A Proper Motion Study of the Haro 6-10 Outflow: Evidence for a Subarcsecond Binary

TL;DR

This study uses VLBI observations of water masers to analyze the outflow dynamics of the Haro 6-10 binary system, revealing a bipolar outflow nearly in the plane of the sky and evidence for an unseen companion driving a large outflow.

Contribution

First direct measurement of maser proper motions in Haro 6-10, linking maser activity to a bipolar outflow and proposing an unseen companion as the outflow driver.

Findings

Maser proper motions trace a bipolar outflow near the plane of the sky.

The outflow is associated with the southern component, Haro 6-10S.

Evidence suggests an unseen companion drives the large outflow.

Abstract

We present single-dish and VLBI observations of an outburst of water maser emission from the young binary system Haro 6-10. Haro 6-10 lies in the Taurus molecular cloud and contains a visible T Tauri star with an infrared companion 1.3" north. Using the Very Long Baseline Array, we obtained five observations spanning 3 months and derived absolute positions for 20 distinct maser spots. Three of the masers can be traced over 3 or more epochs, enabling us to extract absolute proper motions and tangential velocities. We deduce that the masers represent one side of a bipolar outflow that lies nearly in the plane of the sky with an opening angle of ~45\deg. They are located within 50 mas of the southern component of the binary, the visible T Tauri star Haro 6-10S. The mean position angle on the sky of the maser proper motions (~220\deg) suggests they are related to the previously observed giant Herbig-Haro (HH) flow which includes HH410, HH411, HH412, and HH184A-E. A previously observed HH jet and extended radio continuum emission (mean position angle of ~190\deg) must also originate in the vicinity of Haro6-10S and represent a second, distinct outflow in this region. We propose that a yet unobserved companion within 150 mas of Haro6-10S is responsible for the giant HH/maser outflow while the visible star is associated with the HH jet. Despite the presence of H_2 emission in the spectrum of the northern component of the binary, Haro6-10N, none of outflows/jets can be tied directly to this young stellar object.