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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2010.01.027 Byline: Anthony D. Toigo (a), Peter J. Gierasch (b), Bruno Sicardy (c), Emmanuel Lellouch (c) Keywords: Pluto, Atmosphere; Tides, Atmospheric; Occultations; Pluto; Atmospheres, Structure Abstract: Stellar occultations have shown that vertical profiles of density fluctuations in the atmosphere of Pluto typically show wave-like structure with an amplitude of a few percent and vertical wavelengths of a few kilometers. Here we calculate the tidal response of Pluto's atmosphere to solar-induced sublimation 'breathing' from N.sub.2 frost patches. Solutions show global-scale wave-like density structure capable of explaining the observations. The atmospheric response is a combination of eastward and westward migrating tides, together with a zonally symmetric mode. Calculated vertical wavelengths and amplitudes are similar to observations. Author Affiliation: (a) Center for Radiophysics and Space Research, Cornell University, Ithaca, NY 14853-6801, United States (b) Astronomy Department, Cornell University, Ithaca, NY 14853-6801, United States (c) LESIA, Observatoire de Paris, 5 place Jules Janssen, 92195 Meudon, France Article History: Received 31 July 2009; Revised 19 January 2010; Accepted 25 January 2010

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2010.02.009 Byline: Arielle Moullet (a), Mark A. Gurwell (a), Emmanuel Lellouch (b), RaphaA'l Moreno (b) Keywords: IO; Radio observations; Atmospheres, Structure Abstract: 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 345GHz of atmospheric rotational lines of the main atmospheric species SO.sub.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.sub.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.sub.2, SO.sub.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.sub.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.sub.2, and compare well to previously published observations and atmospheric models. Author Affiliation: (a) Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USA (b) LESIA-Observatoire de Paris, Meudon F-02195, France Article History: Received 9 November 2009; Revised 20 January 2010; Accepted 9 February 2010

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2005.08.007 Byline: Athena Coustenis (a), Alberto Negrao (a)(d)(f), Alberto Salama (c), Bernhard Schulz (b), Emmanuel Lellouch (a), Pascal Rannou (d), Pierre Drossart (a), Therese Encrenaz (a), Bernard Schmitt (e), Vincent Boudon (g), Andrei Nikitin (h) Keywords: Titan; Satellites of Saturn; Surfaces; Satellite; Infrared observations; ISO Abstract: The near-infrared spectrum of Titan, Saturn's largest moon and one of the Cassini/Huygens' space mission primary targets, covers the 0.8 to 5 micron region in which it shows several weak CH.sub.4 absorption regions, and in particular one centered near 2.75 micron. Due to the interference of telluric absorption, only part of this window region (2.9-3.1 [mu]m) has previously been observed from the ground [Noll, K.S., Geballe, T.R., Knacke, R., Pendleton, F., Yvonne, J., 1996. Icarus 124, 625-631; Griffith, C.A., Owen, T., Miller, G.A., Geballe, T., 1998. Nature 395, 575-578; Griffith, C.A., Owen, T., Geballe, T.R., Rayner, J., Rannou, P., 2003. Science 300, 628-630; Geballe, T.R., Kim, S.J., Noll, K.S., Griffith, C.A., 2003. Astrophys. J. 583, L39-L42]. We report here on the first spectroscopic observations of Titan covering the whole 2.4-4.9 [mu]m region by two instruments on board the Infrared Space Observatory (ISO) in 1997. These observations show the 2.75-[mu]m window in its complete extent for the first time. In this study we have also used a high-resolution Titan spectrum in the 2.9-3.6 [mu]m region taken with the Keck [Geballe, T.R., Kim, S.J., Noll, K.S., Griffith, C.A., 2003. Astrophys. J. 583, L39-L42; Kim, S.J., Geballe, T.R., Noll, K.S., Courtin, R., 2005. Icarus 173, 522-532] to infer information on the atmospheric parameters (haze extinction, single scattering albedo, methane abundance, etc.) by fitting the methane bands with a detailed microphysical model of Titan's atmosphere (updated from Rannou, P., McKay, C.P., Lorenz, R.D., 2003. Planet. Space Sci. 51, 963-976). We have included in this study an updated version of a database for the CH.sub.4 absorption coefficients [STDS, Wenger, Ch., Champion, J.-P., 1998. J. Quant. Spectrosc. Radiat. Transfer 59, 471-480. See also http://www.u-bourgogne.fr/LPUB/TSM/sTDS.html for latest updates; Boudon, V., Champion, J.-P., Gabard, T., LoA'te, M., Michelot, F., Pierre, G., Rotger, M., Wenger, Ch., Rey, M., 2004. J. Mol. Spectrosc. 228, 620-634]. For the atmosphere we find that (a) the haze extinction profile that best matches the data is one with higher (by 40%) extinction in the atmosphere with respect to Rannou et al. (2003) down to about 30 km where a complete cut-off occurs; (b) the methane mixing ratio at Titan's surface cannot exceed 3% on a disk-average basis, yielding a maximum CH.sub.4 column abundance of 2.27 km-am in Titan's atmosphere. From the derived surface albedo spectrum in the 2.7-3.08 micron region, we bring some constraints on Titan's surface composition. The albedo in the center of the methane window varies from 0.01 to 0.08. These values, compared to others reported in the other methane windows, show a strong compatibility with the water ice spectrum in the near-infrared. Without confirming its existence from this work alone, our data then appear to be compatible with water ice. A variety of other ices, such as CO.sub.2, NH.sub.3, tholin material or hydrocarbon liquid cannot be excluded from our data, but an additional unidentified component with a signature around 2.74 micron is required to satisfy the data. Author Affiliation: (a) LESIA, Observatoire de Paris-Meudon, 5, place Jules Jannsen, F-92195 Meudon Cedex, France (b) California Institute of Technology, Mail Code 100-22, 770 South Wilson Avenue, Pasadena, CA 91125, USA (c) ISO Data Centre, European Space Agency, Villafranca del Castillo, P.O. Box 50727, 28080 Madrid, Spain (d) Service d'Aeronomie/CNRS, Universite de Paris 6-Universite de Versailles, France (e) Laboratoire de Planetologie de Grenoble, 38041 Grenoble Cedex 9, France (f) Observatorio Astronomico and Faculdade de CiA*ncias da Universidade de Lisboa, 1749-016 Lisboa, Portugal (g) Laboratoire de Physique de l'Universite de Bourgogne (LPUB)-CNRS UMR 5027, 9 Av. A. Savary, BP 47870, F-21078 Dijon Cedex, France (h) Laboratory of Theoretical Spectroscopy, Institute of Atmospheric Optics, Russian Academy of Sciences, 634055 Tomsk, Russia Article History: Received 24 March 2005; Revised 31 July 2005

We have observed about 16 absorption lines of the [v.sub.2] S[O.sub.2] vibrational band on Io, in disk-integrated 19-[micro]m spectra taken with the TEXES high spectral resolution mid-infrared spectrograph at the NASA Infrared Telescope Facility in November 2001, December 2002, and January 2004. These are the first ground-based infrared observations of Io's sunlit atmosphere, and provide a new window on the atmosphere that allows better longitudinal and temporal monitoring than previous techniques. Dramatic variations in band strength with longitude are seen that are stable over at least a 2 year period. The depth of the strongest feature, a blend of lines centered at 530.42 [cm.sup.-1], varies from about 7% near longitude 180[degrees] to about 1% near longitude 315[degrees] W, as measured at a spectral resolution of 57,000. Interpretation of the spectra requires modeling of surface temperatures and atmospheric density across Io's disk, and the variation in non-LTE [v.sub.2] vibrational temperature with altitude, and depends on the assumed atmospheric and surface temperature structure. About half of Io's 19-[micro]m radiation comes from the Sun-heated surface, and half from volcanic hot spots with temperatures primarily between 150 and 200 K, which occupy about 8% of the surface. The observations are thus weighted towards the atmosphere over these low-temperature hot spots. If we assume that the atmosphere over the hot spots is representative of the atmosphere elsewhere, and that the atmospheric density is a function of latitude, the most plausible interpretation of the data is that the equatorial atmospheric column density varies from about 1.5 x [10.sup.17] [cm.sup.-2] near longitude 180[degrees] W to about 1.5 x [10.sup.16] [cm.sup.-2] near longitude 300[degrees] W, roughly consistent with HST UV spectroscopy and Lyman-[alpha] imaging. The inferred atmospheric kinetic temperature is less than about 150 K, at least on the anti-Jupiter hemisphere where the bands are strongest, somewhat colder than inferred from HST UV spectroscopy and millimeter-wavelength spectroscopy. This longitudinal variability in atmospheric density correlates with the longitudinal variability in the abundance of optically thick, near-UV bright S[O.sub.2] frost. However it is not clear whether the correlation results from volcanic control (regions of large frost abundance result from greater condensation of atmospheric gases supported by more vigorous volcanic activity in these regions) or sublimation control (regions of large frost abundance produce a more extensive atmosphere due to more extensive sublimation). Comparison of data taken in 2001, 2002, and 2004 shows that with the possible exception of longitudes near 180[degrees] W between 2001 and 2002, Io's atmospheric density does not appear to decrease as Io recedes from the Sun, as would be expected if the atmosphere were supported by the sublimation of surface frost, suggesting that the atmosphere is dominantly supported by direct volcanic supply rather than by frost sublimation. However, other evidence such as the smooth variation in atmospheric abundance with latitude, and atmospheric changes during eclipse, suggest that sublimation support is more important than volcanic support, leaving the question of the dominant atmospheric support mechanism still unresolved. Keywords: Io; Atmospheres, Structure; Infrared observations; Radiative transfer; Spectroscopy

In July 1994, the Shoemaker-Levy 9 (SL9) impacts introduced hydrogen cyanide (HCN) to Jupiter at a well confined latitude band around -44[degrees], over a range of specific longitudes corresponding to each of the 21 fragments (Bezard et al. 1997, Icarus 125, 94-120). This newcomer to Jupiter's stratosphere traces jovian dynamics. HCN rapidly mixed with longitude, so that observations recorded later than several months after impact witnessed primarily the meridional transport of HCN north and south of the impact latitude band. We report spatially resolved spectroscopy of HCN emission 10 months and 6 years following the impacts. We detect a total mass of HCN in Jupiter's stratosphere of 1.5 [+ or -] 0.7 x [10.sup.13] g in 1995 and 1.7 [+ or -] 0.4 x [10.sup.13] g in 2000, comparable to that observed several days following the impacts (Bezard et al. 1997, Icarus 125, 94-120). In 1995, 10 months after impact, HCN spread to -30[degrees] and -65[degrees] latitude (half column masses), consistent with a horizontal eddy diffusion coefficient of [K.sub.yy] = 2-3 x [10.sup.10] [cm.sup.2] [s.sub.-1]. Six years following impact HCN is observed in the northern hemisphere, while still being concentrated at 44[degrees] south latitude. Our meridional distribution of HCN suggests that mixing occurred rapidly north of the equator, with [K.sub.yy] = 2-5 x [10.sup.11] [cm.sup.2] [s.sup.-1], consistent with the findings of Moreno et al. (2003, Planet. Space Sci. 51, 591-611) and Lellouch et al. (2002, Icarus 159, 112-131). These inferred eddy diffusion coefficients for Jupiter's stratosphere at 0.1-0.5 mbar generally exceed those that characterize transport on Earth. The low abundance of HCN detected at high latitudes suggests that, like on Earth, polar regions are dynamically isolated from lower latitudes. Keywords: Jupiter; Atmosphere; Dynamics; IR spectroscopy

Observations of the [H.sup.2] S(0) and S(1) quadrupole lines in the four giant planets by the short-wavelength spectrometer of the Infrared Space Observatory are analyzed. These lines probe pressure levels located between 10 and 1 mbar and allow us to determine the stratospheric hydrogen para fraction for the first time. In Jupiter and Saturn, the stratospheric para fraction is close to its tropopause value. In the stratosphere of these planets as well as in Neptune's, the para fraction presents a significant departure from thermodynamic equilibrium. This situation results from a lagged conversion between the ortho and the para states as molecular hydrogen is transported upward under the influence of turbulent eddy diffusion. In contrast, the uranian stratosphere lies close to thermodynamic equilibrium. The magnitude of the departure from thermodynamic equilibrium appears to be anti-correlated with the amount of stratospheric aerosols. To validate this assumption, we estimate the hydrogen equilibration time with a one-dimensional diffusion model for different conversion processes in the gas phase or on aerosols. The comparison between our results and the tropospheric estimates from Conrath et al. (1998, Icarus, 135, 501-517) shows that paramagnetic conversion on aerosols matches the estimated tropospheric and stratospheric relaxation times in the four giant planets. In contrast, paramagnetic conversion in the gas phase can only explain the relaxation times measured in Jupiter and Saturn atmospheres. This situation provides quantitative evidence for an equilibration mechanism dominated by conversion on aerosols. Keywords: Jovian planets: Atmospheres, composition; Atmospheres, structure

Thirteen lines of the CO band near 4.7 [micro]m have been observed on a jovian hot spot at a resolution of 0.045 [cm.sup.-1]. The measured line profiles indicate that the CO mole fraction is 1.0 [+ or -] 0.2 ppb around the 6-bar level and is larger in the upper troposphere and/or stratosphere. An external source of CO providing an abundance of [4.sup.+3.sub.-2] x [10.sup.16] molecules [cm.sub.-2] is implied by the observations in addition to the amount deposited at high altitude by the Shoemaker-Levy 9 collision. From a simple diffusion model, we estimate that the CO production rate is (1.5-10)x [10.sup.6] molecules [cm.sup.-2] [s.sup.-1] assuming an eddy diffusion coefficient around the tropopause between 300 and 1500 [cm.sup.2] [s.sup.-1]. Precipitation of oxygen atoms from the jovian magnetosphere or photochemistry of water vapor from meteoroidal material can only provide a negligible contribution to this amount. A significant fraction of the CO in Jupiter's upper atmosphere may be formed by shock chemistry due to the infall of kilometer- to subkilometer-size Jupiter family comets. Using the impact rate from Levison et al. (2000, Icarus 143, 415-420) rescaled by Bottke et al. (2002, Icarus 156, 399-433), this source can provide the observed stratospheric CO only if the eddy diffusion coefficient around the tropopause is 100-300 [cm.sup.2] [s.sup.-1]. Higher values, ~700 [cm.sup.2] [s.sup.-1], would require an impact rate larger by a factor of 5-10, which cannot be excluded considering uncertainties in the distribution of Jupiter family comets. Such a large rate is indeed consistent with the observed cratering record of the Galilean satellites (Zahnle et al. 1998, Icarus 13b, 202-222). On The other hand, the ~1 ppb concentration in the lower troposphere requires an internal source. Revisiting the disequilibrium chemistry of CO in Jupiter, we conclude that rapid vertical mixing can provide the required amount of CO at ~6 bar for a global oxygen abundance of 0.2-9 times the solar value considering the uncertainties in the convective mixing rate and in the chemical constants. Key Words: Jupiter, atmosphere; infrared observations; atmospheres, composition.

The atmosphere of Io has been detected at infrared, millimeter, and ultraviolet wavelengths. The observations indicate a predominantly [SO.sub.2] tenuous atmosphere on both the leading and trailing daysides, probably variable but permanently detectable. The observed [SO.sub.2] pressure is on the order of 1 nanobar. There are several indications that the atmosphere is patchy rather than spatially uniform. The observable atmosphere may be produced from sublimation of [SO.sub.2] frost or directly from volcanic output, while surface sputtering may produce a more tenuous atmospheric component in specific regions. The large horizontal pressure gradients probably drive a supersonic meteorology that affects the pressure distribution on both local and large scales and the sublimation/condensation exchanges. SO appears to be a significant minor component along with [SO.sub.2], but its spatial distribution (global or localized) remains uncertain. Fundamental issues are unresolved, as the detailed interpretation of some observations is still ambiguous. The surface pressure and areal extent of the atmosphere are only known to within factors of [approximately]10 and 5, respectively. The vertical structure is extremely poorly characterized. We do not know for sure whether Io's atmosphere is in hydrostatic equilibrium or if the gas is rapidly ejected by volcanic venting. The gas temperature is very difficult to constrain from observations, although detailed models are available. The dominant source of Io's atmosphere remains uncertain. Current data sets would suggest a preference for the concept of an atmosphere in dynamical equilibrium with volcanic sources, but this conclusion must be viewed as tentative. The existence, composition, thickness, and extent of the atmosphere on the nightside are unknown.

Comet P/Schwassmann-Wachmann 1 has a nearly circular orbit at a distance farther from the sun than Jupiter. At this distance, the comet has been observed to undergo strong outbursts, which scientists have a hard time predicting. Moreover, researchers do not have a clear explanation for the comet's peculiar activity. Results of radio spectroscopic observations of the comet are discussed.

The new distribution of phosphorus compounds in the Jovian atmosphere reveals that the PH3 gas occupies a major part of the planet's atmosphere. The PH3, unlike the P406, takes part in the phosphorous cycle of Jupiter. It maintains its abundance above the required equilibrium level of the planet.

Spectroscopic studies of the trailing face of Io reveal two weak absorption features in the 2 micrometer region of Io's spectrum. The spectroscopic studies are performed at a resolution of 1.02 per centimeter using Fourier transform spectroscopy. These spectral features consisting of three absorption bands are produced by the 3nu1 + nu3 and nu1+ 3nu3 modes of solid SO2 in the satellite's atmosphere.

Mesosphere dynamics on the planet Venus is obtained from the mapping of various CO mm-wave lines on the right side of Venus. The spectral lines enable the simultaneous measurement of wind velocity at two levels at 15 different points on the planet. Wind velocity ranges from 90 to 110 kms and consists only of zonal retrograde flow. CO distribution on the planet is constant, maintained by wind circulation.

An analysis of Pluto's atmospheric thermal structure in terms of nitrogen, CO ices, CH4 and surface temperature suggests that nitrogen should be the major gas of Pluto, with CH4, CO and 0.1% level of atmospheric nitrogen. CO omission and CH4 heating explain temperature increase between surface and microbar level. Induction of a haze layer in Pluto's atmosphere explains the temperature rise between the surface, microbar and the lightcurve drop-off.

High signal-to-noise observations at IRAM enables the determination of the origin and vertical distribution of hydrogen cyanide (HCN) in the atmosphere of Neptune. The observations involve the measurement of the 3 to 2 rotational line of HCN in the spectra of Neptune's atmosphere. The line has a frequency of 265.9 GHz. The atmosphere of the planet has a uniform level HCN mixing ratio.

Certain basic characteristics of Io's atmosphere were inferred in a study suggesting that Io's atmosphere has a volcanic source. Observations have been made to analyze the pressure, thermal structure, composition, spatial distribution and temporal variability of Io's atmosphere. Millimeter wavelength observations of SO2 were made on the 30m radiotelescope at the Institut de Radio-Astronomie Millimetrique in Spain. The dynamics of the SO2 atmosphere and new upper limits for atmospheric H2S, SO and CO were derived.

We use a one-dimensional diurnally averaged model of photochemistry and diffusion in Saturn's stratosphere to investigate the influence of extraplanetary debris on atmospheric chemistry. In particular, we consider the effects of an influx of oxygen from micrometeoroid ablation or from ring-particle diffusion; the contribution from cometary impacts, satellite debris, or ring vapor is deemed to be less important. The photochemical model results are compared directly with Infrared Space Observatory (ISO) observations to constrain the influx of extraplanetary oxygen to Saturn. From the ISO observations, we determine that the column densities of [CO.sub.2] and [H.sub.2]O above 10 mbar in Saturn's atmosphere are (6.3 [+ or -] 1) x [10.sup.14] and (1.4 [+ or -] 0.4) x [10.sup.15] [cm.sup.-2], respectively; our models indicate that a globally averaged oxygen influx of (4 [+ or -] 2) x [10.sup.6] O atoms [cm.sup.-2] [s.sup.-1] is required to explain these observations. Models with a locally enhanced influx of [H.sub.2]O operating over a small fraction of the projected area do not provide as good a fit to the ISO [H.sub.2]O observations. If volatile oxygen compounds comprise one-third to one-half of the exogenic source by mass, then Saturn is currently being bombarded with (3 [+ or -] 2) x [10.sup.-16] g [cm.sup.-2] [s.sup.-1] of extraplanetary material. To reproduce the observed [CO.sub.2]/[H.sub.2]O ratio in Saturn's stratosphere, some of the exogenic oxygen must arrive in the form of a carbon--oxygen bonded species such as CO or [CO.sub.2]. An influx consistent with the composition of cometary ices fails to reproduce the high observed [CO.sub.2]/[H.sub.2]O ratio, suggesting that (i) the material has ices that are slightly more carbon-rich than is typical for comets, (ii) a contribution from an organic-rich component is required, or (iii) some of the hydrogen--oxygen bonded material is converted to carbon--oxygen bonded material without photochemistry (e.g., during the ablation process). We have also reanalyzed the 5-[micro]m CO observations of Noll and Larson (Icarus 89, 168-189, 1990) and determine that the CO lines are most sensitive to the 100- to 400-mbar column density for which we derive a range of (0.7-1.5) x [10.sup.17] [cm.sup.-2]; the CO observations do not allow us to distinguish between an external or internal source of CO on Saturn. If we assume that all the extraplanetary oxygen derives from a micrometeoroid source, then the unfocused dust flux at 9.5. AU must be (i) (1 [+ or -] 0.7) x [10.sup.-16]) g [cm.sup.-2] [s.sup.-1] if interseller grains are the source of the external oxygen on Saturn, (ii) (4 [+ or -] 3) x [10.sup.-17] g [cm.sup.-2][s.sup.-1] if IDPs on randomly inclined, highly eccentric orbits (e.g., Halley-type comet grains) are the source of the external oxygen, or (iii) (2 [+ or -] 1.4) x [10.sup.-18] g [cm.sup.-2] [s.sup.-1] if IDPs on low inclination, low eccentricity orbits (e.g., Kuiper-belt grains) are the source of the external oxygen. These estimates can be used in combination with future Cassini dust detection data to determine the ultimate source of the dust at Saturn's distance from the Sun.

The impact of the vapor pressure difference between deuterated and nondeuterated condensing molecules in planetary atmospheres is quantitatively assessed. This difference results in a loss of deuterium in the vapor phase above the condensation level. In Titan, Uranus, and Neptune, the effect on [CH.sub.3]D is too subtle to alter current D/H ratio determinations. In Mars, the effect can induce a large depletion of HDO, starting about one scale height above the condensation level. Although the current infrared measurements of the D/H ratio appear to be almost unaffected, the intensity of disk-averaged millimetric HDO lines can be modified by about 10%. The effect is much stronger in limb sounding and can be easily detected from orbiter observations. Key Words: atmospheres, composition; Mars, atmosphere; isotopes.

We present a radiative equilibrium model for extrasolar giant planets applied to 51 Peg b. The atmospheric model extends from [10.sup.-5] to ~ 10 bar and is limited at the bottom by an optically thick cloud of silicate ([Mg.sub.2]Si[O.sub.4] or MgSi[O.sub.3]) or iron (Fe) particles. Rayleigh scattering at short wavelengths and absorption by the [H.sub.2]--[H.sub.2] and [H.sub.2]--He continuum and molecular bands of [H.sub.2]O, CO, and [CH.sub.4] are included. Atmospheric heating and cooling result, respectively, from absorption of stellar flux and from infrared thermal emission. The solution temperature profiles do not show any temperature inversion, in contrast with the giant planets of the solar system. The lapse rate is subadiabatic at all levels above the cloudtop, justifying the use of radiative equilibrium. We find that, under thermochemical equilibrium, CO dominates over [CH.sub.4] at all levels. The effective temperature is in the range 1150-1270 K and the Bond albedo in the range 0.15-0.42, depending on the location and reflectivity of the lower cloud deck. [Mg.sub.2]Si[O.sub.4] or Fe clouds are weakly reflective in contrast to a MgSi[O.sub.3] cloud. The thermal emission spectrum prevails over the stellar reflected component below 13,000--15,000 [cm.sup.-1] ([Lambda] [is greater than] 0.7 [micro]m); it shows various windows, between the [H.sub.2]O and CO bands, with the brightest centered at 2550 [cm.sup.-1] (3.9 [micro]m). The most prominent CO and [CH.sub.4] bands occur around 2100 (4.7 [micro]m) and 3030 [cm.sup.-1] (3.3 [micro]m). Assuming a jovian abundance for [PH.sub.3], the bands around 2300 (4.3 [micro]m) and 2450 [cm.sup.-1] (4.1 [micro]m) are clearly visible in absorption at a resolving power of ~ 100. We investigated the detectability of the minor species CO and [CH.sub.4] at a resolution of 4000--6000, adequate to separate the planet's absorption features from their stellar and telluric counterparts. Considering photon noise from the star as the only noise source, we find that S/N ratios of about 8 are reached on the molecular features in the 4.7- and 3.3-[micro]m regions after ~ 10 h of integration on an 8-m telescope. On the other hand, the planet-to-star contrast is as low as (2-4) x [10.sup.-4]. Key Words: atmosphere, structure; atmosphere, composition; extrasolar planets.

We present the results of the Infrared Space Observatory Short Wavelength Spectrometer (ISO-SWS) observations of Jupiter related to ammonia. We focus on two spectral regions; the first one (the 10-[micro]m region), ranging from 9.5 to 11.5 [micro]m, probes atmospheric levels between 1 and 0.2 bar, while the second one (the 5-[micro]m window), ranging from 4.8 to 5.5 [micro]m, sounds the atmosphere between 8 and 2 bar. The two spectral windows cannot be fitted with the same ammonia vertical distribution. From the 10-[micro]m region we infer an ammonia distribution of about half the saturation profile above the 1-bar level, where the N/H ratio is roughly solar. A totally different picture is derived from the 5-[micro]m window, where we determine an upper limit of 3.7 x [10.sup.-5] at 1 bar and find an increasing [NH.sub.3] abundance at least down to 4 bar. This profile is similar to that measured by the Galileo probe. The discrepancy between the two spectral regions most likely arises from the spatial heterogeneity of Jupiter, the 5-[micro]m window sounding dry areas unveiled by a locally thin cloud cover (the 5-[micro]m hot spots), and the 10-[micro]m region probing the mean jovian atmosphere above 1 bar. The [sup.15][NH.sub.3] mixing ratio is measured around 400 mbar from [v.sub.2] band absorptions in the 10-[micro]m region. We find the atmosphere of Jupiter highly depleted in [sup.15]N at this pressure level [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII], while [([sup.15]N/[sup.14]N).sub.[direct sum]] = 3.68 x [10.sup.-3]]. It is not clear whether this depletion reveals the global jovian [sup.15]N/[sup.14]N ratio. Instead an isotopic fractionation process, taking place during the ammonia cloud condensation, is indicated as a possible mechanism. A fractionation coefficient [Alpha] higher than 1.08 would explain the observed isotopic ratio, but the lack of laboratory data does not allow us to decide unambiguously on the origin of the observed low [sup.15]N/[sup.14]N ratio. Key Words: atmospheres, composition; infrared observations; Jupiter, atmosphere.

Abstract: SPIRE, the Spectral and Photometric Imaging Receiver, is one of three instruments to fly on the European Space Agency’s Herschel Space Observatory. It contains a three-band imaging photometer operating at 250, 350 and 500μm, and an imaging Fourier transform spectrometer covering 194–672μm. The SPIRE detectors are arrays of feedhorn-coupled bolometers cooled to 0.3K. The photometer has a field of view of 4×8′, observed simultaneously in the three spectral bands. The spectrometer has an approximately circular field of view with a diameter of 2.6′ The spectral resolution can be adjusted between 0.04 and 2cm−1 (resolving power of 20–1000 at 250μm). SPIRE will be used for many galactic and extragalactic science programmes, a number of which will be implemented as Herschel Key Projects. The SPIRE consortium’s Guaranteed Time (GT) programme will devote more than 1000h to Key Projects covering the high-redshift universe and local galaxies, which will be carried out in coordination with other GT programmes, especially that of the PACS consortium. It is also expected that substantial amounts of Herschel Open Time will be used for further extragalactic investigations. The high-redshift part of the SPIRE GT programme will focus on blank-field surveys with a range of depths and areas optimised to sample the luminosity-redshift plane and characterize the bolometric luminosity density of the universe at high-redshift. Fields will be selected that are well covered by Spitzer, SCUBA-2, PACS-GT and near-IR surveys, to facilitate source identifications and enable detailed studies of the redshifts, spectral energy distributions, and other properties of detected galaxies. The local galaxies programme will include a detailed spectral and photometric study of a sample of well resolved nearby galaxies, a survey of more than 300 local galaxies designed to provide a statistical survey of dust in the nearby universe, and a study of the ISM in low-metallicity environments, bridging the gap between the local universe and primordial galaxies. [Copyright &y& Elsevier]