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Register a new userALMA detection of sulfur dioxide and carbon monoxide in the atmosphere of Neptune
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The space and ground-based observations have shown a lot of activities and instabilities in the atmosphere of the giant ice planet Neptune. Using the archival data of high resolution Atacama Large Millimeter/Submillimeter Array (ALMA) with band 7 observation, we present the spectroscopic detection of the rotational emission line of sulfur dioxide (SO$_{2}$) at frequency $ u$ = 343.476 GHz with transition J=57$_{15,43}$$-$58$_{14,44}$. We also re-detect the emission line of carbon monoxide (CO) at frequency $ u$ = 345.795 GHz with transition J=3$-$2. The molecular lines of SO$_{2}$ and CO in the atmosphere of Nepure are detected with the $geq$4$sigma$ statistical significance. The statistical column density of SO$_{2}$ is N(SO$_{2}$) = 2.61$times$10$^{15}$ cm$^{-2}$ with rotational temperature $T_{SO_{2}}$ = 50 K and the statistical column density CO is N(CO) = 1.86$times$10$^{19}$ cm$^{-2}$ with $T_{CO}$ = 29 K. The typical mixing ratio in the atmosphere of Neptune for SO$_{2}$ is 1.24$times$10$^{-10}$ and CO is 0.88$times$10$^{-6}$. The SO$_{2}$ and CO gas in the atmosphere of Neptune may create due to Shoemaker-Levy 9 impacts in Jovian planets since 1994.
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The hydrogen cyanide (HCN) molecule in the planetary atmosphere is key to the formation of building blocks of life. We present the spectroscopic detection of the rotational molecular line of nitrile species hydrogen cyanide (HCN) in the atmosphere of Saturn using the archival data of the Atacama Large Millimeter/Submillimeter Array (ALMA) in band 7 observation. The strong rotational emission line of HCN is detected at frequency $ u$ = 354.505 GHz (>4$sigma$ statistical significance). We also detect the rotational emission line of carbon monoxide (CO) at frequency $ u$ = 345.795 GHz. The statistical column density of hydrogen cyanide and carbon monoxide emission line is N(HCN)$sim$2.42$times$10$^{16}$ cm$^{-2}$ and N(CO)$sim$5.82$times$10$^{17}$ cm$^{-2}$. The abundance of HCN and CO in the atmosphere of Saturn relative to the H$_{2}$ is estimated to be f(HCN)$sim$1.02$times$10$^{-9}$ and f(CO)$sim$2.42$times$10$^{-8}$. We discussed possible chemical pathways to the formation of the detected nitrile gas HCN in the atmosphere of Saturn.
The extremely thin atmosphere of Jupiters volcanic moon Io primarily consists of sulfur (S), sodium (Na), and oxygen (O) molecules that are controlled by the combination of the sublimation and volcanic outgasses. We present the first spectroscopic detection of the two rotational emission lines of acetone (CH$_{3}$COCH$_{3}$) and a single emission line of disulfur monoxide (S$_{2}$O), and carbon monoxide (CO) at frequency $ u$ = 346.539, 346.667, 346.543, and 345.795 GHz respectively using the archival data of high-resolution Atacama Large Millimeter/Submillimeter Array (ALMA) interferometer with band 7 observation. All molecular species are detected with $ge$5$sigma$ statistical significance. Jupiters moon Io is the most volcanically active body in the solar system with a very thin and spatially variable atmosphere. The volcanic gas CH$_{3}$COCH$_{3}$, S$_{2}$O, and CO are mainly coming from volcanic plumes. The statistical column density of CH$_{3}$COCH$_{3}$ line is N(CH$_{3}$COCH$_{3}$) = 3.18$times$10$^{15}$ cm$^{-2}$ but for the cases of S$_{2}$O and CO, the column densities are N(S$_{2}$O) = 2.63$times$10$^{16}$ cm$^{-2}$ and N(CO) = 5.27$times$10$^{15}$ cm$^{-2}$ respectively. The carbon monoxide gas is mainly formed by the photolysis of the volcanic gas acetone.
Plutos icy surface has changed colour and its atmosphere has swelled since its last closest approach to the Sun in 1989. The thin atmosphere is produced by evaporating ices, and so can also change rapidly, and in particular carbon monoxide should be present as an active thermostat. Here we report the discovery of gaseous CO via the 1.3mm wavelength J=2-1 rotational transition, and find that the line-centre signal is more than twice as bright as a tentative result obtained by Bockelee-Morvan et al. in 2000. Greater surface-ice evaporation over the last decade could explain this, or increased pressure could have caused the atmosphere to expand. The gas must be cold, with a narrow line-width consistent with temperatures around 50 K, as predicted for the very high atmosphere, and the line brightness implies that CO molecules extend up to approximately 3 Pluto radii above the surface. The upper atmosphere must have changed markedly over only a decade since the prior search, and more alterations could occur by the arrival of the New Horizons mission in 2015.
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 Plutos atmosphere. The CO and HCN lines probe Plutos 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 Plutos 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 Plutos atmosphere heat budget, the amounts determined in this study are insufficient to explain the well-marked mesosphere and upper atmospheres ~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).
Raman scattering by H$_2$ in Neptunes atmosphere has significant effects on its reflectivity for $lambda <$ 0.5 $mu$m, producing baseline decreases of $sim$ 20% in a clear atmosphere and $sim$ 10% in a hazy atmosphere. Here we present the first radiation transfer algorithm that includes both polarization and Raman scattering and facilitates computation of spatially resolved spectra. New calculations show that Cochran and Traftons (1978, Astrophys. J. 219, 756-762) suggestion that light reflected in the deep CH$_4$ bands is mainly Raman scattered is not valid for current estimates of the CH$_4$vertical distribution, which implies only a 4% Raman contribution. Comparisons with IUE, HST, and groundbased observations confirm that high altitude haze absorption is reducing Neptunes geometric albedo by $sim$6% in the 0.22-0.26 $mu$m range and by $sim$13% in the 0.35-0.45 $mu$m range. We used accurate calculations to evaluate several approximations of Raman scattering. The Karkoschka (1994, Icarus 111, 174-192) method of removing Raman effects from observed spectra is shown to have limited applicability and to undercorrect the depths of weak CH$_4$ absorption bands. The Wallace (1972, Astrophys. J. 176, 249-257) approximation produces geometric albedo values $sim$5% low as originally proposed, but can be much improved by adding scattering contributions from the vibrational transition. The Pollack et al. (1986, Icarus 65, 442-466) approximation is inaccurate and unstable, but can also be improved greatly by several simple modifications. A new approximation provides low errors for zenith angles below 70deg in a clear atmosphere, although intermediate clouds present problems at longer wavelengths.
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