Circular Astronomy

Protoplanetary Disc Oph163131 – Surface Layers Lack Grains Larger than 1 µm

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“The lack of sharp-edged structures in the extended patchy emission argues against the presence of shocks and suggests photoexcitation or stochastic heating of material smoothly flowing away from the star along the disk surface. ”

“The dark lane thickness decreases significantly between 0.6μm and 4.4μm which indicates that the surface layers of Oph163131 lack grains larger than 1μm.”

Extended Emission: The JWST images also show patches of extended emission at low latitudes and large radii, which are interpreted as thermal emission from the star and inner disk, propagating to greater distances at longer wavelengths.

Reference: JWST imaging of edge-on protoplanetary disks. III. Drastic morphological transformation across the mid-infrared in Oph163131 https://arxiv.org/abs/2410.00156

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Oph163131 (full designation SSTC2D J163131.2-242627) is a highly inclined protoplanetary disk located in the Ophiuchus star-forming region, approximately 147 ± 3 parsecs from Earth.

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This disk has been the subject of several recent studies due to its unique characteristics and potential implications for planet formation.

Disk Structure

The disk around Oph163131 is highly inclined, with an inclination angle of approximately 84 degrees. Recent high-resolution observations have revealed several notable features:

  • Two distinct rings in the dust continuum emission
  • An outer ring located at about 100 astronomical units (au) from the central star
  • A clear gap between the rings
  • An inner central emission region

Morphological Transformation: Recent JWST imaging has revealed a drastic morphological transformation across the mid-infrared wavelengths. At shorter wavelengths (2.0 and 4.4 μm), the disk shows two scattering surfaces separated by a dark lane. However, at longer wavelengths (7.7 μm and beyond), the structure changes significantly, with the dark lane disappearing and a compact central source becoming more prominent.

Dust Settling

One of the most significant findings about Oph163131 is the evidence for significant efficient vertical dust settling:

  • The scale height of millimeter-sized dust grains is 0.5 au or less at 100 au from the central star
  • This is about one order of magnitude smaller than the scale height of micron-sized dust grains
  • The observations are consistent with a turbulent viscosity coefficient of α ≲ 10^-5 at 100 au

Gas Distribution

The gas emission in Oph163131 appears significantly more extended than the dust emission, both vertically and radially.

This is consistent with:

  • Vertical settling of dust particles
  • Possible radial drift of dust towards the star

Observational Data

Oph163131 has been studied using various observational techniques:

  • High-angular-resolution ALMA observations at 1.3 mm wavelength, revealing detailed disk structure
  • JWST broadband imaging from 2.0 to 21 μm, providing additional insights into the disk’s properties
  • Previous observations using HST and Keck for scattered light imaging

The combination of these observations has allowed researchers to construct detailed radiative transfer models of the disk, providing valuable insights into its physical structure and evolution.

Citations:

A Highly Settled Disk around Oph163131

M. Villenave , K. R. Stapelfeldt, G. Duchêne , F. Ménard , M. Lambrechts , A. Sierra, C. Flores , W. R. F. Dent, S. Wolff , Á. Ribas , M. Benisty , N. Cuello , and C. Pinte
https://iopscience.iop.org/article/10.3847/1538-4357/ac5fae

Formation of wide-orbit giant planets in protoplanetary disks with a decreasing pebble flux

Nerea Gurrutxaga, Anders Johansen, Michiel Lambrechts and Johan Appelgren

https://www.aanda.org/articles/aa/full_html/2024/02/aa48020-23/aa48020-23.html

JWST imaging of edge-on protoplanetary disks. III. Drastic morphological transformation across the mid-infrared in Oph163131

Marion Villenave, Karl R. Stapelfeldt, Gaspard Duchene, Francois Menard, Marshall D. Perrin, Christophe Pinte, Schuyler G. Wolff, Ryo Tazaki, Deborah L. Padgett

https://www.arxiv.org/abs/2410.00156

Catalog of Circumstellar Disk Oph163131
https://www.circumstellardisks.org/show.php?id=288&name=Oph163131

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