Testing grain-surface chemistry in massive hot-core regions

Bisschop, S. E.; Jørgensen, J. K.; Dishoeck, E. F. van; Wachter, E. De

doi:10.1051/0004-6361:20065963

Cited by 323 publications

(560 citation statements)

References 70 publications

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“…Comparing these values with N CH 3 OH (Table 5), the CH 3 OH abundances would be 2 × 10 −9 −2 × 10 −5 . These abundances are consistent with the values found toward hot molecular cores and infrared dark clouds (Bisschop et al 2007;Leurini et al 2007). …”

Section: Temperature and Mass Estimatessupporting

confidence: 90%

Filamentary structure and Keplerian rotation in the high-mass star-forming region G35.03+0.35 imaged with ALMA

Beltrán

Sánchez-Monge

Cesaroni

et al. 2014

A&A

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Context. Theoretical scenarios propose that high-mass stars are formed by disk-mediated accretion. Aims. To test the theoretical predictions on the formation of massive stars, we wish to make a thorough study at high-angular resolution of the structure and kinematics of the dust and gas emission toward the high-mass star-forming region G35.03+0.35, which harbors a disk candidate around a B-type (proto)star. Methods. We carried out ALMA Cycle 0 observations at 870 μm of dust of typical high-density, molecular outflow, and cloud tracers with resolutions of <0. 5. Complementary Subaru COMICS 25 μm observations were carried out to trace the mid-infrared emission toward this star-forming region. Results. The submillimeter continuum emission has revealed a filamentary structure fragmented into six cores, called A-F. The filament could be in quasi-equilibrium taking into account that the mass per unit length of the filament, 200-375 M /pc, is similar to the critical mass of a thermally and turbulently supported infinite cylinder, ∼335 M /pc. The cores, which are on average separated by ∼0.02 pc, have deconvolved sizes of 1300-3400 AU, temperatures of 35-240 K, H 2 densities >10 7 cm −3 , and masses in the range 1-5 M , and they are subcritical. Core A, which is associated with a hypercompact Hii region and could be the driving source of the molecular outflow observed in the region, is the most chemically rich source in G35.03+0.35 with strong emission of typical hot core tracers such as CH 3 CN. Tracers of high density and excitation show a clear velocity gradient along the major axis of the core, which is consistent with a disk rotating about the axis of the associated outflow. The PV plots along the SE-NW direction of the velocity gradient show clear signatures of Keplerian rotation, although infall could also be present, and they are consistent with the pattern of an edge-on Keplerian disk rotating about a star with a mass in the range 5-13 M . The high t ff /t rot ratio for core A suggests that the structure rotates fast and that the accreting material has time to settle into a centrifugally supported disk. Conclusions. G35.03+0.35 is one of the most convincing examples of Keplerian disks rotating about high-mass (proto)stars. This supports theoretical scenarios according to which high-mass stars, at least B-type stars, would form through disk-mediated accretion.

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Section: Temperature and Mass Estimatessupporting

confidence: 90%

Filamentary structure and Keplerian rotation in the high-mass star-forming region G35.03+0.35 imaged with ALMA

Beltrán

Sánchez-Monge

Cesaroni

et al. 2014

A&A

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“…They also found differences in the abundances of, e.g., C 2 H 5 CN and CH 3 OCH 3 relative to water: while the latter is relatively constant between the three different sources, the C 2 H 5 CN to water abundance ratio varies by orders of magnitude. Similar differences between oxygen-and nitrogen-bearing species have also been seen in other types of star-forming regions (e.g., the sample of high-mass stars surveyed by Bisschop et al 2007). As discussed by Bisschop et al (2008), these differences can be explained through differences in their formation on grain surfaces and, e.g., the initial ice compositions.…”

Section: Chemistry Of 100 Au Regionssupporting

confidence: 62%

Interferometric Studies of Low-Mass Protostars

Jørgensen

2011

Proc. IAU

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Abstract. With the advances in high angular resolution (sub)millimeter observations of lowmass protostars, windows of opportunities are opening up for very detailed studies of the molecular structure of star forming regions on wide range of spatial scales. Deeply embedded protostars provide an important laboratory to study the chemistry of star formation -providing the link between dense regions in molecular clouds from which stars are formed, i.e., the initial conditions and the end product in terms of, e.g., disk and planet formation. High angular resolution observations at (sub)millimeter wavelengths provide an important tool for studying the chemical composition of such low-mass protostars. They for example constrain the spatial molecular abundance variations -and can thereby identify which species are useful tracers of different components of the protostars at different evolutionary stages. In this review I discuss the possibilities and limitations of using high angular resolution (sub)millimeter interferometric observations for studying the chemical evolution of low-mass protostars -with a particular keen eye toward near-future ALMA observations.

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“…Two of the sources, NGC 7538 IRS1 HC and W3 IRS5 c2, have been observed previously by others 24,32 . In the case of NGC 7538 IRS1 HC, the derived CH 3 OH, CH 3 CN and CH 3 OCH 3 columns are consistent with previous observations, while the CH 3 CHO and CH 3 CCH columns are at least an order of magnitude higher in our study.…”

Section: Cn Linesmentioning

confidence: 54%

Complex molecule formation around massive young stellar objects

et al. 2014

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Interstellar complex organic molecules were first identified in the hot inner regions of massive young stellar objects (MYSOs), but have more recently been found in many colder sources, indicating that complex molecules can form at a range of temperatures. Individually these observations provide limited constraints, however, on how complex molecules form, and whether the same formation pathways dominate in cold, warm and hot environments. To address these questions, we use spatially resolved observations from the Submillimeter Array of three MYSOs together with mostly unresolved literature data to explore how molecular ratios depend on environmental parameters, especially temperature. Toward the three MYSOs, we find multiple complex organic emission peaks characterized by different molecular compositions and temperatures. In particular, CH 3 CCH and CH 3 CN seem to always trace a luke-warm (T∼60 K) and a hot (T>100 K) complex chemistry, respectively. These spatial trends are consistent with abundance-temperature correlations of four representative complex organics -CH 3 CCH, CH 3 CN, CH 3 OCH 3 and CH 3 CHO -in a large sample of complex molecule hosts mined from the literature. Together these results indicate a general chemical evolution with temperature, i.e. that new complex molecule formation pathways are activated as a MYSO heats up. This is qualitatively consistent with model predictions. Furthermore, these results suggest that ratios of complex molecules may be developed into a powerful probe of the evolutionary stage of a MYSO, as well as provide information about its formation history.

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Testing grain-surface chemistry in massive hot-core regions

Cited by 323 publications

References 70 publications

Filamentary structure and Keplerian rotation in the high-mass star-forming region G35.03+0.35 imaged with ALMA

Filamentary structure and Keplerian rotation in the high-mass star-forming region G35.03+0.35 imaged with ALMA

Interferometric Studies of Low-Mass Protostars

Complex molecule formation around massive young stellar objects

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