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1. Origin of warm and hot gas emission from low-mass protostars: Herschel-HIFI observations of CO J = 16–15

Author

Kristensen, L. E., primary, van Dishoeck, E. F., additional, Mottram, J. C., additional, Karska, A., additional, Yıldız, U. A., additional, Bergin, E. A., additional, Bjerkeli, P., additional, Cabrit, S., additional, Doty, S., additional, Evans, N. J., additional, Gusdorf, A., additional, Harsono, D., additional, Herczeg, G. J., additional, Johnstone, D., additional, Jørgensen, J. K., additional, van Kempen, T. A., additional, Lee, J.-E., additional, Maret, S., additional, Tafalla, M., additional, Visser, R., additional, and Wampfler, S. F., additional

Published
2017
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2. Sensitive limits on the abundance of cold water vapor in the DM Tauri protoplanetary disk [Letter]

Author

Bergin, E. A., Hogerheijde, M. R., Brinch, C., Fogel, J., Yildiz, U. A., Kristensen, L. E., van Dishoeck, E. F., Bell, T. A., Blake, G. A., Cernicharo, J., Dominik, C., Lis, D., Melnick, G., Neufeld, D., Panic, O., Pearson, J. C., Bachiller, R., Baudry, A., Benedettini, M., Benz, A. O., Bjerkeli, P., Bontemps, S., Braine, J., Bruderer, S., Caselli, P., Codella, C., Daniel, F., di Giorgio, A. M., Doty, S. D., Encrenaz, P., Fich, M., Fuente, A., Giannini, T., Goicoechea, J. R., de Graauw, Th, Helmich, F., Herczeg, G. J., Herpin, F., Jacq, T., Johnstone, D., Jorgensen, J. K., Larsson, B., Liseau, R., Marseille, M., Mc Coey, C., Nisini, B., Olberg, M., Parise, Berengere, Plume, R., Risacher, C., Santiago-Garcia, J., Saraceno, P., Shipman, R., Tafalla, M., van Kempen, T. A., Visser, R., Wampfler, S. F., Wyrowski, F., van der Tak, F., Jellema, W., Tielens, A. G. G. M., Hartogh, P., Stuetzki, J., and Szczerba, R.

Subjects
QB
Abstract

We performed a sensitive search for the ground-state emission lines of ortho- and para-water vapor in the DM Tau protoplanetary disk using the Herschel/HIFI instrument. No strong lines are detected down to 3σ levels in 0.5 km s-1 channels of 4.2 mK for the 110–101 line and 12.6 mK for the 111–000 line. We report a very tentative detection, however, of the 110–101 line in the wide band spectrometer, with a strength of Tmb = 2.7 mK, a width of 5.6 km s-1 and an integrated intensity of 16.0 mK km s-1. The latter constitutes a 6σ detection. Regardless of the reality of this tentative detection, model calculations indicate that our sensitive limits on the line strengths preclude efficient desorption of water in the UV illuminated regions of the disk. We hypothesize that more than 95–99% of the water ice is locked up in coagulated grains that have settled to the midplane.

Published
2010

3. Water vapor toward starless cores: The Herschel view [Letter]

Author

Caselli, P., Keto, E., Pagani, L., Aikawa, Y., Yildiz, U. A., van der Tak, F. F. S., Tafalla, M., Bergin, E. A., Nisini, B., Codella, C., van Dishoeck, E. F., Bachiller, R., Baudry, A., Benedettini, M., Benz, A. O., Bjerkeli, P., Blake, G. A., Bontemps, S., Braine, J., Bruderer, S., Cernicharo, J., Daniel, F., di Giorgio, A. M., Dominik, C., Doty, S. D., Encrenaz, P., Fich, M., Fuente, A., Gaier, T., Giannini, T., Goicoechea, J. R., de Graauw, Th., Helmich, F., Herczeg, G. J., Herpin, F., Hogerheijde, M. R., Jackson, B., Jacq, T., Javadi, H., Johnstone, D., Jorgensen, J. K., Kester, D., Kristensen, L. E., Laauwen, W., Larsson, B., Lis, D., Liseau, R., Luinge, W., Marseille, M., McCoey, C., Megej, A., Melnick, G., Neufeld, D., Olberg, M., Parise, Berengere, Pearson, J. C., Plume, R., Risacher, C., Santiago-Garcia, J., Saraceno, P., Shipman, R., Siegel, P., van Kempen, T. A., Visser, R., Wampfler, S. F., and Wyrowski, F.

Subjects
QB
Abstract

Aims. Previous studies by the satellites SWAS and Odin provided stringent upper limits on the gas phase water abundance of dark clouds (x(H2O) < 7 × 10-9). We investigate the chemistry of water vapor in starless cores beyond the previous upper limits using the highly improved angular resolution and sensitivity of Herschel and measure the abundance of water vapor during evolutionary stages just preceding star formation.\ud Methods. High spectral resolution observations of the fundamental ortho water (o-H2O) transition (557 GHz) were carried out with the Heterodyne Instrument for the Far Infrared onboard Herschel toward two starless cores: Barnard 68 (hereafter B68), a Bok globule, and LDN 1544 (L1544), a prestellar core embedded in the Taurus molecular cloud complex. Detailed radiative transfer and chemical codes were used to analyze the data.\ud Results. The RMS in the brightness temperature measured for the B68 and L1544 spectra is 2.0 and 2.2 mK, respectively, in a velocity bin of 0.59 km s-1. The continuum level is 3.5 ± 0.2 mK in B68 and 11.4 ± 0.4 mK in L1544. No significant feature is detected in B68 and the 3σ upper limit is consistent with a column density of o-H2O N(o-H2O) < 2.5 × 1013 cm-2, or a fractional abundance x(o-H2O) < 1.3 × 10-9, more than an order of magnitude lower than the SWAS upper limit on this source. The L1544 spectrum shows an absorption feature at a 5σ level from which we obtain the first value of the o-H2O column density ever measured in dark clouds: N(o-H2O) = (8 ± 4) × 1012 cm-2. The corresponding fractional abundance is x(o-H2O) 5 × 10-9 at radii >7000 AU and 2 × 10-10 toward the center. The radiative transfer analysis shows that this is consistent with a x(o-H2O) profile peaking at 10-8, 0.1 pc away from the core center, where both freeze-out and photodissociation are negligible.\ud Conclusions. Herschel has provided the first measurement of water vapor in dark regions. Column densities of o-H2O are low, but prestellar cores such as L1544 (with their high central densities, strong continuum, and large envelopes) appear to be very promising tools to finally shed light on the solid/vapor balance of water in molecular clouds and oxygen chemistry in the earliest stages of star formation.

Published
2010

4. Origin of warm and hot gas emission from low-mass protostars: Herschel-HIFI observations of CO J = 16-15 I. Line profiles, physical conditions, and H2O abundance.

Author

Kristensen, L. E., van Dishoeck, E. F., Mottram, J. C., Karska, A., Yıldız, U. A., Bergin, E. A., Bjerkeli, P., Cabrit, S., Doty, S., Evans II, N. J., Gusdorf, A., Harsono, D., Herczeg, G. J., Johnstone, D., Jørgensen, J. K., van Kempen, T. A., Lee, J.-E., Maret, S., Tafalla, M., and Visser, R.

Subjects
PROTOSTARS, STELLAR activity, INTERSTELLAR molecules, STAR formation, STELLAR mass, ASTROCHEMISTRY
Abstract

Context. Through spectrally unresolved observations of high-J CO transitions, Herschel Photodetector Array Camera and Spectrometer (PACS) has revealed large reservoirs of warm (300 K) and hot (700 K) molecular gas around low-mass protostars. The excitation and physical origin of this gas is still not understood. Aims. We aim to shed light on the excitation and origin of the CO ladder observed toward protostars, and on the water abundance in different physical components within protostellar systems using spectrally resolved Herschel-HIFI data. Methods. Observations are presented of the highly excited CO line J = 16-15 (Eup/kB = 750 K) with the Herschel Heterodyne Instrument for the Far Infrared (HIFI) toward a sample of 24 low-mass protostellar objects. The sources were selected from the Herschel "Water in Star-forming regions with Herschel" (WISH) and "Dust, Ice, and Gas in Time" (DIGIT) key programs. Results. The spectrally resolved line profiles typically show two distinct velocity components: a broad Gaussian component with an average FWHM of 20 km s-1 containing the bulk of the flux, and a narrower Gaussian component with a FWHM of 5 km s-1 that is often offset from the source velocity. Some sources show other velocity components such as extremely-high-velocity features or "bullets". All these velocity components were first detected in H2O line profiles. The average rotational temperature over the entire profile, as measured from comparison between CO J = 16-15 and 10-9 emission, is ~300 K. A radiative-transfer analysis shows that the average H2O/CO column-density ratio is ~0.02, suggesting a total H2O abundance of ~2 × 10-6, independent of velocity. Conclusions. Two distinct velocity profiles observed in the HIFI line profiles suggest that the high-J CO ladder observed with PACS consists of two excitation components. The warm PACS component (300 K) is associated with the broad HIFI component, and the hot PACS component (700 K) is associated with the offset HIFI component. The former originates in either outflow cavity shocks or the disk wind, and the latter in irradiated shocks. The low water abundance can be explained by photodissociation. The ubiquity of the warm and hot CO components suggest that fundamental mechanisms govern the excitation of these components; we hypothesize that the warm component arises when H2 stops being the dominant coolant. In this scenario, the hot component arises in cooling molecular H2-poor gas just prior to the onset of H2 formation. High spectral resolution observations of highly excited CO transitions uniquely shed light on the origin of warm and hot gas in low-mass protostellar objects. [ABSTRACT FROM AUTHOR]

Published
2017
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5. Water in star-forming regions withHerschel(WISH)

Author

Karska, A., primary, Herczeg, G. J., additional, van Dishoeck, E. F., additional, Wampfler, S. F., additional, Kristensen, L. E., additional, Goicoechea, J. R., additional, Visser, R., additional, Nisini, B., additional, San José-García, I., additional, Bruderer, S., additional, Śniady, P., additional, Doty, S., additional, Fedele, D., additional, Yıldız, U. A., additional, Benz, A. O., additional, Bergin, E., additional, Caselli, P., additional, Herpin, F., additional, Hogerheijde, M. R., additional, Johnstone, D., additional, Jørgensen, J. K., additional, Liseau, R., additional, Tafalla, M., additional, van der Tak, F., additional, and Wyrowski, F., additional

Published
2013
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7. Water in star-forming regions withHerschel(WISH)

Author

Kristensen, L. E., primary, van Dishoeck, E. F., additional, Bergin, E. A., additional, Visser, R., additional, Yıldız, U. A., additional, San Jose-Garcia, I., additional, Jørgensen, J. K., additional, Herczeg, G. J., additional, Johnstone, D., additional, Wampfler, S. F., additional, Benz, A. O., additional, Bruderer, S., additional, Cabrit, S., additional, Caselli, P., additional, Doty, S. D., additional, Harsono, D., additional, Herpin, F., additional, Hogerheijde, M. R., additional, Karska, A., additional, van Kempen, T. A., additional, Liseau, R., additional, Nisini, B., additional, Tafalla, M., additional, van der Tak, F., additional, and Wyrowski, F., additional

Published
2012
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11. First hyperfine resolved far-infrared OH spectrum from a star-forming region

Author

Wampfler, S. F., primary, Bruderer, S., additional, Kristensen, L. E., additional, Chavarría, L., additional, Bergin, E. A., additional, Benz, A. O., additional, van Dishoeck, E. F., additional, Herczeg, G. J., additional, van der Tak, F. F. S., additional, Goicoechea, J. R., additional, Doty, S. D., additional, and Herpin, F., additional

Published
2011
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12. Herschel/HIFI spectroscopy of the intermediate mass protostar NGC 7129 FIRS 2

Author

Johnstone, D., primary, Fich, M., additional, McCoey, C., additional, van Kempen, T. A., additional, Fuente, A., additional, Kristensen, L. E., additional, Cernicharo, J., additional, Caselli, P., additional, Visser, R., additional, Plume, R., additional, Herczeg, G. J., additional, van Dishoeck, E. F., additional, Wampfler, S., additional, Bachiller, R., additional, Baudry, A., additional, Benedettini, M., additional, Bergin, E., additional, Benz, A. O., additional, Bjerkeli, P., additional, Blake, G., additional, Bontemps, S., additional, Braine, J., additional, Bruderer, S., additional, Codella, C., additional, Daniel, F., additional, di Giorgio, A. M., additional, Dominik, C., additional, Doty, S. D., additional, Encrenaz, P., additional, Giannini, T., additional, Goicoechea, J. R., additional, de Graauw, Th., additional, Helmich, F., additional, Herpin, F., additional, Hogerheijde, M. R., additional, Jacq, T., additional, Jørgensen, J. K., additional, Larsson, B., additional, Lis, D., additional, Liseau, R., additional, Marseille, M., additional, Melnick, G., additional, Neufeld, D., additional, Nisini, B., additional, Olberg, M., additional, Parise, B., additional, Pearson, J., additional, Risacher, C., additional, Santiago-García, J., additional, Saraceno, P., additional, Shipman, R., additional, Tafalla, M., additional, van der Tak, F., additional, Wyrowski, F., additional, Yıldız, U. A., additional, Caux, E., additional, Honingh, N., additional, Jellema, W., additional, Schieder, R., additional, Teyssier, D., additional, and Whyborn, N., additional

Published
2010
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13. Herschel/HIFI observations of high-JCO lines in the NGC 1333 low-mass star-forming region

Author

Yıldız, U. A., primary, van Dishoeck, E. F., additional, Kristensen, L. E., additional, Visser, R., additional, Jørgensen, J. K., additional, Herczeg, G. J., additional, van Kempen, T. A., additional, Hogerheijde, M. R., additional, Doty, S. D., additional, Benz, A. O., additional, Bruderer, S., additional, Wampfler, S. F., additional, Deul, E., additional, Bachiller, R., additional, Baudry, A., additional, Benedettini, M., additional, Bergin, E., additional, Bjerkeli, P., additional, Blake, G. A., additional, Bontemps, S., additional, Braine, J., additional, Caselli, P., additional, Cernicharo, J., additional, Codella, C., additional, Daniel, F., additional, di Giorgio, A. M., additional, Dominik, C., additional, Encrenaz, P., additional, Fich, M., additional, Fuente, A., additional, Giannini, T., additional, Goicoechea, J. R., additional, de Graauw, Th., additional, Helmich, F., additional, Herpin, F., additional, Jacq, T., additional, Johnstone, D., additional, Larsson, B., additional, Lis, D., additional, Liseau, R., additional, Liu, F.-C., additional, Marseille, M., additional, McCoey, C., additional, Melnick, G., additional, Neufeld, D., additional, Nisini, B., additional, Olberg, M., additional, Parise, B., additional, Pearson, J. C., additional, Plume, R., additional, Risacher, C., additional, Santiago-García, J., additional, Saraceno, P., additional, Shipman, R., additional, Tafalla, M., additional, Tielens, A. G. G. M., additional, van der Tak, F., additional, Wyrowski, F., additional, Dieleman, P., additional, Jellema, W., additional, Ossenkopf, V., additional, Schieder, R., additional, and Stutzki, J., additional

Published
2010
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14. Herschel/HIFI detections of hydrides towards AFGL 2591

Author

Bruderer, S., primary, Benz, A. O., additional, van Dishoeck, E. F., additional, Melchior, M., additional, Doty, S. D., additional, van der Tak, F., additional, Stäuber, P., additional, Wampfler, S. F., additional, Dedes, C., additional, Yıldız, U. A., additional, Pagani, L., additional, Giannini, T., additional, de Graauw, Th., additional, Whyborn, N., additional, Teyssier, D., additional, Jellema, W., additional, Shipman, R., additional, Schieder, R., additional, Honingh, N., additional, Caux, E., additional, Bächtold, W., additional, Csillaghy, A., additional, Monstein, C., additional, Bachiller, R., additional, Baudry, A., additional, Benedettini, M., additional, Bergin, E., additional, Bjerkeli, P., additional, Blake, G. A., additional, Bontemps, S., additional, Braine, J., additional, Caselli, P., additional, Cernicharo, J., additional, Codella, C., additional, Daniel, F., additional, di Giorgio, A. M., additional, Dominik, C., additional, Encrenaz, P., additional, Fich, M., additional, Fuente, A., additional, Goicoechea, J. R., additional, Helmich, F., additional, Herczeg, G. J., additional, Herpin, F., additional, Hogerheijde, M. R., additional, Jacq, T., additional, Johnstone, D., additional, Jørgensen, J. K., additional, Kristensen, L. E., additional, Larsson, B., additional, Lis, D., additional, Liseau, R., additional, Marseille, M., additional, McCoey, C., additional, Melnick, G., additional, Neufeld, D., additional, Nisini, B., additional, Olberg, M., additional, Parise, B., additional, Pearson, J. C., additional, Plume, R., additional, Risacher, C., additional, Santiago-García, J., additional, Saraceno, P., additional, Tafalla, M., additional, van Kempen, T. A., additional, Visser, R., additional, and Wyrowski, F., additional

Published
2010
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15. Variations in H2O+/H2O ratios toward massive star-forming regions

Author

Wyrowski, F., primary, van der Tak, F., additional, Herpin, F., additional, Baudry, A., additional, Bontemps, S., additional, Chavarria, L., additional, Frieswijk, W., additional, Jacq, T., additional, Marseille, M., additional, Shipman, R., additional, van Dishoeck, E. F, additional, Benz, A. O., additional, Caselli, P., additional, Hogerheijde, M. R., additional, Johnstone, D., additional, Liseau, R., additional, Bachiller, R., additional, Benedettini, M., additional, Bergin, E., additional, Bjerkeli, P., additional, Blake, G., additional, Braine, J., additional, Bruderer, S., additional, Cernicharo, J., additional, Codella, C., additional, Daniel, F., additional, di Giorgio, A. M., additional, Dominik, C., additional, Doty, S. D., additional, Encrenaz, P., additional, Fich, M., additional, Fuente, A., additional, Giannini, T., additional, Goicoechea, J. R., additional, de Graauw, Th., additional, Helmich, F., additional, Herczeg, G. J., additional, Jørgensen, J. K., additional, Kristensen, L. E., additional, Larsson, B., additional, Lis, D., additional, McCoey, C., additional, Melnick, G., additional, Nisini, B., additional, Olberg, M., additional, Parise, B., additional, Pearson, J. C., additional, Plume, R., additional, Risacher, C., additional, Santiago, J., additional, Saraceno, P., additional, Tafalla, M., additional, van Kempen, T. A., additional, Visser, R., additional, Wampfler, S., additional, Yıldız, U. A., additional, Black, J. H., additional, Falgarone, E., additional, Gerin, M., additional, Roelfsema, P., additional, Dieleman, P., additional, Beintema, D., additional, De Jonge, A., additional, Whyborn, N., additional, Stutzki, J., additional, and Ossenkopf, V., additional

Published
2010
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16. Herschelobservations of the hydroxyl radical (OH) in young stellar objects

Author

Wampfler, S. F., primary, Herczeg, G. J., additional, Bruderer, S., additional, Benz, A. O., additional, van Dishoeck, E. F., additional, Kristensen, L. E., additional, Visser, R., additional, Doty, S. D., additional, Melchior, M., additional, van Kempen, T. A., additional, Yıldız, U. A., additional, Dedes, C., additional, Goicoechea, J. R., additional, Baudry, A., additional, Melnick, G., additional, Bachiller, R., additional, Benedettini, M., additional, Bergin, E., additional, Bjerkeli, P., additional, Blake, G. A., additional, Bontemps, S., additional, Braine, J., additional, Caselli, P., additional, Cernicharo, J., additional, Codella, C., additional, Daniel, F., additional, di Giorgio, A. M., additional, Dominik, C., additional, Encrenaz, P., additional, Fich, M., additional, Fuente, A., additional, Giannini, T., additional, de Graauw, Th., additional, Helmich, F., additional, Herpin, F., additional, Hogerheijde, M. R., additional, Jacq, T., additional, Johnstone, D., additional, Jørgensen, J. K., additional, Larsson, B., additional, Lis, D., additional, Liseau, R., additional, Marseille, M., additional, Mc Coey, C., additional, Neufeld, D., additional, Nisini, B., additional, Olberg, M., additional, Parise, B., additional, Pearson, J. C., additional, Plume, R., additional, Risacher, C., additional, Santiago-García, J., additional, Saraceno, P., additional, Shipman, R., additional, Tafalla, M., additional, van der Tak, F. F. S., additional, Wyrowski, F., additional, Roelfsema, P., additional, Jellema, W., additional, Dieleman, P., additional, Caux, E., additional, and Stutzki, J., additional

Published
2010
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17. Water abundances in high-mass protostellar envelopes:Herschelobservations with HIFI

Author

Marseille, M. G., primary, van der Tak, F. F. S., additional, Herpin, F., additional, Wyrowski, F., additional, Chavarría, L., additional, Pietropaoli, B., additional, Baudry, A., additional, Bontemps, S., additional, Cernicharo, J., additional, Jacq, T., additional, Frieswijk, W., additional, Shipman, R., additional, van Dishoeck, E. F., additional, Bachiller, R., additional, Benedettini, M., additional, Benz, A. O., additional, Bergin, E., additional, Bjerkeli, P., additional, Blake, G. A., additional, Braine, J., additional, Bruderer, S., additional, Caselli, P., additional, Caux, E., additional, Codella, C., additional, Daniel, F., additional, Dieleman, P., additional, di Giorgio, A. M., additional, Dominik, C., additional, Doty, S. D., additional, Encrenaz, P., additional, Fich, M., additional, Fuente, A., additional, Gaier, T., additional, Giannini, T., additional, Goicoechea, J. R., additional, de Graauw, Th., additional, Helmich, F., additional, Herczeg, G. J., additional, Hogerheijde, M. R., additional, Jackson, B., additional, Javadi, H., additional, Jellema, W., additional, Johnstone, D., additional, Jørgensen, J. K., additional, Kester, D., additional, Kristensen, L. E., additional, Larsson, B., additional, Laauwen, W., additional, Lis, D., additional, Liseau, R., additional, Luinge, W., additional, McCoey, C., additional, Megej, A., additional, Melnick, G., additional, Neufeld, D., additional, Nisini, B., additional, Olberg, M., additional, Parise, B., additional, Pearson, J. C., additional, Plume, R., additional, Risacher, C., additional, Roelfsema, P., additional, Santiago-García, J., additional, Saraceno, P., additional, Siegel, P., additional, Stutzki, J., additional, Tafalla, M., additional, van Kempen, T. A., additional, Visser, R., additional, Wampfler, S. F., additional, and Yıldız, U. A., additional

Published
2010
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18. Hydrides in young stellar objects: Radiation tracers in a protostar-disk-outflow system

Author

Benz, A. O., primary, Bruderer, S., additional, van Dishoeck, E. F., additional, Stäuber, P., additional, Wampfler, S. F., additional, Melchior, M., additional, Dedes, C., additional, Wyrowski, F., additional, Doty, S. D., additional, van der Tak, F., additional, Bächtold, W., additional, Csillaghy, A., additional, Megej, A., additional, Monstein, C., additional, Soldati, M., additional, Bachiller, R., additional, Baudry, A., additional, Benedettini, M., additional, Bergin, E., additional, Bjerkeli, P., additional, Blake, G. A., additional, Bontemps, S., additional, Braine, J., additional, Caselli, P., additional, Cernicharo, J., additional, Codella, C., additional, Daniel, F., additional, di Giorgio, A. M., additional, Dieleman, P., additional, Dominik, C., additional, Encrenaz, P., additional, Fich, M., additional, Fuente, A., additional, Giannini, T., additional, Goicoechea, J. R., additional, de Graauw, Th., additional, Helmich, F., additional, Herczeg, G. J., additional, Herpin, F., additional, Hogerheijde, M. R., additional, Jacq, T., additional, Jellema, W., additional, Johnstone, D., additional, Jørgensen, J. K., additional, Kristensen, L. E., additional, Larsson, B., additional, Lis, D., additional, Liseau, R., additional, Marseille, M., additional, McCoey, C., additional, Melnick, G., additional, Neufeld, D., additional, Nisini, B., additional, Olberg, M., additional, Ossenkopf, V., additional, Parise, B., additional, Pearson, J. C., additional, Plume, R., additional, Risacher, C., additional, Santiago-García, J., additional, Saraceno, P., additional, Schieder, R., additional, Shipman, R., additional, Stutzki, J., additional, Tafalla, M., additional, Tielens, A. G. G. M., additional, van Kempen, T. A., additional, Visser, R., additional, and Yıldız, U. A., additional

Published
2010
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19. Water in low-mass star-forming regions withHerschel

Author

Kristensen, L. E., primary, Visser, R., additional, van Dishoeck, E. F., additional, Yıldız, U. A., additional, Doty, S. D., additional, Herczeg, G. J., additional, Liu, F.-C., additional, Parise, B., additional, Jørgensen, J. K., additional, van Kempen, T. A., additional, Brinch, C., additional, Wampfler, S. F., additional, Bruderer, S., additional, Benz, A. O., additional, Hogerheijde, M. R., additional, Deul, E., additional, Bachiller, R., additional, Baudry, A., additional, Benedettini, M., additional, Bergin, E. A., additional, Bjerkeli, P., additional, Blake, G. A., additional, Bontemps, S., additional, Braine, J., additional, Caselli, P., additional, Cernicharo, J., additional, Codella, C., additional, Daniel, F., additional, de Graauw, Th., additional, di Giorgio, A. M., additional, Dominik, C., additional, Encrenaz, P., additional, Fich, M., additional, Fuente, A., additional, Giannini, T., additional, Goicoechea, J. R., additional, Helmich, F., additional, Herpin, F., additional, Jacq, T., additional, Johnstone, D., additional, Kaufman, M. J., additional, Larsson, B., additional, Lis, D., additional, Liseau, R., additional, Marseille, M., additional, McCoey, C., additional, Melnick, G., additional, Neufeld, D., additional, Nisini, B., additional, Olberg, M., additional, Pearson, J. C., additional, Plume, R., additional, Risacher, C., additional, Santiago-García, J., additional, Saraceno, P., additional, Shipman, R., additional, Tafalla, M., additional, Tielens, A. G. G. M., additional, van der Tak, F., additional, Wyrowski, F., additional, Beintema, D., additional, de Jonge, A., additional, Dieleman, P., additional, Ossenkopf, V., additional, Roelfsema, P., additional, Stutzki, J., additional, and Whyborn, N., additional

Published
2010
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20. Water in massive star-forming regions: HIFI observations of W3 IRS5

Author

Chavarría, L., primary, Herpin, F., additional, Jacq, T., additional, Braine, J., additional, Bontemps, S., additional, Baudry, A., additional, Marseille, M., additional, van der Tak, F., additional, Pietropaoli, B., additional, Wyrowski, F., additional, Shipman, R., additional, Frieswijk, W., additional, van Dishoeck, E. F., additional, Cernicharo, J., additional, Bachiller, R., additional, Benedettini, M., additional, Benz, A. O., additional, Bergin, E., additional, Bjerkeli, P., additional, Blake, G. A., additional, Bruderer, S., additional, Caselli, P., additional, Codella, C., additional, Daniel, F., additional, di Giorgio, A. M., additional, Dominik, C., additional, Doty, S. D., additional, Encrenaz, P., additional, Fich, M., additional, Fuente, A., additional, Giannini, T., additional, Goicoechea, J. R., additional, de Graauw, Th., additional, Hartogh, P., additional, Helmich, F., additional, Herczeg, G. J., additional, Hogerheijde, M. R., additional, Johnstone, D., additional, Jørgensen, J. K., additional, Kristensen, L. E., additional, Larsson, B., additional, Lis, D., additional, Liseau, R., additional, McCoey, C., additional, Melnick, G., additional, Nisini, B., additional, Olberg, M., additional, Parise, B., additional, Pearson, J. C., additional, Plume, R., additional, Risacher, C., additional, Santiago-García, J., additional, Saraceno, P., additional, Stutzki, J., additional, Szczerba, R., additional, Tafalla, M., additional, Tielens, A., additional, van Kempen, T. A., additional, Visser, R., additional, Wampfler, S. F., additional, Willem, J., additional, and Yıldız, U. A., additional

Published
2010
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21. Herschel-PACS spectroscopy of the intermediate mass protostar NGC 7129 FIRS 2

Author

Fich, M., primary, Johnstone, D., additional, van Kempen, T. A., additional, McCoey, C., additional, Fuente, A., additional, Caselli, P., additional, Kristensen, L. E., additional, Plume, R., additional, Cernicharo, J., additional, Herczeg, G. J., additional, van Dishoeck, E. F., additional, Wampfler, S., additional, Gaufre, P., additional, Gill, J. J., additional, Javadi, H., additional, Justen, M., additional, Laauwen, W., additional, Luinge, W., additional, Ossenkopf, V., additional, Pearson, J., additional, Bachiller, R., additional, Baudry, A., additional, Benedettini, M., additional, Bergin, E., additional, Benz, A. O., additional, Bjerkeli, P., additional, Blake, G., additional, Bontemps, S., additional, Braine, J., additional, Bruderer, S., additional, Codella, C., additional, Daniel, F., additional, di Giorgio, A. M., additional, Dominik, C., additional, Doty, S. D., additional, Encrenaz, P., additional, Giannini, T., additional, Goicoechea, J. R., additional, de Graauw, Th., additional, Helmich, F., additional, Herpin, F., additional, Hogerheijde, M. R., additional, Jacq, T., additional, Jørgensen, J. K., additional, Larsson, B., additional, Lis, D., additional, Liseau, R., additional, Marseille, M., additional, Melnick, G., additional, Nisini, B., additional, Olberg, M., additional, Parise, B., additional, Risacher, C., additional, Santiago, J., additional, Saraceno, P., additional, Shipman, R., additional, Tafalla, M., additional, van der Tak, F., additional, Visser, R., additional, Wyrowski, F., additional, and Yıldız, U. A., additional

Published
2010
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22. Water abundance variations around high-mass protostars: HIFI observations of the DR21 region

Author

van der Tak, F. F. S., primary, Marseille, M. G., additional, Herpin, F., additional, Wyrowski, F., additional, Baudry, A., additional, Bontemps, S., additional, Braine, J., additional, Doty, S., additional, Frieswijk, W., additional, Melnick, G., additional, Shipman, R., additional, van Dishoeck, E. F., additional, Benz, A. O., additional, Caselli, P., additional, Hogerheijde, M., additional, Johnstone, D., additional, Liseau, R., additional, Bachiller, R., additional, Benedettini, M., additional, Bergin, E., additional, Bjerkeli, P., additional, Blake, G., additional, Bruderer, S., additional, Cernicharo, J., additional, Codella, C., additional, Daniel, F., additional, di Giorgio, A. M., additional, Dominik, C., additional, Encrenaz, P., additional, Fich, M., additional, Fuente, A., additional, Giannini, T., additional, Goicoechea, J., additional, de Graauw, Th., additional, Helmich, F., additional, Herczeg, G., additional, Jørgensen, J., additional, Kristensen, L., additional, Larsson, B., additional, Lis, D., additional, McCoey, C., additional, Neufeld, D., additional, Nisini, B., additional, Olberg, M., additional, Parise, B., additional, Pearson, J., additional, Plume, R., additional, Risacher, C., additional, Santiago, J., additional, Saraceno, P., additional, Tafalla, M., additional, van Kempen, T., additional, Visser, R., additional, Wampfler, S., additional, Yıldız, U., additional, Ravera, L., additional, Roelfsema, P., additional, Siebertz, O., additional, and Teyssier, D., additional

Published
2010
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23. Water cooling of shocks in protostellar outflows

Author

Nisini, B., primary, Benedettini, M., additional, Codella, C., additional, Giannini, T., additional, Liseau, R., additional, Neufeld, D., additional, Tafalla, M., additional, van Dishoeck, E. F., additional, Bachiller, R., additional, Baudry, A., additional, Benz, A. O., additional, Bergin, E., additional, Bjerkeli, P., additional, Blake, G., additional, Bontemps, S., additional, Braine, J., additional, Bruderer, S., additional, Caselli, P., additional, Cernicharo, J., additional, Daniel, F., additional, Encrenaz, P., additional, di Giorgio, A. M., additional, Dominik, C., additional, Doty, S., additional, Fich, M., additional, Fuente, A., additional, Goicoechea, J. R., additional, de Graauw, Th., additional, Helmich, F., additional, Herczeg, G., additional, Herpin, F., additional, Hogerheijde, M., additional, Jacq, T., additional, Johnstone, D., additional, Jørgensen, J., additional, Kaufman, M., additional, Kristensen, L., additional, Larsson, B., additional, Lis, D., additional, Marseille, M., additional, McCoey, C., additional, Melnick, G., additional, Olberg, M., additional, Parise, B., additional, Pearson, J., additional, Plume, R., additional, Risacher, C., additional, Santiago, J., additional, Saraceno, P., additional, Shipman, R., additional, van Kempen, T. A., additional, Visser, R., additional, Viti, S., additional, Wampfler, S., additional, Wyrowski, F., additional, van der Tak, F., additional, Yıldız, U. A., additional, Delforge, B., additional, Desbat, J., additional, Hatch, W. A., additional, Péron, I., additional, Schieder, R., additional, Stern, J. A., additional, Teyssier, D., additional, and Whyborn, N., additional

Published
2010
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24. Origin of the hot gas in low-mass protostars

Author

van Kempen, T. A., primary, Kristensen, L. E., additional, Herczeg, G. J., additional, Visser, R., additional, van Dishoeck, E. F., additional, Wampfler, S. F., additional, Bruderer, S., additional, Benz, A. O., additional, Doty, S. D., additional, Brinch, C., additional, Hogerheijde, M. R., additional, Jørgensen, J. K., additional, Tafalla, M., additional, Neufeld, D., additional, Bachiller, R., additional, Baudry, A., additional, Benedettini, M., additional, Bergin, E. A., additional, Bjerkeli, P., additional, Blake, G. A., additional, Bontemps, S., additional, Braine, J., additional, Caselli, P., additional, Cernicharo, J., additional, Codella, C., additional, Daniel, F., additional, di Giorgio, A. M., additional, Dominik, C., additional, Encrenaz, P., additional, Fich, M., additional, Fuente, A., additional, Giannini, T., additional, Goicoechea, J. R., additional, de Graauw, Th., additional, Helmich, F., additional, Herpin, F., additional, Jacq, T., additional, Johnstone, D., additional, Kaufman, M. J., additional, Larsson, B., additional, Lis, D., additional, Liseau, R., additional, Marseille, M., additional, McCoey, C., additional, Melnick, G., additional, Nisini, B., additional, Olberg, M., additional, Parise, B., additional, Pearson, J. C., additional, Plume, R., additional, Risacher, C., additional, Santiago-García, J., additional, Saraceno, P., additional, Shipman, R., additional, van der Tak, F., additional, Wyrowski, F., additional, Yıldız, U. A., additional, Ciechanowicz, M., additional, Dubbeldam, L., additional, Glenz, S., additional, Huisman, R., additional, Lin, R. H., additional, Morris, P., additional, Murphy, J. A., additional, and Trappe, N., additional

Published
2010
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39. OH far-infrared emission from low- and intermediate-mass protostars surveyed with Herschel-PACS.

Author

Wampfler, S. F., Bruderer, S., Karska, A., Herczeg, G. J., van Dishoeck, E. F., Kristensen, L. E., Goicoechea, J. R., Benz, A. O., Doty, S. D., McCoey, C., Baudry, A., Giannini, T., and Larsson, B.

Subjects
WATER chemistry, STREAM chemistry, PROTOSTARS, ASTRONOMY, ASTROPHYSICS
Abstract

Context. The OH radical is a key species in the water chemistry network of star-forming regions, because its presence is tightly related to the formation and destruction of water. Previous studies of the OH far-infrared emission from low- and intermediate-mass protostars suggest that the OH emission mainly originates from shocked gas and not from the quiescent protostellar envelopes. Aims. We aim to study the excitation of OH in embedded low- and intermediate-mass protostars, determine the influence of source parameters on the strength of the emission, investigate the spatial extent of the OH emission, and further constrain its origin. Methods. This paper presents OH observations from 23 low- and intermediate-mass young stellar objects obtained with the PACS integral field spectrometer on-board Herschel in the context of the "Water In Star-forming regions with Herschel" (WISH) key program. Radiative transfer codes are used to model the OH excitation. Results. Most low-mass sources have compact OH emission (≲5000 AU scale), whereas the OH lines in most intermediate-mass sources are extended over the whole 47."0 × 47."0 PACS detector field-of-view (≳20 000 AU). The strength of the OH emission is correlated with various source properties such as the bolometric luminosity and the envelope mass, but also with the [OI] and H2O emission. Rotational diagrams for sources with many OH lines show that the level populations of OH can be approximated by a Boltzmann distribution with an excitation temperature at around 70 K. Radiative transfer models of spherically symmetric envelopes cannot reproduce the OH emission fluxes nor their broad line widths, strongly suggesting an outflow origin. Slab excitation models indicate that the observed excitation temperature can either be reached if the OH molecules are exposed to a strong far-infrared continuum radiation field or if the gas temperature and density are sufficiently high. Using realistic source parameters and radiation fields, it is shown for the case of Ser SMM1 that radiative pumping plays an important role in transitions arising from upper level energies higher than 300 K. The compact emission in the low-mass sources and the required presence of a strong radiation field and/or a high density to excite the OH molecules points toward an origin in shocks in the inner envelope close to the protostar. [ABSTRACT FROM AUTHOR]

Published
2013
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40. Water in star-forming regions with Herschel (WISH) II. Evolution of 557 GHz 110-101 emission in low-mass protostars.

Author

Kristensen, L. E., van Dishoeck, E. F., Bergin, E. A., Visser, R., Yildiz, U. A., San Jose-Garcia, I., Jørgensen, J. K., Herczeg, G. J., Johnstone, D., Wampfler, S. F., Benz, A. O., Bruderer, S., Cabrit, S., Caselli, P., Doty, S. D., Harsono, D., Herpin, F., Hogerheijde, M. R., Karska, A., and van Kempen, T. A.

Subjects
ASTRONOMICAL observations, STAR formation, SPECTRAL energy distribution, PROTOSTARS, BIPOLAR outflows (Astrophysics)
Abstract

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 Lʘ) 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. H2O was observed in the ground-slate 110-101 transition at 557 GHz (Eup/kB -∼ 60K) 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-R and tub-mm continuum data (including PACS data from our programme) are used to constrain the spectral energy distribution (SED) of each source. H20 intensities are compared to inferred envelope properties, e.g., mass and density, outflow properties and CO 3-2 emission. Results. H2O emission is detected in all objects except one (TMCIA). 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 (nix Class 0, one Class 1) indicative of infalling envelopes, and regular P-Cygni profiles in four sources (three Class 1, 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 H2O/CO abundance ratio an a function of velocity in nearly the name 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 in low, ≳10-10. The different H2O profile components show a clear evolutionary trend: in the younger Class 0 sources the emission in dominated by outflow components originating inside an infalling envelope. When large-scale infall diminishes during the Class I phase, the outflow weakens and H2O emission all but disappears. [ABSTRACT FROM AUTHOR]

Published
2012
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41. Modelling Herschel observations of hot molecular gas emission from embedded low-mass protostars.

Author

Visser, R., Kristensen, L. E., Bruderer, S., Van Dishoeck, E. F., Herczeg, G. J., Brinch, C., Doty, S. D., Harsono, D., and Wolfire, M. G.

Subjects
PROTOSTARS, HEATING, STELLAR luminosity function, SOLAR heating, ASTRONOMICAL observations
Abstract

Aims. Young stars interact vigorously with their surroundings, as evident from the highly rotationally excited CO (up to Eu/k = 4000 K) and H2O emission (up to 600 K) detected by the Herschel Space Observatory in embedded low-mass protostars. Our aim is to construct a model that reproduces the observations quantitatively, to investigate the origin of the emission, and to use the lines as probes of the various heating mechanisms. Methods. The model consists of a spherical envelope with a power-law density structure and a bipolar outflow cavity. Three heating mechanisms are considered: passive heating by the protostellar luminosity, ultraviolet irradiation of the outflow cavity walls, and small-scale C-type shocks along the cavity walls. Most of the model parameters are constrained from independent observations; the two remaining free parameters considered here are the protostellar UV luminosity and the shock velocity. Line fluxes are calculated for CO and H2O and compared to Herschel data and complementary ground-based data for the protostars NGC 1333 IRAS2A, HH 46 and DK Cha. The three sources are selected to span a range of evolutionary phases (early Stage 0 to late Stage I) and physical characteristics such as luminosity and envelope mass. Results. The bulk of the gas in the envelope, heated by the protostellar luminosity, accounts for 3-10% of the CO luminosity summed over all rotational lines up to J = 40-39; it is best probed by low-J CO isotopologue lines such as C18O 2-1 and 3-2. The UV-heated gas and the C-type shocks, probed by 12CO 10-9 and higher-J lines, contribute 20-80% each. The model fits show a tentative evolutionary trend: the CO emission is dominated by shocks in the youngest source and by UV-heated gas in the oldest one. This trend is mainly driven by the lower envelope density in more evolved sources. The total H2O line luminosity in all cases is dominated by shocks (>99%). The exact percentages for both species are uncertain by at least a factor of 2 due to uncertainties in the gas temperature as function of the incident UV flux. However, on a qualitative level and within the context of our model, both UV-heated gas and C-type shocks are needed to reproduce the emission in far-infrared rotational lines of CO and H2O. [ABSTRACT FROM AUTHOR]

Published
2012
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42. WISHES COMING TRUE: WATER IN LOW-MASS STAR-FORMING REGIONS WITH HERSCHEL.

Author

Kristensen, L. E., Visser, R., van Dishoeck, E. F., Yıldız, U. A., Herczeg, G. J., Doty, S., Jørgensen, J. K., van Kempen, T. A., Brinch, C., Wampfler, S., Bruderer, S., and Benz, A. O.

Subjects
PLANETARY water, STELLAR evolution, ASTRONOMICAL observations, PROTOSTARS
Abstract

Water is a key molecule for tracing physical and chemical processes in star-forming regions. The key program "Water in star-forming regions with Herschel" is observing several water transitions towards low-mass protostars with HIFI. Results regarding the 557 GHz transition of water are reported here showing that the line is surpris- ingly broad, and consists of several different velocity components. The bulk of the emission comes from shocks, where the abundance is increased by several orders of magnitude to ~10-4. The abundance of water in the outer envelope is determined to ~10-8, whereas only an upper limit of 10-5 is derived for the inner, warm envelope. [ABSTRACT FROM AUTHOR]

Published
2011
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