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We present the first comprehensive study of NaCl and KCl gases in Io’s atmosphere in order to investigate their characteristics and infer properties of Io’s volcanoes and subsurface magma chambers. In this work, we compile all past spectral line observations of NaCl and KCl in Io's atmosphere from the Atacama Large Millimeter/submillimeter Array and use atmospheric models to constrain the physical properties of the gases on several dates between 2012 and 2018. NaCl and KCl appear to be largely spatially confined, and for observations with high spectral resolution, the temperatures are high (∼500–1000 K), implying a volcanic origin. The ratio of NaCl:KCl was found to be ∼5–6 in 2015 June and ∼3.5–10 in 2016 June, which is consistent with predictions based on observations of Io's extended atmosphere and less than half the Na/K ratio in chondrites. Assuming these gases are volcanic in origin, these ratios imply a magma temperature of ∼1300 K, such that the magma will preferentially outgas KCl over NaCl.

Saturn's cloud-top zonal winds have been measured since the Voyager days. Contrary to Jupiter, the jets are mostly prograde and with a noticeable broad super-rotating jet between 35°S and 35°N with peak velocities reaching ~450 m/s between 10°S and 10°N (e.g. Sanchez-Lavega et al. 2000). The Cassini mission revealed, during its Grand Finale, that these winds extend as deep as 8000 km below the clouds (Galanti et al. 2019). Above the tropopause, in the stratosphere, there has been no direct determination of the zonal winds, although thermal wind balance calculations have shown the signature of Saturn's semi-annual oscillation (SAO) in the tropical zone (Fouchet et al. 2008, Guerlet et al. 2011, 2018). These derivations lack an initial condition, in terms of wind speeds, located in the sensitivity zone of the temperature measurements. It thus remains unknown if the SAO jets alternate in direction as a function of altitude. In addition, more and more sophisticated general circulation models are being developed to constrain the dynamics of Saturn's stratosphere (Friedson & Moses 2012, Spiga et al. 2020, Bardet et al. 2021). These models now crucially need observational constraints. We used the Atacama Large Millimeter/submillimeter Array (ALMA) to map Saturn's stratospheric zonal winds. We derive the zonal winds as a function of latitude from the Doppler shifts induced by the winds on the spatially and spectrally resolved spectral lines. In this paper, we will present and discuss our results.

The detection of phosphine (PH3) in the atmosphere of Venus has been recently reported based on millimeter-wave radio observations (Greaves et al. 2020), and its re-analyses (Greaves et al. 2021a/b). In this Matters Arising we perform an independent reanalysis, identifying several issues in the interpretation of the spectroscopic data. As a result, we determine sensitive upper-limits for PH3 in Venus' atmosphere (>75 km, above the cloud decks) that are discrepant with the findings in G2020 and G2021a/b. The measurements target the fundamental first rotational transition of PH3 (J=1-0) at 266.944513 GHz, which was observed with the James Clerk Maxwell Telescope (JCMT) in June 2017 and with the Atacama Large Millimeter/submillimeter Array (ALMA) in March 2019. This line's center is near the SO2 (J=309,21-318,24) transition at 266.943329 GHz (only 1.3 km/s away from the PH3 line) which represents a potential source of contamination. The JCMT and ALMA data, as presented in G2020, are at spectral resolutions comparable to the frequency separation of the two lines. Moreover, the spectral features identified are several km/s in width, and therefore do not permit distinct spectroscopic separation of the candidate spectral lines of PH3 and SO2. We present the radiative transfer modelling we have performed and then discuss the ALMA and JCMT analyses in turn.

Ground-based interferometry at mm-cm wavelengths provides a powerful tool for characterizing satellite surfaces and atmospheres. We present the science enabled by the ALMA (current) and ngVLA (proposed) arrays, including recent results as well as future work in the context of planned and proposed spacecraft missions.

We present thermal observations of Ganymede from the Atacama Large Millimeter Array (ALMA) in 2016-2019 at a spatial resolution of 300-900 km (0.1-0.2'' angular resolution) and frequencies of 97.5, 233, and 343.5 GHz (wavelengths of 3, 1.3, and 0.87 mm); the observations collectively covered all Ganymede longitudes. We determine the global thermophysical properties using a thermal model that considers subsurface emission and depth- and temperature-dependent thermophysical and dielectric properties, in combination with a retrieval algorithm. The data are sensitive to emission from the upper $\sim$0.5 meter of the surface, and we find a millimeter emissivity of 0.75-0.78 and (sub)surface porosities of 10-40%, corresponding to effective thermal inertias of 400-800 J m^{-2} K^{-1} s^{-1/2}. Combined with past infrared results, as well as modeling presented here of a previously-unpublished Galileo PPR nighttime infrared observation, the multi-wavelength constraints are consistent with a compaction profile whereby the porosity drops from ~85% at the surface to 10{+30/-10}% at depth over a compaction length scale of tens of cm. We present maps of temperature residuals from the best-fit global models which indicate localized variations in thermal surface properties at some (but not all) dark terrains and at impact craters, which appear 5-8 K colder than the model. Equatorial regions are warmer than predicted by the model, in particular near the centers of the leading and trailing hemispheres, while the mid-latitudes (~30-60 degrees) are generally colder than predicted; these trends are suggestive of an exogenic origin., Comment: Fixed typo in Eqn 1; article published in Planetary Science Journal, Vol 2, Issue 1, id.5 (Feb 2021)

Following the detection of CO and HCN in Pluto's atmosphere, we report on new ALMA observations of Pluto with two main goals: (i) obtaining spatially-resolved measurements (~0.06'' on the ~0.15'' disk subtended by Pluto and its atmosphere) of CO(3-2) and HCN(4-3) (ii) targetting new chemical compounds, primarily hydrogen isocyanide (HNC). The CO line shows an absorption core at beam positions within Pluto's disk, a direct signature of Pluto's cold mesosphere. Analysis provides tentative evidence for a non-uniform temperature field in the lower atmosphere (near 30 km), with summer pole latitudes being 7$\pm$3.5 K warmer than low latitudes. This unexpected result may point to shorter radiative timescales in the atmosphere than previously thought. The HCN emission is considerably more extended than CO, peaking at radial distances beyond Pluto limb, and providing a new method to determine Pluto's HCN vertical profile in 2017. The mean (column-averaged) location of HCN is at 690+/-75 km altitude, with an upper atmosphere (> 800 km) mixing ratio of ~ 1.8 x 10$^{-4}$. Little or no HCN (, Icarus, accepted. 37 pages, including 15 figures. Abstract slightly rewritten to fit with character limit

We present 1-mm observations constructed from ALMA [Atacama Large (sub)Millimeter Array] data of SO$_2$, SO and KCl when Io went from sunlight into eclipse (20 March 2018), and vice versa (2 and 11 September 2018). There is clear evidence of volcanic plumes on 20 March and 2 September. The plumes distort the line profiles, causing high-velocity ($\gtrsim$500 m/s) wings, and red/blue-shifted shoulders in the line profiles. During eclipse ingress, the SO$_2$ flux density dropped exponentially, and the atmosphere reformed in a linear fashion when re-emerging in sunlight, with a "post-eclipse brightening" after $\sim$10 minutes. While both the in-eclipse decrease and in-sunlight increase in SO was more gradual than for SO$_2$, the fact that SO decreased at all is evidence that self-reactions at the surface are important and fast, and that in-sunlight photolysis of SO$_2$ is the dominant source of SO. Disk-integrated SO$_2$ in-sunlight flux densities are $\sim$2--3 times higher than in-eclipse, indicative of a roughly 30--50\% contribution from volcanic sources to the atmosphere. Typical column densities and temperatures are $N \approx (1.5 \pm 0.3) \times 10^{16}$ cm$^{-2}$ and $T \approx 220-320$ K both in-sunlight and in-eclipse, while the fractional coverage of the gas is 2--3 times lower in-eclipse than in-sunlight. The low level SO$_2$ emissions present during eclipse may be sourced by stealth volcanism or be evidence of a layer of non-condensible gases preventing complete collapse of the SO$_2$ atmosphere. The melt in magma chambers at different volcanoes must differ in composition to explain the absence of SO and SO$_2$, but simultaneous presence of KCl over Ulgen Patera., 20 pages, 15 figures. Planetary Science Journal, 2020, In Press

We observed Ceres at three epochs in 2015 November and 2017 September and October with ALMA 12-meter array and in 2017 October with the ALMA Compact Array (ACA), all at ~265 GHz continuum (wavelengths of ~1.1 mm) to map the temperatures of Ceres over a full rotation at each epoch. We also used 2017 October ACA observations to search for HCN. The disk-averaged brightness temperature of Ceres is measured to be between 170 K and 180 K during our 2017 observations. The rotational lightcurve of Ceres shows a double peaked shape with an amplitude of about 4%. Our HCN search returns a negative result with an upper limit production rate of ~2$\times$10$^{24}$ molecules s$^{-1}$, assuming globally uniform production and a Haser model. A thermophysical model suggests that Ceres's top layer has higher dielectric absorption than lunar-like materials at a wavelength of 1 mm. However, previous observations showed that the dielectric absorption of Ceres decreases towards longer wavelengths. Such distinct dielectric properties might be related to the hydrated phyllosilicate composition of Ceres and possibly abundant $\mu$m-sized grains on its surface. The thermal inertia of Ceres is constrained by our modeling as likely being between 40 and 160 tiu, much higher than previous measurements at infrared wavelengths. Modeling also suggests that Ceres's lightcurve is likely dominated by spatial variations in its physical or compositional properties that cause changes in Ceres's observed thermal properties and dielectric absorption as it rotates., Comment: 21 pages, 4 figures, 3 tables

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) $\textit{gas}$ could be a signature of the geological activity venting from an otherwise hidden exo-Io. Analyzing $\sim$ 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 $\mathcal{Q}_p \lesssim 10^{11}$. This tidal energy is focused into the satellite driving a $\sim 10^{5 \pm 2}$ 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 $\textit{more than sufficient}$ to provide the $\sim$ 10$^{10 \pm 1}$ Na cm$^{-2}$ required by the equivalent width of exoplanet transmission spectra. Furthermore, the benchmark observations of both Jupiter's extended ($\sim 1000$ R$_J$) 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 49-b 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., Comment: 23 pages, 5 figures, accepted to ApJ

Io’s atmosphere is predominately SO 2 that is sustained by a combination of volcanic outgassing and sublimation. The loss from the atmosphere is the main mass source for Jupiter’s large magnetosphere. Numerous previous studies attributed various transient phenomena in Io’s environment and Jupiter’s magnetosphere to a sudden change in the mass loss from the atmosphere supposedly triggered by a change in volcanic activity. Since the gas in volcanic plumes does not escape directly, such causal correlation would require a transient volcano-induced change in atmospheric abundance, which has never been observed so far. Here we report four observations of atmospheric SO 2 and NaCl from the same hemisphere of Io, obtained with the IRAM NOEMA interferometer on 11 December 2016, 14 March, 6 and 29 April 2017. These observations are compared to measurements of volcanic hot spots and Io’s neutral and plasma environment. We find a stable NaCl column density in Io’s atmosphere on the four dates. The SO 2 column density derived for December 2016 is about 30% lower compared to the SO 2 column density found in the period of March to April 2017. This increase in SO 2 from December 2016 to March 2017 might be related to increasing volcanic activity observed at several sites in spring 2017, but the stability of the volcanic trace gas NaCl and resulting decrease in NaCl/SO 2 ratio do not support this interpretation. Observed dimmings in both the sulfur ion torus and Na neutral cloud suggest rather a decrease in mass loading in the period of increasing SO 2 abundance. The dimming Na brightness and stable atmospheric NaCl furthermore dispute an earlier suggested positive correlation of the sodium cloud and the hot spot activity at Loki Patara, which considerably increased in this period. The environment of Io overall appears to be in a rather quiescent state, preventing further conclusions. Only Jupiter’s aurora morphology underwent several short-term changes, which are apparently unrelated to Io’s quiescent environment or the relatively stable atmosphere.

arXiv:1903.12116v1 [astro-ph.EP] for this version [v1] Thu, 28 Mar 2019 17:01:33 UTC (3,201 KB), The presence of winds in Titan’s lower and middle atmosphere has been determined by a variety of techniques, including direct measurements from the Huygens Probe1 over 0–150 km; Doppler shifts of molecular spectral lines in the optical, thermal infrared and millimetre ranges2–4, which together have probed the ~100–450 km altitude range; inferences from the thermal field over 10–0.001 mbar (that is, ~100–500 km)5,6; and inferences from central flashes in stellar occultation curves7–9. These measurements predominantly indicated strong prograde winds, reaching maximum speeds of ~150–200 m s−1 in the upper stratosphere, with important latitudinal and seasonal variations. However, these observations provided incomplete atmospheric sounding; in particular, the wind regime in Titan’s upper mesosphere and thermosphere (500–1,200 km) has remained unconstrained so far. Here we report direct wind measurements based on Doppler shifts of six molecular species observed with the Atacama Large Millimeter/submillimeter Array (ALMA). We show that contrary to expectations, strong prograde winds extend up to the thermosphere, with the circulation progressively turning into an equatorial jet regime as the altitude increases, reaching ~340 m s−1 at 1,000 km. We suggest that these winds may represent the dynamical response of forcing by waves launched at upper stratospheric/mesospheric levels and/or of magnetospheric–ionospheric interaction. We also demonstrate that the distribution of the hydrogen isocyanide (HNC) molecule is restricted to Titan’s thermosphere above ~870 km altitude. © 2019, The Author(s), under exclusive licence to Springer Nature Limited., E.L., R.M. and S.V. acknowledge support from the Programme National de Planetologie (PNP-INSU).

2013 FY27 is the ninth intrinsically brightest Trans-Neptunian Object (TNO). We observed 2013 FY27 at thermal wavelengths with ALMA and in the optical with Magellan to determine its size and albedo for the first time and compare it to other dwarf planets. The geometric albedo of 2013 FY27 was found to be 0.17 -0.030+0.045, giving an effective diameter of D = 765 +80-85 km. 2013 FY27 has a size within the transition region between the largest few TNOs that have higher albedos and higher densities than smaller TNOs. No significant short-term optical light curve was found, with variations less than 0.06 mags over hours and days. The Sloan optical colors of 2013 FY27 are g-r=0.76 +-0.02 and r-i=0.31 +-0.03 mags, which is a moderately red color. This color is different than the neutral or ultra-red colors found for the ten largest TNOs, making 2013 FY27 one of the largest known moderately red TNOs, which only start to be seen, and in abundance, at diameters less than 800 km. This suggests something physically different might be associated with TNOs larger than 800 km. It could be that moderately red surfaces are older or less ice rich and TNOs larger than 800 km have fresher surfaces or are able to hold onto more volatile ices. Its also possible TNOs larger than 800 km are more fully differentiated, giving them different surface compositions. A satellite at 0.17 arcsec away and 3.0 +-0.2 mags fainter than 2013 FY27 was found through Hubble Space Telescope observations. Almost all the largest TNOs have satellites, and the relative small size of 2013 FY27's satellite suggests it was created through a direct collision, similar to satellites known around the largest TNOs. Assuming the satellite has a similar albedo as the primary, it is about 190 km in diameter, making the primary D = 740 +85-90 km., AJ

Millimeter and submillimeter heterodyne spectroscopy offers the possibility of probing the mesosphere of Venus and monitoring minor species and winds. ALMA presents a unique opportunity to map mesospheric species of Venus. During Cycle 0, we have observed Venus on November 14 and 15, 2011, using the compact configuration of ALMA. The diameter of Venus was 11″ and the illumination factor was about 90%. Maps of CO, SO, SO 2 and HDO have been built from transitions recorded in the 335–347 GHz frequency range. A mean mesospheric thermal profile has been inferred from the analysis of the CO transition at the disk center, to be used in support of minor species retrieval. Maps of SO and SO 2 abundance show significant local variations over the disk and contrast variations by as much as a factor 4. In the case of SO 2 , the spatial distribution appears more “patchy”, i.e. shows short-scale structures apparently disconnected from day-side and latitudinal variations. For both molecules, significant changes occur over a timescale of one day. From the disk averaged spectrum of SO recorded on November 14 at 346.528 GHz, we find that the best fit is obtained with a cutoff in the SO vertical distribution at 88±2 km and a uniform mixing ratio of 8.0±2.0 ppb above this level. The SO 2 map of November 14, derived from the weaker transition at 346.652 GHz, shows a clear maximum in the morning side at low latitudes, which is less visible in the map of November 15. We find that the best fit for SO 2 is obtained for a cutoff in the vertical distribution at 88±3 km and a uniform mixing ratio of 12.0±3.5 ppb above this level. The HDO maps retrieved from the 335.395 GHz show some enhancement in the northern hemisphere, but less contrasted variations than for the sulfur species maps, with little change between November 14 and 15. Assuming a typical D/H ratio of 200 times the terrestrial value in the mesosphere of Venus, we find that the disk averaged HDO spectrum is best fitted with a uniform H 2 O mixing ratio of 2.5±0.6 ppm (corresponding to a HDO mixing ratio of 0.165±0.040 ppm). We note that our spectrum is also compatible with a H 2 O mixing ratio of 1.5 ppm in the 80–90 km altitude range, and a mixing ratio of 3 ppm outside this range, as suggested by the photochemical model of Zhang et al. (2012, Icarus , vol. 217, pp. 714–739). Our results are in good general agreement with previous single dish submillimeter observations of Sandor and Clancy (2005, Icarus , vol. 177, pp. 129–143), Gurwell et al. (2007, Icarus , vol. 188, p. 288), and Sandor et al. (2010, Icarus , vol. 208, pp. 49–60; 2012, Icarus, vol. 217, pp. 839–844 ) and with SPICAV/Venus Express results of Fedorova et al. (2008, J. Geophys. Res. , vol. 113, p. E00B25) and Belyaev et al. (2012).

Context. The large and vertically non-uniform abundance of CO in Neptune’s atmosphere has been interpreted as the result of past cometary impact(s), either single or distributed in size and time, which could also be at the origin of Neptune’s HCN. Aims. We aim to provide observational support for this scenario by searching for other comet-induced species, in particular carbon sulfide (CS) which has been observed continuously in Jupiter since the 1994 Shoemaker-Levy 9 impacts. Methods. In April 2016 we used the ALMA interferometer to search for CS(7-6) at 342.883 GHz in Neptune. Results. We report on the detection of CS in Neptune’s atmosphere, the first unambiguous observation of a sulfur-bearing species in a giant planet beyond Jupiter. Carbon sulfide appears to be present only at submillibar levels, with a column density of (2.0–3.1) × 1012 cm-2, and a typical mixing ratio of (2−20) × 10-11 that depends on its precise vertical location. The favoured origin of CS is deposition by a putative large comet impact several centuries ago, and the strong depletion of CS with respect to CO – compared to the Jupiter case – is likely due to the CS sticking to aerosols or clustering to form polymers in Neptune’s lower stratosphere. Conclusions. The CS detection, along with recent analyses of the CO profile, reinforces the presumption of a large comet impact into Neptune ~1000 yr ago, that delivered CO, CS, and HCN at the same time.

Observations of the Pluto-Charon system, acquired with the ALMA interferometer on June 12-13, 2015, have yielded a detection of the CO(3-2) and HCN(4-3) rotational transitions from Pluto, providing a strong confirmation of the presence of CO, and the first observation of HCN, in Pluto's atmosphere. The CO and HCN lines probe Pluto's atmosphere up to ~450 km and ~900 km altitude, respectively. The CO detection yields (i) a much improved determination of the CO mole fraction, as 515+/-40 ppm for a 12 ubar surface pressure (ii) clear evidence for a well-marked temperature decrease (i.e., mesosphere) above the 30-50 km stratopause and a best-determined temperature of 70+/-2 K at 300 km, in agreement with recent inferences from New Horizons / Alice solar occultation data. The HCN line shape implies a high abundance of this species in the upper atmosphere, with a mole fraction >1.5x10-5 above 450 km and a value of 4x10-5 near 800 km. The large HCN abundance and the cold upper atmosphere imply supersaturation of HCN to a degree (7-8 orders of magnitude) hitherto unseen in planetary atmospheres, probably due to the slow kinetics of condensation at the low pressure and temperature conditions of Pluto's upper atmosphere. HCN is also present in the bottom ~100 km of the atmosphere, with a 10-8 - 10-7 mole fraction; this implies either HCN saturation or undersaturation there, depending on the precise stratopause temperature. The HCN column is (1.6+/-0.4)x10^14 cm-2, suggesting a surface-referred net production rate of ~2x10^7 cm-2s-1. Although HCN rotational line cooling affects Pluto's atmosphere heat budget, the amounts determined in this study are insufficient to explain the well-marked mesosphere and upper atmosphere's ~70 K temperature. We finally report an upper limit on the HC3N column density (< 2x10^13 cm-2) and on the HC15N / HC14N ratio (< 1/125)., Revised version. Icarus, in press, Oct. 11, 2016. 57 pages, including 13 figures and 4 tables

Lellouch, E. et. al., The sensitivity of ALMA makes it possible to detect thermal mm/submm emission from small and/or distant solar system bodies at the sub-mJy level. While the measured fluxes are primarily sensitive to the objects' diameters, deriving precise sizes is somewhat hampered by the uncertain effective emissivity at these wavelengths. Following recent work presenting ALMA data for four trans-Neptunian objects (TNOs) with satellites, we report on ALMA 233 GHz (1.29 mm) flux measurements of four Centaurs (2002 GZ32, Bienor, Chiron, Chariklo) and two other TNOs (Huya and Makemake), sampling a range of sizes, albedos, and compositions. These thermal fluxes are combined with previously published fluxes in the mid/far infrared in order to derive their relative emissivity at radio (mm/submm) wavelengths, using the Near Earth Asteroid Standard Model (NEATM) and thermophysical models. We reassess earlier thermal measurements of these and other objects-including Pluto/Charon and Varuna-exploring, in particular, effects due to non-spherical shape and varying apparent pole orientation whenever information is available, and show that these effects can be key for reconciling previous diameter determinations and correctly estimating the spectral emissivities. We also evaluate the possible contribution to thermal fluxes of established (Chariklo) or claimed (Chiron) ring systems. For Chariklo, the rings do not impact the diameter determinations by more than ~5%; for Chiron, invoking a ring system does not help in improving the consistency between the numerous past size measurements. As a general conclusion, all the objects, except Makemake, have radio emissivities significantly lower than unity. Although the emissivity values show diversity, we do not find any significant trend with physical parameters such as diameter, composition, beaming factor, albedo, or color, but we suggest that the emissivity could be correlated with grain size. The mean relative radio emissivity is found to be 0.70 ± 0.13, a value that we recommend for the analysis of further mm/submm data. © ESO, 2017., B.S. and R.L. received funding from the European Research Council under the European Community's H2020 2014-2020 ERC grant Agreement No. 669416 "Lucky Star". E.L., S.F. and R.M. were supported by the French Programme National de Planetologie. T.M. and P.S.-S. acknowledge financial support by the European Union's Horizon 2020 Research and Innovation Programme, under Grant Agreement No. 687378. P.S.-S. has further received funding from the Spanish grant AYA-2014-56637-C2-1-P and the Proyecto de Excelencia de la Junta de Andalucia J.A. 2012-FQM1776.

Once completed, the Atacama Large Millimeter Array (ALMA) will be the most powerful (sub)millimeter interferometer in terms of sensitivity, spatial resolution and imaging. This paper presents the capabilities of ALMA applied to the observation of Centaurs and Trans-Neptunian Objects, and their possible output in terms of physical properties. Realistic simulations were performed to explore the performances of the different frequency bands and array configurations, and several projects are detailed along with their feasibility, their limitations and their possible targets. Determination of diameters and albedos via the radiometric method appears to be possible on ~500 objects, while sampling of the thermal lightcurve to derive the bodies' ellipticity could be performed at least 30 bodies that display a significant optical lightcurve. On a limited number of objects, the spatial resolution allows for direct measurement of the size or even surface mapping with a resolution down to 13 milliarcseconds. Finally, ALMA could separate members of multiple systems with a separation power comparable to that of the HST. The overall performance of ALMA will make it an invaluable instrument to explore the outer solar system, complementary to space-based telescopes and spacecrafts., Comment: Accepted for publication in Icarus (23 pages, 7 figures)

著者人数: 69名, Accepted: 2015-03-13, 資料番号: SA1150146000

This is a white paper for project ngVLA This paper discusses compelling science cases for a future long-baseline interferometer operating at millimeter and centimeter wavelengths, like the proposed Next Generation Vary Large Array (ngVLA). We report on the activities of the Cradle of Life science working group, which focused on the formation of low- and high-mass stars, the formation of planets and evolution of protoplanetary disks, the physical and compositional study of Solar System bodies, and the possible detection of radio signals from extraterrestrial civilizations. We propose 19 scientific projects based on the current specification of the ngVLA. Five of them are highlighted as possible Key Science Projects: (1) Resolving the density structure and dynamics of the youngest HII regions and high-mass protostellar jets, (2) Unveiling binary/multiple protostars at higher resolution, (3) Mapping planet formation regions in nearby disks on scales down to 1 AU, (4) Studying the formation of complex molecules, and (5) Deep atmospheric mapping of giant planets in the Solar System. For each of these projects, we discuss the scientific importance and feasibility. The results presented here should be considered as the beginning of a more in-depth analysis of the science enabled by such a facility, and are by no means complete or exhaustive.

The composition of Io's tenuous atmosphere is poorly constrained. Only the major species SO2 and a handful of minor species have been positively identified, but a variety of other molecular species should be present, based on thermochemical equilibrium models of volcanic gas chemistry and the composition of Io's environment. This paper focuses on the spectral search for expected yet undetected molecular species (KCl, SiO, S2O) and isotopes (34SO2). We analyze a disk-averaged spectrum of a potentially line-rich spectral window around 345 GHz, obtained in 2010 at the APEX-12m antenna (Atacama Pathfinder EXperiment). Using different models assuming either extended atmospheric distributions or a purely volcanically-sustained atmosphere, we tentatively measure the KCl relative abundance with respect to SO2 and derive a range of 4x10^{-4}-8x10^{-3}. We do not detect SiO or S2O and present new upper limits on their abundances. We also present the first measurement of the 34S/32S isotopic ratio in gas phase on Io, which appears to be twice as high as the Earth and ISM reference values. Strong lines of SO2 and SO are also analyzed to check for longitudinal variations of column density and relative abundance. Our models show that, based on their predicted relative abundance with respect to SO2 in volcanic plumes, both the tentative KCl detection and SiO upper limit are compatible with a purely volcanic origin for these species., Accepted for publication in ApJ. 11 pages, 4 figures

The dynamics of the upper mesosphere of Venus (~85-115 km) have been characterized as a combination of a retrograde superrotating zonal wind (RSZ) with a subsolar-to-antisolar flow (SSAS). Numerous mm-wave single-dish observations have been obtained and could directly measure mesospheric line-of-sight winds by mapping Doppler-shifts on CO rotational lines, but their limited spatial resolution makes their interpretation difficult. By using interferometric facilities, one can obtain better resolution on Doppler-shifts maps, allowing in particular to put firmer constraints on the respective contributions of the SSAS and RSZ circulations to the global mesospheric wind field. We report on interferometric observations of the CO(1-0) line obtained with the IRAM-Plateau de Bure interferometer in November 2007 and June 2009, that could map the upper mesosphere dynamics on the morning hemisphere with a very good spatial resolution (3.5-5.5"). All the obtained measurements show, with a remarkably good temporal stability, that the wind globally flows in the (sky) East-West direction, corresponding in the observed geometry either to an unexpected prograde zonal wind or a SSAS flow. A very localized inversion of the wind direction, that could correspond to a RSZ wind, is also repeatedly detected in the night hemisphere. The presence of significant meridional winds is not evidenced. Using models with different combinations of zonal and SSAS winds, we find that the data is best reproduced by a dominant SSAS flow with a maximal velocity at the terminator of ~200 m/s, displaying large diurnal and latitudinal asymmetries, combined with an equatorial RSZ wind of 70-100 m/s, overall indicating a wind-field structure consistent with but much more complex than the usual representation of the mesospheric dynamics., Comment: Accepted for publication in A&A

International audience; Many of the key properties of Io's atmosphere, such as its spatial distribution, temperature, column density and composition, are still not fully assessed despite decades of extensive observations. The contribution of the possible gas sources to the atmospheric replenishment are then still unclear. This paper presents disk-resolved observations performed with the Submillimeter Array (SMA) at 345 GHz of atmospheric rotational lines of the main atmospheric species SO 2, and, for the first time, of the minor species SO and NaCl. All these species appear concentrated on the anti-jovian hemisphere, but do not share the same spatial distribution. The obtained maps and line-averaged fluxes are compared to realistic models simulating gas sources including volcanic plume outgassing, SO 2 frost sublimation and photolysis. Arguments in favor of each sources are examined and compared to observations, putting constraints on their relative roles for each species. While sublimation clearly appears as the favored major source for SO 2, SO 2 photolysis may account for most of the production of SO. Using constraints on the volcanic plumes distribution from Galileo results, we find that direct volcanic input can only contribute for a minor fraction of atmospheric SO 2, but represent a more significant source for SO atmosphere, and is likely to be the only source for NaCl. Temperature and column densities findings are also presented for SO 2, and compare well to previously published observations and atmospheric models.

International audience; We report on direct wind measurements in Venus' mesosphere (90-115 km), performed in support of Venus Express, and based on CO millimeter observations. Most observations, sampling the CO(2-1) and CO(1-0) lines, were acquired with the IRAM 30-m telescope, over four distinct periods: (i) Summer 2006; (ii) May-June 2007, in association with the coordinated ground-based campaign; (iii) August 2007 inferior conjunction and (iv) September 2007. In the latter period, additional measurements (CO(3-2)) were obtained with the APEX 12-m telescope. Overall, the measurements indicate a large body of temporal variability of the Venus mesospheric field, but general features emerge: (i) winds strongly increase with altitude within the mesosphere, by a factor of 2-3 over a decade in pressure; (ii) many, but not all, of our observations can be viewed as the superposition of zonal retrograde and subsolar-to-antisolar (SSAS) flows of comparable speeds, typically 30-50 m/s near 0.1 mbar ( ˜93km) and 90-120 m/s near 0.01 mbar ( ˜102km) (iii) the wind field was very stable over three consecutive observing days in May-June 2007, but much more variable on a similar time base in August 2007 (iv) at a ˜2000km resolution, the nightside wind field appears very complex, with evidence that the SSAS flow does not reach high latitudes, and possible evidence for additional meridional winds. Our Summer 2006 observations, which sample Venus' dayside, seem to suggest that a prograde zonal flow is superimposed to the SSAS circulation for this period. This surprising result, which implies a pre-midnight convergence of the wind field, requires confirmation, and fruitful comparisons may be obtained from the analysis of motions in the O 2 emission images, as observed by Venus Express.

Context. Small body (12929) 1999 TZ1 is listed by the Minor Planet Center (MPC) as a Centaur. However, its location close to the Lagrangian point L5 of Jupiter is typical of a Trojan object with large inclination. Aims. The aim of this work is to provide a global physical and dynamical characterization of this object and to reassess its classification. Methods. We obtained multi-wavelength observations with IRTF (Hawaii), OSN and IRAM-30 m (Spain), and performed a dynamical simulation of the evolution of its orbital parameters. Results. Visible photometry monitoring shows a rotation curve with a period (if considered double-peaked) of 10.4 ± 0.1 ha nd an absolute R magnitude HR = 9.792 ± 0.025. Near-IR spectroscopy indicates a featureless reflectance spectra, with a low spectral slope of 7.2 ± 0.11%/100 nm. Thermal observations at 250 GHz provide a 4.5σ detection with a flux of 1.22 ± 0.27 mJy. The combination of the visible and millimeter datasets, assuming a standard thermal model, leads to a geometric albedo pv = 0.053 +0.015 −0.010 and a mean diameter of 51.5 ± 5k m. Conclusions. The low albedo and spectral slope measured are typical of Jupiter’s Trojans, but cannot exclude a Centaur nature. However, the dynamical lifetime of the object was estimated to be longer than 1 Gy, which is unlikely for a Centaur and suggests that (12929) 1999 TZ1 is a Trojan asteroid.

We report Submillimeter Array observations of SO2 emission in the circumstellar envelope of the red supergiant VY CMa, with an angular resolution of ~1". SO2 emission appears in three distinct outflow regions surrounding the central continuum peak emission that is spatially unresolved. No bipolar structure is noted in the sources. A fourth source of SO2 is identified as a spherical wind centered at the systemic velocity. We estimate the SO2 column density and rotational temperature assuming local thermal equilibrium (LTE) as well as perform non-LTE radiative transfer analysis using RADEX. Column densities of SO2 are found to be ~10^16 cm^-2 in the outflows and in the spherical wind. Comparison with existing maps of the two parent species OH and SO shows the SO2 distribution to be consistent with that of OH. The abundance ratio f_SO2/f_SO is greater than unity for all radii greater than at least 3x10^16 cm. SO2 is distributed in fragmented clumps compared to SO, PN, and SiS molecules. These observations lend support to specific models of circumstellar chemistry that predict f_SO2/f_SO>1 and may suggest the role of localized effects such as shocks in the production of SO2 in the circumstellar envelope., Accepted for publication in ApJ

International audience; Context. Previously published measurements of the millimeter-wave thermal rotational lightcurve of dwarf-planet (1) Ceres show incompatible results, proposing peak-to-peak lightcurve amplitudes during the ~9 h rotation period of either 4% or 50%, the latter being difficult to explain physically. Aims: Better calibrated measurements are necessary to firmly assess the behavior of Ceres' thermal lightcurve, and to relate possible brightness temperature variations to the distribution of local surface properties such as bolometric albedo and emissivity. Methods: One partial lightcurve of 6.5 h was obtained with the Submillimeter Array (Hawaii) in subcompact configuration at 235 GHz in January 2009, providing better absolute and relative calibration than the previously used single-dish facilities. Results: The observed disk-averaged lightcurve is compatible with no variation over the measurement window, and has an upper limit of 3% on its amplitude. Conclusions: The results obtained rule out the possibility of extreme brightness temperature variations, and the upper limit on the lightcurve amplitude could be physically realized by a combination of albedo distribution and realistic ground emissivity variations.