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Post Info TOPIC: Class I protostar WL 17

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Posts: 131433
Date:
 WL 17 Permalink Title: WL 17: A Young Embedded Transition Disk Author: Patrick D. Sheehan, Josh A. Eisner We present the highest spatial resolution ALMA observations to date of the Class I protostar WL 17 in the rho Ophiuchus L1688 molecular cloud complex, which show that it has a 12 AU hole in the center of its disk. We consider whether WL 17 is actually a Class II disk being extincted by foreground material, but find that such models do not provide a good fit to the broadband SED and also require such high extinction that it would presumably arise from dense material close to the source such as a remnant envelope. Self-consistent models of a disk embedded in a rotating collapsing envelope can nicely reproduce both the ALMA 3 mm observations and the broadband SED of WL 17. This suggests that WL 17 is a disk in the early stages of its formation, and yet even at this young age the inner disk has been depleted. Although there are multiple pathways for such a hole to be created in a disk, if this hole were produced by the formation of planets it could place constraints on the timescale for the growth of planetesimals in protoplanetary disks. Read more (395kb, PDF) __________________

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Posts: 131433
Date:
 Class I protostar WL 17 Permalink Title: First Magnetic Field Detection on a Class I ProtostarAuthors: Christopher M. Johns-Krull, Thomas P. Greene, Greg W. Doppmann, Kevin R. CoveyStrong stellar magnetic fields are believed to truncate the inner accretion disks around young stars, redirecting the accreting material to the high latitude regions of the stellar surface. In the past few years, observations of strong stellar fields on T Tauri stars with field strengths in general agreement with the predictions of magnetospheric accretion theory have bolstered this picture. Currently, nothing is known about the magnetic field properties of younger, more embedded Class I young stellar objects (YSOs). It is believed that protostars accrete much of their final mass during the Class I phase, but the physics governing this process remains poorly understood. Here, we use high resolution near infrared spectra obtained with NIRSPEC on Keck and with Phoenix on Gemini South to measure the magnetic field properties of the Class I protostar WL 17. We find clear signatures of a strong stellar magnetic field. Analysis of this data suggests a surface average field strength of $2.9 \pm 0.43$ kG on WL 17. We present our field measurements and discuss how they fit with the general model of magnetospheric accretion in young stars. Read more  (41kb, PDF) __________________
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