# Farthest observed protoplanetary disk observed at radio frequencies? Catalog

This could be a naive question or maybe too easy to solve (I do not really know!).

Brief context: I'm interested in a certain planetary system at $$d \sim 300 \, \mathrm{pc}$$. It would be really nice to estimate the disk surface mass $$\Sigma(r)$$ "observationally" from the infrared part of the spectral energy distribution, as Philip J. Armitage points out in "Astrophysics of Planet Formation" - Cambridge University Press (2020):

In the mm/sub-mm region of the spectrum (i.e. λ ∼ 1 mm) the bulk of the emission comes instead from optically thin regions of the disk. Taking the limit where the entire disk is optically thin at the frequencies of interest

$$F_\nu = \frac{B_\nu (\overline{T}_\mathrm{dust}) \kappa_\nu}{D^2} \int\limits_{r_{in}}^{r_{out}} \, 2\pi r\, \Sigma \, dr$$

If we know the distance to the source, the opacity, and the disk temperature, a measurement of the flux density at optically thin wavelengths determines the disk mass

I know there are a few systems resolved, e.g., by ALMA (see DSHARP) The researchers will use NASA’s James Webb Space Telescope to survey 17 of the 20 nearby protoplanetary disks observed by Chile’s Atacama Large Millimeter/submillimeter Array (ALMA) in 2018 for its Disk Substructures at High Angular Resolution Project (DSHARP)... Credits: ALMA (ESO/NAOJ/NRAO), S. Andrews et al.; N. Lira source

but I have no information about distances of each one of the disks observed. A quick estimation would be considering

$$\delta_{\mathrm{resol}}\sim \frac{D}{d}$$

where $$d \sim 300$$ pc is the distance and $$D \overset{?}{\sim} 100$$ au is the system diameter.

D = 100 * u.au
d = 300 * u.pc