| Home | << 1 2 3 4 5 6 7 8 9 10 >> [11–20] |
|
| Records | |||||
|---|---|---|---|---|---|
| Author | Mookerjea, B.; Giesen, T.; Stutzki, J.; Cernicharo, J.; Goicoechea, J. R.; De Luca, M.; Bell, T. A.; Gupta, H.; Gerin, M.; Persson, C. M.; Sonnentrucker, P.; Makai, Z.; Black, J.; Boulanger, F.; Coutens, A.; Dartois, E.; Encrenaz, P.; Falgarone, E.; Geballe, T.; Godard, B.; Goldsmith, P. F.; Gry, C.; Hennebelle, P.; Herbst, E.; Hily-Blant, P.; Joblin, C.; Ka<c5><ba>mierczak, M.; Kołos, R.; Krełowski, J.; Lis, D. C.; Martin-Pintado, J.; Menten, K. M.; Monje, R.; Pearson, J. C.; Perault, M.; Phillips, T. G.; Plume, R.; Salez, M.; Schlemmer, S.; Schmidt, M.; Teyssier, D.; Vastel, C.; Yu, S.; Dieleman, P.; Güsten, R.; Honingh, C. E.; Morris, P.; Roelfsema, P.; Schieder, R.; Tielens, A. G. G. M.; Zmuidzinas, J. | ||||
| Title | Excitation and abundance of C3 in star forming cores. Herschel/HIFI observations of the sight-lines to W31C and W49N | Type | Journal Article | ||
| Year | 2010 | Publication | Astron. Astrophys. | Abbreviated Journal | |
| Volume | 521 | Issue | Pages | L13 | |
Keywords  |
HEB mixer applications, HIFI, Herschel, ISM: lines and bands / ISM: molecules / radiative transfer / ISM: individual objects: W49N / ISM: individual objects: W31C | ||||
| Abstract | We present spectrally resolved observations of triatomic carbon (C3) in several ro-vibrational transitions between the vibrational ground state and the low-energy ν2 bending mode at frequencies between 1654–1897 GHz along the sight-lines to the submillimeter continuum sources W31C and W49N, using Herschel's HIFI instrument. We detect C3 in absorption arising from the warm envelope surrounding the hot core, as indicated by the velocity peak position and shape of the line profile. The sensitivity does not allow to detect C3 absorption due to diffuse foreground clouds. From the column densities of the rotational levels in the vibrational ground state probed by the absorption we derive a rotation temperature (Trot) of ~50-70 K, which is a good measure of the kinetic temperature of the absorbing gas, as radiative transitions within the vibrational ground state are forbidden. It is also in good agreement with the dust temperatures for W31C and W49N. Applying the partition function correction based on the derived Trot, we get column densities N(C3) ~ 7–9 × 1014 cm-2 and abundance x(C3) ~ 10-8 with respect to H2. For W31C, using a radiative transfer model including far-infrared pumping by the dust continuum and a temperature gradient within the source along the line of sight we find that a model with x(C3) = 10-8, Tkin = 30–50 K, N(C3) = 1.5 × 1015 cm-2 fits the observations reasonably well and provides parameters in very good agreement with the simple excitation analysis. | ||||
| Address | |||||
| Corporate Author | Thesis | ||||
| Publisher | Place of Publication | Editor | |||
| Language | Summary Language | Original Title | |||
| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | ISBN | Medium | |||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | Serial | 1099 | |||
| Permanent link to this record | |||||
| Author | Dedes, C.; Röllig, M.; Mookerjea, B.; Okada, Y.; Ossenkopf, V.; Bruderer, S.; Benz, A. O.; Melchior, M.; Kramer, C.; Gerin, M.; Güsten, R.; Akyilmaz, M.; Berne, O.; Boulanger, F.; De Lange, G.; Dubbeldam, L.; France, K.; Fuente, A.; Goicoechea, J. R.; Harris, A.; Huisman, R.; Jellema, W.; Joblin, C.; Klein, T.; Le Petit, F.; Lord, S.; Martin, P.; Martin-Pintado, J.; Neufeld, D. A.; Philipp, S.; Phillips, T.; Pilleri, P.; Rizzo, J. R.; Salez, M.; Schieder, R.; Simon, R.; Siebertz, O.; Stutzki, J.; van der Tak, F.; Teyssier, D.; Yorke, H. | ||||
| Title | The origin of the [C II] emission in the S140 photon-dominated regions. New insights from HIFI | Type | Journal Article | ||
| Year | 2010 | Publication | Astron. Astrophys. | Abbreviated Journal | |
| Volume | 521 | Issue | Pages | L24 | |
| Keywords |
HEB mixer applications, HIFI, Herschel, ISM: structure / ISM: kinematics and dynamics / ISM: molecules / photon-dominated region (PDR) / submillimeter: general | ||||
| Abstract | Using Herschel's HIFI instrument, we observe C ii along a cut through S140, as well as high-J transitions of CO and HCO+ at two positions on the cut, corresponding to the externally irradiated ionization front and the embedded massive star-forming core IRS1. The HIFI data were combined with available ground-based observations and modeled using the KOSMA-Ï„ model for photon-dominated regions (PDRs). We derive the physical conditions in S140 and in particular the origin of C ii emission around IRS1. We identify three distinct regions of C ii emission from the cut, one close to the embedded source IRS1, one associated with the ionization front, and one further into the cloud. The line emission can be understood in terms of a clumpy model of PDRs. At the position of IRS1, we identify at least two distinct components contributing to the [C ii] emission, one of them a small, hot component, which can possibly be identified with the irradiated outflow walls. This is consistent with the C ii peak at IRS1 coinciding with shocked H2 emission at the edges of the outflow cavity. We note that previously available observations of IRS1 can be reproduced well by a single-component KOSMA-Ï„ model. Thus, it is HIFI's unprecedented spatial and spectral resolution, as well as its sensitivity that has allowed us to uncover an additional hot gas component in the S140 region. | ||||
| Address | |||||
| Corporate Author | Thesis | ||||
| Publisher | Place of Publication | Editor | |||
| Language | Summary Language | Original Title | |||
| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | ISBN | Medium | |||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | Serial | 1091 | |||
| Permanent link to this record | |||||
| Author | Joblin, C.; Pilleri, P.; Montillaud, J.; Fuente, A.; Gerin, M.; Berné, O.; Ossenkopf, V.; Le Bourlot, J.; Teyssier, D.; Goicoechea, J. R.; Le Petit, F.; Röllig, M.; Akyilmaz, M.; Benz, A. O.; Boulanger, F.; Bruderer, S.; Dedes, C.; France, K.; Güsten, R.; Harris, A.; Klein, T.; Kramer, C.; Lord, S. D.; Martin, P. G.; Martin-Pintado, J.; Mookerjea, B.; Okada, Y.; Phillips, T. G.; Rizzo, J. R.; Simon, R.; Stutzki, J.; van der Tak, F.; Yorke, H. W.; Steinmetz, E.; Jarchow, C.; Hartogh, P.; Honingh, C. E.; Siebertz, O.; Caux, E.; Colin, B. | ||||
| Title | Gas morphology and energetics at the surface of PDRs: New insights with Herschel observations of NGC 7023 | Type | Journal Article | ||
| Year | 2010 | Publication | Astron. Astrophys. | Abbreviated Journal | |
| Volume | 521 | Issue | Pages | L25 | |
| Keywords |
HEB mixer applications, HIFI, Herschel, ISM: structure / ISM: kinematics and dynamics / ISM: molecules / submillimeter: ISM | ||||
| Abstract | Context. We investigate the physics and chemistry of the gas and dust in dense photon-dominated regions (PDRs), along with their dependence on the illuminating UV field. Aims. Using Herschel/HIFI observations, we study the gas energetics in NGC 7023 in relation to the morphology of this nebula. NGC 7023 is the prototype of a PDR illuminated by a B2V star and is one of the key targets of Herschel. Methods. Our approach consists in determining the energetics of the region by combining the information carried by the mid-IR spectrum (extinction by classical grains, emission from very small dust particles) with that of the main gas coolant lines. In this letter, we discuss more specifically the intensity and line profile of the 158 μm (1901 GHz) [C ii] line measured by HIFI and provide information on the emitting gas. Results. We show that both the [C ii] emission and the mid-IR emission from polycyclic aromatic hydrocarbons (PAHs) arise from the regions located in the transition zone between atomic and molecular gas. Using the Meudon PDR code and a simple transfer model, we find good agreement between the calculated and observed [C ii] intensities. Conclusions. HIFI observations of NGC 7023 provide the opportunity to constrain the energetics at the surface of PDRs. Future work will include analysis of the main coolant line [O i] and use of a new PDR model that includes PAH-related species. |
||||
| Address | |||||
| Corporate Author | Thesis | ||||
| Publisher | Place of Publication | Editor | |||
| Language | Summary Language | Original Title | |||
| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | ISBN | Medium | |||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | Serial | 1095 | |||
| Permanent link to this record | |||||
| Author | Velusamy, T.; Langer, W. D.; Pineda, J. L.; Goldsmith, P. F.; Li, D.; Yorke, H. W. | ||||
| Title | [CII] observations of H2 molecular layers in transition clouds | Type | Journal Article | ||
| Year | 2010 | Publication | Astron. Astrophys. | Abbreviated Journal | |
| Volume | 521 | Issue | Pages | L18 | |
| Keywords |
HEB mixer applications, HIFI, Herschel, ISM: structure / ISM: molecules / ISM: atoms / submillimeter: ISM | ||||
| Abstract | We present the first results on the diffuse transition clouds observed in [CII] line emission at 158 μm (1.9 THz) towards Galactic longitudes near 340° (5 LOSs) & 20° (11 LOSs) as part of the HIFI tests and GOT C+ survey. Out of the total 146 [CII] velocity components detected by profile fitting we identify 53 as diffuse molecular clouds with associated 12CO emission but without 13CO emission and characterized by AV < 5 mag. We estimate the fraction of the [CII] emission in the diffuse HI layer in each cloud and then determine the [CII] emitted from the molecular layers in the cloud. We show that the excess [CII] intensities detected in a few clouds is indicative of a thick H2 layer around the CO core. The wide range of clouds in our sample with thin to thick H2 layers suggests that these are at various evolutionary states characterized by the formation of H2 and CO layers from HI and C+, respectively. In about 30% of the clouds the H2 column densities (“dark gasâ€) traced by the [CII] is 50% or more than that traced by 12CO emission. On the average ~25% of the total H2 in these clouds is in an H2 layer which is not traced by CO. We use the HI, [CII], and 12CO intensities in each cloud along with simple chemical models to obtain constraints on the FUV fields and cosmic ray ionization rates. | ||||
| Address | |||||
| Corporate Author | Thesis | ||||
| Publisher | Place of Publication | Editor | |||
| Language | Summary Language | Original Title | |||
| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | ISBN | Medium | |||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | Serial | 1102 | |||
| Permanent link to this record | |||||
| Author | Pineda, J. L.; Velusamy, T.; Langer, W. D.; Goldsmith, P. F.; Li, D.; Yorke, H. W. | ||||
| Title | A sample of [C II] clouds tracing dense clouds in weak FUV fields observed by Herschel | Type | Journal Article | ||
| Year | 2010 | Publication | Astron. Astrophys. | Abbreviated Journal | |
| Volume | 521 | Issue | Pages | L19 | |
| Keywords |
HEB mixer applications, HIFI, Herschel, ISM: structure / photon-dominated region / ISM: supernova remnants / evolution | ||||
| Abstract | The [C ii] fine-structure line at 158 μm is an excellent tracer of the warm diffuse gas in the ISM and the interfaces between molecular clouds and their surrounding atomic and ionized envelopes. Here we present the initial results from Galactic observations of terahertz C+ (GOT C+), a Herschel key project devoted to studying the [C ii] emission in the Galactic plane using the HIFI instrument. We used the [C ii] emission, together with observations of CO, as a probe to understand the effects of newly formed stars on their interstellar environment and characterize the physical and chemical state of the star-forming gas. We collected data along 16 lines-of-sight passing near star-forming regions in the inner Galaxy near longitudes 330° and 20°. We identified fifty-eight [C ii] components that are associated with high-column density molecular clouds as traced by 13CO emission. We combined [C ii], 12CO, and 13CO observations to derive the physical conditions of the [C ii]-emitting regions in our sample of high-column density clouds based on comparing results from a grid of photon dominated region (PDR) models. From this unbiased sample, our results suggest that most of the [C ii] emission originates in clouds with H2 volume densities between 103.5 and 105.5 cm-3 and weak FUV strength (χ0 = 1–10). We find two regions where our analysis suggest high densities >105 cm-3 and strong FUV fields (χ0 = 104–106), likely associated with massive star formation. We suggest that [C ii] emission in conjunction with CO isotopes is a good tool for differentiating regions of massive star formation (high densities/strong FUV fields) and regions that are distant from massive stars (lower densities/weaker FUV fields) along the line-of-sight. | ||||
| Address | |||||
| Corporate Author | Thesis | ||||
| Publisher | Place of Publication | Editor | |||
| Language | Summary Language | Original Title | |||
| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | ISBN | Medium | |||
| Area | Expedition | Conference | |||
| Notes | Approved | no | |||
| Call Number | Serial | 1101 | |||
| Permanent link to this record | |||||