Search results for "Planetary Science"
showing 10 items of 4367 documents
Contribution of environmental factors to temperature distribution at different resolution levels on the forefield of the Loven Glaciers (Svalbard)
2007
ABSTRACTThe climate and its components (temperature and precipitation) are organised according to different spatial scales that are structured hierarchically. The aim of this paper is to explore the dependence between temperature and deterministic factors at different scales on a 10 km2 study area on the northwestern coast of Svalbard. A GIS was developed which contained three sources of information: temperature, remotely sensed imagery and digital elevation models (DEM), and derived raster data layers. The first layer, temperatures, was acquired at regularly observed temporal intervals from 53 stations. The second layer comprised remotely sensed images (aerial photography and SPOT imagery)…
Ocean Acidification and the End-Permian Mass Extinction: To What Extent does Evidence Support Hypothesis?
2012
International audience; Ocean acidification in modern oceans is linked to rapid increase in atmospheric CO 2 , raising concern about marine diversity, food security and ecosystem services. Proxy evidence for acidification during past crises may help predict future change, but three issues limit confidence of comparisons between modern and ancient ocean acidification, illustrated from the end-Permian extinction, 252 million years ago: (1) problems with evidence for ocean acidification preserved in sedimentary rocks, where proposed marine dissolution surfaces may be subaerial. Sedimentary evidence that the extinction was partly due to ocean acidification is therefore inconclusive; (2) Fossils…
THEMIS: A Parameter Estimation Framework for the Event Horizon Telescope
2020
This is an open access article.-- Full list of authors: Broderick, Avery E.; Gold, Roman; Karami, Mansour; Preciado-López, Jorge A.; Tiede, Paul; Pu, Hung-Yi; Akiyama, Kazunori; Alberdi, Antxon; Alef, Walter; Asada, Keiichi; Azulay, Rebecca; Baczko, Anne-Kathrin; Baloković, Mislav; Barrett, John; Bintley, Dan; Blackburn, Lindy; Boland, Wilfred; Bouman, Katherine L.; Bower, Geoffrey C.; Bremer, Michael; Brinkerink, Christiaan D.; Brissenden, Roger; Britzen, Silke; Broguiere, Dominique; Bronzwaer, Thomas; Byun, Do-Young; Carlstrom, John E.; Chael, Andrew; Chatterjee, Shami; Chatterjee, Koushik; Chen, Ming-Tang; Chen, Yongjun; Cho, Ilje; Conway, John E.; Cordes, James M.; Crew, Geoffrey B.; Cu…
Blast waves from violent explosive activity at Yasur Volcano, Vanuatu
2013
[1] Infrasonic and seismic waveforms were collected during violent strombolian activity at Yasur Volcano (Vanuatu). Averaging ~3000 seismic events showed stable waveforms, evidencing a low-frequency (0.1–0.3 Hz) signal preceding ~5–6 s the explosion. Infrasonic waveforms were mostly asymmetric with a sharp compressive (5–106 Pa) onset, followed by a small long-lasting rarefaction phase. Regardless of the pressure amplitude, the ratio between the positive and negative phases was constant. These waveform characteristics closely resembled blast waves. Infrared imagery showed an apparent cold spherical front ~20 m thick, which moved between 342 and 405 m/s before the explosive hot gas/fragments…
Slender Ca II H fibrils mapping magnetic fields in the low solar chromosphere
2017
S. Jafarzadeh et. al.
Diving into exoplanets: Are water seas the most common?
2019
One of the basic tenets of exobiology is the need for a liquid substratum in which life can arise, evolve, and develop. The most common version of this idea involves the necessity of water to act as such a substratum, both because that is the case on Earth and because it seems to be the most viable liquid for chemical reactions that lead to life. Other liquid media that could harbor life, however, have occasionally been put forth. In this work, we investigate the relative probability of finding superficial seas on rocky worlds that could be composed of nine different, potentially abundant, liquids, including water. We study the phase space size of habitable zones defined for those substance…
Plasma sloshing in pulse-heated solar and stellar coronal loops
2016
There is evidence that coronal heating is highly intermittent, and flares are the high energy extreme. The properties of the heat pulses are difficult to constrain. Here hydrodynamic loop modeling shows that several large amplitude oscillations (~ 20% in density) are triggered in flare light curves if the duration of the heat pulse is shorter that the sound crossing time of the flaring loop. The reason is that the plasma has not enough time to reach pressure equilibrium during the heating and traveling pressure fronts develop. The period is a few minutes for typical solar coronal loops, dictated by the sound crossing time in the decay phase. The long period and large amplitude make these os…
Morphological Properties of Slender Ca ${\rm{II}}$ H Fibrils Observed by Sunrise II
2017
R. Gafeira et. al.
Bright Hot Impacts by Erupted Fragments Falling Back on the Sun: Magnetic Channelling
2016
Dense plasma fragments were observed to fall back on the solar surface by the Solar Dynamics Observatory after an eruption on 7 June 2011, producing strong EUV brightenings. Previous studies investigated impacts in regions of weak magnetic field. Here we model the $\sim~300$ km/s impact of fragments channelled by the magnetic field close to active regions. In the observations, the magnetic channel brightens before the fragment impact. We use a 3D-MHD model of spherical blobs downfalling in a magnetized atmosphere. The blob parameters are constrained from the observation. We run numerical simulations with different ambient density and magnetic field intensity. We compare the model emission i…
A tale of two emergences: Sunrise II observations of emergence sites in a solar active region
2017
R. Centeno et. al.