Heat transport and ice sublimation in comets are interrelated processes reflecting properties acquired at the time of formation and during subsequent evolution. The Microwave Instrument on the ...Rosetta Orbiter (MIRO) acquired maps of the subsurface temperature of comet 67P/Churyumov-Gerasimenko, at 1.6 mm and 0.5 mm wavelengths, and spectra of water vapor. The total H2O production rate varied from 0.3 kg s-1 in early June 2014 to 1.2 kg s-1 in late August and showed periodic variations related to nucleus rotation and shape. Water outgassing was localized to the "neck" region of the comet. Subsurface temperatures showed seasonal and diurnal variations, which indicated that the submillimeter radiation originated at depths comparable to the diurnal thermal skin depth. A low thermal inertia (~10 to 50 J K-1 m-2 s-0.5), consistent with a thermally insulating powdered surface, is inferred.
Extrasolar satellites are generally too small to be detected by nominal searches. By analogy to the most active body in the solar system, Io, we describe how sodium (Na i) and potassium (K i) gas ...could be a signature of the geological activity venting from an otherwise hidden exo-Io. Analyzing ∼a dozen close-in gas giants hosting robust alkaline detections, we show that an Io-sized satellite can be stable against orbital decay below a planetary tidal . This tidal energy is also focused into the satellite driving an ∼105 2 higher mass-loss rate than Io's supply to Jupiter's Na exosphere based on simple atmospheric loss estimates. The remarkable consequence is that several exo-Io column densities are, on average, more than sufficient to provide the ∼1010 1 Na cm−2 required by the equivalent width of exoplanet transmission spectra. Furthermore, the benchmark observations of both Jupiter's extended (∼1000 RJ) Na exosphere and Jupiter's atmosphere in transmission spectroscopy yield similar Na column densities that are purely exogenic in nature. As a proof of concept, we fit the "high-altitude" Na at WASP-49b with an ionization-limited cloud similar to the observed Na profile about Io. Moving forward, we strongly encourage time-dependent ingress and egress monitoring along with spectroscopic searches for other volcanic volatiles.
We analyze albedo data obtained using the Herschel Space Observatory that reveal the existence of two distinct types of surface among midsized trans-Neptunian objects. A color-albedo diagram shows ...two large clusters of objects, one redder and higher albedo and another darker and more neutrally colored. Crucially, all objects in our sample located in dynamically stable orbits within the classical Kuiper Belt region and beyond are confined to the bright red group, implying a compositional link. Those objects are believed to have formed further from the Sun than the dark neutral bodies. This color-albedo separation is evidence for a compositional discontinuity in the young solar system.
Abstract
In the face of global warming, academics have started to consider and analyze the environmental and carbon footprint associated with their professional activity. Among the several sources of ...greenhouse gas emissions from research activities, air travel—one of the most visible and unequal fractions of this footprint—has received much attention. Of particular interest is the question of how air travel may be related to scientific success or visibility as defined by current academic evaluation norms, notably bibliometric indicators. Existing studies, conducted over a small sample of individuals or within specific disciplines, have demonstrated that the number of citations may be related to air-travel frequency, but have failed to identify a link between air travel and publication rate or
h
-index. Here, using a comprehensive dataset aggregating the answers from over 6000 respondents to a survey sent to randomly selected scientists and staff across all research disciplines in France, we show that higher individual air travel is associated with a stronger publication rate and
h
-index. This relationship is robust to the inclusion of the effects of gender, career stage, and disciplines. Our analysis suggests that flying is a means for early-career scientists to obtain scientific visibility, and for senior scientists to maintain this visibility.
Observations of the nucleus of 67P/Churyumov-Gerasimenko in the millimeter-wave continuum have been obtained by the Microwave Instrument for the Rosetta Orbiter (MIRO). We present data obtained at ...wavelengths of 0.5 mm and 1.6 mm during September 2014 when the nucleus was at heliocentric distances between 3.45 and 3.27 AU. The data are fit to simple models of the nucleus thermal emission in order to characterize the observed behavior and make quantitative estimates of important physical parameters, including thermal inertia and absorption properties at the MIRO wavelengths. MIRO brightness temperatures on the irregular surface of 67P are strongly affected by the local solar illumination conditions, and there is a strong latitudinal dependence of the mean brightness temperature as a result of the seasonal orientation of the comet’s rotation axis with respect to the Sun. The MIRO emission exhibits strong diurnal variations, which indicate that it arises from within the thermally varying layer in the upper centimeters of the surface. The data are quantitatively consistent with very low thermal inertia values, between 10–30 J K-1 m-2 s-1/2, with the 0.5 mm emission arising from 1 cm beneath the surface and the 1.6 mm emission from a depth of 4 cm. Although the data are generally consistent with simple, homogeneous models, it is difficult to match all of its features, suggesting that there may be some vertical structure within the upper few centimeters of the surface. The MIRO brightness temperatures at high northern latitudes are consistent with sublimation of ice playing an important role in setting the temperatures of these regions where, based on observations of gas and dust production, ice is known to be sublimating.
Abstract
The scrutiny over the carbon footprint of research and higher education has increased rapidly in the last few years. This has resulted in a series of publications providing various estimates ...of the carbon footprint of one or several research activities, principally at the scale of a university or a research center or, more recently, a field of research. The variety of tools or methodologies on which these estimates rely unfortunately prevents any aggregation or direct comparison. This is because carbon footprint assessments are very sensitive to key parameters (e.g., emission factors) or hypotheses (e.g., scopes). Hence, it is impossible to address fundamental questions such as: is the carbon footprint of research structurally different between disciplines? Are plane trips a major source of carbon emissions in academic research? Massive collection and curation of carbon footprint data, across a large array of research situations and disciplines, is hence an important, timely and necessary challenge to answer these questions. This paper presents a framework to collect and analyse large amounts of homogeneous research carbon emission data in a network of research entities at the national scale. It relies on an open-source web application,
GES 1point5
, designed to estimate the carbon footprint of a department, research lab or team in any country of the world. Importantly,
GES 1point5
is also designed to aggregate all input data and corresponding GHG emissions estimates into a comprehensive database.
GES 1point5
therefore enables (i) the identification of robust local or national determinants of the carbon footprint of research and (ii) the estimation of the carbon footprint of the entire research sector at national scale. A preliminary analysis of the carbon footprint of more than one hundred laboratories in France is presented to illustrate the potential of the framework. It shows that the average emissions are 479 t CO
2
e for a research lab and 3.6 t CO
2
e for an average lab member (respectively 404 and 3.1 t CO
2
e without accounting for the indirect radiative effects of aviation), with the current scope of
GES 1point5
. Availability and implementation:
GES 1point5
is available online at
http://labos1point5.org/ges-
1point5
and its source code can be downloaded from the GitLab platform at
https://framagit.org/
labos1point5/l1p5-vuejs
.
Titan’s atmospheric composition and dynamical state have previously been studied over numerous epochs by both ground- and space-based facilities. However, stratospheric measurements remain sparse ...during Titan’s northern summer and fall. The lack of seasonal symmetry in observations of Titan’s temperature field and chemical abundances raises questions about the nature of the middle atmosphere’s meridional circulation and evolution over Titan’s 29 yr seasonal cycle that can only be answered through long-term monitoring campaigns. Here, we present maps of Titan’s stratospheric temperature, acetonitrile (or methyl cyanide; CH _3 CN) abundance, and monodeuterated methane (CH _3 D) abundance following Titan’s northern summer solstice obtained with Band 9 (∼0.43 mm) Atacama Large Millimeter/submillimeter Array observations. We find that increasing temperatures toward high southern latitudes, currently in winter, resemble those observed during Titan’s northern winter by the Cassini mission. Acetonitrile abundances have changed significantly since previous (sub)millimeter observations, and we find that the species is now highly concentrated at high southern latitudes. The stratospheric CH _3 D content is found to range between 4 and 8 ppm in these observations, and we infer the CH _4 abundance to vary between ∼0.9% and 1.6% through conversion with previously measured D/H values. A global value of CH _4 = 1.15% was retrieved, lending further evidence to the temporal and spatial variability of Titan’s stratospheric methane when compared with previous measurements. Additional observations are required to determine the cause and magnitude of stratospheric enhancements in methane during these poorly understood seasons on Titan.
Spectro-imaging observations of on Jupiter Lellouch, Emmanuel
Philosophical transactions of the Royal Society of London. Series A: Mathematical, physical, and engineering sciences,
11/2006, Letnik:
364, Številka:
1848
Journal Article
Recenzirano
Narrow-band filter, high-spectral-resolution (0.2 cm, in, ) and vibrational (, emissions appear to be morphologically different, especially in the north, where the latter notably exhibits a ‘hot ...spot’
near, band, detected on Jupiter for the first time. They can be used to determine, ) spectro-imaging infrared observations of Jupiter's auroral zones, acquired in October 1999 and October 2000 with the FTS/BEAR
instrument at the Canada–France–Hawaii Telescope, have provided maps of the emission from the H, column densities, rotational (, column densities. The thermostatic role played by, lines, including two hot lines from the 3, =150–170° System III longitude. The spectra include a total of 14, =3 level with respect to local thermodynamical equilibrium. Rotational temperatures and associated column densities are generally
higher and lower, respectively, than inferred previously from, observations. These features can be explained by the combination of both a large positive temperature gradient in the sub-microbar
auroral atmosphere and non-local thermal equilibrium effects affecting preferentially hot and combination bands. Spatial variations
in line intensities are mostly owing to correlated variations in the, lines. H, ) temperatures. We find the mean, =3 state to be lower (960±50 K) than the mean, S, and, about 250 K higher than other regions., =2 (1170±75 K), indicating an underpopulation of the, at ionospheric levels may provide an explanation. The exception is the northern ‘hot spot’, which exhibits a, (1) quadrupole line and several, of the
Titan, the largest of Saturn's moons, shares remarkable similarities with Earth. Its thick atmosphere is composed primarily of nitrogen; it features the most complex organic chemistry known outside ...of Earth and, uniquely, hosts an analog to Earth's hydrological cycle, with methane forming clouds, rain and seas. Using the latest data from the ongoing Cassini–Huygens missions, laboratory measurements and numerical simulations, this comprehensive reference examines the physical processes that shape Titan's fascinating atmospheric structure and chemistry, weather, climate, circulation and surface geology. The text also surveys leading theories about Titan's origin and evolution, and assesses their implications for understanding the formation of other complex planetary bodies. Written by an international team of specialists, chapters offer detailed, comparative treatments of Titan's known properties and discuss the latest frontiers in the Cassini–Huygens mission, offering students and researchers of planetary science, geology, astronomy and space physics an insightful reference and guide.
The collapse of Io's primary atmosphere in Jupiter eclipse Tsang, Constantine C. C.; Spencer, John R.; Lellouch, Emmanuel ...
Journal of geophysical research. Planets,
August 2016, 2016-08-00, 20160801, 2016-08, Letnik:
121, Številka:
8
Journal Article
Recenzirano
Odprti dostop
Volcanic outgassing due to tidal heating is the ultimate source of a tenuous SO2 atmosphere around Jupiter's moon Io. The question of whether SO2 frost on the surface plays a part, and to what ...degree, in maintaining Io's atmosphere with the constant volcanic outgassing is still debated. It is believed that for a sublimation‐supported atmosphere, the primary atmosphere should collapse during eclipses by Jupiter, as the SO2 vapor pressure is strongly coupled to the temperature of the ice on the surface. No direct observations of Io's atmosphere in eclipse have previously been possible, due to the simultaneous need for high spectral and time sensitivity, as well as a high signal‐to‐noise ratio. Here we present the first ever high‐resolution spectra at 19 µm of Io's SO2 atmosphere in Jupiter eclipse from the Gemini telescope. The strongest atmospheric band depth is seen to dramatically decay from 2.5 ± (0.08)% before the eclipse to 0.18 ± (0.16)% after 40 min in eclipse. Further modeling indicates that the atmosphere has collapsed shortly after eclipse ingress, implying that the atmosphere of Io has a strong sublimation‐controlled component. The atmospheric column density—from pre‐eclipse to in‐eclipse—drops by a factor of 5 ± 2.
Key Points
Io's atmosphere observed by Gemini‐TEXES at 19 µm
SO2 band depths drop significantly in Jupiter eclipse
Modeling indicate primary, molecular atmosphere has collapsed, indicating ice sublimation support
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