scholarly journals An Analytic Model for an Evolving Protoplanetary Disk with a Disk Wind

2019 ◽  
Vol 879 (2) ◽  
pp. 98 ◽  
Author(s):  
John Chambers
2018 ◽  
Vol 614 ◽  
pp. A119 ◽  
Author(s):  
B. Tabone ◽  
A. Raga ◽  
S. Cabrit ◽  
G. Pineau des Forêts

Context. The molecular richness of fast protostellar jets within 20–100 au of their source, despite strong ultraviolet irradiation, remains a challenge for the models investigated so far. Aim.We aim to investigate the effect of interaction between a time-variable jet and a surrounding steady disk wind, to assess the possibility of jet chemical enrichement by the wind, and the characteristic signatures of such a configuration. Methods. We have constructed an analytic model of a jet bow shock driven into a surrounding slower disk wind in the thin shell approximation. The refilling of the post bow shock cavity from below by the disk wind is also studied. An extension of the model to the case of two or more successive internal working surfaces (IWS) is made. We then compared this analytic model with numerical simulations with and without a surrounding disk wind. Results. We find that at early times (of order the variability period), jet bow shocks travel in refilled pristine disk wind material, before interacting with the cocoon of older bow shocks. This opens the possibility of bow shock chemical enrichment (if the disk wind is molecular and dusty) and of probing the unperturbed disk wind structure near the jet base. Several distinctive signatures of the presence of a surrounding disk wind are identified, in the bow shock morphology and kinematics. Numerical simulations validate our analytical approach and further show that at large scale, the passage of many jet IWS inside a disk wind produces a stationary V-shaped cavity, closing down onto the axis at a finite distance from the source.


2018 ◽  
Vol 611 ◽  
pp. A16 ◽  
Author(s):  
Alice S. Booth ◽  
Catherine Walsh ◽  
Mihkel Kama ◽  
Ryan A. Loomis ◽  
Luke T. Maud ◽  
...  

Sulphur-bearing volatiles are observed to be significantly depleted in interstellar and circumstellar regions. This missing sulphur is postulated to be mostly locked up in refractory form. With ALMA we have detected sulphur monoxide (SO), a known shock tracer, in the HD 100546 protoplanetary disk. Two rotational transitions: J = 77–66 (301.286 GHz) and J = 78–67 (304.078 GHz) are detected in their respective integrated intensity maps. The stacking of these transitions results in a clear 5σ detection in the stacked line profile. The emission is compact but is spectrally resolved and the line profile has two components. One component peaks at the source velocity and the other is blue-shifted by 5 km s−1. The kinematics and spatial distribution of the SO emission are not consistent with that expected from a purely Keplerian disk. We detect additional blue-shifted emission that we attribute to a disk wind. The disk component was simulated using LIME and a physical disk structure. The disk emission is asymmetric and best fit by a wedge of emission in the north-east region of the disk coincident with a “hot-spot” observed in the CO J = 3–2 line. The favoured hypothesis is that a possible inner disk warp (seen in CO emission) directly exposes the north-east side of the disk to heating by the central star, creating locally the conditions to launch a disk wind. Chemical models of a disk wind will help to elucidate why the wind is particularly highlighted in SO emission and whether a refractory source of sulphur is needed. An alternative explanation is that the SO is tracing an accretion shock from a circumplanetary disk associated with the proposed protoplanet embedded in the disk at 50 au. We also report a non-detection of SO in the protoplanetary disk around HD 97048.


NASPA Journal ◽  
1999 ◽  
Vol 36 (4) ◽  
Author(s):  
Ellen Lavelle ◽  
Bill Rickford

Models of college student development have demonstrated an insensitivity to the differences that exist among various students, although such differences are very important in a world where student bodies in higher education are increasingly diverse. The authors present a model based on The Dakota Inventory of Student Orientations, which may be useful for program developmen that fosters reflection, self discovery, perspective-taking, and collaboration among students with varying orientations towards learning.


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