Year: 2017
Type: article
Abstract: We report the first detection of a substantial brightening event in an isotopologue of a key molecular ion, HCO+, within a protoplanetary disk of a T Tauri star. The H13CO+ rotational transition was observed three times toward IM Lup between 2014 July and 2015 May with the Atacama Large Millimeter/submillimeter Array. The first two observations show similar spectrally integrated line and continuum fluxes, while the third observation shows a doubling in the disk-integrated line flux compared to the continuum, which does not change between the three epochs. We explore models of an X-ray active star irradiating the disk via stellar flares, and find that the optically thin H13CO+ emission variation can potentially be explained via X-ray-driven chemistry temporarily enhancing the HCO+ abundance in the upper layers of the disk atmosphere during large or prolonged flaring events. If the HCO+ enhancement is indeed caused by an X-ray flare, future observations should be able to spatially resolve these events and potentially enable us to watch the chemical aftermath of the high-energy stellar radiation propagating across the face of protoplanetary disks, providing a new pathway to explore ionization physics and chemistry, including electron density, in disks.
Authors: L. Ilsedore Cleeves, Edwin A. Bergin, Karin I. Öberg, Sean Andrews, David Wilner, Ryan Loomis
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
Awards: G433322167, G4518818167, INSPIRE Track 1: Following the Carbon Trail in Planetary Formation, G58316358, G6273510985, Collaborative Research: Making a Habitable Planet - The Evolution of the Volatile Inventory in Gas-Rich Planet-Forming Disks, OVERVIEW OF SCIENCE GOALS-THE EARLY STAGES OF PLANETARY BIRTH, SETTLING OF DUST TO A DUST RICH MIDPLANE LEAD TO THE SEQUESTRATION OF SOLIDS A GAS RIC, G767601387, G8210229802
OpenAlex ID: W2621481175