The [ITAL]Submillimeter Wave Astronomy Satellite[/ITAL]: Science Objectives and Instrument Description

Melnick, Gary J.; Stauffer, J. R.; Ashby, M. L. N.; Bergin, Edwin A.; Chin, G.; Erickson, N. R.; Goldsmith, Paul F.; Harwit, Martin; Howe, J. E.; Kleiner, S. C.; Koch, David; Neufeld, David A.; Patten, B. M.; Plume, R.; Schieder, R.; Snell, R. L.; Tolls, Volker; Wang, Zhong; Winnewisser, G.; Zhang, Yun Fei

doi:10.1086/312856

Cited by 175 publications

(88 citation statements)

References 16 publications

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“…Water was also observed with the Submillimeter Wave Astronomy Satellite, SWAS, (Melnick et al 2000) by Nuefeld et al (2000) on May 19-23, 1999. The production rate derived by these authors (8 × 10 28 s −1 ) is 50% lower than that derived by Biver et al (2002) from contemporaneous radio observations of hydroxyl molecules.…”

Section: Introductionmentioning

confidence: 73%

The gas and dust coma of Comet C/1999 H1 (Lee)

Lara¹,

Rodrigo²,

Tozzi³

et al. 2004

A&A

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Abstract. Comet Lee (C/1999 H1) was observed on June 6, 1999 when it was at r h = 0.98 AU and ∆ = 1.195 AU. The spectrophotometric observations, between 0.6 and 1 µm, were aimed at the detection of the CI( 1 D) doublet λλ 9823/9850 Å. The non-detection of these lines, with a 3σ flux upper limit of the order of 4.6 × 10 −17 erg cm −2 s −1 , confirms the CO depletion already noted by other authors. Several CN and NH 2 emission bands lie in that spectral range, making it possible to derive production rates for both species as ∼3.1 × 10 26 s −1 and 1.2 × 10 27 s −1 , respectively. The oxygen forbidden line at 6300 Å was used to obtain Q H 2 O = (1.22 ± 0.7) × 10 29 s −1 . Assuming that CN and NH 2 are directly produced by HCN and NH 3 , Comet Lee has a HCN/H 2 O ≈ 0.25% and NH 3 /H 2 O ≈ 1% at r h = 0.98 AU, in reasonable agreement with what has been found in other long-period comets. The structural analysis carried out on cometary images acquired with broad band R Bessel filter clearly displays two pairs of ion rays likely produced by the H 2 O + doublet at 6198 and 6200 Å, wavelengths covered by the bandpass filter. Identical features are found in the images acquired with the Gunn i filter. The dust brightness profiles in the east-west direction do not deviate from a ρ −m law (with 0.7 < m ≤ 1.2) as expected for a steady state model coma with a constant dust production rate and expanding at constant velocity. The dust production rate, as obtained from the A f ρ parameter, is ∼500 cm, which compared with the gas production rate classifies this comet as a dust poor one with relatively high (6.5-11.7) gas-to-dust mass ratio. Analysis of the normalized reflectivity gradient (i.e. continuum color) as a function of ρ indicates a slight reddening of the solid component in the coma at large cometocentric distances, whereas the average dust color within an aperture of 20 000 km, centered at the nucleus, is ∼9% per 1000 Å. Mie scattering computations applied to an ensemble of particles indicate that the dust coma is characterised by a relative broad size distribution with a typical mean size of 1 µm. These grains might be composed of a mixture of silicates and icy material.

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Section: Introductionmentioning

confidence: 73%

The gas and dust coma of Comet C/1999 H1 (Lee)

Lara¹,

Rodrigo²,

Tozzi³

et al. 2004

A&A

View full text Add to dashboard Cite

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“…Water has been observed previously in deeply embedded, low-mass protostars, primarily with space-based observatories such as ISO, SWAS, Odin and Spitzer (Kessler et al 1996;Melnick et al 2000;Nordh et al 2003;Werner et al 2004). ISO and Spitzer both observed spectrally unresolved water lines in the wavelength range of 5-180 μm (Ceccarelli et al 1998;Boogert et al 2000;Giannini et al 2001;Larsson et al 2002;Maret et al 2002;Watson et al 2007), where many higherexcited water lines (E up /k B ∼ few 100 K) were detected.…”

Section: Introductionmentioning

confidence: 95%

Water in star-forming regions withHerschel(WISH)

Kristensen

Dishoeck

Bergin

et al. 2012

A&A

253

589

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Context. Water is a key tracer of dynamics and chemistry in low-mass star-forming regions, but spectrally resolved observations have so far been limited in sensitivity and angular resolution, and only data from the brightest low-mass protostars have been published. Aims. The first systematic survey of spectrally resolved water emission in 29 low-mass (L < 40 L ) protostellar objects is presented. The sources cover a range of luminosities and evolutionary states. The aim is to characterise the line profiles to distinguish physical components in the beam and examine how water emission changes with protostellar evolution. Methods. H 2 O was observed in the ground-state 1 10 -1 01 transition at 557 GHz (E up /k B ∼ 60 K) as single-point observations with the Heterodyne Instrument for the Far-Infrared (HIFI) on Herschel in 29 deeply embedded Class 0 and I low-mass protostars. Complementary far-IR and sub-mm continuum data (including PACS data from our programme) are used to constrain the spectral energy distribution (SED) of each source. H 2 O intensities are compared to inferred envelope properties, e.g., mass and density, outflow properties and CO 3-2 emission. Results. H 2 O emission is detected in all objects except one (TMC1A). The line profiles are complex and consist of several kinematic components tracing different physical regions in each system. In particular, the profiles are typically dominated by a broad Gaussian emission feature, indicating that the bulk of the water emission arises in outflows, not in the quiescent envelope. Several sources show multiple shock components appearing in either emission or absorption, thus constraining the internal geometry of the system. Furthermore, the components include inverse P-Cygni profiles in seven sources (six Class 0, one Class I) indicative of infalling envelopes, and regular P-Cygni profiles in four sources (three Class I, one Class 0) indicative of expanding envelopes. Molecular "bullets" moving at > ∼ 50 km s −1 with respect to the source are detected in four Class 0 sources; three of these sources were not known to harbour bullets previously. In the outflow, the H 2 O/CO abundance ratio as a function of velocity is nearly the same for all line wings, increasing from 10 −3 at low velocities (<5 km s −1 ) to > ∼ 10 −1 at high velocities (>10 km s −1 ). The water abundance in the outer cold envelope is low, > ∼ 10 −10 . The different H 2 O profile components show a clear evolutionary trend: in the younger Class 0 sources the emission is dominated by outflow components originating inside an infalling envelope. When large-scale infall diminishes during the Class I phase, the outflow weakens and H 2 O emission all but disappears.

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“…Most of the water is rotationally cold throughout the cometary atmosphere (Crovisier, 1984;Weaver and Mumma, 1984;Bockelée-Morvan, 1987;Xie and Mumma, 1992; the Microwave Instrument for the Rosetta orbiter, MIRO, the Swedish-led satellite mission Odin (Nordh et al, 2003), and the Submillimeter Wave Astronomy Satellite, SWAS (Melnick et al, 2000). In this paper we present the results from the SWAS observing campaign for comet 9P/Tempel 1 and Deep NASA's Submillimeter Wave Astronomy Satellite is a complete space-borne radio observatory (Melnick et al, 2000).…”

Section: P/tempel 1 the Target Comet Of The Deep Impact Mission Ismentioning

confidence: 99%

“…In this paper we present the results from the SWAS observing campaign for comet 9P/Tempel 1 and Deep NASA's Submillimeter Wave Astronomy Satellite is a complete space-borne radio observatory (Melnick et al, 2000). for the SWAS telescope (Melnick et al, 2000), and the velocity-integrated line intensity is denoted as I mb = T mb dv. A sample spectrum is shown in Fig.…”

Section: P/tempel 1 the Target Comet Of The Deep Impact Mission Ismentioning

confidence: 99%