Early Planet Formation in Embedded Disks (eDisk) XIV: Flared Dust Distribution and Viscous Accretion Heating of the Disk around R CrA IRS 7B-a
We performed radiative transfer calculations and observing simulations to reproduce the 1.3-mm dust-continuum and C$^{18}$O (2-1) images in the Class I protostar R CrA IRS7B-a, observed with the ALMA Large Program ``Early Planet Formation in Embedded Disks (eDisk)". We found that the dust disk...
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Zusammenfassung: | We performed radiative transfer calculations and observing simulations to
reproduce the 1.3-mm dust-continuum and C$^{18}$O (2-1) images in the Class I
protostar R CrA IRS7B-a, observed with the ALMA Large Program ``Early Planet
Formation in Embedded Disks (eDisk)". We found that the dust disk model
passively heated by the central protostar cannot reproduce the observed peak
brightness temperature of the 1.3-mm continuum emission ($\sim$195 K),
regardless of the assumptions about the dust opacity. Our calculation suggests
that viscous accretion heating in the disk is required to reproduce the
observed high brightness temperature. The observed intensity profile of the
1.3-mm dust-continuum emission along the disk minor axis is skewed toward the
disk far side. Our modeling reveals that such an asymmetric intensity
distribution requires flaring of the dust along the disk's vertical direction
with the scale-height following $h/r \sim r^{0.3}$ as function of radius. These
results are in sharp contrast to those of Class II disks, which show
geometrically flat dust distributions and lower dust temperatures. From our
modeling of the C$^{18}$O (2-1) emission, the outermost radius of the gas disk
is estimated to be $\sim$80 au, larger than that of the dust disk ($\sim$62
au), to reproduce the observed distribution of the C$^{18}$O (2-1) emission in
IRS 7B-a. Our modeling unveils a hot and thick dust disk plus a larger gas disk
around one of the eDisk targets, which could be applicable to other
protostellar sources in contrast to more evolved sources. |
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DOI: | 10.48550/arxiv.2401.08722 |