Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Abstract： Kinematic signatures of the jet, winds, multicavities, and episodic shells arising in the unified model of bipolar outflows developed in Shang et al.(2020), in which an outflow forms by radially directed, wide-angle toroidally magnetized winds interacting with magnetized isothermal toroids, are extracted in the form of position--velocity diagrams. Elongated outflow lobes, driven by magnetized winds and their interplay with the environment, are dominated by extended bubble structures with mixing layers beyond the conventional thin-shell models. The axial cylindrically stratified density jet carries a broad profile near the base, across the projected velocity of the wide-angle wind, and narrows down along the axis with the collimated flow. The reverse shock encloses the magnetized free wind, forms an innermost cavity, and deflects the flow pattern. Shear, Kelvin--Helmholtz instabilities, and pseudopulses add fine and distinctive features between the jet--shell components, and the fluctuating jet velocities. The broad webbed velocity features connect the extremely high and the low velocities across the multicavities, mimicking nested outflowing slower-wind components. Rings and ovals in the perpendicular cuts trace multicavities at different heights, and the compressed ambient gap regions enrich the low-velocity features with protruding spikes. Our kinematic signatures capture the observed systematics of the high-, intermediate-, and low-velocity components from Class 0 to II jet--outflow systems in molecular and atomic lines. The nested shells observed in HH 212, HH 30, and DG Tau B are naturally explained. Outflows as bubbles are ubiquitous and form an inevitable integrative outcome of the interaction between wind and ambient media.
Peer Review Status:
Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Abstract： Kinematic signatures of the jet, winds, multicavities, and episodic shells arising in the unified model of bipolar outflows developed in Shang et al.(2020), in which an outflow forms by radially directed, wide-angle toroidally magnetized winds interacting with magnetized isothermal toroids, are extracted in the form of position--velocity diagrams. Elongated outflow lobes, driven by magnetized winds and their interplay with the environment, are dominated by extended bubble structures with mixing layers beyond the conventional thin-shell models. The axial cylindrically stratified density jet carries a broad profile near the base, across the projected velocity of the wide-angle wind, and narrows down along the axis with the collimated flow. The reverse shock encloses the magnetized free wind, forms an innermost cavity, and deflects the flow pattern. Shear, Kelvin--Helmholtz instabilities, and pseudopulses add fine and distinctive features between the jet--shell components, and the fluctuating jet velocities. The broad webbed velocity features connect the extremely high and the low velocities across the multicavities, mimicking nested outflowing slower-wind components. Rings and ovals in the perpendicular cuts trace multicavities at different heights, and the compressed ambient gap regions enrich the low-velocity features with protruding spikes. Our kinematic signatures capture the observed systematics of the high-, intermediate-, and low-velocity components from Class 0 to II jet--outflow systems in molecular and atomic lines. The nested shells observed in HH 212, HH 30, and DG Tau B are naturally explained. Outflows as bubbles are ubiquitous and form an inevitable integrative outcome of the interaction between wind and ambient media.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Abstract： We explore a new, efficient mechanism that can power toroidally magnetized jets up to two to three times their original terminal velocity after they enter a self-similar phase of magnetic acceleration. Underneath the elongated outflow lobe formed by a magnetized bubble, a wide-angle free wind, through the interplay with its ambient toroid, is compressed and accelerated around its axial jet. The extremely magnetic bubble can inflate over its original size, depending on the initial Alfv\'en Mach number $M_A$ of the launched flow. The shape-independent slope $\partial{}v_r/\partial{}r=2/3t$ is a salient feature of the self-similarity in the acceleration phase. Peculiar kinematic signatures are observable in the position--velocity (PV) diagrams and can combine with other morphological signatures as probes for the density-collimated jets arising in toroidally dominated magnetized winds. The apparent second acceleration is powered by the decrease of the toroidal magnetic field but operates far beyond the scales of the primary magnetocentrifugal launch region and the free asymptotic terminal state. Rich implications may connect the jets arising from the youngest protostellar outflows such as HH 211 and HH 212 and similar systems with parsec-scale jets across the mass and evolutionary spectra.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Michihiro Takami
Hans Moritz Guenther
P. Christian Schneider
Tracy L. Beck
Jennifer L. Karr
Youichi Ohyama
Roberto Galvan-Madrid
Taichi Uyama
Marc White
Konstantin Grankin
Deirdre Coffey
Chun-Fan Liu
Misato Fukagawa
Nadine Manset
Wen-Ping Chen
Tae-Soo Pyo
Hsien Shang
Thomas P. Ray
Masaaki Otsuka
Mei-Yin Chou
Abstract： We present Gemini-NIFS, VLT-SINFONI and Keck-OSIRIS observations of near-infrared [Fe II] emission associated with the well-studied jets from three active T Tauri stars; RW Aur A, RY Tau and DG Tau taken from 2012-2021. We primarily covered the redshifted jet from RW Aur A, and the blueshifted jets from RY Tau and DG Tau, to investigate long-term time variabilities potentially related to the activities of mass accretion and/or the stellar magnetic fields. All of these jets consist of several moving knots with tangential velocities of 70-240 km s-1, ejected from the star with different velocities and at irregular time intervals. Via comparison with literature, we identify significant differences in tangential velocities for the DG Tau jet between 1985-2008 and 2008-2021. The sizes of the individual knots appear to increase with time, and in turn, their peak brightnesses in the 1.644-micron emission decreased up to a factor of ~30 during the epochs of our observations. A variety of the decay timescales measured in the [Fe II] 1.644 micron emission can be attributed to different pre-shock conditions if the moving knots are unresolved shocks. However, our data do not exclude the possibility that these knots are due to non-uniform density/temperature distributions with another heating mechanism, or in some cases due to stationary shocks without proper motions. Spatially resolved observations of these knots with significantly higher angular resolutions are necessary to better understand their physical nature.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Shih-Ying Hsu
Sheng-Yuan Liu
Tie Liu
Dipen Sahu
Chin-Fei Lee
Kenichi Tatematsu
Kee-Tae Kim
Naomi Hirano
Yao-Lun Yang
Doug Johnstone
Hongli Liu
Mika Juvela
Leonardo Bronfman
Huei-Ru Vivien Chen
Somnath Dutta
David J. Eden
Kai-Syun Jhan
Yi-Jehng Kuan
Chang Won Lee
Jeong-Eun Lee
Abstract： The presence of complex organic molecules (COMs) in the interstellar medium (ISM) is of great interest since it may link to the origin and prevalence of life in the universe. Aiming to investigate the occurrence of COMs and their possible origins, we conducted a chemical census toward a sample of protostellar cores as part of the ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP) project. We report the detection of 11 hot corino sources, which exhibit compact emissions from warm and abundant COMs, among 56 Class 0/I protostellar cores. All the hot corino sources discovered are likely Class 0 and their sizes of the warm region ($>$ 100 K) are comparable to 100 au. The luminosity of the hot corino sources exhibits positive correlations with the total number of methanol and the extent of its emissions. Such correlations are consistent with the thermal desorption picture for the presence of hot corino and suggest that the lower luminosity (Class 0) sources likely have a smaller region with COMs emissions. With the same sample selection method and detection criteria being applied, the detection rates of the warm methanol in the Orion cloud (15/37) and the Perseus cloud (28/50) are statistically similar when the cloud distances and the limited sample size are considered. Observing the same set of COM transitions will bring a more informative comparison between the cloud properties.
Peer Review Status:Awaiting Review
Hits
Hits
Downloads
Comment