The impact of the presence of water ice on the analysis of debris disk observations

Aims. Asteroid (31) Euphrosyne is one of the biggest objects in the asteroid main belt and it is also the largest member of its namesake family. The Euphrosyne family occupies a highly inclined region in the outer main belt and contains a remarkably large number of members, which is interpreted as an outcome of a disruptive cratering event. Methods. The goals of this adaptive-optics imaging study are threefold: to characterize the shape of Euphrosyne, to constrain its density, and to search for the large craters that may be associated with the family formation event. Results. We obtained disk-resolved images of Euphrosyne using SPHERE/ZIMPOL at the ESO 8.2 m VLT as part of our large program (ID: 199.C-0074, PI: Vernazza). We reconstructed its 3D shape via the ADAM shape modeling algorithm based on the SPHERE images and the available light curves of this asteroid. We analyzed the dynamics of the satellite with the Genoid meta-heuristic algorithm. Finally, we studied the shape of Euphrosyne using hydrostatic equilibrium models. Conclusions. Our SPHERE observations show that Euphrosyne has a nearly spherical shape with the sphericity index of 0.9888 and its surface lacks large impact craters. Euphrosyne’s diameter is 268 ± 6 km, making it one of the top ten largest main belt asteroids. We detected a satellite of Euphrosyne – S/2019 (31) 1 – that is about 4 km across, on a circular orbit. The mass determined from the orbit of the satellite together with the volume computed from the shape model imply a density of 1665 ± 242 kg m−3, suggesting that Euphrosyne probably contains a large fraction of water ice in its interior. We find that the spherical shape of Euphrosyne is a result of the reaccumulation process following the impact, as in the case of (10) Hygiea. However, our shape analysis reveals that, contrary to Hygiea, the axis ratios of Euphrosyne significantly differ from those suggested by fluid hydrostatic equilibrium following reaccumulation.

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ICE PROPULSION ABILITY OF VESSELS WITH NONTRADITIONAL FORM

Russian Journal of Water Transport ◽

10.37890/jwt.vi65.136 ◽

2020 ◽

pp. 143-156

Author(s):

Vasily A. Lobanov

Keyword(s):

Experimental Data ◽

Statistical Analysis ◽

Empirical Equation ◽

Main Attention ◽

Resistance Level ◽

Water Ice ◽

Ship Hulls ◽

The Impact ◽

Ice Resistance ◽

Different Thickness

In article the fact related to the significant increase in structure of the ice category fleet internal and mixed a river sea operation with non-traditional ship hulls forms is stated. With the CAE technologies use such vessels interaction nature with ice cakes and small ice cakes of different thickness and concentration in the ice channel is studied and analyzed. The main attention is paid to a research concerning the influence of different forms bulbous fore ends on change of the vessel ice resistance level. Qualitative features of such bulbous vessels contact with the water ice environment are noted. The statistical analysis concerning the obtained experimental data on the impact assessment related to constructive, dynamic and ice factors on ice propulsion ability of vessels with non-traditional forms is carried out. The quantitative forecast of such influence in the form of the multifactorial regression empirical equation is given.

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Upper limits on the water vapour content of the β Pictoris debris disk

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935655 ◽

2019 ◽

Vol 628 ◽

pp. A127 ◽

Cited By ~ 3

Author(s):

M. Cavallius ◽

G. Cataldi ◽

A. Brandeker ◽

G. Olofsson ◽

B. Larsson ◽

...

Keyword(s):

Solar System ◽

Far Infrared ◽

Kinetic Temperature ◽

Line Flux ◽

Water Vapour Content ◽

Water Ice ◽

Upper Limit ◽

Upper Limits ◽

Debris Disk ◽

Lower Limits

Context. The debris disk surrounding β Pictoris has been observed with ALMA to contain a belt of CO gas with a distinct peak at ~85 au. This CO clump is thought to be the result of a region of enhanced density of solids that collide and release CO through vaporisation. The parent bodies are thought to be comparable to solar system comets, in which CO is trapped inside a water ice matrix. Aims. Since H2O should be released along with CO, we aim to put an upper limit on the H2O gas mass in the disk of β Pictoris. Methods. We used archival data from the Heterodyne Instrument for the Far-Infrared (HIFI) aboard the Herschel Space Observatory to study the ortho-H2O 110–101 emission line. The line is undetected. Using a python implementation of the radiative transfer code RADEX, we converted upper limits on the line flux to H2O gas masses. The resulting lower limits on the CO/H2O mass ratio are compared to the composition of solar system comets. Results. Depending on the assumed gas spatial distribution, we find a 95% upper limit on the ortho-H2O line flux of 7.5 × 10−20 W m−2 or 1.2 × 10−19 W m−2. These translate into an upper limit on the H2O mass of 7.4 × 1016–1.1 × 1018 kg depending on both the electron density and gas kinetic temperature. The range of derived gas-phase CO/H2O ratios is marginally consistent with low-ratio solar system comets.

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Mesospheric dust and its secondary effects as observed by the ESPRIT payload

Annales Geophysicae ◽

10.5194/angeo-27-1119-2009 ◽

2009 ◽

Vol 27 (3) ◽

pp. 1119-1128 ◽

Cited By ~ 5

Author(s):

O. Havnes ◽

L. H. Surdal ◽

C. R. Philbrick

Keyword(s):

Charge Density ◽

Lower Layer ◽

Bound Water ◽

Impact Angle ◽

Dust Particles ◽

Height Range ◽

Dust Layer ◽

Water Ice ◽

Dust Charge ◽

The Impact

Abstract. The dust detector on the ESPRIT rocket detected two extended dust/aerosol layers during the launch on 1 July 2006. The lower layer at height ~81.5–83 km coincided with a strong NLC and PMSE layer. The maximum dust charge density was ~−3.5×109 e m−3 and the dust layer was characterized by a few strong dust layers where the dust charge density at the upper edges changed by factors 2–3 over a distance of ≲10 m, while the same change at their lower edges were much more gradual. The upper edge of this layer is also sharp, with a change in the probe current from zero to IDC=−10−11 A over ~10 m, while the same change at the low edge occurs over ~500 m. The second dust layer at ~85–92 km was in the height range of a comparatively weak PMSE layer and the maximum dust charge density was ~−108 e m−3. This demonstrates that PMSE can be formed even if the ratio of the dust charge density to the electron density P=NdZd /n_e≲0.01. In spite of the dust detector being constructed to reduce possible secondary charging effects from dust impacts, it was found that they were clearly present during the passage through both layers. The measured secondary charging effects confirm recent results that dust in the NLC and PMSE layers can be very effective in producing secondary charges with up to ~50 to 100 electron charges being rubbed off by one impacting large dust particle, if the impact angle is θi≳20–35°. This again lends support to the suggested model for NLC and PMSE dust particles (Havnes and Næsheim, 2007) as a loosely bound water-ice clump interspersed with a considerable number of sub-nanometer-sized meteoric smoke particles, possibly also contaminated with meteoric atomic species.

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Gas chromatography using ice-coated fused silica columns: study of adsorption of sulfur dioxide on water ice

Atmospheric Chemistry and Physics ◽

10.5194/acp-18-7527-2018 ◽

2018 ◽

Vol 18 (10) ◽

pp. 7527-7537 ◽

Cited By ~ 2

Author(s):

Stefan Langenberg ◽

Ulrich Schurath

Keyword(s):

Gas Chromatography ◽

Sulfur Dioxide ◽

Vertical Displacement ◽

Fused Silica ◽

Water Ice ◽

Temperature Range ◽

Reaction With Water ◽

The Impact ◽

Peak Retention Time ◽

Established Technique

Abstract. The well established technique of gas chromatography is used to investigate interactions of sulfur dioxide with a crystalline ice film in a fused silica wide bore column. Peak shape analysis of SO2 chromatograms measured in the temperature range 205–265 K is applied to extract parameters describing a combination of three processes: (i) physisorption of SO2 at the surface, (ii) dissociative reaction with water and (iii) slow uptake into bulk ice. Process (ii) is described by a dissociative Langmuir isotherm. The pertinent monolayer saturation capacity is found to increase with temperature. The impact of process (iii) on SO2 peak retention time is found to be negligible under our experimental conditions.By analyzing binary chromatograms of hydrophobic n-hexane and hydrophilic acetone, the premelt surface layer is investigated in the temperature range 221–263 K, possibly giving rise to irregular adsorption. Both temperature dependencies fit simple van't Hoff equations as expected for process (i), implying that irregular adsorption of acetone is negligible in the investigated temperature range. Adsorption enthalpies of −45 ± 5 and −23±2 kJ mol−1 are obtained for acetone and n-hexane.The motivation of our study was to assess the vertical displacement of SO2 and acetone in the wake of aircraft by adsorption on ice particles and their subsequent sedimentation. Our results suggest that this transport mechanism is negligible.

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Gas-Chromatography using ice coated fused silica-columns: Study of adsorption of sulfur dioxide on water-ice

10.5194/acp-2017-800 ◽

2017 ◽

Author(s):

Stefan Langenberg ◽

Ulrich Schurath

Keyword(s):

Gas Chromatography ◽

Sulfur Dioxide ◽

Vertical Displacement ◽

Fused Silica ◽

Experimental Conditions ◽

Water Ice ◽

Temperature Range ◽

Reaction With Water ◽

The Impact ◽

Peak Retention Time

Abstract. The well-established technique of gas chromatography is used to investigate interactions of sulfur dioxide with a crystalline ice film in a fused silica wide-bore column. Peak shape analysis of SO2 chromatograms measured in the temperature range 205–265 K is applied to extract parameters describing a combination of three processes: (i) physisorption of SO2 at the surface; (ii) dissociative reaction with water; (iii) slow uptake into bulk ice. Process (ii) is described by a dissociative Langmuir isotherm. The pertinent monolayer saturation capacity is found to increase with temperature. The impact of process (iii) on SO2 peak retention time is found to be negligible under our experimental conditions. By analyzing binary chromatograms of hydrophobic n-hexane and hydrophilic acetone, the premelt surface layer is probed in the temperature range 221–263 K possibly giving rise to irregular adsorption. Both temperature dependencies fit simple van't Hoff equations as expected for process (i), implying that irregular adsorption of acetone is negligible in the probed temperature range. Adsorption enthalpies of −45 &pm; 5 kJ mol−1 and −23 &pm; 2 kJ mol−1 are obtained for acetone and n-hexane. Our study was motivated to assess the vertical displacement of SO2 and acetone in the wake of aircraft by adsorption on ice particles and their subsequent sedimentation. Our results suggest that this transport mechanism is negligible.

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Constraining the detectability of water ice in debris disks

Astronomy and Astrophysics ◽

10.1051/0004-6361/201936014 ◽

2019 ◽

Vol 629 ◽

pp. A141

Author(s):

M. Kim ◽

S. Wolf ◽

A. Potapov ◽

H. Mutschke ◽

C. Jäger

Keyword(s):

Scattered Light ◽

Spectral Energy ◽

Debris Disks ◽

Water Ice ◽

Spatially Resolved ◽

Infrared Telescope ◽

Effective Medium Theories ◽

Debris Disk ◽

Highly Porous ◽

Entire Planet

Context. Water ice is important for the evolution and preservation of life. Identifying the distribution of water ice in debris disks is therefore of great interest in the field of astrobiology. Furthermore, icy dust grains are expected to play important roles throughout the entire planet formation process. However, currently available observations only allow deriving weak conclusions about the existence of water ice in debris disks. Aims. We investigate whether it is feasible to detect water ice in typical debris disk systems. We take the following ice destruction mechanisms into account: sublimation of ice, dust production through planetesimal collisions, and photosputtering by UV-bright central stars. We consider icy dust mixture particles with various shapes consisting of amorphous ice, crystalline ice, astrosilicate, and vacuum inclusions (i.e., porous ice grains). Methods. We calculated optical properties of inhomogeneous icy dust mixtures using effective medium theories, that is, Maxwell-Garnett rules. Subsequently, we generated synthetic debris disk observables, such as spectral energy distributions and spatially resolved thermal reemission and scattered light intensity and polarization maps with our code DMS. Results. We find that the prominent ~3 and 44 μm water ice features can be potentially detected in future observations of debris disks with the James Webb Space Telescope (JWST) and the Space Infrared telescope for Cosmology and Astrophysics (SPICA). We show that the sublimation of ice, collisions between planetesimals, and photosputtering caused by UV sources clearly affect the observational appearance of debris disk systems. In addition, highly porous ice (or ice-rich aggregates) tends to produce highly polarized radiation at around 3 μm. Finally, the location of the ice survival line is determined by various dust properties such as a fractional ratio of ice versus dust, physical states of ice (amorphous or crystalline), and the porosity of icy grains.

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Experimental Analysis of Heat Transfer From Ice Rink Floors

Solar Energy ◽

10.1115/isec2006-99133 ◽

2006 ◽

Author(s):

Jung Mun ◽

Moncef Krarti

Keyword(s):

Heat Transfer ◽

Thermal Resistance ◽

Thermal Insulation ◽

Air Temperature ◽

Experimental Analysis ◽

Experimental Results ◽

Water Ice ◽

Set Up ◽

Time Required ◽

The Impact

This paper describes an experimental set-up to evaluate the refrigeration loads for ice rink floors under controlled conditions. The ice-rink set-up was instrumented to measure the temperatures along various locations within the ice-rink floor including the water/ice layer. In addition, the energy used to freeze the water is monitored over the entire charging cycle to evaluate the performance of the ice rink floor for various insulation thermal resistance values (or R-values). Four floor insulation configurations are considered in the experimental analysis of R-0 (no insulation), R-4.2, R-6.7 and R-10 (in IP unit: hr.ft2.°F/Btu). The impact of the air temperature above the ice rink is also evaluated. The experimental results confirm that the addition of the thermal insulation beneath the ice-rink floor reduces the refrigeration load, decreased the time required to freeze the water above the ice rink, and helps maintain lower average ice temperature.

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Limits on methane release and generation via hypervelocity impact of Martian analogue materials

International Journal of Astrobiology ◽

10.1017/s1473550413000384 ◽

2013 ◽

Vol 13 (2) ◽

pp. 132-140 ◽

Cited By ~ 2

Author(s):

M. C. Price ◽

N. K. Ramkissoon ◽

S. McMahon ◽

K. Miljković ◽

J. Parnell ◽

...

Keyword(s):

Hypervelocity Impact ◽

Potential Mechanism ◽

Mars Atmosphere ◽

Water Ice ◽

Methane Release ◽

Basaltic Rocks ◽

Background Levels ◽

The Impact ◽

Impact Events ◽

Insight Into

AbstractThe quantity of methane in Mars' atmosphere, and the potential mechanism(s) responsible for its production, are still unknown. In order to test viable, abiotic, methangenic processes, we experimentally investigated two possible impact mechanisms for generating methane. In the first suite of experiments, basaltic rocks were impacted at 5 km s−1 and the quantity of gases (CH4, H2, He, N2, O2, Ar and CO2) released by the impacts was measured. In the second suite of experiments, a mixture of water ice, CO2 ice and anhydrous olivine grains was impacted to see if the shock induced rapid serpentinization of the olivine, and thus production of methane. The results of both suites of experiments demonstrate that impacts (at scales achievable in the laboratory) do not give rise to detectably enhanced quantities of methane release above background levels. Supporting hydrocode modelling was also performed to gain insight into the pressures and temperatures occurring during the impact events.

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Probing the impact of varied migration and gas accretion rates for the formation of giant planets in the pebble accretion scenario

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3629 ◽

2020 ◽

Vol 501 (2) ◽

pp. 2017-2028

Author(s):

N Ndugu ◽

B Bitsch ◽

A Morbidelli ◽

A Crida ◽

E Jurua

Keyword(s):

Semimajor Axis ◽

Small Mass ◽

Type I ◽

Type Ii ◽

Water Ice ◽

Low Viscosity ◽

Planetary Mass ◽

Gap Opening ◽

Gas Accretion ◽

The Impact

ABSTRACT The final orbital position of growing planets is determined by their migration speed, which is essentially set by the planetary mass. Small mass planets migrate in type-I migration, while more massive planets migrate in type-II migration, which is thought to depend mostly on the viscous evolution rate of the disc. A planet is most vulnerable to inward migration before it reaches type-II migration and can lose a significant fraction of its semimajor axis at this stage. We investigated the influence of different disc viscosities, the dynamical torque, and gas accretion from within the horseshoe region as mechanisms for slowing down planet migration. Our study confirms that planets growing in low viscosity environments migrate less, due to the earlier gap opening and slower type-II migration rate. We find that taking the gas accretion from the horseshoe region into account allows an earlier gap opening and this results in less inward migration of growing planets. Furthermore, this effect increases the planetary mass compared to simulations that do not take the effect of gas accretion from the horseshoe region. Moreover, combining the effect of the dynamical torque with the effect of gas accretion from the horseshoe region, significantly slows down inward migration. Taking these effects into account could allow the formation of cold Jupiters (a > 1 au) closer to the water ice line region compared to previous simulations that did not take these effects into account. We, thus, conclude that gas accretion from within the horseshoe region and the dynamical torque play crucial roles in shaping planetary systems.

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