Dust formation by the colliding-wind WC5+O9 binary WR19 at periastron passage

TL;DR

This study investigates the periodic dust formation in the Wolf-Rayet binary WR19, linking dust episodes to the binary's high-eccentricity orbit and periastron passage, supported by infrared photometry and radial velocity data.

Contribution

It provides evidence that WR19's episodic dust formation is linked to its binary orbit, with detailed observations confirming the timing and nature of these events.

Findings

Dust formation episodes are periodic with a 10.1-year cycle.

WR19 is a high-eccentricity binary with e=0.8.

Dust formation correlates with periastron passage.

Abstract

We present infrared photometry of the episodic dust-making Wolf-Rayet system WR19 (LS3), tracking its fading from a third observed dust-formation episode in 2007 and strengthening the view that these episodes are periodic (P = 10.1+/-0.1 y). Radial velocities of the O9 component observed between 2001 and 2008 show RV variations consistent with WC19 being a spectroscopic binary of high eccentricity (e=0.8), having periastron passage in 2007.14, shortly before the phase of dust formation. In this respect, WR19 resembles the archetypical episodic dust-making colliding-wind binary system WR140.