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Your search keyword '"Klaassen, P. D."' showing total 22 results
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22 results on '"Klaassen, P. D."'

1. Kinematics and stability of high-mass protostellar disk candidates at sub-arcsecond resolution? Insights from the IRAM NOEMA large programme CORE

Author

Ahmadi, A., primary, Beuther, H., additional, Bosco, F., additional, Gieser, C., additional, Suri, S., additional, Mottram, J. C., additional, Kuiper, R., additional, Henning, T., additional, Sánchez-Monge, Á., additional, Linz, H., additional, Pudritz, R. E., additional, Semenov, D., additional, Winters, J. M., additional, Möller, T., additional, Beltrán, M. T., additional, Csengeri, T., additional, Galván-Madrid, R., additional, Johnston, K. G., additional, Keto, E., additional, Klaassen, P. D., additional, Leurini, S., additional, Longmore, S. N., additional, Lumsden, S. L., additional, Maud, L. T., additional, Moscadelli, L., additional, Palau, A., additional, Peters, T., additional, Ragan, S. E., additional, Urquhart, J. S., additional, Zhang, Q., additional, and Zinnecker, H., additional

Published
2023
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2. Kinematics and stability of high-mass protostellar disk candidates at sub-arcsecond resolution

Author

Ahmadi, A., Beuther, H., Bosco, F., Gieser, C., Suri, S., Mottram, J.C., Kuiper, R., Henning, T., Sanchez-Monge, A., Linz, H., Pudritz, R.E., Semenov, D., Winters, J.M., Möller, T., Beltran, M. T., Csengeri, T., Galvan-Madrid, R., Johnston, K.G., Keto, E., Klaassen, P. D., Leurini, S., Longmore, S.N., Lumsden, S.L., Maud, L.T., Moscadelli, L., Palau, A., Peters, T., Ragan, S.E., Urquhart, J.S., Zhang, Q., Zinnecker, H., Ahmadi, A., Beuther, H., Bosco, F., Gieser, C., Suri, S., Mottram, J.C., Kuiper, R., Henning, T., Sanchez-Monge, A., Linz, H., Pudritz, R.E., Semenov, D., Winters, J.M., Möller, T., Beltran, M. T., Csengeri, T., Galvan-Madrid, R., Johnston, K.G., Keto, E., Klaassen, P. D., Leurini, S., Longmore, S.N., Lumsden, S.L., Maud, L.T., Moscadelli, L., Palau, A., Peters, T., Ragan, S.E., Urquhart, J.S., Zhang, Q., and Zinnecker, H.

Abstract

Context. The fragmentation mode of high-mass molecular clumps and the accretion processes that form the most massive stars (M & 8 M) are still not well understood. A growing number of case studies have found massive young stellar objects (MYSOs) to harbour disk-like structures, painting a picture that the formation of high-mass stars may proceed through disk accretion, similar to that of lower mass stars. However, the properties of such structures have yet to be uniformly and systematically characterised. Massive disks are prone to fragmentation via gravitational instabilities due to high gas densities and accretion rates. Therefore, it is important to study the stability of such disks in order to put into context the role of disk fragmentation in setting the final stellar mass distribution in high-mass star forming regions. Aims. The aim of this work is to uniformly study the kinematic properties of a large sample of MYSOs and characterise the stability of possible circumstellar disks against gravitational fragmentation. Methods. We have undertaken a large observational program (CORE) making use of interferometric observations from the Northern Extended Millimetre Array (NOEMA) for a sample of 20 luminous (L > 104 L) protostellar objects in the 1.37 mm wavelength regime in both continuum and spectral line emission, reaching 0.400 resolution (800 au at 2 kpc). Results. We present the gas kinematics of the full sample and detect dense gas emission surrounding 15 regions within the CORE sample. Using the dense gas tracer CH3CN, we find velocity gradients across 13 cores perpendicular to the directions of bipolar molecular outflows, making them excellent disk candidates. The extent of the CH3CN emission tracing the disk candidates varies from 1800 − 8500 au. Analysing the free-fall to rotational timescales, we find that the sources are rotationally supported. The rotation profiles of some disk candidates are well described by differential rotation while for others the

Published
2023

3. The sharp ALMA view of infall and outflow in the massive protocluster G31.41+0.31

Author

Beltrán, M. T., primary, Rivilla, V. M., additional, Cesaroni, R., additional, Galli, D., additional, Moscadelli, L., additional, Ahmadi, A., additional, Beuther, H., additional, Etoka, S., additional, Goddi, C., additional, Klaassen, P. D., additional, Kuiper, R., additional, Kumar, M. S. N., additional, Lorenzani, A., additional, Peters, T., additional, Sánchez-Monge, Á., additional, Schilke, P., additional, van der Tak, F., additional, and Vig, S., additional

Published
2022
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4. Complex organic molecules in low-mass protostars on Solar System scales

Author

Nazari, P., primary, van Gelder, M. L., additional, van Dishoeck, E. F., additional, Tabone, B., additional, van ’t Hoff, M. L. R., additional, Ligterink, N. F. W., additional, Beuther, H., additional, Boogert, A. C. A., additional, Caratti o Garatti, A., additional, Klaassen, P. D., additional, Linnartz, H., additional, Taquet, V., additional, and Tychoniec, Ł., additional

Published
2021
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5. Fragmentation in the massive G31.41+0.31 protocluster

Author

Beltrán, M. T., primary, Rivilla, V. M., additional, Cesaroni, R., additional, Maud, L. T., additional, Galli, D., additional, Moscadelli, L., additional, Lorenzani, A., additional, Ahmadi, A., additional, Beuther, H., additional, Csengeri, T., additional, Etoka, S., additional, Goddi, C., additional, Klaassen, P. D., additional, Kuiper, R., additional, Kumar, M. S. N., additional, Peters, T., additional, Sánchez-Monge, Á., additional, Schilke, P., additional, van der Tak, F., additional, Vig, S., additional, and Zinnecker, H., additional

Published
2021
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6. Multi-scale view of star formation in IRAS 21078+5211: from clump fragmentation to disk wind

Author

Moscadelli, L., primary, Beuther, H., additional, Ahmadi, A., additional, Gieser, C., additional, Massi, F., additional, Cesaroni, R., additional, Sánchez-Monge, Á., additional, Bacciotti, F., additional, Beltrán, M. T., additional, Csengeri, T., additional, Galván-Madrid, R., additional, Henning, Th., additional, Klaassen, P. D., additional, Kuiper, R., additional, Leurini, S., additional, Longmore, S. N., additional, Maud, L. T., additional, Möller, T., additional, Palau, A., additional, Peters, T., additional, Pudritz, R. E., additional, Sanna, A., additional, Semenov, D., additional, Urquhart, J. S., additional, Winters, J. M., additional, and Zinnecker, H., additional

Published
2021
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7. Complex organic molecules in low-mass protostars on Solar System scales

Author

van Gelder, M. L., primary, Tabone, B., additional, Tychoniec, Ł., additional, van Dishoeck, E. F., additional, Beuther, H., additional, Boogert, A. C. A., additional, Caratti o Garatti, A., additional, Klaassen, P. D., additional, Linnartz, H., additional, Müller, H. S. P., additional, and Taquet, V., additional

Published
2020
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8. From clump to disc scales in W3 IRS4

Author

Mottram, J. C., primary, Beuther, H., additional, Ahmadi, A., additional, Klaassen, P. D., additional, Beltrán, M. T., additional, Csengeri, T., additional, Feng, S., additional, Gieser, C., additional, Henning, Th., additional, Johnston, K. G., additional, Kuiper, R., additional, Leurini, S., additional, Linz, H., additional, Longmore, S. N., additional, Lumsden, S., additional, Maud, L. T., additional, Moscadelli, L., additional, Palau, A., additional, Peters, T., additional, Pudritz, R. E., additional, Ragan, S. E., additional, Sánchez-Monge, Á., additional, Semenov, D., additional, Urquhart, J. S., additional, Winters, J. M., additional, and Zinnecker, H., additional

Published
2020
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10. ALMA evidence for an SiO disc and disc wind from G17.64+0.16

Author

Maud, L. T., Cesaroni, R., Kumar, M. S. N., van der Tak, F. F. S., Allen, V., Hoare, M. G., Klaassen, P. D., Harsono, D., Hogerheijde, M. R., Sánchez-Monge, Á., Schilke, P., Ahmadi, A., Beltrán, M. T., Beuther, H., Csengeri, T., Etoka, S., Fuller, G., Galván-Madrid, R., Goddi, C., Henning, Th., Johnston, K. G., Kuiper, R., Lumsden, S., Moscadelli, L., Mottram, J. C., Peters, T., Rivilla, V. M., Testi, L., Vig, S., de Wit, W. J., Zinnecker, H., FORMATION STELLAIRE 2020, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), and Astronomy

Subjects
stars: winds, outflows, stars: formation, stars: protostars, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], EARLY EVOLUTION, INFRARED REFLECTION NEBULA, Astrophysics::Cosmology and Extragalactic Astrophysics, stars: pre-main sequence, IMAGING POLARIMETRY, submillimeter: stars, stars: massive, SUBMILLIMETER ARRAY OBSERVATIONS, DISTANCE-LIMITED SAMPLE, LINE-DRIVEN ABLATION, RADIO-EMISSION, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, MASSIVE STAR-FORMATION, CIRCUMSTELLAR DISCS, Astrophysics::Galaxy Astrophysics, ComputingMilieux_MISCELLANEOUS, RADIATION PRESSURE
Abstract

We present high angular resolution (similar to 0.2 '') continuum and molecular emission line Atacama Large Millimeter/sub-millimeter Array (ALMA) observations of G17.64+0.16 in Band 6 (220-230 GHz) taken as part of a campaign in search of circumstellar discs around (proto)-O-stars. At a resolution of similar to 400 au the main continuum core is essentially unresolved and isolated from other strong and compact emission peaks. We detect SiO (5-4) emission that is marginally resolved and elongated in a direction perpendicular to the large-scale outflow seen in the (CO)-C-13 (2-1) line using the main ALMA array in conjunction with the Atacama Compact Array (ACA). Morphologically, the SiO appears to represent a disc-like structure. Using parametric models we show that the position-velocity profile of the SiO is consistent with the Keplerian rotation of a disc around an object between 10 and 30M(circle dot) in mass, only if there is also radial expansion from a separate structure. The radial motion component can be interpreted as a disc wind from the disc surface. Models with a central stellar object mass between 20 and 30 M-circle dot are the most consistent with the stellar luminosity (1 x 10(5) L-circle dot) and indicative of an O-type star. The H30 alpha millimetre recombination line (231.9 GHz) is also detected, but spatially unresolved, and is indicative of a very compact, hot, ionised region co-spatial with the dust continuum core. The broad line-width of the H30 alpha emission (full-width-half-maximum = 81.9 km s(-1)) is not dominated by pressure-broadening but is consistent with underlying bulk motions. These velocities match those required for shocks to release silicon from dust grains into the gas phase. CH3CN and CH3OH thermal emission also shows two arc shaped plumes that curve away from the disc plane. Their coincidence with OH maser emission suggests that they could trace the inner working surfaces of a wide-angle wind driven by G17.64 which impacts the diffuse remnant natal cloud before being redirected into the large-scale outflow direction. Accounting for all observables, we suggest that G17.64 is consistent with a O-type young stellar object in the final stages of protostellar assembly, driving a wind, but that has not yet developed into a compact HII region. The existance and detection of the disc in G17.64 is likely related to its isolated and possibly more evolved nature, traits which may underpin discs in similar sources.

Published
2018

11. IRAS 23385+6053: An embedded massive cluster in the making

Author

Cesaroni, R., Beuther, H., Ahmadi, A., Beltran, M.T., Csengeri, T., Galvan-Madrid, R., Gieser, C., Henning, T., Johnston, K.G., Klaassen, P. D., Kuiper, R., Leurini, S., Linz, H., Longmore, S., Lumsden, S.L., Maud, L.T., Moscadelli, L., Mottram, J.C., Palau, A., Peters, T., Pudritz, R.E., Sanchez-Monge, A., Schilke, P., Semenov, D., Suri, S., Urquhart, J.S., Winters, J.M., Zhang, Q., Zinnecker, H., Cesaroni, R., Beuther, H., Ahmadi, A., Beltran, M.T., Csengeri, T., Galvan-Madrid, R., Gieser, C., Henning, T., Johnston, K.G., Klaassen, P. D., Kuiper, R., Leurini, S., Linz, H., Longmore, S., Lumsden, S.L., Maud, L.T., Moscadelli, L., Mottram, J.C., Palau, A., Peters, T., Pudritz, R.E., Sanchez-Monge, A., Schilke, P., Semenov, D., Suri, S., Urquhart, J.S., Winters, J.M., Zhang, Q., and Zinnecker, H.

Abstract

Context. This study is part of the project “CORE”, an IRAM/NOEMA large program consisting of observations of the millimeter continuum and molecular line emission towards 20 selected high-mass star forming regions. The goal of the program is to search for circumstellar accretion disks, study the fragmentation process of molecular clumps, and investigate the chemical composition of the gas in these regions. Aims. We focus on IRAS 23385+6053, which is believed to be the least evolved source of the CORE sample. This object is characterized by a compact molecular clump that is IR dark shortward of 24 µm and is surrounded by a stellar cluster detected in the near-IR. Our aim is to study the structure and velocity field of the clump. Methods. The observations were performed at ∼1.4 mm and employed three configurations of NOEMA and additional single-dish maps, merged with the interferometric data to recover the extended emission. Our correlator setup covered a number of lines from well-known hot core tracers and a few outflow tracers. The angular (∼0.′′45–0.′′9) and spectral (0.5 km s−1) resolutions were sufficient to resolve the clump in IRAS 23385+6053 and investigate the existence of large-scale motions due to rotation, infall, or expansion. Results. We find that the clump splits into six distinct cores when observed at sub-arcsecond resolution. These are identified through their 1.4 mm continuum and molecular line emission. We produce maps of the velocity, line width, and rotational temperature from the methanol and methyl cyanide lines, which allow us to investigate the cores and reveal a velocity and temperature gradient in the most massive core. We also find evidence of a bipolar outflow, possibly powered by a low-mass star. Conclusions. We present the tentative detection of a circumstellar self-gravitating disk lying in the most massive core and powering a largescale outflow previously known in the literature. In our scenario, the star powering the flow is responsib

Published
2019

12. Fragmentation, rotation, and outflows in the high-mass star-forming region IRAS 23033+5951

Author

Bosco, F., primary, Beuther, H., additional, Ahmadi, A., additional, Mottram, J. C., additional, Kuiper, R., additional, Linz, H., additional, Maud, L., additional, Winters, J. M., additional, Henning, T., additional, Feng, S., additional, Peters, T., additional, Semenov, D., additional, Klaassen, P. D., additional, Schilke, P., additional, Urquhart, J. S., additional, Beltrán, M. T., additional, Lumsden, S. L., additional, Leurini, S., additional, Moscadelli, L., additional, Cesaroni, R., additional, Sánchez-Monge, Á., additional, Palau, A., additional, Pudritz, R., additional, Wyrowski, F., additional, and Longmore, S., additional

Published
2019
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13. Substructures in the Keplerian disc around the O-type (proto-)star G17.64+0.16 (Corrigendum)

Author

Maud, L. T., primary, Cesaroni, R., additional, Kumar, M. S. N., additional, Rivilla, V. M., additional, Ginsburg, A., additional, Klaassen, P. D., additional, Harsono, D., additional, Sánchez-Monge, Á., additional, Ahmadi, A., additional, Allen, V., additional, Beltrán, M. T., additional, Beuther, H., additional, Galván-Madrid, R., additional, Goddi, C., additional, Hoare, M. G., additional, Hogerheijde, M. R., additional, Johnston, K. G., additional, Kuiper, R., additional, Moscadelli, L., additional, Peters, T., additional, Testi, L., additional, van der Tak, F. F. S., additional, and de Wit, W. J., additional

Published
2019
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14. IRAS 23385+6053: an embedded massive cluster in the making

Author

Cesaroni, R., primary, Beuther, H., additional, Ahmadi, A., additional, Beltrán, M. T., additional, Csengeri, T., additional, Galván-Madrid, R., additional, Gieser, C., additional, Henning, T., additional, Johnston, K. G., additional, Klaassen, P. D., additional, Kuiper, R., additional, Leurini, S., additional, Linz, H., additional, Longmore, S., additional, Lumsden, S. L., additional, Maud, L. T., additional, Moscadelli, L., additional, Mottram, J. C., additional, Palau, A., additional, Peters, T., additional, Pudritz, R. E., additional, Sánchez-Monge, Á., additional, Schilke, P., additional, Semenov, D., additional, Suri, S., additional, Urquhart, J. S., additional, Winters, J. M., additional, Zhang, Q., additional, and Zinnecker, H., additional

Published
2019
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15. Chasing discs around O-type (proto)stars

Author

Maud, L. T., primary, Cesaroni, R., additional, Kumar, M. S. N., additional, van der Tak, F. F. S., additional, Allen, V., additional, Hoare, M. G., additional, Klaassen, P. D., additional, Harsono, D., additional, Hogerheijde, M. R., additional, Sánchez-Monge, Á., additional, Schilke, P., additional, Ahmadi, A., additional, Beltrán, M. T., additional, Beuther, H., additional, Csengeri, T., additional, Etoka, S., additional, Fuller, G., additional, Galván-Madrid, R., additional, Goddi, C., additional, Henning, Th., additional, Johnston, K. G., additional, Kuiper, R., additional, Lumsden, S., additional, Moscadelli, L., additional, Mottram, J. C., additional, Peters, T., additional, Rivilla, V. M., additional, Testi, L., additional, Vig, S., additional, de Wit, W. J., additional, and Zinnecker, H., additional

Published
2018
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16. The feedback of an HC HII region on its parental molecular core

Author

Moscadelli, L., primary, Rivilla, V. M., additional, Cesaroni, R., additional, Beltrán, M. T., additional, Sánchez-Monge, Á, additional, Schilke, P., additional, Mottram, J. C., additional, Ahmadi, A., additional, Allen, V., additional, Beuther, H., additional, Csengeri, T., additional, Etoka, S., additional, Galli, D., additional, Goddi, C., additional, Johnston, K. G., additional, Klaassen, P. D., additional, Kuiper, R., additional, Kumar, M. S. N., additional, Maud, L. T., additional, Möller, T., additional, Peters, T., additional, Van der Tak, F., additional, and Vig, S., additional

Published
2018
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17. Accelerating infall and rotational spin-up in the hot molecular core G31.41+0.31

Author

Beltrán, M. T., primary, Cesaroni, R., additional, Rivilla, V. M., additional, Sánchez-Monge, Á., additional, Moscadelli, L., additional, Ahmadi, A., additional, Allen, V., additional, Beuther, H., additional, Etoka, S., additional, Galli, D., additional, Galván-Madrid, R., additional, Goddi, C., additional, Johnston, K. G., additional, Klaassen, P. D., additional, Kölligan, A., additional, Kuiper, R., additional, Kumar, M. S. N., additional, Maud, L. T., additional, Mottram, J. C., additional, Peters, T., additional, Schilke, P., additional, Testi, L., additional, van der Tak, F, additional, and Walmsley, C. M., additional

Published
2018
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19. The evolution of young HII regions

Author

Klaassen, P. D., primary, Johnston, K. G., additional, Urquhart, J. S., additional, Mottram, J. C., additional, Peters, T., additional, Kuiper, R., additional, Beuther, H., additional, van der Tak, F.F.S., additional, and Goddi, C., additional

Published
2018
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20. Chasing discs around O-type (proto)stars: Evidence from ALMA observations

Author

Cesaroni, R., primary, Sánchez-Monge, Á., additional, Beltrán, M. T., additional, Johnston, K. G., additional, Maud, L. T., additional, Moscadelli, L., additional, Mottram, J. C., additional, Ahmadi, A., additional, Allen, V., additional, Beuther, H., additional, Csengeri, T., additional, Etoka, S., additional, Fuller, G. A., additional, Galli, D., additional, Galván-Madrid, R., additional, Goddi, C., additional, Henning, T., additional, Hoare, M. G., additional, Klaassen, P. D., additional, Kuiper, R., additional, Kumar, M. S. N., additional, Lumsden, S., additional, Peters, T., additional, Rivilla, V. M., additional, Schilke, P., additional, Testi, L., additional, van der Tak, F., additional, Vig, S., additional, Walmsley, C. M., additional, and Zinnecker, H., additional

Published
2017
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21. Outflow forces in intermediate-mass star formation

Author

van Kempen, T. A., primary, Hogerheijde, M. R., additional, van Dishoeck, E. F., additional, Kristensen, L. E., additional, Belloche, A., additional, Klaassen, P. D., additional, Leurini, S., additional, San Jose-Garcia, I., additional, Aykutalp, A., additional, Choi, Y., additional, Endo, A., additional, Frieswijk, W., additional, Harsono, D., additional, Karska, A., additional, Koumpia, E., additional, van der Marel, N., additional, Nagy, Z., additional, Pérez-Beaupuits, J.-P., additional, Risacher, C., additional, van Weeren, R. J., additional, Wyrowski, F., additional, Yıldız, U. A., additional, Güsten, R., additional, Boland, W., additional, and Baryshev, A., additional

Published
2016
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