Direct detection of the Enceladus water torus with<i>Herschel</i>

Hartogh, P.; Lellouch, E.; Moreno, R.; Bockelée‐Morvan, Dominique; Biver, Nicolás; Cassidy, Timothy A.; Rengel, Miriam; Jarchow, C.; Cavalié, T.; Crovisier, J.; Helmich, Frank; Kidger, M.

doi:10.1051/0004-6361/201117377

Cited by 86 publications

(102 citation statements)

References 37 publications

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“…If, however, such disc-averaged observations were undertaken at any other time in Saturn's seasonal cycle, the ring contribution would be non-negligible. The ring contribution was added to the measurement error as a source of uncertainty in the spectral modelling, and we will further discuss the importance of the Enceladus water torus (Hartogh et al 2011) in Sect. 4.2.…”

Section: Estimating Saturn's Ring Contributionmentioning

confidence: 99%

“…Sub-saturated tropospheric H 2 O was detected by de in the 5-μm region. However, an external influx of oxygen compounds from micrometeoroid ablation, cometary impacts or a connection to Saturn's rings and satellites (particularly Enceladus, Hartogh et al 2011) has long been postulated as a potential source. Water was previously detected in Saturn's stratosphere in the sub-millimetre by ISO Moses et al 2000b) and SWAS (Bergin et al 2000), but recent observations by Herschel/HIFI (Hartogh et al 2011) have revealed that an extended cold water vapour torus exists around Saturn's equatorial plane due to plume activity on Enceladus.…”

Section: Water H 2 Omentioning

confidence: 99%

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Sub-millimetre spectroscopy of Saturn’s trace gases fromHerschel/SPIRE

Fletcher

Swinyard

Salji

et al. 2012

A&A

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Aims. We provide an extensive new sub-millimetre survey of the trace gas composition of Saturn's atmosphere using the broad spectral range (15-51 cm −1 ) and high spectral resolution (0.048 cm −1 ) offered by Fourier transform spectroscopy by the Herschel/SPIRE instrument (Spectral and Photometric Imaging REceiver). Observations were acquired in June 2010, shortly after equinox, with negligible contribution from Saturn's ring emission. Methods. Tropospheric temperatures and the vertical distributions of phosphine and ammonia are derived using an optimal estimation retrieval algorithm to reproduce the sub-millimetre data. The abundance of methane, water and upper limits on a range of different species are estimated using a line-by-line forward model. Results. Saturn's disc-averaged temperature profile is found to be quasi-isothermal between 60 and 300 mbar, with uncertainties of 7 K due to the absolute calibration of SPIRE. Modelling of PH 3 rotational lines confirms the vertical profile derived in previous studies and shows that negligible PH 3 is present above the 10-to 20-mbar level. The upper tropospheric abundance of NH 3 appears to follow a vapour pressure distribution throughout the region of sensitivity in the SPIRE data, but the degree of saturation is highly uncertain. The tropospheric CH 4 abundance and Saturn's bulk C/H ratio are consistent with Cassini studies. We improve the upper limits on several species (H 2 S, HCN, HCP and HI); provide the first observational constraints on others (SO 2 , CS, methanol, formaldehyde, CH 3 Cl); and confirm previous upper limits on HF, HCl and HBr. Stratospheric emission from H 2 O is suggested at 36.6 and 38.8 cm −1 with a 1σ significance level, and these lines are used to derive mole fractions and column abundances consistent with ISO and SWAS estimations a decade earlier.

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Section: Estimating Saturn's Ring Contributionmentioning

confidence: 99%

Section: Water H 2 Omentioning

confidence: 99%

Sub-millimetre spectroscopy of Saturn’s trace gases fromHerschel/SPIRE

Fletcher

Swinyard

Salji

et al. 2012

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“…Both comets were the subjects of deep investigations using Herschel, including measurements of the D/H ratio in water (Hartogh et al 2011;Bockelée-Morvan et al 2012). The observations of 103P/Hartley 2 presented here were executed in the framework of the guaranteed time key programme "Water and related chemistry in the Solar System" (Hartogh et al 2009). Those of C/2009 P1 (Garradd) correspond to an open time proposal.…”

Section: Introductionmentioning

confidence: 99%

Searches for HCl and HF in comets 103P/Hartley 2 and C/2009 P1 (Garradd) with theHerschelSpace Observatory

Bockelée‐Morvan

Biver

Crovisier

et al. 2014

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Context. Hydrogen chloride (HCl) and hydrogen fluoride (HF) are expected to be the main reservoirs of fluorine and chlorine over a wide range of conditions, wherever hydrogen is predominantly molecular. They are found to be strongly depleted in dense molecular clouds, suggesting freeze-out onto grains in such cold environments. We can then expect that HCl and HF were also the major carriers of Cl and F in the gas and icy phases of the outer solar nebula, and were incorporated into comets. Aims. We aimed to measure the HCl and HF abundances in cometary ices as they can provide insights on the halogen chemistry in the early solar nebula. Methods. We searched for the J(1−0) lines of HCl and HF at 626 and 1232 GHz, respectively, using the Heterodyne Instrument for the Far-Infrared (HIFI) onboard the Herschel Space Observatory. HCl was searched for in comets 103P/Hartley 2 and C/2009 P1 (Garradd), whereas observations of HF were conducted in comet C/2009 P1 (Garradd). In addition, observations of H 2 O and H 2 18 O lines were performed in C/2009 P1 (Garradd) to measure the H 2 O production rate at the time of the HCl and HF observations. Three lines of CH 3 OH were serendipitously observed in the HCl receiver setting. Results. HCl is not detected, whereas a marginal (3.6-σ) detection of HF is obtained. The upper limits for the HCl abundance relative to water are 0.011% and 0.022%, for comet 103P/Hartley 2 and C/2009 P1 (Garradd), respectively, showing that HCl is depleted with respect to the solar Cl/O abundance by a factor more than 6 +6 −3 in 103P/Hartley 2, where the error is related to the uncertainty in the chlorine solar abundance. The marginal HF detection obtained in C/2009 P1 (Garradd) corresponds to an HF abundance relative to water of (1.8 ± 0.5) × 10 −4 , which is approximately consistent with a solar photospheric F/O abundance. The inferred water production rate in comet C/2009 P1 (Garradd) is (1.1±0.3)×10 29 s −1 and (0.75±0.05)×10 29 s −1 on 17 and 23 February 2012, respectively. CH 3 OH abundances relative to water are 2.7 ± 0.3% and 3.4 ± 0.6%, for comets 103P/Hartley 2 and C/2009 P1 (Garradd), respectively. Conclusions. The observed depletion of HCl suggests that HCl was not the main reservoir of chlorine in the regions of the solar nebula where these comets formed. HF was possibly the main fluorine compound in the gas phase of the outer solar nebula. However, this needs to be confirmed by future measurements.

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“…Because of its significant brightness (m v ∼ 8.5 at perihelion), it was an interesting target for the study of distant cometary activity. We report here on observations undertaken at r h = 3.3 AU post-perihelion with the PACS (Poglitsch et al 2010) andSPIRE (Griffin et al 2010) instruments on Herschel (Pilbratt et al 2010), in the framework of the Herschel guaranteed time key project called "Water and related chemistry in the Solar System" (Hartogh et al 2009). These observations are complemented by production rate measurements of several species with the Nançay radio telescope and the 30-m telescope of the Institut de Radioastronomie millimétrique (IRAM) at 3.2-3.3 AU pre-and post-perihelion.…”

Section: Introductionmentioning

confidence: 99%

A study of the distant activity of comet C/2006 W3 (Christensen) withHerscheland ground-based radio telescopes

Bockelée‐Morvan¹,

Hartogh

Crovisier³

et al. 2010

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Comet C/2006 W3 (Christensen) was observed in November 2009 at 3.3 AU from the Sun with Herschel.The PACS instrument acquired images of the dust coma in 70-μm and 160-μm filters and spectra covering several H 2 O rotational lines. Spectra in the range 450-1550 GHz were acquired with SPIRE. The comet emission continuum from 70 to 672 μm was measured, but no lines were detected. The spectral energy distribution indicates thermal emission from large particles and provides a measure of the size distribution index and dust production rate. The upper limit to the water production rate is compared to the production rates of other species (CO, CH 3 OH, HCN, H 2 S, OH) measured with the IRAM 30-m and Nançay telescopes. The coma is found to be strongly enriched in species more volatile than water, in comparison to comets observed closer to the Sun. The CO to H 2 O production rate ratio exceeds 220%. The dust-to-gas production rate ratio is on the order of 1.

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Direct detection of the Enceladus water torus withHerschel

Cited by 86 publications

References 37 publications

Sub-millimetre spectroscopy of Saturn’s trace gases fromHerschel/SPIRE

Sub-millimetre spectroscopy of Saturn’s trace gases fromHerschel/SPIRE

Searches for HCl and HF in comets 103P/Hartley 2 and C/2009 P1 (Garradd) with theHerschelSpace Observatory

A study of the distant activity of comet C/2006 W3 (Christensen) withHerscheland ground-based radio telescopes

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