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  • 1. Hjalmarson, Å.
    et al.
    Frisk, U.
    Olberg, M.
    Bergman, P.
    Bernath, P.
    Biver, N.
    Black, J. H.
    Booth, R. S.
    Buat, V.
    Crovisier, J.
    Curry, C. L.
    Dahlgren, M.
    Encrenaz, P. J.
    Falgarone, E.
    Feldman, P. A.
    Fich, M.
    Florén, H. G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Fredrixon, M.
    Gerin, M.
    Gregersen, E. M.
    Hagström, M.
    Harju, J.
    Hasegawa, T.
    Horellou, C.
    Johansson, L. E. B.
    Kyrölä, E.
    Kwok, S.
    Larsson, B.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Lecacheux, A.
    Liljeström, T.
    Lindqvist, M.
    Liseau, R.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Llewellyn, E. J.
    Mattila, K.
    Mégie, G.
    Mitchell, G. F.
    Murtagh, D.
    Nyman, L.-Å.
    Nordh, H. L.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Olofsson, A. O. H.
    Olofsson, G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Olofsson, H.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Pagani, L.
    Persson, G.
    Plume, R.
    Rickman, H.
    Ristorcelli, I.
    Rydbeck, G.
    Sandqvist, Aa.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    von Schéele, F.
    Serra, G.
    Torchinsky, S.
    Tothill, N. F.
    Volk, K.
    Wiklind, T.
    Wilson, C. D.
    Winnberg, A.
    Witt, G.
    Highlights from the first year of Odin observations2003Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 402, s. L39-L46Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Key Odin operational and instrumental features and highlights from our sub-millimetre and millimetre wave observations of H2O, H218O, NH3, 15NH3 and O2 are presented, with some insights into accompanying Odin Letters in this A&A issue. We focus on new results where Odin's high angular resolution, high frequency resolution, large spectrometer bandwidths, high sensitivity or/and frequency tuning capability are crucial: H2O mapping of the Orion KL, W3, DR21, S140 regions, and four comets; H2O observations of Galactic Centre sources, of shock enhanced H2O towards the SNR IC443, and of the candidate infall source IRAS 16293-2422; H218O detections in Orion KL and in comet Ikeya-Zhang; sub-mm detections of NH3 in Orion KL (outflow, ambient cloud and bar) and ρ Oph, and very recently, of 15NH3 in~Orion KL. Simultaneous sensitive searches for the 119 GHz line of O2 have resulted in very low abundance limits, which are difficult to accomodate in chemical models. We also demonstrate, by means of a quantitative comparison of Orion KL H2O results, that the Odin and SWAS observational data sets are very consistently calibrated. Odin is a Swedish-led satellite project funded jointly by the Swedish National Space Board (SNSB), the Canadian Space Agency (CSA), the National Technology Agency of Finland (Tekes), and the Centre National d'études Spatiales (CNES, France). The Swedish Space Corporation (SSC) has been the prime industrial contractor, and is also responsible for the satellite operation from its Odin Mission Control Centre at SSC in Solna and its Odin Control Centre at ESRANGE near Kiruna in northern Sweden. See also the SNSB Odin web page: http://www.snsb.se/eng_odin_intro.shtml

  • 2.
    Larsson, B.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Liseau, R.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Bergman, P.
    Bernath, P.
    Black, J. H.
    Booth, R. S.
    Buat, V.
    Curry, C. L.
    Encrenaz, P.
    Falgarone, E.
    Feldman, P.
    Fich, M.
    Florén, H. G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Frisk, U.
    Gerin, M.
    Gregersen, E. M.
    Harju, J.
    Hasegawa, T.
    Johansson, L. E. B.
    Kwok, S.
    Lecacheux, A.
    Liljeström, T.
    Mattila, K.
    Mitchell, G. F.
    Nordh, L. H.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Olberg, M.
    Olofsson, G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Pagani, L.
    Plume, R.
    Ristorcelli, I.
    Sandqvist, Aa.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Schéele, F. v.
    Tothill, N. F. H.
    Volk, K.
    Wilson, C. D.
    Hjalmarson, Å.
    First NH3 detection of the Orion Bar2003Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 402, s. L69-L72Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Odin has successfully observed three regions in the Orion A cloud, i.e. Ori KL, Ori S and the Orion Bar, in the 572.5 GHz rotational ground state line of ammonia, ortho-NH3 (J,K) = (1,0) -> (0,0), and the result for the Orion Bar represents the first detection in an ammonia line. Several velocity components are present in the data. Specifically, the observed line profile from the Orion Bar can be decomposed into two components, which are in agreement with observations in high-J CO lines by Wilson et al. (\cite{wilson01}). Using the source model for the Orion Bar by these authors, our Odin observation implies a total ammonia abundance of NH3/H2 = 5x 10-9. Based on observations with Odin, a Swedish-led satellite project funded jointly by the Swedish National Space Board (SNSB), the Canadian Space Agency (CSA), the National Technology Agency of Finland (Tekes) and Centre National d'Études Spatiales (CNES). The Swedish Space Corporation has been the industrial prime contractor.

  • 3.
    Larsson, B.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Liseau, R.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Men'shchikov, A. B.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    The ISO-LWS map of the Serpens cloud core. II. The line spectra2002Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 386, s. 1055-1073Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present spectrophotometric ISO imaging with the LWS and the CAM-CVF of the Serpens molecular cloud core. The LWS map is centred on the far infrared and submillimetre source FIRS 1/SMM 1 and its size is 8',x 8'. The fine structure line emission in [O I] 63 mu m and [C II] 157 mu m is extended on the arcminute scale and can be successfully modelled to originate in a PDR with G0 = 15 +/- 10 and n(H2) in the range of (104-105) cm-3. Extended emission might also be observed in the rotational line emission of H2O and high-J CO. However, lack of sufficient angular resolution prevents us from excluding the possibility that the emssion regions of these lines are point like, which could be linked to the embedded objects SMM 9/S 68 and SMM 4. Toward the Class 0 source SMM 1, the LWS observations reveal, in addition to fine structure line emission, a rich spectrum of molecular lines, superposed onto a strong, optically thick dust continuum (Larsson et al. \cite{Lar00}). The sub-thermally excited and optically thick CO, H2O and OH lines are tracing an about 103 AU source with temperatures higher than 300 K and densities above 106 cm-3 (M=0.01 Msun). The molecular abundances, X=N(mol)/N(H2), are X=(1, 0.1, 0.02, ge 0.025) x 10-4 for CO, H2O, OH and 13CO, respectively. Our data are consistent with an ortho-to-para ratio of 3 for H2O. OH appears highly overabundant, which we tentatively ascribe to an enhanced (X-ray) ionisation rate in the Serpens cloud core (zeta >> 10-18 s-1). We show that geometry is of concern for the correct interpretation of the data and based on 2D-radiative transfer modelling of the disk/torus around SMM 1, which successfully reproduces the entire observed SED and the observed line profiles of low-to-mid-J CO isotopomers, we can exclude the disk to be the source of the LWS-molecular line emission. The same conclusion applies to models of dynamical collapse (``inside-out'' infall). The 6{' '} pixel resolution of the CAM-CVF permits us to see that the region of rotational H2 emission is offset from SMM 1 by 30{' '}, at position angle 340deg, which is along the known jet flow from the Class 0 object. This H2 gas is extinguished by AV = 4.5 mag and at a temperature of 10310 K, which suggests that the heating of the gas is achieved through relatively slow shocks. Although we are not able to establish any firm conclusion regarding the detailed nature of the shock waves, our observations of the molecular line emission from SMM 1 are to a limited extent explainable in terms of an admixture of J-shocks and of C-shocks, the latter with speeds of about (15-20) km s-1, whereas dynamical infall is not directly revealed by our data. Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, The Netherlands and the UK) and with the participation of ISAS and NASA.

  • 4.
    Larsson, B.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Liseau, R.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Men'shchikov, A. B.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Olofsson, G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Caux, E.
    Ceccarelli, C.
    Lorenzetti, D.
    Molinari, S.
    Nisini, B.
    Nordh, L.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Saraceno, P.
    Sibille, F.
    Spinoglio, L.
    White, G. J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    The ISO-LWS map of the Serpens cloud core. I. The SEDs of the IR/SMM sources2000Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 363, s. 253-268Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Iso-Lws mapping observations of the Serpens molecular cloud core are presented. The spectral range is 50 - 200 μ m and the map size is 8',x 8'. These observations suffer from severe source confusion at Fir wavelengths and we employ a Maximum Likelihood Method for the spectro-spatial deconvolution. The strong and fairly isolated source SMM 1/FIRS 1 presented a test case, whose modelled spectral energy distribution (SED), within observational errors, is identical to the observed one. The model results for the other infrared and submillimetre sources are therefore likely to represent their correct SEDs. Simulations demonstrating the reliability and potential of the developed method support this view. It is found that some sources do not exhibit significant Fir emission and others are most likely not pointlike at long wavelengths. In contrast, the SEDs of a number of SMMs are well fit by modified single-temperature blackbodies over the entire accessible spectral range. For the majority of sources the peak of the SEDs is found within the spectral range of the Lws and derived temperatures are generally higher (>= 30 K) than have been found by earlier deconvolution attempts using Iras data. SMM sizes are found to be only a few arcsec in diameter. In addition, the SMMs are generally optically thick even at Lws wavelengths, i.e. estimated lambda (TAu=1) are in the range 160-270 μ m. The Rayleigh-Jeans tails are less steep than expected for optically thin dust emission. This indicates that the SMMs are optically thick out to longer wavelengths than previously assumed, an assertion confirmed by self-consistent radiative transfer calculations. Models were calculated for five sources, for which sufficient data were available, viz. SMM 1, 2, 3, 4 and 9. These models are optically thick out to millimetre wavelengths (wavelength of unit optical depth 900 to 1 400 μ m). Envelope masses for these SMMs are in the range 2-6 Msun, which is of course considerably more massive than estimates based on the optically thin assumption. The luminosities are in the range 10-70 Lsun, suggesting the formation of low-mass to intermediate mass stars, so that the existence of such massive envelopes argues for extreme youth of the SMMs in the Serpens cloud core. Finally, we present, for the first time, the full infrared SEDs for the outburst source DEOS, both at high and low intensity states. Based on observations with Iso, an Esa project with instruments funded by Esa Member States (especially the PI countries: France, Germany, the Netherlands and the United Kingdom) and with the participation of Isas and Nasa.

  • 5.
    Liseau, R.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Larsson, B.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Brandeker, A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Bergman, P.
    Bernath, P.
    Black, J. H.
    Booth, R.
    Buat, V.
    Curry, C.
    Encrenaz, P.
    Falgarone, E.
    Feldman, P.
    Fich, M.
    Florén, H.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Frisk, U.
    Gerin, M.
    Gregersen, E.
    Harju, J.
    Hasegawa, T.
    Hjalmarson, Å.
    Johansson, L.
    Kwok, S.
    Lecacheux, A.
    Liljeström, T.
    Mattila, K.
    Mitchell, G.
    Nordh, L.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Olberg, M.
    Olofsson, G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Pagani, L.
    Plume, R.
    Ristorcelli, I.
    Sandqvist, Aa.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Schéele, F. v.
    Serra, G.
    Tothill, N.
    Volk, K.
    Wilson, C.
    First detection of NH3 (10 -> 00) from a low mass cloud core. On the low ammonia abundance of the rho Oph A core2003Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 402, s. L73-L76Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Odin has successfully observed the molecular core rho Oph A in the 572.5 GHz rotational ground state line of ammonia, NH3 (JK = 10 -> 00). The interpretation of this result makes use of complementary molecular line data obtained from the ground (C17O and CH3OH) as part of the Odin preparatory work. Comparison of these observations with theoretical model calculations of line excitation and transfer yields a quite ordinary abundance of methanol, X(CH3OH)= 3 x 10-9. Unless NH3 is not entirely segregated from C17O and CH3OH, ammonia is found to be significantly underabundant with respect to typical dense core values, viz. X(NH3) = 8 x 10-10. Based on observations with Odin, a Swedish-led satellite project funded jointly by the Swedish National Space Board (SNSB), the Canadian Space Agency (CSA), the National Technology Agency of Finland (Tekes) and Centre National d'Études Spatiales (CNES). The Swedish Space Corporation has been the industrial prime contractor. and based on observations collected with the Swedish ESO Submillimeter Telescope, SEST, in La Silla, Chile.

  • 6.
    Liseau, René
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    X-ray and He I 1.0830 μm emission from protostellar jets2006Ingår i: Astronomy & Astrophysics, ISSN 0004-6361, Vol. 459, nr 3, s. 843-847Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Context: .The high energies of protostellar jets, implied by recent observations of X-rays from such flows, came very much as a surprise. Inferred shock velocities are considerably higher than what was previously known, hence putting even larger energy demands on the driving sources of the jets. The statistics of X-ray emitting jets are still poor, yet a few cases exist which seem to imply a correlation between the presence of He I 1.0830 μm emission and X-ray radiation in a given source.

    Aims: .This tentative correlation needs confirmation and explanation. If the jet regions of He I 1.0830 μm emission are closely associated with those producing X-rays, high resolution infrared spectroscopy can be used to observationally study the velocity fields in the hot plasma regions of the jets. This would provide the necessary evidence to test and further develop theoretical models of intermediately fast (>500{-}1500 km s-1) interstellar shock waves.

    Methods: .The HH 154 jet flow from the embedded protostellar binary L 1551 IRS 5 provides a case study, since adequate IR and X-ray spectroscopic data are in existence. The thermal X-ray spectrum is fed into a photoionization code to compute, in particular, the line emission of He I and H I and to account for the observed unusual line intensity ratios.

    Results: .The advanced model is capable of accounting for most observables, but shows also major weaknesses. It seems not unlikely that these could, in principle, be overcome by a time dependent hydrodynamical calculation with self-consistent cooling. However, such sophisticated model development is decisively beyond the scope of the present work.

    Conclusions: .Continued X-ray observations, coordinated with simultaneous high resolution infrared spectroscopy, are highly desirable.

  • 7.
    Liseau, René
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Fridlund, C. V. Malcolm
    Larsson, Bengt
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Physics of Outflows: The Binary Protostar L1551 IRS 5 and its Jets2005Ingår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 619, s. 959-967Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Recent observations of the deeply embedded L1551 IRS 5 system permit the detailed examination of the properties of both the stellar binary and the binary jet. For the individual components of the stellar binary, we determine their masses, mass accretion rates, effective temperatures, and luminosities. For the atomic wind/jet flow, we determine the mass-loss rate, yielding observationally determined values of the ratio of the mass loss to the mass accretion rate f. For the X-ray-emitting region in the northern jet, we have obtained the jet velocity and derive the extinction and the densities on different spatial scales. Examining the observational evidence within the framework of the X-wind theory leads us to conclude that these models are indeed potentially able to account for the observational data for this deeply embedded source.

  • 8. Olofsson, A. O. H.
    et al.
    Olofsson, G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Hjalmarson, Å.
    Bergman, P.
    Black, J. H.
    Booth, R. S.
    Buat, V.
    Curry, C. L.
    Encrenaz, P. J.
    Falgarone, E.
    Feldman, P.
    Fich, M.
    Florén, H. G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Frisk, U.
    Gerin, M.
    Gregersen, E. M.
    Harju, J.
    Hasegawa, T.
    Johansson, L. E. B.
    Kwok, S.
    Larsson, B.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Lecacheux, A.
    Liljeström, T.
    Liseau, R.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Mattila, K.
    Mitchell, G. F.
    Nordh, H. L.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Olberg, M.
    Olofsson, H.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Pagani, L.
    Plume, R.
    Ristorcelli, I.
    Rydbeck, G.
    Sandqvist, Aa.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    von Schéele, F.
    Serra, G.
    Tothill, N. F.
    Volk, K.
    Wilson, C. D.
    Odin water mapping in the Orion KL region2003Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 402, s. L47-L54Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    New results from water mapping observations of the Orion KL region using the submm/mm wave satellite Odin (2.1\arcmin beam size at 557 GHz), are presented. The ortho-H2O \jkktrans{1}{1}{0}{1}{0}{1} ground state transition was observed in a 7arcminx 7arcmin rectangular grid with a spacing of 1\arcmin, while the same line of H218O was measured in two positions, Orion KL itself and 2\arcmin south of Orion KL. In the main water species, the KL molecular outflow is largely resolved from the ambient cloud and it is found to have an extension of 60\arcsec-110\arcsec. The H2O outflow profile exhibits a rather striking absorption-like asymmetry at the line centre. Self-absorption in the near (or ``blue'') part of the outflow (and possibly in foreground quiescent halo gas) is tentatively suggested to play a role here. We argue that the dominant part of the KL H218O outflow emission emanates from the compact (size ~ 15\arcsec) low-velocity flow and here estimate an H2O abundance of circa 10-5 compared to all H2 in the flow - an order of magnitude below earlier estimates of the H2O abundance in the shocked gas of the high-velocity flow. The narrow ambient cloud lines show weak velocity trends, both in the N-S and E-W directions. H218O is detected for the first time in the southern position at a level of ~ 0.15 K and we here estimate an H2O abundance of (1-8) x 10-8. Odin is a Swedish-led satellite project funded jointly by the Swedish National Space Board (SNSB), the Canadian Space Agency (CSA), the National Technology Agency of Finland (Tekes), and the Centre National d'Études Spatiales (CNES, France). The Swedish Space Corporation (SSC) was the industrial prime contractor and is also responsible for the satellite operation.

  • 9. Pagani, L.
    et al.
    Olofsson, A. O. H.
    Bergman, P.
    Bernath, P.
    Black, J. H.
    Booth, R. S.
    Buat, V.
    Crovisier, J.
    Curry, C. L.
    Encrenaz, P. J.
    Falgarone, E.
    Feldman, P. A.
    Fich, M.
    Floren, H. G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Frisk, U.
    Gerin, M.
    Gregersen, E. M.
    Harju, J.
    Hasegawa, T.
    Hjalmarson, Å.
    Johansson, L. E. B.
    Kwok, S.
    Larsson, B.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Lecacheux, A.
    Liljeström, T.
    Lindqvist, M.
    Liseau, R.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Mattila, K.
    Mitchell, G. F.
    Nordh, L. H.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Olberg, M.
    Olofsson, G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Ristorcelli, I.
    Sandqvist, Aa.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    von Scheele, F.
    Serra, G.
    Tothill, N. F.
    Volk, K.
    Wiklind, T.
    Wilson, C. D.
    Low upper limits on the O2 abundance from the Odin satellite2003Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 402, s. L77-L81Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    For the first time, a search has been conducted in our Galaxy for the 119 GHz transition connecting to the ground state of O2, using the Odin satellite. Equipped with a sensitive 3 mm receiver (Tsys(SSB) = 600 K), Odin has reached unprecedented upper limits on the abundance of O2, especially in cold dark clouds where the excited state levels involved in the 487 GHz transition are not expected to be significantly populated. Here we report upper limits for a dozen sources. In cold dark clouds we improve upon the published SWAS upper limits by more than an order of magnitude, reaching N(O2)/N(H2) <= 10-7 in half of the sources. While standard chemical models are definitively ruled out by these new limits, our results are compatible with several recent studies that derive lower O2 abundances. Goldsmith et al. (\cite{SWAS2002}) recently reported a SWAS tentative detection of the 487 GHz transition of O2 in an outflow wing towards rho Oph A in a combination of 7 beams covering approximately 10arcmin x 14arcmin . In a brief (1.3 hour integration time) and partial covering of the SWAS region (~65% if we exclude their central position), we did not detect the corresponding 119 GHz line. Our 3 sigma upper limit on the O2 column density is 7.3x 1015 cm-2. We presently cannot exclude the possibility that the SWAS signal lies mostly outside of the 9\arcmin Odin beam and has escaped our sensitive detector. Based on observations with Odin, a Swedish-led satellite project funded jointly by the Swedish National Space Board (SNSB), the Canadian Space Agency (CSA), the National Technology Agency of Finland (Tekes) and Centre National d'Études Spatiales (CNES). The Swedish Space Corporation was the industrial prime contractor and is operating Odin.

  • 10. Ristorcelli, I.
    et al.
    Falgarone, E.
    Schöier, F.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Cabrit, S.
    Gerin, M.
    Baron, Ph.
    Frisk, U.
    Harju, J.
    Hjalmarson, Å.
    Klotz, A.
    Larsson, B.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Liseau, R.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Pagani, L.
    Odin observation of water in the IRAS 16293-2422 low-mass star forming region2005Ingår i: Astrochemistry: Recent Successes and Current Challenges: Proceedings of the 231st Symposium of the International Astronomical Union held in Pacific Grove, California, USA, August 29-September 2, 2005, 2005, Vol. 235, s. 227P-Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    We present the Odin satellite submillimeter measurement of the ground state transition of ortho-water at 557 GHz around the low-mass protostar IRAS16293-2422. The three following regions have been probed: the on-source position, and the two regions of interaction between the molecular outflows and the dense ambient cloud, i .e. on the SiO peak E1, and near the deuterated peak (cf Lis et al.(2002)). The three spectra reveal broad emission, with a narrow and deep absorption feature at the velocity of the quiescent gas. The water line profiles and intensities have been compared and combined with the CO(3- 2) and HCO+ lines from Lis et al.(2002) after convolution over the Odin beam. The contribution from the central envelope on the water line emission has been estimated with the infall model of Shoier et al. 2002. We show that the water emission is dominated by the outflows, particularly in the red wing of the lines. Using a c-shock modelling (Cabrit et al. 2005), we derive an abundance of X(H2O) 1 - 3 × 10-5 of H2, and shock velocities of 12 - 15 km/s. We also show that the absorption feature is due to the cold outer halo and corresponds to a lower limit of a few 10-9 on the H2O abundance.

  • 11.
    Sandqvist, Aa.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Bergman, P.
    Black, J. H.
    Booth, R.
    Buat, V.
    Curry, C. L.
    Encrenaz, P.
    Falgarone, E.
    Feldman, P.
    Fich, M.
    Floren, H. G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Frisk, U.
    Gerin, M.
    Gregersen, E. M.
    Harju, J.
    Hasegawa, T.
    Hjalmarson, Å.
    Johansson, L. E. B.
    Kwok, S.
    Larsson, B.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Lecacheux, A.
    Liljeström, T.
    Lindqvist, M.
    Liseau, R.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Mattila, K.
    Mitchell, G. F.
    Nordh, L.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Olberg, M.
    Olofsson, A. O. H.
    Olofsson, G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Pagani, L.
    Plume, R.
    Ristorcelli, I.
    Schéele, F. v.
    Serra, G.
    Tothill, N. F. H.
    Volk, K.
    Wilson, C. D.
    Winnberg, A.
    Odin observations of H2O in the Galactic Centre2003Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 402, s. L63-L67Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Odin satellite has been used to detect emission and absorption in the 557-GHz H216O line in the Galactic Centre towards the Sgr Astar Circumnuclear Disk (CND), and the Sgr A +20 km s-1 and +50 km s-1 molecular clouds. Strong broad H2O emission lines have been detected in all three objects. Narrow H2O absorption lines are present at all three positions and originate along the lines of sight in the 3-kpc Spiral Arm, the -30 km s-1 Spiral Arm and the Local Sgr Spiral Arm. Broad H2O absorption lines near -130 km s-1 are also observed, originating in the Expanding Molecular Ring. A new molecular feature (the ``High Positive Velocity Gas'' - HPVG) has been identified in the positive velocity range of ~+120 to +220 km s-1, seen definitely in absorption against the stronger dust continuum emission from the +20 km s-1 and +50 km s-1 clouds and possibly in emission towards the position of Sgr Astar CND. The 548-GHz H218O isotope line towards the CND is not detected at the 0.02 K (rms) level. Based on observations with Odin, a Swedish-led satellite project funded jointly by the Swedish National Space Board (SNSB), the Canadian Space Agency (CSA), the National Technology Agency of Finland (Tekes) and Centre National d'Études Spatiales (CNES). The Swedish Space Corporation was the industrial prime contractor and is also responsible for the satellite operation.

  • 12. Wilson, C. D.
    et al.
    Mason, A.
    Gregersen, E.
    Olofsson, A. O. H.
    Bergman, P.
    Booth, R.
    Boudet, N.
    Buat, V.
    Curry, C. L.
    Encrenaz, P.
    Falgarone, E.
    Feldman, P.
    Fich, M.
    Floren, H. G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Frisk, U.
    Gerin, M.
    Harju, J.
    Hasegawa, T.
    Hjalmarson, Å.
    Juvela, M.
    Kwok, S.
    Larsson, B.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Lecacheux, A.
    Liljestrom, T.
    Liseau, R.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Mattila, K.
    Mitchell, G.
    Nordh, L.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Olberg, M.
    Olofsson, G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Pagani, L.
    Plume, R.
    Ristorcelli, I.
    Sandqvist, Aa.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Serra, G.
    Tothill, N.
    Volk, K.
    von Scheele, F.
    Submillimeter emission from water in the W3 region2003Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 402, s. L59-L62Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Using the Odin satellite, we have mapped the submillimeter emission from the 110-101 transition of ortho-water in the W3 star-forming region. A 5arcminx 5arcmin map of the W3 IRS4 and W3 IRS5 region reveals strong water lines at half the positions in the map. The relative strength of the Odin lines compared to previous observations by SWAS suggests that we are seeing water emission from an extended region. Across much of the map the lines are double-peaked, with an absorption feature at -39 km s-1; however, some positions in the map show a single strong line at -43 km s-1. We interpret the double-peaked lines as arising from optically thick, self-absorbed water emission near the W3 IRS5, while the narrower blue-shifted lines originate in emission near W3 IRS4. In this model, the unusual appearance of the spectral lines across the map results from a coincidental agreement in velocity between the emission near W3 IRS4 and the blue peak of the more complex lines near W3 IRS5. The strength of the water lines near W3 IRS4 suggests we may be seeing water emission enhanced in a photon-dominated region. Based on observations with Odin, a Swedish-led satellite project funded jointly by the Swedish National Space Board (SNSB), the Canadian Space Agency (CSA), the National Technology Agency of Finland (Tekes), and Centre National d'Études Spatiales (CNES). The Swedish Space Corporation was the industrial prime contractor and is also responsible for the satellite operation.

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