Browse
Submit Data
Databases
API
Help

Dataset Information

22 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Using the transit of Venus to probe the upper planetary atmosphere.

ABSTRACT: During a planetary transit, atoms with high atomic number absorb short-wavelength radiation in the upper atmosphere, and the planet should appear larger during a primary transit observed in high-energy bands than in the optical band. Here we measure the radius of Venus with subpixel accuracy during the transit in 2012 observed in the optical, ultraviolet and soft X-rays with Hinode and Solar Dynamics Observatory missions. We find that, while Venus's optical radius is about 80 km larger than the solid body radius (the top of clouds and haze), the radius increases further by >70 km in the extreme ultraviolet and soft X-rays. This measures the altitude of the densest ion layers of Venus's ionosphere (CO2 and CO), useful for planning missions in situ, and a benchmark case for detecting transits of exoplanets in high-energy bands with future missions, such as the ESA Athena.

SUBMITTER: Reale F

PROVIDER: S-EPMC4557371 | biostudies-other | 2015

REPOSITORIES: biostudies-other

ACCESS DATA

Json Xml

Similar Datasets

Planetary-scale streak structure reproduced in high-resolution simulations of the Venus atmosphere with a low-stability layer.

Project description:Cloud patterns are important clues for revealing the atmospheric circulation of Venus. Recently, a planetary-scale streak structure has been discovered in middle- and lower-cloud images of Venus' night-side taken by IR2, the 2-?m camera, on board the Akatsuki orbiter. However, its formation mechanism has not been investigated. Here we succeed, for the first time, in reproducing the patterns of the observed streak structure, as regions of strong downward flows that develop in high-resolution global simulations of the Venus atmosphere. The streaks are formed in both hemispheres with equatorial symmetry, which is caused by equatorial Rossby-like and Kelvin-like waves with zonal wavenumber one. The low-stability layer that has been suggested by past observations is essential for reproducing the streak structure. The streaks of downward flow result from the interaction of the meridionally tilted phase lines of the Rossby-like waves and the characteristics of baroclinic instability produced around the low-stability layer.

| S-EPMC6327047 | biostudies-literature

Sulfur monoxide dimer chemistry as a possible source of polysulfur in the upper atmosphere of Venus.

Project description:The abundance of SO dimers (SO)2 in the upper atmosphere of Venus and their implications for the enigmatic ultraviolet absorption has been investigated in several studies over the past few years. However, the photochemistry of sulfur species in the upper atmosphere of Venus is still not well understood and the identity of the missing ultraviolet absorber(s) remains unknown. Here we update an existing photochemical model of Venus' upper atmosphere by including the photochemistry of SO dimers. Although the spectral absorption profile of SO dimers fits the unknown absorber, their abundance is found to be too low for them to contribute significantly to the absorption. It is more likely that their photolysis and/or reaction products could contribute more substantively. Reactions of SO dimers are found to be important sources of S2O, and possibly higher order SnO species and polysulfur, Sn. All of these species absorb in the critical ultraviolet region and are expected to be found in both the aerosol and gas phase. indicating that in-situ high resolution aerosol mass spectrometry might be a useful technique for identifying the ultraviolet absorber on Venus.

| S-EPMC7794339 | biostudies-literature

Weak, Quiet Magnetic Fields Seen in the Venus Atmosphere.

Project description:The existence of a strong internal magnetic field allows probing of the interior through both long term changes of and short period fluctuations in that magnetic field. Venus, while Earth's twin in many ways, lacks such a strong intrinsic magnetic field, but perhaps short period fluctuations can still be used to probe the electrical conductivity of the interior. Toward the end of the Venus Express mission, an aerobraking campaign took the spacecraft below the ionosphere into the very weakly electrically conducting atmosphere. As the spacecraft descended from 150 to 140 km altitude, the magnetic field became weaker on average and less noisy. Below 140 km, the median field strength became steady but the short period fluctuations continued to weaken. The weakness of the fluctuations indicates they might not be useful for electromagnetic sounding of the atmosphere from a high altitude platform such as a plane or balloon, but possibly could be attempted on a lander.

| S-EPMC4806375 | biostudies-other

Generation of gravity waves from thermal tides in the Venus atmosphere.

Project description:Gravity waves play essential roles in the terrestrial atmosphere because they propagate far from source regions and transport momentum and energy globally. Gravity waves are also observed in the Venus atmosphere, but their characteristics have been poorly understood. Here we demonstrate activities of small-scale gravity waves using a high-resolution Venus general circulation model with less than 20 and 0.25 km in the horizontal and vertical grid intervals, respectively. We find spontaneous gravity wave radiation from nearly balanced flows. In the upper cloud layer (~70 km), the thermal tides in the super-rotation are primary sources of small-scale gravity waves in the low-latitudes. Baroclinic/barotropic waves are also essential sources in the mid- and high-latitudes. The small-scale gravity waves affect the three-dimensional structure of the super-rotation and contribute to material mixing through their breaking processes. They propagate vertically and transport momentum globally, which decelerates the super-rotation in the upper cloud layer (~70 km) and accelerates it above ~80 km.

| S-EPMC8211692 | biostudies-literature

Redox state of Earth's magma ocean and its Venus-like early atmosphere.

Project description:Exchange between a magma ocean and vapor produced Earth's earliest atmosphere. Its speciation depends on the oxygen fugacity (fO2) set by the Fe3+/Fe2+ ratio of the magma ocean at its surface. Here, we establish the relationship between fO2 and Fe3+/Fe2+ in quenched liquids of silicate Earth-like composition at 2173 K and 1 bar. Mantle-derived rocks have Fe3+/(Fe3++Fe2+) = 0.037 ± 0.005, at which the magma ocean defines an fO2 0.5 log units above the iron-wüstite buffer. At this fO2, the solubilities of H-C-N-O species in the magma ocean produce a CO-rich atmosphere. Cooling and condensation of H2O would have led to a prebiotic terrestrial atmosphere composed of CO2-N2, in proportions and at pressures akin to those observed on Venus. Present-day differences between Earth's atmosphere and those of her planetary neighbors result from Earth's heliocentric location and mass, which allowed geologically long-lived oceans, in-turn facilitating CO2 drawdown and, eventually, the development of life.

| S-EPMC7688334 | biostudies-literature

Tracing the oxygen isotope composition of the upper Earth's atmosphere using cosmic spherules.

Project description:Molten I-type cosmic spherules formed by heating, oxidation and melting of extraterrestrial Fe,Ni metal alloys. The entire oxygen in these spherules sources from the atmosphere. Therefore, I-type cosmic spherules are suitable tracers for the isotopic composition of the upper atmosphere at altitudes between 80 and 115 km. Here we present data on I-type cosmic spherules collected in Antarctica. Their composition is compared with the composition of tropospheric O2. Our data suggest that the Earth's atmospheric O2 is isotopically homogenous up to the thermosphere. This makes fossil I-type micrometeorites ideal proxies for ancient atmospheric CO2 levels.

| S-EPMC5461487 | biostudies-literature

The Great Cold Spot in Jupiter's upper atmosphere.

Project description:Past observations and modeling of Jupiter's thermosphere have, due to their limited resolution, suggested that heat generated by the aurora near the poles results in a smooth thermal gradient away from these aurorae, indicating a quiescent and diffuse flow of energy within the subauroral thermosphere. Here we discuss Very Large Telescope-Cryogenic High-Resolution IR Echelle Spectrometer observations that reveal a small-scale localized cooling of ~200?K within the nonauroral thermosphere. Using Infrared Telescope Facility NSFCam images, this feature is revealed to be quasi-stable over at least a 15?year period, fixed in magnetic latitude and longitude. The size and shape of this "Great Cold Spot" vary significantly with time, strongly suggesting that it is produced by an aurorally generated weather system: the first direct evidence of a long-term thermospheric vortex in the solar system. We discuss the implications of this spot, comparing it with short-term temperature and density variations at Earth.

| S-EPMC5439487 | biostudies-other

Parker Solar Probe Imaging of the Night Side of Venus.

Project description:We present images of Venus from the Wide-Field Imager for Parker Solar Probe (WISPR) telescope on board the Parker Solar Probe (PSP) spacecraft, obtained during PSP's third and fourth flybys of Venus on 2020 July 11 and 2021 February 20, respectively. Thermal emission from the surface is observed on the night side, representing the shortest wavelength observations of this emission ever, the first detection of the Venusian surface by an optical telescope observing below 0.8 μm. Consistent with previous observations at 1 μm, the cooler highland areas are fainter than the surrounding lowlands. The irradiances measured by WISPR are consistent with model predictions assuming a surface temperature of T = 735 K. In addition to the thermal emission, the WISPR images also show bright nightglow emission at the limb, and we compare the WISPR intensities with previous spectroscopic measurements of the molecular oxygen nightglow lines from Venus Express.

| S-EPMC9286398 | biostudies-literature

Formation of nitrogenated organic aerosols in the Titan upper atmosphere.

Project description:Many aspects of the nitrogen fixation process by photochemistry in the Titan atmosphere are not fully understood. The recent Cassini mission revealed organic aerosol formation in the upper atmosphere of Titan. It is not clear, however, how much and by what mechanism nitrogen is incorporated in Titan's organic aerosols. Using tunable synchrotron radiation at the Advanced Light Source, we demonstrate the first evidence of nitrogenated organic aerosol production by extreme ultraviolet-vacuum ultraviolet irradiation of a N(2)/CH(4) gas mixture. The ultrahigh-mass-resolution study with laser desorption ionization-Fourier transform-ion cyclotron resonance mass spectrometry of N(2)/CH(4) photolytic solid products at 60 and 82.5 nm indicates the predominance of highly nitrogenated compounds. The distinct nitrogen incorporations at the elemental abundances of H(2)C(2)N and HCN, respectively, are suggestive of important roles of H(2)C(2)N/HCCN and HCN/CN in their formation. The efficient formation of unsaturated hydrocarbons is observed in the gas phase without abundant nitrogenated neutrals at 60 nm, and this is confirmed by separately using (13)C and (15)N isotopically labeled initial gas mixtures. These observations strongly suggest a heterogeneous incorporation mechanism via short lived nitrogenated reactive species, such as HCCN radical, for nitrogenated organic aerosol formation, and imply that substantial amounts of nitrogen is fixed as organic macromolecular aerosols in Titan's atmosphere.

| S-EPMC2906555 | biostudies-literature

The Upper Esophageal Sphincter Distensibility Index Measured Using Functional Lumen Imaging Probe Identifies Defective Barrier Function of the Upper Esophageal Sphincter.

Project description:Background/aimsThe mechanism via which supra-esophageal symptoms are generated is unclear. We assessed upper esophageal sphincter (UES) function in novel fashion using functional lumen imaging probe (FLIP) topography. We hypothesize that symptoms related to aspiration of esophageal contents may be associated with a more distensible UES.MethodsFLIP and reflux symptom index score data from patients undergoing diagnostic evaluation for an esophageal complaint over a 10-month period were analyzed retrospectively. UES distensibility on FLIP was studied at 40-70 mL volumes with in-depth analysis at 50 and 60 mL. Symptoms were compared between patients with low, middle, and high UES-distensibility index (UES-DI). Receiver-operating characteristic analysis was performed to determine associations between the UES-DI and individual reflux symptom index symptom item scores.ResultsOne hundred and eleven subjects were included. Overall, the associations between UES-DI and symptoms that could be related to supra-esophageal aspiration were strongest at the 50 mL FLIP volume. Choking item score was highest in the high UES-DI group (2.8) vs 1.4 (P < 0.001) in the middle UES-DI and 1.1 (P = 0.004) in the low UES-DI groups. Similarly, the cough item score was highest in the high UES-DI group (2.7) vs 1.5 (P = 0.009) and 0.9 (P = 0.002) groups.ConclusionA higher UES-DI measures defective barrier function which could may be the main pathophysiology that generates supra-esophageal symptoms.

| S-EPMC9274470 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data