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4 results on '"protostars [Stars]"'

1. An observational correlation between magnetic field, angular momentum and fragmentation in the envelopes of Class 0 protostars?

Author

Eric Keto, Qizhou Zhang, Shih-Ping Lai, Valeska Valdivia, Josep M. Girart, Anaëlle Maury, Victoria Cabedo-Soto, Patrick Hennebelle, M. Gaudel, Ramprasad Rao, Maud Galametz, Département d'Astrophysique (ex SAP) (DAP), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Harvard-Smithsonian Center for Astrophysics (CfA), Smithsonian Institution-Harvard University [Cambridge], Institut d'Estudis Espacials de Catalunya (IEEC-CSIC), Institut de Ciencies de l'Espai [Barcelona] (ICE-CSIC), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA (UMR_8112)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), National Tsing Hua University [Hsinchu] (NTHU), European Project: 679937,H2020,ERC-2015-STG,MagneticYSOs(2016), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Harvard University-Smithsonian Institution, Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres (LERMA), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), European Commission, Ministerio de Ciencia e Innovación (España), Agencia Estatal de Investigación (España), and Ministerio de Ciencia, Innovación y Universidades (España)

Subjects
Angular momentum, FOS: Physical sciences, Astrophysics, Kinetic energy, 7. Clean energy, 01 natural sciences, Submillimeter Array, protostars [Stars], 0103 physical sciences, Protostar, Astrophysics::Solar and Stellar Astrophysics, instrumentation: interferometers, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), formation [Stars], Astrophysics::Galaxy Astrophysics, Physics, ISM: kinematics and dynamics, [PHYS]Physics [physics], stars: formation, Magnetic energy, stars: protostars, 010308 nuclear & particles physics, Velocity gradient, magnetic fields [ISM], ISM [Submillimeter], Astronomy and Astrophysics, interferometers [Instrumentation], Astrophysics - Astrophysics of Galaxies, Magnetic field, kinematics and dynamics [ISM], Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), submillimeter: ISM, Outflow, Astrophysics::Earth and Planetary Astrophysics, ISM: magnetic fields, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

Aims. The main goal of the following analysis is to assess the potential role of magnetic fields in regulating the envelope rotation, the formation of disks and the fragmentation of Class 0 protostars in multiple systems. Methods. We use the Submillimeter Array to carry out observations of the dust polarized emission at 0.87 mm, in the envelopes of a large sample of 20 Class 0 protostars. We estimate the mean magnetic field orientation over the central 1000 au envelope scales to characterize the orientation of the main component of the organized magnetic field at the envelope scales in these embedded protostars. This direction is compared to that of the protostellar outflow in order to study the relation between their misalignment and the kinematics of the circumstellar gas. The latter is traced via velocity gradient observed in the molecular line emission (mainly N2H+) of the gas at intermediate envelope scales. Results. We discover a strong relationship between the misalignment of the magnetic field orientation with the outflow and the amount of angular momentum observed at similar scales in the protostellar envelope, revealing a potential link between the kinetic and the magnetic energy at envelope scales. The relation could be driven by favored B-misalignments in more dynamical envelopes or a dependence of the envelope dynamics with the large-scale B initial configuration. Comparing the trend with the presence of fragmentation, we observe that single sources are mostly associated with conditions of low angular momentum in the inner envelope and good alignment of the magnetic field with protostellar outflows, at intermediate scales. Our results suggest that the properties of the magnetic field in protostellar envelopes bear a tight relationship with the rotating-infalling gas directly involved in the star and disk formation: we find that it may not only influence the fragmentation of protostellar cores into multiple stellar systems, but also set the conditions establishing the pristine properties of planet-forming disks., This project has received funding from the European Research Council (ERC) under the European Union Horizon 2020 research and innovation programme (MagneticYSOs project, grant agreement No. 679937, PI: Maury). J.M.G. is supported by the grant AYA2017-84390- C2-R (AEI/FEDER, UE).

Published
2020

2. A statistical analysis of dust polarization properties in ALMA observations of Class 0 protostellar cores

Author

Vincent Guillet, V. J. M. Le Gouellec, Charles L. H. Hull, R. Mignon-Risse, Valeska Valdivia, Anaëlle Maury, F. Louvet, Patrick Hennebelle, M. González, A. Verliat, Josep M. Girart, European Southern Observatory (ESO), Institut d'astrophysique spatiale (IAS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut de Ciencies de l'Espai [Barcelona] (ICE-CSIC), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Institut d'Estudis Espacials de Catalunya (IEEC-CSIC), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Université Paris-Saclay, Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA (UMR_8112)), Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Storengy France, European Southern Observatory, Ministerio de Ciencia, Innovación y Universidades (España), Japan Society for the Promotion of Science, National Astronomical Observatory of Japan, European Commission, Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), and Université Paris-Seine-Université Paris-Seine-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)

Subjects
FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 7. Clean energy, 01 natural sciences, symbols.namesake, Paramagnetism, Polarization, protostars [Stars], 0103 physical sciences, Radiative transfer, Protostar, Astrophysics::Solar and Stellar Astrophysics, Planck, 010303 astronomy & astrophysics, formation [Stars], Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, Earth and Planetary Astrophysics (astro-ph.EP), Physics, polarization, stars: formation, stars: protostars, jets and outflows [ISM], 010308 nuclear & particles physics, magnetic fields [ISM], stars: magnetic field, Estimator, Astronomy and Astrophysics, Polarization (waves), Astrophysics - Astrophysics of Galaxies, Interstellar medium, magnetic field [Stars], ISM: jets and outflows, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), symbols, Astrophysics::Earth and Planetary Astrophysics, ISM: magnetic fields, Magnetohydrodynamics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - Earth and Planetary Astrophysics
Abstract

Context. Recent observational progress has challenged the dust grain-alignment theories used to explain the polarized dust emission routinely observed in star-forming cores. Aims. In an effort to improve our understanding of the dust grain alignment mechanism(s), we have gathered a dozen ALMA maps of (sub)millimeter-wavelength polarized dust emission from Class 0 protostars and carried out a comprehensive statistical analysis of dust polarization quantities. Methods. We analyze the statistical properties of the polarization fraction Pfrac and the dispersion of polarization position angles S. More specifically, we investigate the relationship between S and Pfrac as well as the evolution of the product S × Pfrac as a function of the column density of the gas in the protostellar envelopes. We compare the observed trends with those found in polarization observations of dust in the interstellar medium and in synthetic observations of non-ideal magneto-hydrodynamic (MHD) simulations of protostellar cores. Results. We find a significant S Pfrac-0.79 correlation in the polarized dust emission from protostellar envelopes seen with ALMA; the power-law index significantly differs from the one observed by Planck in star-forming clouds. The product S × Pfrac, which is sensitive to the dust grain alignment efficiency, is approximately constant across three orders of magnitude in envelope column density (from NH2 = 1022 cm-2 to NH2 = 1025 cm-2), with a mean value of 0.36-0.17+0.10. This suggests that the grain alignment mechanism producing the bulk of the polarized dust emission in star-forming cores may not systematically depend on the local conditions such as the local gas density. However, in the lowest-luminosity sources in our sample, we find a hint of less efficient dust grain alignment with increasing column density. Our observations and their comparison with synthetic observations of MHD models suggest that the total intensity versus the polarized dust are distributed at different intrinsic spatial scales, which can affect the statistics from the ALMA observations, for example, by producing artificially high Pfrac. Finally, synthetic observations of MHD models implementing radiative alignment torques (RATs) show that the statistical estimator S × Pfrac is sensitive to the strength of the radiation field in the core. Moreover, we find that the simulations with a uniform perfect alignment (PA) of dust grains yield, on average, much higher S × Pfrac values than those implementing RATs; the ALMA values lie among those predicted by PA, and they are significantly higher than the ones obtained with RATs, especially at large column densities. Conclusions. Ultimately, our results suggest that dust alignment mechanism(s) are efficient at producing dust polarized emission in the various local conditions typical of Class 0 protostars. The grain alignment efficiency found in these objects seems to be higher than the efficiency produced by the standard RAT alignment of paramagnetic grains. Further studies will be needed to understand how more efficient grain alignment via, for example, different irradiation conditions, dust grain characteristics, or additional grain alignment mechanisms can reproduce the observations., V.J.M.L.G. acknowledges the support of the ESO Studentship Program. A.J.M. acknowledges support from the Joint ALMA Observatory Visitor Program, and ESO Visitor program. J.M.G. is supported by the Spanish grant AYA2017-84390-C2-R (AEI/FEDER, UE). C.L.H.H. acknowledges the support of both the NAOJ Fellowship as well as JSPS KAKENHI grants 18K13586 and 20K14527. This work has benefited from the support of the European Research Council under the Horizon 2020 Framework Programme (Starting Grant MagneticYSOs with grant agreement no. 679937)

Published
2020

3. Chemical and kinematic structure of extremely high-velocity molecular jets in the Serpens Main star-forming region

Author

Ewine F. van Dishoeck, Lars E. Kristensen, Łukasz Tychoniec, Valentin J. M. Le Gouellec, John J. Tobin, Charles L. H. Hull, Leiden Observatory [Leiden], Universiteit Leiden [Leiden], National Astronomical Observatory of Japan (NAOJ), Joint ALMA Observatory (JAO), National Radio Astronomy Observatory (NRAO)-European Southern Observatory (ESO), Centre for Star and Planet Formation (STARPLAN), Globe Institute, Faculty of Health and Medical Sciences, University of Copenhagen = Københavns Universitet (KU)-University of Copenhagen = Københavns Universitet (KU)-Faculty of Health and Medical Sciences, University of Copenhagen = Københavns Universitet (KU)-University of Copenhagen = Københavns Universitet (KU), National Radio Astronomy Observatory [Charlottesville] (NRAO), National Radio Astronomy Observatory (NRAO), European Southern Observatory (ESO), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Max-Planck-Institut für Extraterrestrische Physik (MPE), European Project: 291141,EC:FP7:ERC,ERC-2011-ADG_20110209,CHEMPLAN(2012), Universiteit Leiden, European Southern Observatory (ESO)-National Radio Astronomy Observatory (NRAO), University of Copenhagen = Københavns Universitet (UCPH)-University of Copenhagen = Københavns Universitet (UCPH)-Faculty of Health and Medical Sciences, University of Copenhagen = Københavns Universitet (UCPH)-University of Copenhagen = Københavns Universitet (UCPH), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010504 meteorology & atmospheric sciences, Serpens, FOS: Physical sciences, Kinematics, Astrophysics, Star (graph theory), 01 natural sciences, 0103 physical sciences, profiles [line], Protostar, ISM [submillimeter], 010303 astronomy & astrophysics, Chemical composition, Solar and Stellar Astrophysics (astro-ph.SR), protostars [stars], 0105 earth and related environmental sciences, Physics, Jet (fluid), Momentum (technical analysis), stars: protostars, jets and outflows [ISM], astrochemistry, Astronomy and Astrophysics, line: profiles, Astrophysics - Astrophysics of Galaxies, interferometric [techniques], ISM: jets and outflows, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, techniques: interferometric, Astrophysics of Galaxies (astro-ph.GA), submillimeter: ISM, Outflow, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

The fastest molecular component to the protostellar outflows -- extremely high-velocity (EHV) molecular jets -- are still puzzling since they are seen only rarely. The first aim is to analyze the interaction between the EHV jet and the slow outflow by comparing their outflow force content. The second aim is to analyze the chemical composition of the different outflow velocity components and to reveal the spatial location of molecules. ALMA 3 mm and 1.3 mm observations of five outflow sources at 130 -- 260 au resolution in the Serpens Main cloud are presented. Observations of CO, SiO, H$_2$CO and HCN reveal the kinematic and chemical structure of those flows. Three velocity components are distinguished: the slow and the fast wing, and the EHV jet. Out of five sources, three have the EHV component. Comparison of outflow forces reveals that only the EHV jet in the youngest source Ser-emb 8 (N) has enough momentum to power the slow outflow. The SiO abundance is generally enhanced with velocity, while HCN is present in the slow and the fast wing, but disappears in the EHV jet. For Ser-emb 8 (N), HCN and SiO show a bow-shock shaped structure surrounding one of the EHV peaks suggesting sideways ejection creating secondary shocks upon interaction with the surroundings. Also, the SiO abundance in the EHV gas decreases with distance from this protostar, whereas that in the fast wing increases. H$_2$CO is mostly associated with low-velocity gas but also appears surprisingly in one of the bullets in the Ser-emb~8~(N) EHV jet. The high detection rate suggests that the presence of the EHV jet may be more common than previously expected. The origin and temporal evolution of the abundances of SiO, HCN and H$_2$CO through high-temperature chemistry are discussed. The data are consistent with a low C/O ratio in the EHV gas versus high C/O ratio in the fast and slow wings., Comment: 25 pages, 20 figures, Accepted for publication in the Astronomy & Astrophysics

Published
2019

4. A LOFAR detection of the low mass young star T Tau at 149 MHz

Author

Adam Stewart, M. Pietka, Stephane Corbel, Tom Ray, Anna M. M. Scaife, A. Drabent, Alexander J. van der Horst, Matthias Hoeft, P. Zarka, Jean-Mathias Greißmeier, Colm P. Coughlan, Martin Bell, Rachael E. Ainsworth, Joeri van Leeuwen, Jochen Eislöffel, Ralph A. M. J. Wijers, J. W. Broderick, Sera Markoff, Dublin Institute for Advanced Studies (DIAS), Thüringer Landessternwarte Tautenburg (TLS), School of Physics and Astronomy [Southampton], University of Southampton, Max-Planck-Institut für Astrophysik (MPA), Max-Planck-Gesellschaft, Unité Scientifique de la Station de Nançay (USN), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Astronomical Institute Anton Pannekoek (AI PANNEKOEK), University of Amsterdam [Amsterdam] (UvA), Oxford Astrophysics, University of Oxford [Oxford], Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), ERC-2012-StG-307215 LODESTONE, European Project: 307215,EC:FP7:ERC,ERC-2012-StG_20111012,LODESTONE(2013), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), University of Oxford, High Energy Astrophys. & Astropart. Phys (API, FNWI), Université d'Orléans (UO)-Observatoire des Sciences de l'Univers en région Centre (OSUC), PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Observatoire de Paris, and PSL Research University (PSL)-PSL Research University (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)

Subjects
Electron density, 010504 meteorology & atmospheric sciences, Young stellar object, Astrophysics::High Energy Astrophysical Phenomena, Flux, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astronomy & Astrophysics, 7. Clean energy, 01 natural sciences, 0103 physical sciences, individual (T Tauri) [stars], Protostar, pre-main sequence [stars], 010303 astronomy & astrophysics, stars [radio continuum], Astrophysics::Galaxy Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), protostars [stars], 0105 earth and related environmental sciences, Physics, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Astronomy and Astrophysics, LOFAR, Astrophysics - Astrophysics of Galaxies, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), thermal [radiation mechanisms], Content (measure theory), Spectral energy distribution, Low Mass
Abstract

Radio observations of young stellar objects (YSOs) enable the study of ionised plasma outflows from young protostars via their free-free radiation. Previous studies of the low-mass young system T Tau have used radio observations to model the spectrum and estimate important physical properties of the associated ionised plasma (local electron density, ionised gas content and emission measure). However, without an indication of the low-frequency turnover in the free-free spectrum, these properties remain difficult to constrain. This paper presents the detection of T Tau at 149 MHz with the Low Frequency Array (LOFAR) - the first time a YSO has been observed at such low frequencies. The recovered total flux indicates that the free-free spectrum may be turning over near 149 MHz. The spectral energy distribution is fitted and yields improved constraints on local electron density ($(7.2 \pm 2.1)\times10^{3}$ cm$^{-3}$), ionised gas mass ($(1.0 \pm 1.8)\times10^{-6}$ M$_{\odot}$) and emission measure ($(1.67 \pm 0.14)\times10^5$ pc cm$^{-6}$)., Comment: 10 pages, accepted for publication in ApJ

Published
2017

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