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>

Contrapropagating Ultrasonic Flowmeter Using Clad Buffer Rods for High Temperature Measurements

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
D. R. França ◽  
C.-K. Jen ◽  
Y. Ono
Keyword(s):  
High Temperature ◽  
Temperature Variation ◽  
Signal To Noise Ratio ◽  
Flow Speed ◽  
Ultrasonic Flowmeter ◽  
Ultrasonic Signals ◽  
Transit Times ◽  
Temperature Application ◽  
The Difference ◽  
In Transit

This work proposes clad buffer rods driven by shear transducers as the main building block of contrapropagating ultrasonic flowmeters for high temperature application. It is demonstrated that the superior signal-to-noise ratio exhibited by clad buffer rods (compared with the reported nonclad counterparts) improves precision in transit time measurements, leading to more accurate flow speed determination. In addition, it is shown that clad buffer rods generate specific ultrasonic signals for temperature calibration of flowmeters, allowing temperature variation while still measuring accurately the flow speed. On the basis of these experimental results, a contrapropagating ultrasonic flowmeter was designed and installed in a heater machine for flow speed measurements of hot oil at temperatures near 130°C. For a temperature variation of 3°C, the difference between upstream and downstream ultrasonic transit times, which is proportional to the flow speed at a given temperature, was measured within 1 ns accuracy.

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.

Bias in estimates of mb at small magnitudes

1976 ◽  
Vol 66 (6) ◽  
pp. 1887-1904
Author(s):  
J. F. Evernden ◽  
W. M. Kohler
Keyword(s):  
Signal To Noise Ratio ◽  
High Signal ◽  
Systematic Bias ◽  
Station Correction ◽  
Signal To Noise ◽  
Identification Criterion ◽  
The Difference ◽  
Operational Networks ◽  
Worldwide Network ◽  
Simple Parameter

abstract A possibly significant factor in application of an identification criterion such as MS:mb is systematic bias in mb magnitude estimates at small magnitudes due to a variety of factors. Magnitude bias is the difference in magnitude value, positive or negative, between an observed network-based magnitude value and the expected magnitude value if all stations of the network had detected the event at high signal-to-noise ratio. This paper constitutes a partial study of the general problem; it evaluates the bias effects expected from both conceptual and operational networks when using parameters for noise and signal levels and standard deviations derived from observations, and when correcting observed station mb values solely via a simple parameter station correction factor. The analysis shows that any bias effects on mb inherent in any operational or potential worldwide network are so small as to have negligible effect on use of an MS:mb discriminant.

scholarly journals Light Leakage of Multidomain Vertical Alignment LCDs Using a Colorimetric Model in the Dark State

2018 ◽  
Vol 2018 ◽  
pp. 1-6
Author(s):  
Chuen-Lin Tien ◽  
Rong-Ji Lin ◽  
Shang-Min Yeh
Keyword(s):  
Liquid Crystal ◽  
Contrast Ratio ◽  
Liquid Crystal Displays ◽  
Vertical Alignment ◽  
Dark State ◽  
Proposed Model ◽  
Color Shift ◽  
Depolarization Of Light ◽  
The Difference ◽  
Color Filters

Light leakage from liquid crystal displays in the dark state is relatively larger and leads to a degraded contrast ratio and color shift. This work describes a novel colorimetric model based on the Muller matrix that includes depolarization of light propagating through liquid crystal molecules, polarizers, and color filters. In this proposed model, the chromaticity can be estimated in the bump and no-bump regions of an LCD. We indicate that the difference between simulation and measurement of chromaticity is about 0.01. Light leakage in the bump region is three times that in no-bump region in the dark state.

scholarly journals KELT-9 as an Eclipsing Double-lined Spectroscopic Binary: A Unique and Self-consistent Solution to the System

2022 ◽  
Vol 163 (2) ◽  
pp. 40
Author(s):  
Anusha Pai Asnodkar ◽  
Ji Wang ◽  
B. Scott Gaudi ◽  
P. Wilson Cauley ◽  
Jason D. Eastman ◽  
...  
Keyword(s):  
Radial Velocities ◽  
Data Sets ◽  
Dynamical Mass ◽  
Orbital Inclination ◽  
Hot Jupiters ◽  
Atmospheric Escape ◽  
Spectroscopic Binary ◽  
Consistent Solution ◽  
Using Data ◽  
In Transit

Abstract Transiting hot Jupiters present a unique opportunity to measure absolute planetary masses due to the magnitude of their radial velocity signals and known orbital inclination. Measuring planet mass is critical to understanding atmospheric dynamics and escape under extreme stellar irradiation. Here we present the ultrahot Jupiter system KELT-9 as a double-lined spectroscopic binary. This allows us to directly and empirically constrain the mass of the star and its planetary companion without reference to any theoretical stellar evolutionary models or empirical stellar scaling relations. Using data from the PEPSI, HARPS-N, and TRES spectrographs across multiple epochs, we apply least-squares deconvolution to measure out-of-transit stellar radial velocities. With the PEPSI and HARPS-N data sets, we measure in-transit planet radial velocities using transmission spectroscopy. By fitting the circular orbital solution that captures these Keplerian motions, we recover a planetary dynamical mass of 2.17 ± 0.56 M J and stellar dynamical mass of 2.11 ± 0.78 M ⊙, both of which agree with the discovery paper. Furthermore, we argue that this system, as well as systems like it, are highly overconstrained, providing multiple independent avenues for empirically cross-validating model-independent solutions to the system parameters. We also discuss the implications of this revised mass for studies of atmospheric escape.

scholarly journals Western Europe is warming much faster than expected

2009 ◽  
Vol 5 (1) ◽  
pp. 1-12 ◽  
Author(s):  
G. J. van Oldenborgh ◽  
S. Drijfhout ◽  
A. van Ulden ◽  
R. Haarsma ◽  
A. Sterl ◽  
...  
Keyword(s):  
Western Europe ◽  
Climate Models ◽  
Signal To Noise Ratio ◽  
Warming Trend ◽  
North Atlantic Current ◽  
Climate Fluctuations ◽  
The North ◽  
The Difference ◽  
Decadal Climate ◽  
Random Fluctuations

Abstract. The warming trend of the last decades is now so strong that it is discernible in local temperature observations. This opens the possibility to compare the trend to the warming predicted by comprehensive climate models (GCMs), which up to now could not be verified directly to observations on a local scale, because the signal-to-noise ratio was too low. The observed temperature trend in western Europe over the last decades appears much stronger than simulated by state-of-the-art GCMs. The difference is very unlikely due to random fluctuations, either in fast weather processes or in decadal climate fluctuations. In winter and spring, changes in atmospheric circulation are important; in spring and summer changes in soil moisture and cloud cover. A misrepresentation of the North Atlantic Current affects trends along the coast. Many of these processes ontinue to affect trends in projections for the 21st century. This implies that climate predictions for western Europe probably underestimate the effects of anthropogenic climate change.

scholarly journals New chemical scheme for giant planet thermochemistry

2020 ◽  
Vol 634 ◽  
pp. A78 ◽  
Author(s):  
O. Venot ◽  
T. Cavalié ◽  
R. Bounaceur ◽  
P. Tremblin ◽  
L. Brouillard ◽  
...  
Keyword(s):  
Experimental Studies ◽  
Giant Planet ◽  
Brown Dwarfs ◽  
Planetary Atmospheres ◽  
Atmospheric Composition ◽  
Planetary Formation ◽  
Hot Jupiters ◽  
Chemical Scheme ◽  
High Level ◽  
Kinetics Of

Context. Several chemical networks have been developed to study warm (exo)planetary atmospheres. The kinetics of the reactions related to the methanol chemistry included in these schemes have been questioned. Aims. The goal of this paper is to update the methanol chemistry for such chemical networks based on recent publications in the combustion literature. We also aim to study the consequences of this update on the atmospheric compositions of (exo)planetary atmospheres and brown dwarfs. Methods. We performed an extensive review of combustion experimental studies and revisited the sub-mechanism describing methanol combustion in a scheme published in 2012. The updated scheme involves 108 species linked by a total of 1906 reactions. We then applied our 1D kinetic model with this new scheme to the case studies HD 209458b, HD 189733b, GJ 436b, GJ 1214b, ULAS J1335+11, Uranus, and Neptune; we compared these results with those obtained with the former scheme. Results. The update of the scheme has a negligible impact on the atmospheres of hot Jupiters. However, the atmospheric composition of warm Neptunes and brown dwarfs is modified sufficiently to impact observational spectra in the wavelength range in which James Webb Space Telescope will operate. Concerning Uranus and Neptune, the update of the chemical scheme modifies the abundance of CO and thus impacts the deep oxygen abundance required to reproduce the observational data. For future 3D kinetics models, we also derived a reduced scheme containing 44 species and 582 reactions. Conclusions. Chemical schemes should be regularly updated to maintain a high level of reliability on the results of kinetic models and be able to improve our knowledge of planetary formation.

scholarly journals Is the Level of Noise in a School Environment be Harmful to the Hearing of Teachers?

2020 ◽  
Vol 24 (04) ◽  
pp. e503-e507
Author(s):  
Gabriela Guenther Ribeiro Novanta ◽  
Sergio Luiz Garavelli ◽  
Andre Luiz Lopes Sampaio
Keyword(s):  
Classroom Environment ◽  
School Environment ◽  
Otoacoustic Emissions ◽  
Signal To Noise Ratio ◽  
Signal Amplitude ◽  
Daily Basis ◽  
Outer Hair Cells ◽  
Distortion Product ◽  
Teachers And Students ◽  
The Difference

Abstract Introduction The excessive noise observed in the school environment can cause damages or losses to the learning process as well as risks to the health of teachers and students, such as physical, mental and social impairments, including, among them, hearing loss. Objective To assess otoacoustic emissions in teachers and determine whether classroom noise reduces distortion-product otoacoustic emissions (DPOAEs) amplitude and signal-to-noise ratio (SNR). Method Sixty-seven teachers were evaluated using otoacoustic emissions testing in two situations: after hearing rest and after the working day. Results Signal amplitude (p = 0.044 [2 kHz]; p = 0.01 [4 kHz]) and SNR for frequencies of 2 kHz (p = 0.008) and 4 kHz (p = 0.001) decreased significantly between time points. Mean classroom noise was associated with the magnitude of the difference in signal amplitude at 2 kHz (p = 0.017) and 4 kHz (p = 0.015), and SNR at 4 kHz (p = 0.023). Conclusions There was a decrease in the amplitude and in the SNR after exposure to the noise in the classroom environment. The high levels of sound pressure that teachers are exposed to on a daily basis can cause a temporary change in the outer hair cells of the Corti organ, and these changes may become permanent over time.

Exoplanets: Atmospheres of Hot Jupiters

2019 ◽  
Author(s):  
Dmitry V. Bisikalo ◽  
Pavel V. Kaygorodov ◽  
Valery I. Shematovich
Keyword(s):  
Solar System ◽  
Alternative Hypothesis ◽  
Atmospheric Composition ◽  
Current Status ◽  
Hot Jupiters ◽  
History Of ◽  
Exoplanetary Atmospheres ◽  
Host Stars ◽  
Gaseous Envelopes ◽  
Hot Jupiter

The history of exoplanetary atmospheres studies is strongly based on the observations and investigations of the gaseous envelopes of hot Jupiters—exoplanet gas giants that have masses comparable to the mass of Jupiter and orbital semi-major axes shorter than 0.1 AU. The first exoplanet around a solar-type star was a hot Jupiter discovered in 1995. Researchers found an object that had completely atypical parameters compared to planets known in the solar system. According to their estimates, the object might have a mass about a half of the Jovian mass and a very short orbital period (four days), which means that it has an orbit roughly corresponding to the orbit of Mercury. Later, many similar objects were discovered near different stars, and they acquired a common name—hot Jupiters. It is still unclear what the mechanism is for their origin, because generally accepted theories of planetary evolution predict the formation of giant planets only at large orbital distances, where they can accrete enough matter before the protoplanetary disc disappears. If this is true, before arriving at such low orbits, hot Jupiters might have a long migration path, caused by interactions with other massive planets and/or with the gaseous disc. In favor of this model is the discovery of many hot Jupiters in elliptical and highly inclined orbits, but on the other hand several observed hot Jupiters have circular orbits with low inclination. An alternative hypothesis is that the cores of future hot Jupiters are super-Earths that may later intercept matter from the protoplanetary disk falling on the star. The scientific interest in hot Jupiters has two aspects. The first is the peculiarity of these objects: they have no analogues in the solar system. The second is that, until recently, only for hot Jupiters was it possible to obtain observational characteristics of their atmospheres. Many of the known hot Jupiters are eclipsing their host stars, so, from their light curve and spectral data obtained during an eclipse, it became possible to obtain information about their shape and their atmospheric composition. Thus it is possible to conclude that hot Jupiters are a common type of exoplanet, having no analogues in the solar system. Many aspects of their evolution and internal structure remain unclear. Being very close to their host stars, hot Jupiters must interact with the stellar wind and stellar magnetic field, as well as with stellar flares and coronal mass ejections, allowing researchers to gather information about them. According to UV observations, at least a fraction of hot Jupiters have extended gaseous envelopes, extending far beyond of their upper atmospheres. The envelopes are observable with current astronomical instruments, so it is possible to develop their astrophysical models. The history of hot Jupiter atmosphere studies during the past 20 years and the current status of modern theories describing the extended envelopes of hot Jupiters are excellent examples of the progress in understanding planetary atmospheres formation and evolution both in the solar system and in the extrasolar planetary systems.

scholarly journals HD 189733 b: bow shock or no shock?

2018 ◽  
Vol 619 ◽  
pp. A96 ◽  
Author(s):  
S. Kohl ◽  
M. Salz ◽  
S. Czesla ◽  
J. H. M. M. Schmitt
Keyword(s):  
Time Series ◽  
Neutral Hydrogen ◽  
Periodic Variation ◽  
Bow Shock ◽  
Time Variability ◽  
Stellar Activity ◽  
Hot Jupiters ◽  
Upper Limits ◽  
In Transit ◽  
Infrared Triplet

Context. Hot Jupiters are surrounded by extended atmospheres of neutral hydrogen. Observations have provided evidence for in-transit hydrogen Hα absorption as well as variable pre-transit absorption signals. These have been interpreted in terms of a bow shock or an accretion stream that transits the host star before the planet. Aims. We test the hypothesis of planetary-related Hα absorption by studying the time variability of the Hα and stellar activity-sensitive calcium lines in high-resolution TIGRE (Telescopio Internacional de Guanajuato Robótico Espectroscópico) spectra of the planet host HD 189733. Methods. In the framework of an observing campaign spanning several months, the host star was observed several times per week randomly sampling the orbital phases of the planet. We determine the equivalent width in the Hα and Ca IRT(calcium infrared triplet) lines, and subtract stellar rotationally induced activity from the Hα time series via its correlation with the IRT evolution. The residuals are explored for significant differences between the pre-, in-, and out-of-transit phases. Results. We find strong stellar rotational variation with a lifetime of about 20–30 days in all activity indicators, but the corrected Hα time series exhibits no significant periodic variation. We exclude the presence of more than 6.2 mÅ pre-transit absorption and 5.6 mÅ in-transit absorption in the corrected Hα data at a 99% confidence level. Conclusions. Previously observed Hα absorption signals exceed our upper limits, but they could be related to excited atmospheric states. The Hα variability in the HD 189733 system is dominated by stellar activity, and observed signals around the planetary transit may well be caused by short-term stellar variability.

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