not meant to be used as an independent tool to process raw CHEOPS data but, instead, to be used as an add-on to the official pipeline. We test archi using CHEOPS simulated images, and show that photometry of background stars in CHEOPS images is only slightly degraded (by a factor of 2–3) with respect to the main target. This opens a potential for the use of CHEOPS to produce photometric time-series of several close-by targets at once, as well as to use different stars in the image to calibrate systematic errors. We also show one clear scientific application where the study of the companion light curve can be important for the understanding of the contamination on the main target.

archi: pipeline for light curve extraction of CHEOPS background stars

2020 ◽  
Author(s):  
André M. Silva ◽  
Sérgio G. Sousa ◽  
Nuno Santos ◽  
Olivier D. S. Demangeon ◽  
Mafalda X. Matos
Keyword(s):  
Time Series ◽  
Light Curve ◽  
Central Star ◽  
Scientific Application ◽  
Exoplanetary Systems ◽  
Main Target ◽  
Precision Time ◽  
Simulated Images ◽  
Official Data

<p>High precision time-series photometry from space is being used for a number of scientific cases. In this context, the recently launched CHaracterizing ExOPlanet Satellite (CHEOPS) (ESA) mission promises to bring 20 ppm precision over an exposure time of 6 h, when targeting nearby bright stars, having in mind the detailed characterization of exoplanetary systems through transit measurements. However, the official CHEOPS (ESA) mission pipeline only provides photometry for the main target (the central star in the field). In order to explore the potential of CHEOPS photometry for all stars in the field, we present archi, an additional open-source pipeline module to analyse the background stars present in the image. As archi uses the official data reduction pipeline data as input, it is not meant to be used as an independent tool to process raw CHEOPS data but, instead, to be used as an add-on to the official pipeline. We test archi using CHEOPS simulated images, and show that photometry of background stars in CHEOPS images is only slightly degraded (by a factor of 2–3) with respect to the main target. This opens a potential for the use of CHEOPS to produce photometric time-series of several close-by targets at once, as well as to use different stars in the image to calibrate systematic errors. We also show one clear scientific application where the study of the companion light curve can be important for the understanding of the contamination on the main target.</p>

Characterization of the polar plumes from high cadence LASCO-C2 observations

2002 ◽  
Vol 29 (3) ◽  
pp. 343-348 ◽  
Author(s):  
A. Llebaria ◽  
A. Thernisien ◽  
P. Lamy
Keyword(s):  
Polar Plumes ◽  
High Cadence

scholarly journals TESS unveils the phase curve of WASP-33b

2020 ◽  
Vol 639 ◽  
pp. A34 ◽  
Author(s):  
C. von Essen ◽  
M. Mallonn ◽  
C. C. Borre ◽  
V. Antoci ◽  
K. G. Stassun ◽  
...  
Keyword(s):  
Light Curve ◽  
Signal To Noise Ratio ◽  
Phase Curve ◽  
Hot Jupiters ◽  
Brightness Temperatures ◽  
Pulsation Spectrum ◽  
Stellar Pulsations ◽  
Detailed Determination

We present the detection and characterization of the full-orbit phase curve and secondary eclipse of the ultra-hot Jupiter WASP-33b at optical wavelengths, along with the pulsation spectrum of the host star. We analyzed data collected by the Transiting Exoplanet Survey Satellite (TESS) in sector 18. WASP-33b belongs to a very short list of highly irradiated exoplanets that were discovered from the ground and were later visited by TESS. The host star of WASP-33b is of δ Scuti-type and shows nonradial pulsations in the millimagnitude regime, with periods comparable to the period of the primary transit. These completely deform the photometric light curve, which hinders our interpretations. By carrying out a detailed determination of the pulsation spectrum of the host star, we find 29 pulsation frequencies with a signal-to-noise ratio higher than 4. After cleaning the light curve from the stellar pulsations, we confidently report a secondary eclipse depth of 305.8 ± 35.5 parts-per-million (ppm), along with an amplitude of the phase curve of 100.4 ± 13.1 ppm and a corresponding westward offset between the region of maximum brightness and the substellar point of 28.7 ± 7.1 degrees, making WASP-33b one of the few planets with such an offset found so far. Our derived Bond albedo, AB = 0.369 ± 0.050, and heat recirculation efficiency, ɛ = 0.189 ± 0.014, confirm again that he behavior of WASP-33b is similar to that of other hot Jupiters, despite the high irradiation received from its host star. By connecting the amplitude of the phase curve to the primary transit and depths of the secondary eclipse, we determine that the day- and nightside brightness temperatures of WASP-33b are 3014 ± 60 K and 1605 ± 45 K, respectively. From the detection of photometric variations due to gravitational interactions, we estimate a planet mass of MP = 2.81 ± 0.53 MJ. Based on analyzing the stellar pulsations in the frame of the planetary orbit, we find no signals of star-planet interactions.

scholarly journals CHARACTERIZATION OF THE X-RAY LIGHT CURVE OF THE γ Cas-LIKE B1e STAR HD 110432

2012 ◽  
Vol 755 (1) ◽  
pp. 64 ◽  
Author(s):  
Myron A. Smith ◽  
Raimundo Lopes de Oliveira ◽  
Christian Motch
Keyword(s):  
Light Curve ◽  
X Ray

scholarly journals Characterization of an Instrument Model for Exoplanet Transit Spectrum Estimation through Wide-scale Analysis on HST Data

2021 ◽  
Vol 163 (1) ◽  
pp. 22
Author(s):  
Noah Huber-Feely ◽  
Mark R. Swain ◽  
Gael Roudier ◽  
Raissa Estrela
Keyword(s):  
Light Curve ◽  
Model Performance ◽  
Distribution Functions ◽  
Model Parameters ◽  
Spectrum Estimation ◽  
Parent Distribution ◽  
Wide Scale ◽  
And Performance ◽  
In Transit

Abstract Instrument models (IMs) enable the reduction of systematic error in transit spectroscopy light-curve data, but, since the model formulation can influence the estimation of science model parameters, characterization of the instrument model effects is crucial to the interpretation of the reduced data. We analyze a simple instrument model and assess its validity and performance across Hubble WFC3 and STIS instruments. Over a large, n = 63, sample of observed targets, a Markov chain Monte Carlo sampler computes the parent distribution of each instrument model parameter. Possible parent distribution functions are then fit and tested against the empirical IM distribution. Correlation and other analyses are then performed to find IM relationships. The model is shown to perform well across the two instruments and three filters analyzed and, further, the Student’s t distribution is shown to closely fit the empirical parent distribution of IM parameters and the Gaussian distribution is shown to poorly model the observed distribution. This parent distribution can be used in the MCMC prior fitting and demonstrates IM consistency for wide-scale atmospheric analysis using this model. Finally, we propose a simple metric based on light-curve residuals to determine model performance, and we demonstrate its ability to determine whether a derived spectrum under this IM is high quality and robust.

High-cadence Light Curve of AT2018HHO in M31 During Its Maximum Light

2019 ◽  
Vol 3 (10) ◽  
pp. 144
Author(s):  
SanJulian-Jacques, Daniel ◽  
Fernandez-Torreiro, Mateo ◽  
Perez-Fournon, Ismael
Keyword(s):  
Light Curve ◽  
Maximum Light ◽  
High Cadence

scholarly journals ZTF J1901+5309: a 40.6-min orbital period eclipsing double white dwarf system

2020 ◽  
Vol 494 (1) ◽  
pp. L91-L96 ◽  
Author(s):  
Michael W Coughlin ◽  
Kevin Burdge ◽  
E Sterl Phinney ◽  
Jan van Roestel ◽  
Eric C Bellm ◽  
...  
Keyword(s):  
Gravitational Wave ◽  
Orbital Period ◽  
White Dwarf ◽  
Binary Systems ◽  
Demographic Analysis ◽  
Effective Temperatures ◽  
Orbital Periods ◽  
High Cadence

ABSTRACT The Zwicky Transient Facility has begun to discover binary systems with orbital periods that are less than 1 h. Combined with dedicated follow-up systems, which allow for high-cadence photometry of these sources, systematic confirmation and characterization of these sources are now possible. Here, we report the discovery of ZTF J190125.42+530929.5, a 40.6-min orbital period, eclipsing double white dwarf binary. Both photometric modelling and spectroscopic modelling confirm its nature, yielding an estimated inclination of $i = 86.2^{+0.6}_{-0.2}\, \rm deg$ and primary and secondary effective temperatures of $\textrm{{T}}_\textrm{eff} = 28\,000^{+500}_{-500}$ and $17\,600^{+400}_{-400}\, \mathrm{ K}$, respectively. This system adds to a growing list of sources for future gravitational-wave detectors and contributes to the demographic analysis of double degenerates.

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