3.3 cm JVLA observations of transitional disks: searching for centimeter pebbles

TL;DR

This study uses high-resolution JVLA radio observations at 3.3 cm to detect and analyze centimeter-sized pebbles in transitional disks around young stars, revealing diverse emission mechanisms and disk structures.

Contribution

It provides the first detailed radio continuum analysis of multiple transitional disks at centimeter wavelengths, identifying dust pebbles and emission mechanisms.

Findings

Five out of ten disks detected in radio continuum.

Some disks show emission consistent with large dust grains (pebbles).

Other disks exhibit emission likely from photoevaporation or jets.

Abstract

We present sensitive (rms-noises $\sim$ 4 -- 25 $\mu$Jy) and high angular resolution ($\sim$1--2$"$) 8.9 GHz (3.3 cm) Karl G. Jansky Very Large Array (JVLA) radio continuum observations of 10 presumed transitional disks associated with young low-mass stars. We report the detection of radio continuum emission in 5 out of the 10 objects (RXJ1615, UX Tau A, LkCa15, RXJ1633, and SR24s). In the case of LkCa15, the centimeter emission is extended, and has a similar morphology to that of the transitional disk observed at mm wavelengths with an inner depression. For these five detections, we construct the Spectral Energy Distributions (SEDs) from the centimeter to submillimeter wavelengths, and find that they can be well fitted with a single (RXJ 1633 and UX Tau A) or a two component power-law (LkCa 15, RXJ 1615, and SR24s). For the cases where a single power-law fits well the data, the centimeter emission is likely produced by optically thin dust with large grains i.e. centimeter-size pebbles) present in the transitional disks. For the cases where a double power-law fits the data, the centimeter emission might be produced by the combination of photoevaporation and/or a free-free jet. We conclude that RXJ1633 and UX Tau A are excellent examples of transitional disks where the structure of the emission from centimeter/millimeter pebbles can be studied. In the other cases, some other physical emitting mechanisms are also important in the centimeter regime.