Search

Your search keyword '"Tolls, Volker"' showing total 14 results
Start Over Author "Tolls, Volker" Journal the astrophysical journal
14 results on '"Tolls, Volker"'

1. Distribution of Water Vapor in Molecular Clouds. II

Author

Melnick, Gary J., primary, Tolls, Volker, additional, Snell, Ronald L., additional, Kaufman, Michael J., additional, Bergin, Edwin A., additional, Goicoechea, Javier R., additional, Goldsmith, Paul F., additional, González-Alfonso, Eduardo, additional, Hollenbach, David J., additional, Lis, Dariusz C., additional, and Neufeld, David A., additional

Published
2020
Full Text
View/download PDF

3. Probing ISM Structure in Trumpler 14 and Carina I Using the Stratospheric Terahertz Observatory 2

Author

Seo, Young Min, primary, Goldsmith, Paul F., additional, Walker, Christopher K., additional, Hollenbach, David J., additional, Wolfire, Mark G., additional, Kulesa, Craig A., additional, Tolls, Volker, additional, Bernasconi, Pietro N., additional, Kavak, Ümit, additional, van der Tak, Floris F. S., additional, Shipman, Russ, additional, Gao, Jian Rong, additional, Tielens, Alexander, additional, Burton, Michael G., additional, Yorke, Harold, additional, Young, Erick, additional, Peters, William L., additional, Young, Abram, additional, Groppi, Christopher, additional, Davis, Kristina, additional, Pineda, Jorge L., additional, Langer, William D., additional, Kawamura, Jonathan H., additional, Stark, Antony, additional, Melnick, Gary, additional, Rebolledo, David, additional, Wong, Graeme F., additional, Horiuchi, Shinji, additional, and Kuiper, Thomas B., additional

Published
2019
Full Text
View/download PDF

6. HERSCHELSEARCH FOR O2TOWARD THE ORION BAR

Author

Melnick, Gary J., primary, Tolls, Volker, additional, Goldsmith, Paul F., additional, Kaufman, Michael J., additional, Hollenbach, David J., additional, Black, John H., additional, Encrenaz, Pierre, additional, Falgarone, Edith, additional, Gerin, Maryvonne, additional, Hjalmarson, Åke, additional, Li, Di, additional, Lis, Dariusz C., additional, Liseau, René, additional, Neufeld, David A., additional, Pagani, Laurent, additional, Snell, Ronald L., additional, van der Tak, Floris, additional, and van Dishoeck, Ewine F., additional

Published
2012
Full Text
View/download PDF

7. DISTRIBUTION OF WATER VAPOR IN MOLECULAR CLOUDS

Author

Melnick, Gary J., primary, Tolls, Volker, additional, Snell, Ronald L., additional, Bergin, Edwin A., additional, Hollenbach, David J., additional, Kaufman, Michael J., additional, Li, Di, additional, and Neufeld, David A., additional

Published
2010
Full Text
View/download PDF

9. SPITZERMAPPING OF MOLECULAR HYDROGEN PURE ROTATIONAL LINES IN NGC 1333: A DETAILED STUDY OF FEEDBACK IN STAR FORMATION

Author

Maret, Sébastien, primary, Bergin, Edwin A., additional, Neufeld, David A., additional, Green, Joel D., additional, Watson, Dan M., additional, Harwit, Martin O., additional, Kristensen, Lars E., additional, Melnick, Gary J., additional, Sonnentrucker, Paule, additional, Tolls, Volker, additional, Werner, Michael W., additional, Willacy, Karen, additional, and Yuan, Yuan, additional

Published
2009
Full Text
View/download PDF

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

Author

Melnick, Gary J., primary, Stauffer, John R., additional, Ashby, Matthew L. N., additional, Bergin, Edwin A., additional, Chin, Gordon, additional, Erickson, Neal R., additional, Goldsmith, Paul F., additional, Harwit, Martin, additional, Howe, John E., additional, Kleiner, Steven C., additional, Koch, David G., additional, Neufeld, David A., additional, Patten, Brian M., additional, Plume, René, additional, Schieder, Rudolf, additional, Snell, Ronald L., additional, Tolls, Volker, additional, Wang, Zhong, additional, Winnewisser, Gisbert, additional, and Zhang, Yun Fei, additional

Published
2000
Full Text
View/download PDF

12. SPITZER SPECTRAL LINE MAPPING OF PROTOSTELLAR OUTFLOWS. I. BASIC DATA AND OUTFLOW ENERGETICS

Author

Neufeld, David A., Nisini, Brunella, Giannini, Teresa, Melnick, Gary J., Bergin, Edwin A., Yuan, Yuan, Maret, Sebastien, Tolls, Volker, Gusten, Rolf, and Kaufman, Michael J.

Abstract

We report the results of spectroscopic mapping observations carried out toward protostellar outflows in the BHR71, L1157, L1448, NGC 2071, and VLA 1623 molecular regions using the Infrared Spectrograph (IRS) of the Spitzer Space Telescope. These observations, covering the 5.2-37 mm spectral region, provide detailed maps of the eight lowest pure rotational lines of molecular hydrogen and of the [S I] 25.25 mm and [Fe II] 26.0 mm fine-structure lines. The molecular hydrogen lines, believed to account for a large fraction of the radiative cooling from warm molecular gas that has been heated by a non-dissociative shock, allow the energetics of the outflows to be elucidated. Within the regions mapped toward these five outflow sources, total H2 luminosities ranging from 0.02 to 0.75 L were inferred for the sum of the eight lowest pure rotational transitions. By contrast, the much weaker [Fe II] 26.0 mm fine-structure transition traces faster, dissociative shocks; here, only a small fraction of the fast shock luminosity emerges as line radiation that can be detected with Spitzer/IRS.

Published
2009

13. SPITZER MAPPING OF MOLECULAR HYDROGEN PURE ROTATIONAL LINES IN NGC 1333: A DETAILED STUDY OF FEEDBACK IN STAR FORMATION

Author

Maret, Sebastien, Bergin, Edwin A., Neufeld, David A., Green, Joel D., Watson, Dan M., Harwit, Martin O., Kristensen, Lars E., Melnick, Gary J., Sonnentrucker, Paule, Tolls, Volker, Werner, Michael W., Willacy, Karen, and Yuan, Yuan

Abstract

We present mid-infrared spectral maps of the NGC 1333 star-forming region, obtained with the infrared spectrometer on board the Spitzer Space Telescope. Eight pure H2 rotational lines, from S(0) to S(7), are detected and mapped. The H2 emission appears to be associated with the warm gas shocked by the multiple outflows present in the region. A comparison between the observed intensities and the predictions of detailed shock models indicates that the emission arises in both slow (12-24 km s-1) and fast (36-53 km s-1) C-type shocks with an initial ortho-to-para ratio (opr) [?]1. The present H2 opr exhibits a large degree of spatial variations. In the postshocked gas, it is usually about 2, i.e., close to the equilibrium value ([?]3). However, around at least two outflows, we observe a region with a much lower ([?]0.5) opr. This region probably corresponds to gas which has been heated up recently by the passage of a shock front, but whose ortho-to-para has not reached equilibrium yet. This, together with the low initial opr needed to reproduce the observed emission, provide strong evidence that H2 is mostly in para form in cold molecular clouds. The H2 lines are found to contribute to 25%-50% of the total outflow luminosity, and thus can be used to ascertain the importance of star formation feedback on the natal cloud. From these lines, we determine the outflow mass loss rate and, indirectly, the stellar infall rate, the outflow momentum and the kinetic energy injected into the cloud over the embedded phase. The latter is found to exceed the binding energy of individual cores, suggesting that outflows could be the main mechanism for core disruption.

Published
2009

14. DISTRIBUTION OF WATER VAPOR IN MOLECULAR CLOUDS

Author

Melnick, Gary J., Tolls, Volker, Snell, Ronald L., Bergin, Edwin A., Hollenbach, David J., Kaufman, Michael J., and, Di Li, and Neufeld, David A.

Abstract

We report the results of a large-area study of water vapor along the Orion Molecular Cloud ridge, the purpose of which was to determine the depth-dependent distribution of gas-phase water in dense molecular clouds. We find that the water vapor measured toward 77 spatial positions along the face-on Orion ridge, excluding positions surrounding the outflow associated with BN/KL and IRc2, display integrated intensities that correlate strongly with known cloud surface tracers such as CN, C2H, 13CO J = 5-4, and HCN, and less well with the volume tracer N2H+. Moreover, at total column densities corresponding to A V< 15 mag, the ratio of H2O to C18O integrated intensities shows a clear rise approaching the cloud surface. We show that this behavior cannot be accounted for by either optical depth or excitation effects, but suggests that gas-phase water abundances fall at large A V. These results are important as they affect measures of the true water-vapor abundance in molecular clouds by highlighting the limitations of comparing measured water-vapor column densities with such traditional cloud tracers as 13CO or C18O. These results also support cloud models that incorporate freeze out of molecules as a critical component in determining the depth-dependent abundance of water vapor.

Published
2011

Catalog

Books, media, physical & digital resources
See catalog results