Cold CO gas in the disk of the young eruptive star EX Lup

TL;DR

This study investigates the cold CO gas in the disk of the young eruptive star EX Lup, revealing insights into disk properties during episodic accretion events in T Tauri stars.

Contribution

It provides the first characterization of CO gas in an EXor disk using line observations and radiative transfer modeling, enhancing understanding of disk composition during outbursts.

Findings

Detection of $^{12}$CO and $^{13}$CO lines in EX Lup

Modeling reveals disk gas properties comparable to T Tauri disks

Insights into the gas component during episodic accretion events

Abstract

EX Lupi-type objects (EXors) form a sub-class of T Tauri stars, defined by sudden sporadic flare-ups of 1-5 magnitudes at optical wavelengths. These eruptions are attributed to enhanced mass accretion from the circumstellar disk to the star, and may constitute important events in shaping the structure of the inner disk and the forming planetary system. Although disk properties must play a fundamental role in driving the outbursts, they are surprisingly poorly known. In order to characterize the dust and gas components of EXor disks, here we report on observations of the $^{12}$CO J=3-2 and 4-3 lines, and the $^{13}$CO 3-2 line in EX Lup, the prototype of the EXor class. We reproduce the observed line fluxes and profiles with a line radiative transfer model, and compare the obtained parameters with corresponding ones of other T Tauri disks.