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 Atmospheric characterization of hot Jupiters using hierarchical models of Spitzer observations

2021 ◽  
Author(s):  
Dylan Keating ◽  
Nicolas B Cowan
Keyword(s):  
Hierarchical Model ◽  
Information Criterion ◽  
Phase Curve ◽  
Bayesian Hierarchical ◽  
Hot Jupiters ◽  
Hierarchical Modelling ◽  
Brightness Temperatures ◽  
Eclipse Observations ◽  
The Individual

Abstract The field of exoplanet atmospheric characterization is trending towards comparative studies involving many planetary systems, and using Bayesian hierarchical modelling is a natural next step. Here we demonstrate two use cases. We first use hierarchical modelling to quantify variability in repeated observations by reanalyzing a suite of ten Spitzer secondary eclipse observations of the hot Jupiter XO-3b. We compare three models: one where we fit ten separate eclipse depths, one where we use a single eclipse depth for all ten observations, and a hierarchical model. By comparing the Widely Applicable Information Criterion of each model, we show that the hierarchical model is preferred over the others. The hierarchical model yields less scatter across the suite of eclipse depths—and higher precision on the individual eclipse depths—than does fitting the observations separately. We find that the hierarchical eclipse depth uncertainty is larger than the uncertainties on the individual eclipse depths, which suggests either slight astrophysical variability or that single eclipse observations underestimate the true eclipse depth uncertainty. Finally, we fit a suite of published dayside brightness measurements for 37 planets using a hierarchical model of brightness temperature versus irradiation temperature. The hierarchical model gives tighter constraints on the individual brightness temperatures than the non-hierarchical model. Although we tested hierarchical modelling on Spitzer eclipse data of hot Jupiters, it is applicable to observations of smaller planets like hot neptunes and super earths, as well as for photometric and spectroscopic transit or phase curve observations.

scholarly journals Fabrication and characterization of molybdenum(VI)complex-TiO2 nanoparticles modified electrode for the electrocatalytic determination of L-cysteine

2011 ◽  
Vol 76 (4) ◽  
pp. 575-589 ◽  
Author(s):  
Mohammad Mazloum-Ardakani ◽  
Hadi Beitollahi ◽  
Zahra Taleat ◽  
Masoud Salavati-Niasari
Keyword(s):  
Cyclic Voltammetry ◽  
Tio2 Nanoparticles ◽  
Signal To Noise Ratio ◽  
Carbon Paste ◽  
Good Electrocatalytic Activity ◽  
Electron Transfer Rate Constant ◽  
Charge Transfer Coefficient ◽  
Electrocatalytic Determination

A novel voltammetric sensor for the determination of L-cysteine (L-Cys) was fabricated based on a TiO2 nanoparticles/bis [bis(salicylidene-1,4-phenylenediamine)-molybdenum(VI)] carbon paste electrode. The electrochemical behavior of the sensor was investigated in detail by cyclic voltammetry. The apparent electron transfer rate constant (ks) and charge transfer coefficient (?) of the TiO2 nanoparticles / molybdenum(VI) complex/CPE were also determined by cyclic voltammetry and found to be about 4.53 s?1 and 0.54, respectively. The sensor displayed good electrocatalytic activity towards the oxidation of LCys. The peak potential for the oxidation of L-Cys was lowered by at least 130 mV compared with that obtained at an unmodified CPE. Under optimal conditions, the linear range spans L-Cys concentrations from 1.5?10?6 M to 1.2?10?3 M and the detection limit was 0.70 ? 0.01 ?M at a signal-to-noise ratio of 2. In addition, the sensor showed good stability and reproducibility.

scholarly journals Atmospheric Characterization via Broadband Color Filters on the PLAnetary Transits and Oscillations of stars (PLATO) Mission

2020 ◽  
Author(s):  
John Lee Grenfell ◽  
Mareike Godolt ◽  
Juan Cabrera ◽  
Ludmila Carone ◽  
Antonio Garcia Munoz ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Space Mission ◽  
Atmospheric Composition ◽  
Phase Curve ◽  
Wavelength Interval ◽  
Hot Jupiters ◽  
The Difference ◽  
In Transit ◽  
Color Filters ◽  
Planetary Transits

<p>We assess broadband color filters for the two fast cameras on the PLAnetary Transits and Oscillations (PLATO) of stars space mission with respect to exoplanetary atmospheric characterization. We focus on Ultra Hot Jupiters and Hot Jupiters placed 25pc and 100pc away from the Earth and warm Super-Earths placed 10pc and 25pc away. Our analysis takes as input literature values for the difference in transit depth between the broadband lower (500-675nm) wavelength interval (hereafter referred to as ”blue“) and the upper (675-1125nm) broadband wavelength interval (hereafter referred to as ”red“) for transmission, occultation and phase curve analyses. Planets orbiting main sequence central stars with stellar classes F, G, K and M are investigated. We calculate the signal-to-noise ratio with respect to photon and instrument noise for detecting the difference in transit depth between the two spectral intervals. Results suggest that bulk atmospheric composition and planetary geometric albedos could be detected for (Ultra) Hot Jupiters up to ~100pc (~25pc) with strong (moderate) Rayleigh extinction. Phase curve information could be extracted for Ultra Hot Jupiters orbiting K and G dwarf stars up to 25pc away. For warm Super-Earths, basic atmospheric types (primary and water-dominated) and the presence of sub-micron hazes in the upper atmosphere could be distinguished for up to a handful of cases up to ~10pc (manuscript accepted in Experimental Astronomy).</p>

Biological crystals formation studied by HTREM and image analysis

1996 ◽  
Vol 54 ◽  
pp. 74-75
Author(s):  
P. Houlle ◽  
F.J.G. Cuisinier ◽  
J.C. Voegel ◽  
P. Schutz
Keyword(s):  
Image Analysis ◽  
Signal To Noise Ratio ◽  
High Resolution Electron Microscopy ◽  
Data Set ◽  
Simulation Techniques ◽  
Resolution Electron ◽  
Human Dentine ◽  
Simulated Images

High resolution electron microscopy (HREM) allows the determination of the molecular crystal structure by comparing HREM images with simulated images. Direct comparison was not possible for small crystalline areas such as nanometer-sized particles or for thin crystals with weak image contrast. To overcome these problems, we used numerical image analysis to gain access to the structure informations within these minute crystals. We used this approach for the characterization of the initial mineralization steps during human amelogenesis, chicken bone and human dentine crystals growth.Our method consists in HREM associated with both numerical image analysis and image simulation techniques (EMS) Image analysis was performed using the IMAGIC statistical. Nanoparticle subimages, 128 × 128 pixels in size, were extracted from the original micrographs by interactive selection. A circular mask with a radius of 50 pixels was applied. The mean intensity of each subimage was set to zero and its internal variance was normalized to 10. Double direct alignment procedures were used to align the images in rotation and translation against an alignment reference extracted from the data set. An average image was finally calculated to improve the signal to noise ratio.

scholarly journals Three short-period Jupiters from TESS

2020 ◽  
Vol 639 ◽  
pp. A76 ◽  
Author(s):  
L. D. Nielsen ◽  
R. Brahm ◽  
F. Bouchy ◽  
N. Espinoza ◽  
O. Turner ◽  
...  
Keyword(s):  
Stellar System ◽  
Phase Curve ◽  
Mass Determination ◽  
Tidal Dissipation ◽  
Giant Star ◽  
Hot Jupiters ◽  
Short Period ◽  
Host Stars ◽  
Interesting System

We report the confirmation and mass determination of three hot Jupiters discovered by the Transiting Exoplanet Survey Satellite (TESS) mission: HIP 65Ab (TOI-129, TIC-201248411) is an ultra-short-period Jupiter orbiting a bright (V = 11.1 mag) K4-dwarf every 0.98 days. It is a massive 3.213 ± 0.078 MJ planet in a grazing transit configuration with an impact parameter of b = 1.17−0.08+0.10. As a result the radius is poorly constrained, 2.03−0.49+0.61RJ. The planet’s distance to its host star is less than twice the separation at which it would be destroyed by Roche lobe overflow. It is expected to spiral into HIP 65A on a timescale ranging from 80 Myr to a few gigayears, assuming a reduced tidal dissipation quality factor of Qs′ = 107 − 109. We performed a full phase-curve analysis of the TESS data and detected both illumination- and ellipsoidal variations as well as Doppler boosting. HIP 65A is part of a binary stellar system, with HIP 65B separated by 269 AU (3.95 arcsec on sky). TOI-157b (TIC 140691463) is a typical hot Jupiter with a mass of 1.18 ± 0.13 MJ and a radius of 1.29 ± 0.02 RJ. It has a period of 2.08 days, which corresponds to a separation of just 0.03 AU. This makes TOI-157 an interesting system, as the host star is an evolved G9 sub-giant star (V = 12.7). TOI-169b (TIC 183120439) is a bloated Jupiter orbiting a V = 12.4 G-type star. It has a mass of 0.79 ±0.06 MJ and a radius of 1.09−0.05+0.08RJ. Despite having the longest orbital period (P = 2.26 days) of the three planets, TOI-169b receives the most irradiation and is situated on the edge of the Neptune desert. All three host stars are metal rich with [Fe / H] ranging from 0.18 to0.24.

scholarly journals QUANTUM ESTIMATION FOR QUANTUM TECHNOLOGY

2009 ◽  
Vol 07 (supp01) ◽  
pp. 125-137 ◽  
Author(s):  
MATTEO G. A. PARIS
Keyword(s):  
Quantum Noise ◽  
Signal To Noise Ratio ◽  
Logarithmic Derivative ◽  
Quantum Fisher Information ◽  
Optimization Procedure ◽  
Nonlinear Functions ◽  
Quantum Observables ◽  
Quantum Technology

Several quantities of interest in quantum information, including entanglement and purity, are nonlinear functions of the density matrix and cannot, even in principle, correspond to proper quantum observables. Any method aimed to determine the value of these quantities should resort to indirect measurements and thus corresponds to a parameter estimation problem whose solution, i.e. the determination of the most precise estimator, unavoidably involves an optimization procedure. We review local quantum estimation theory and present explicit formulas for the symmetric logarithmic derivative and the quantum Fisher information of relevant families of quantum states. Estimability of a parameter is defined in terms of the quantum signal-to-noise ratio and the number of measurements needed to achieve a given relative error. The connections between the optmization procedure and the geometry of quantum statistical models are discussed. Our analysis allows to quantify quantum noise in the measurements of non observable quantities and provides a tools for the characterization of signals and devices in quantum technology.

Determination of the Best Emulsion for the Microscopy of Crystals

1981 ◽  
Vol 39 ◽  
pp. 32-33
Author(s):  
David A. Grano ◽  
Kenneth H. Downing
Keyword(s):  
Spatial Frequency ◽  
Information Transfer ◽  
Signal To Noise Ratio ◽  
Experimental Situation ◽  
Photographic Emulsion ◽  
Modulation Transfer ◽  
Signal To Noise ◽  
Frequency Space ◽  
Noise Ratio

The retrieval of high-resolution information from images of biological crystals depends, in part, on the use of the correct photographic emulsion. We have been investigating the information transfer properties of twelve emulsions with a view toward 1) characterizing the emulsions by a few, measurable quantities, and 2) identifying the “best” emulsion of those we have studied for use in any given experimental situation. Because our interests lie in the examination of crystalline specimens, we've chosen to evaluate an emulsion's signal-to-noise ratio (SNR) as a function of spatial frequency and use this as our critereon for determining the best emulsion.The signal-to-noise ratio in frequency space depends on several factors. First, the signal depends on the speed of the emulsion and its modulation transfer function (MTF). By procedures outlined in, MTF's have been found for all the emulsions tested and can be fit by an analytic expression 1/(1+(S/S0)2). Figure 1 shows the experimental data and fitted curve for an emulsion with a better than average MTF. A single parameter, the spatial frequency at which the transfer falls to 50% (S0), characterizes this curve.

Computer-Assisted High-Re Solution TEM

1990 ◽  
Vol 48 (1) ◽  
pp. 162-163
Author(s):  
F.A. Ponce ◽  
H. Hikashi
Keyword(s):  
Signal To Noise Ratio ◽  
Accurate Determination ◽  
Computer Software ◽  
Video Camera ◽  
Image Contrast ◽  
Objective Lens ◽  
Computer Assisted ◽  
Optical Parameters ◽  
Astigmatism Correction

The determination of the atomic positions from HRTEM micrographs is only possible if the optical parameters are known to a certain accuracy, and reliable through-focus series are available to match the experimental images with calculated images of possible atomic models. The main limitation in interpreting images at the atomic level is the knowledge of the optical parameters such as beam alignment, astigmatism correction and defocus value. Under ordinary conditions, the uncertainty in these values is sufficiently large to prevent the accurate determination of the atomic positions. Therefore, in order to achieve the resolution power of the microscope (under 0.2nm) it is necessary to take extraordinary measures. The use of on line computers has been proposed [e.g.: 2-5] and used with certain amount of success.We have built a system that can perform operations in the range of one frame stored and analyzed per second. A schematic diagram of the system is shown in figure 1. A JEOL 4000EX microscope equipped with an external computer interface is directly linked to a SUN-3 computer. All electrical parameters in the microscope can be changed via this interface by the use of a set of commands. The image is received from a video camera. A commercial image processor improves the signal-to-noise ratio by recursively averaging with a time constant, usually set at 0.25 sec. The computer software is based on a multi-window system and is entirely mouse-driven. All operations can be performed by clicking the mouse on the appropiate windows and buttons. This capability leads to extreme friendliness, ease of operation, and high operator speeds. Image analysis can be done in various ways. Here, we have measured the image contrast and used it to optimize certain parameters. The system is designed to have instant access to: (a) x- and y- alignment coils, (b) x- and y- astigmatism correction coils, and (c) objective lens current. The algorithm is shown in figure 2. Figure 3 shows an example taken from a thin CdTe crystal. The image contrast is displayed for changing objective lens current (defocus value). The display is calibrated in angstroms. Images are stored on the disk and are accessible by clicking the data points in the graph. Some of the frame-store images are displayed in Fig. 4.

Characterization of Impressed Current Technique to Model Corrosion of Reinforcement in Concrete

2020 ◽  
Vol 11 (1) ◽  
pp. 93-99
Author(s):  
Abu Zakir Morshed ◽  
Sheikh Shakib ◽  
Tanzim Jahin
Keyword(s):  
Immersion Time ◽  
Chloride Content ◽  
Engineering Science ◽  
Coastal Regions ◽  
Faraday’S Law ◽  
Current Technique ◽  
Corrosion Cell ◽  
Impressed Current

Corrosion of reinforcement is an important durability concern for the structures exposed to coastal regions. Since corrosion of reinforcement involves long periods of time, impressed current technique is usually used to accelerate the corrosion of reinforcement in laboratories. Characterization of impressed current technique was the main focus of this research,which involved determination of optimum chloride content and minimum immersion time of specimens for which the application of Faraday’s law could be efficient. To obtain optimum chloride content, the electrolytes in the corrosion cell were prepared similar to that of concrete pore solutions. Concrete prisms of 200 mm by 200 mm by 300 mm were used to determine the minimum immersion time for saturation. It was found that the optimum chloride content was 35 gm/L and the minimum immersion time for saturation was 140 hours. Accounting the results, a modified expression based on Faraday’s law was proposed to calculate weight loss due to corrosion. Journal of Engineering Science 11(1), 2020, 93-99

The Determination of Sense via Deleuze and Blanchot: Paradoxes of the Habitual, the Immemorial, and the Eternal Return

2008 ◽  
Vol 2 (2) ◽  
pp. 155-177 ◽  
Author(s):  
Eugene Brently Young
Keyword(s):  
Eternal Return

Eternal return is the paradox that accounts for the interplay between difference and repetition, a dynamic at the heart of Deleuze's philosophy, and Blanchot's approach to this paradox, even and especially through what it elides, further illuminates it. Deleuze draws on Blanchot's characterisations of difference, forgetting, and the unlivable to depict the ‘sense’ produced via eternal return, which, for Blanchot, is where repetition implicates or ‘carries’ pure difference. However, for Deleuze, difference and the unlivable are also developed by the living repetition or ‘contraction’ of habit, which results in his distinctive characterization of ‘force’, ‘levity’, and sense in eternal return.

Sign in / Sign up

Export Citation Format

Share Document