The 3.1 μm absorption feature on asteroids (24) Themis and (65) Cybele is not due to surface water ice

Previous research on Asteroids (24) Themis and (65) Cybele have shown the presence of an absorption feature at 3.1 &#956;m reported to be directly linked to surface water ice. We searched for water vapor escaping from these asteroids with the Herschel Space Observatory HIFI (Heterodyne Instrument for the Far Infrared) Instrument. While no H2O line emission was detected, we obtained sensitive 3&#963; water production rate upper limits of Q(H2O)< 4.1&#215;1026 molecules s&#8722;1 for Themis and Q(H2O) <7.6 &#215; 1026 molecules s&#8722;1 for the case of Cybele. Using a thermophysical model, we merged data from the Subaru/Cooled Mid-Infrared Camera and Spectrometer and the Herschel SPIRE (Spectral and Photometric Imaging Receiver) instrument with the contents of a multi-observatory database and thus derived new radiometric properties for these two asteroids. For Themis, we obtained a thermal inertia G = 20 +25-10 J m&#8722;2 s&#8722;1/2 K&#8722;1, a diameter 192 +10-7 km, and a geometric V-band albedo pV=0.07&#177;0.01. For Cybele, we found a thermal inertia G = 25+28-19 J m&#8722;2 s&#8722;1/2 K&#8722;1, a diameter 282&#177;9 km, and an albedo pV=0.042&#177;0.005. Using all inputs, we estimated that water ice intimately mixed with the asteroids&#8217; dark surface material would cover <0.0017% (for Themis) and <0.0033% (for Cybele) of their surfaces, while an areal mixture with very clean ice (Bond albedo 0.8 for Themis and 0.7 for Cybele) would cover <2.2% (for Themis) and <1.5% (for Cybele) of their surfaces. Based on these very low percentage coverage values, it is clear that while surface (and subsurface) water ice may exist in small localized amounts on both asteroids, it is not the reason for the observed 3.1 &#956;m absorption feature.

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Low Water outgassing from (24) Themis and (65) Cybele – Implications on 3.1 µm water absorption spectra understanding

10.5194/epsc2020-719 ◽

2020 ◽

Author(s):

Laurence O'Rourke ◽

Thomas Müller ◽

Nicolas Biver ◽

Dominique Bockelée-Morvan ◽

Sunao Hasegawa ◽

...

Keyword(s):

Surface Water ◽

Line Emission ◽

Thermal Inertia ◽

Far Infrared ◽

Absorption Feature ◽

Water Ice ◽

V Band ◽

Upper Limits ◽

Thermophysical Model ◽

Water Production Rate

Asteroids (24) Themis and (65) Cybele have an absorption feature at 3.1 &#181;m reported to be directly linked to surface water ice. We searched for water vapour escaping from these asteroids with the Herschel Space Observatory Heterodyne Instrument for the Far Infrared (HIFI). While no H2O line emission was detected, we obtain sensitive 3&#963; water production rate upper limits of Q(H2O) < 4.1 &#215; 1026 mol. s&#8722;1 for Themis and Q(H2O) < 7.6 &#215; 1026 mol. s&#8722;1 for Cybele. Using a Thermophysical Model (TPM), we merge data from Subaru/Comics and Herschel/SPIRE with the contents of a multi-observatory database to derive new radiometric properties for these two asteroids. For Themis, we find a thermal inertia &#915; = 20+25-10 J m-2 s-1/2 K-1, a diameter 192 +10-7 km and a geometric V-band albedo pV = 0.07 &#177;0.01. For Cybele we obtain a thermal inertia &#915; = 25 +28-19 J m-2 s-1/2 K-1, a diameter 282 &#177; 9 km, and an albedo pV = 0.042&#177; 0.005. Using all inputs, we estimate that water ice intimately mixed with the asteroids&#8217; dark surface material would cover < 0.0017% for Themis and < 0.0033% for Cybele of their surfaces, while an areal mixture with very clean ice (bond albedo 0.8 for Themis and 0.7 for Cybele) would cover < 2.2% for Themis and < 1.5% for Cybele, of their surfaces. While surface (& sub-surface) water ice may exist in small localized amounts on both asteroids, it is not the reason for the observed 3.1&#181;m absorption feature.

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ISO: Asteroid Results and Thermophysical Modeling

Highlights of Astronomy ◽

10.1017/s1539299600017019 ◽

2005 ◽

Vol 13 ◽

pp. 749-751

Author(s):

Thomas G. Müller

Keyword(s):

Thermal Inertia ◽

Far Infrared ◽

Rotational Behaviour ◽

Sources Of Information ◽

Infrared Space Observatory ◽

Thermophysical Model ◽

Infrared Surveys ◽

Thermophysical Modeling ◽

Ir Photometry

AbstractThrough a recently developed thermophysical model, observations from the Infrared Space Observatory (ISO) were combined with visual photometry, lightcurves, close-up observations and direct measurement. In this way, many applications were possible, ranging from simple diameter and albedo determination of serendipitously seen asteroids to sophisticated studies of mineralogic aspects and regolith properties, like emissivity, roughness or thermal inertia for well-known asteroids. The possibility to combine all sources of information in one single model lead also to a better understanding of thermophysical effects, like beaming or the before/after opposition effect. Thus, the mineralogic signatures can be recognized easier and asteroid data from infrared surveys and individual IR photometry can be interpreted more accurately, even in cases where shape or rotational behaviour are not known. Some well-studied asteroids are now even considered as excellent far-infrared calibrators.

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Evaluation of Far Infrared Camera for Surface Image Velocimeter Versatile in Day and Night Measurement

Journal of Korea Water Resources Association ◽

10.3741/jkwra.2015.48.8.659 ◽

2015 ◽

Vol 48 (8) ◽

pp. 659-672 ◽

Cited By ~ 2

Author(s):

Yu Kwonkyu ◽

◽

Kim Seojun ◽

Yoo Byeongnam ◽

Bae Inhyuk

Keyword(s):

Infrared Camera ◽

Far Infrared ◽

Surface Image

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Ego-localization Robust for Illumination Condition Changes based on Far-infrared Camera and Millimeter-wave Radar Fusion

2020 IEEE 23rd International Conference on Intelligent Transportation Systems (ITSC) ◽

10.1109/itsc45102.2020.9294170 ◽

2020 ◽

Author(s):

Haruya Kyutoku ◽

Tokihiko Akita ◽

Seiichi Mita

Keyword(s):

Millimeter Wave ◽

Infrared Camera ◽

Far Infrared ◽

Illumination Condition ◽

Millimeter Wave Radar ◽

Wave Radar

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A thermophysical and dynamical study of the Hildas (1162) Larissa and (1911) Schubart

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab251 ◽

2021 ◽

Author(s):

Cristian F Chavez ◽

T G Müller ◽

J P Marshall ◽

J Horner ◽

H Drass ◽

...

Keyword(s):

Thermal Inertia ◽

Infrared Camera ◽

Asteroid Belt ◽

Effective Diameter ◽

Early Solar System ◽

Dynamical Study ◽

Axis Ratio ◽

Ellipsoidal Shape ◽

Dynamical Simulations ◽

Taxonomical Classification

Abstract The Hilda asteroids are among the least studied populations in the asteroid belt, despite their potential importance as markers of Jupiter’s migration in the early Solar system. We present new mid-infrared observations of two notable Hildas, (1162) Larissa and (1911) Schubart, obtained using the Faint Object infraRed CAmera for the SOFIA Telescope (FORCAST), and use these to characterise their thermal inertia and physical properties. For (1162) Larissa, we obtain an effective diameter of 46.5$^{+2.3}_{-1.7}$ km, an albedo of 0.12 ± 0.02, and a thermal inertia of 15$^{+10}_{-8}$ Jm−2s1/2K−1. In addition, our Larissa thermal measurements are well matched with an ellipsoidal shape with an axis ratio a/b=1.2 for the most-likely spin properties. Our modelling of (1911) Schubart is not as refined, but the thermal data point towards a high-obliquity spin-pole, with a best-fit a/b=1.3 ellipsoidal shape. This spin-shape solution is yielding a diameter of 72$^{+3}_{-4}$ km, an albedo of 0.039± 0.02, and a thermal inertia below 30 Jm−2s1/2K−1 (or 10$^{+20}_{-5}$ Jm−2s1/2K−1). As with (1162) Larissa, our results suggest that (1911) Schubart is aspherical, and likely elongated in shape. Detailed dynamical simulations of the two Hildas reveal that both exhibit strong dynamical stability, behaviour that suggests that they are primordial, rather than captured objects. The differences in their albedos, along with their divergent taxonomical classification, suggests that despite their common origin, the two have experienced markedly different histories.

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Nitrogen patterns in subsurface waters of the Yzeron stream: effect of combined sewer overflows and subsurface–surface water mixing

Water Science & Technology ◽

10.2166/wst.2013.531 ◽

2013 ◽

Vol 68 (12) ◽

pp. 2632-2637 ◽

Cited By ~ 1

Author(s):

A. M. Aucour ◽

T. Bariac ◽

P. Breil ◽

P. Namour ◽

L. Schmitt ◽

...

Keyword(s):

Surface Water ◽

Cold Season ◽

Low Flow ◽

Subsurface Water ◽

Urban Stream ◽

Nitrogen Forms ◽

Combined Sewer Overflows ◽

Combined Sewer ◽

Subsurface Waters ◽

Sewer Overflows

Urbanization subjects streams to increased nitrogen loads. Therefore studying nitrogen forms at the interface between urban stream and groundwater is important for water resource management. In this study we report results on water δ18O and nitrogen forms in subsurface waters of a stream (Yzeron, France). The sites studied were located upstream and downstream of combined sewer overflows (CSO) in a rural area and a periurban area, respectively. Water δ18O allowed us to follow the mixing of subsurface water with surface water. Dissolved organic nitrogen and organic carbon of fine sediment increased by 20–30% between rural and periurban subsurface waters in the cold season, under high flow. The highest nitrate levels were observed in rural subsurface waters in the cold season. The lowest nitrate levels were found in periurban subsurface waters in the warm season, under low flow. They corresponded to slow exchange of subsurface waters with channel water. Thus reduced exchange between surface and subsurface waters and organic-matter-rich input seemed to favor nitrate reduction in the downstream, periurban, subsurface waters impacted by CSO.

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“TNOs are Cool”: A survey of the trans-Neptunian region

Astronomy and Astrophysics ◽

10.1051/0004-6361/201732564 ◽

2018 ◽

Vol 618 ◽

pp. A136 ◽

Cited By ~ 7

Author(s):

E. Vilenius ◽

J. Stansberry ◽

T. Müller ◽

M. Mueller ◽

C. Kiss ◽

...

Keyword(s):

Power Law ◽

Total Mass ◽

Size Range ◽

Family Members ◽

Far Infrared ◽

Effective Diameter ◽

Water Ice ◽

The Family ◽

The Individual ◽

Geometric Albedo

Context. A group of trans-Neptunian objects (TNOs) are dynamically related to the dwarf planet 136108 Haumea. Ten of them show strong indications of water ice on their surfaces, are assumed to have resulted from a collision, and are accepted as the only known TNO collisional family. Nineteen other dynamically similar objects lack water ice absorptions and are hypothesized to be dynamical interlopers. Aims. We have made observations to determine sizes and geometric albedos of six of the accepted Haumea family members and one dynamical interloper. Ten other dynamical interlopers have been measured by previous works. We compare the individual and statistical properties of the family members and interlopers, examining the size and albedo distributions of both groups. We also examine implications for the total mass of the family and their ejection velocities. Methods. We use far-infrared space-based telescopes to observe the target TNOs near their thermal peak and combine these data with optical magnitudes to derive sizes and albedos using radiometric techniques. Using measured and inferred sizes together with ejection velocities, we determine the power-law slope of ejection velocity as a function of effective diameter. Results. The detected Haumea family members have a diversity of geometric albedos ~0.3–0.8, which are higher than geometric albedos of dynamically similar objects without water ice. The median geometric albedo for accepted family members is pV = 0.48−0.18+0.28, compared to 0.08−0.05+0.07 for the dynamical interlopers. In the size range D = 175−300 km, the slope of the cumulative size distribution is q = 3.2−0.4+0.7 for accepted family members, steeper than the q = 2.0 ± 0.6 slope for the dynamical interlopers with D < 500 km. The total mass of Haumea’s moons and family members is 2.4% of Haumea’s mass. The ejection velocities required to emplace them on their current orbits show a dependence on diameter, with a power-law slope of 0.21–0.50.

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Molecular gas in the Herschel-selected strongly lensed submillimeter galaxies at z ~ 2–4 as probed by multi-J CO lines

Astronomy and Astrophysics ◽

10.1051/0004-6361/201731391 ◽

2017 ◽

Vol 608 ◽

pp. A144 ◽

Cited By ~ 41

Author(s):

C. Yang ◽

A. Omont ◽

A. Beelen ◽

Y. Gao ◽

P. van der Werf ◽

...

Keyword(s):

Star Formation ◽

High Redshift ◽

Line Emission ◽

Far Infrared ◽

Molecular Gas ◽

Kinetic Temperature ◽

Large Area ◽

Line Energy ◽

Submillimeter Galaxies ◽

Dust Mass

We present the IRAM-30 m observations of multiple-J CO (Jup mostly from 3 up to 8) and [C I](3P2 → 3P1) ([C I](2–1) hereafter) line emission in a sample of redshift ~2–4 submillimeter galaxies (SMGs). These SMGs are selected among the brightest-lensed galaxies discovered in the Herschel-Astrophysical Terahertz Large Area Survey (H-ATLAS). Forty-seven CO lines and 7 [C I](2–1) lines have been detected in 15 lensed SMGs. A non-negligible effect of differential lensing is found for the CO emission lines, which could have caused significant underestimations of the linewidths, and hence of the dynamical masses. The CO spectral line energy distributions (SLEDs), peaking around Jup ~ 5–7, are found to be similar to those of the local starburst-dominated ultra-luminous infrared galaxies and of the previously studied SMGs. After correcting for lensing amplification, we derived the global properties of the bulk of molecular gas in the SMGs using non-LTE radiative transfer modelling, such as the molecular gas density nH2 ~ 102.5–104.1 cm-3 and the kinetic temperature Tk ~ 20–750 K. The gas thermal pressure Pth ranging from~105 K cm-3 to 106 K cm-3 is found to be correlated with star formation efficiency. Further decomposing the CO SLEDs into two excitation components, we find a low-excitation component with nH2 ~ 102.8–104.6 cm-3 and Tk ~ 20–30 K, which is less correlated with star formation, and a high-excitation one (nH2 ~ 102.7–104.2 cm-3, Tk ~ 60–400 K) which is tightly related to the on-going star-forming activity. Additionally, tight linear correlations between the far-infrared and CO line luminosities have been confirmed for the Jup ≥ 5 CO lines of these SMGs, implying that these CO lines are good tracers of star formation. The [C I](2–1) lines follow the tight linear correlation between the luminosities of the [C I](2–1) and the CO(1–0) line found in local starbursts, indicating that [C I] lines could serve as good total molecular gas mass tracers for high-redshift SMGs as well. The total mass of the molecular gas reservoir, (1–30) × 1010M⊙, derived based on the CO(3–2) fluxes and αCO(1–0) = 0.8 M⊙ ( K km s-1 pc2)-1, suggests a typical molecular gas depletion time tdep ~ 20–100 Myr and a gas to dust mass ratio δGDR ~ 30–100 with ~20%–60% uncertainty for the SMGs. The ratio between CO line luminosity and the dust mass L′CO/Mdust appears to be slowly increasing with redshift for high-redshift SMGs, which need to be further confirmed by a more complete SMG sample at various redshifts. Finally, through comparing the linewidth of CO and H2O lines, we find that they agree well in almost all our SMGs, confirming that the emitting regions of the CO and H2O lines are co-spatially located.

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Transient flow between aquifers and surface water: analytically derived field-scale hydraulic heads and fluxes

Hydrology and Earth System Sciences ◽

10.5194/hess-16-649-2012 ◽

2012 ◽

Vol 16 (3) ◽

pp. 649-669 ◽

Cited By ~ 2

Author(s):

G. H. de Rooij

Keyword(s):

Surface Water ◽

Transient Flow ◽

Hydrological Cycle ◽

Realistic Model ◽

Water Levels ◽

Subsurface Water ◽

Water Model ◽

Infinite Strip ◽

Catchment Scale ◽

Basin Scale

Abstract. The increasing importance of catchment-scale and basin-scale models of the hydrological cycle makes it desirable to have a simple, yet physically realistic model for lateral subsurface water flow. As a first building block towards such a model, analytical solutions are presented for horizontal groundwater flow to surface waters held at prescribed water levels for aquifers with parallel and radial flow. The solutions are valid for a wide array of initial and boundary conditions and additions or withdrawals of water, and can handle discharge into as well as lateral infiltration from the surface water. Expressions for the average hydraulic head, the flux to or from the surface water, and the aquifer-scale hydraulic conductivity are developed to provide output at the scale of the modelled system rather than just point-scale values. The upscaled conductivity is time-variant. It does not depend on the magnitude of the flux but is determined by medium properties as well as the external forcings that drive the flow. For the systems studied, with lateral travel distances not exceeding 10 m, the circular aquifers respond very differently from the infinite-strip aquifers. The modelled fluxes are sensitive to the magnitude of the storage coefficient. For phreatic aquifers a value of 0.2 is argued to be representative, but considerable variations are likely. The effect of varying distributions over the day of recharge damps out rapidly; a soil water model that can provide accurate daily totals is preferable over a less accurate model hat correctly estimates the timing of recharge peaks.

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