X-raying circumstellar material around young stars

TL;DR

This paper demonstrates how combining X-ray and optical/near-IR data can effectively measure the gas-to-dust ratio in circumstellar material around young stars, revealing diverse compositions from dust-rich to gaseous disks.

Contribution

It introduces a method to constrain the gas-to-dust ratio in circumstellar environments using combined X-ray and optical/near-IR observations, applied to three different systems.

Findings

Gas-to-dust ratios vary across systems from dust-rich to gas-rich disks.

X-ray absorption effectively probes gas content, complementing dust measurements.

Method provides new insights into circumstellar material composition.

Abstract

Young stars are surrounded by copious amounts of circumstellar material. Its composition, in particular its gas-to-dust ratio, is an important parameter. However, measuring this ratio is challenging, because gas mass estimates are often model dependent. X-ray absorption is sensitive to the gas along the line-of-sight while optical/near-IR extinction depends on the dust content. Therefore, the gas-to-dust ratio of an absorber is given by the ratio between X-ray and optical/near-IR extinction. We present three systems where we used X-ray and optical/near-IR data to constrain the gas-to-dust ratio of circumstellar material; from a dust-rich debris disk to gaseous protoplanetary disks.