Multiple Sources toward the High-mass Young Star S140 IRS1

TL;DR

This study investigates the complex structure of the high-mass young stellar object S140 IRS1, revealing multiple sources and outflows, and discusses models like thermal jets and equatorial winds to explain its features.

Contribution

The paper provides high-resolution multi-wavelength observations of S140 IRS1, identifying multiple YSOs and continuum sources, and proposes models for the nature of IRS 1A.

Findings

Detection of elongated IRS 1A at multiple wavelengths

Identification of a new continuum source IRS 1C

Presence of multiple continuum clumps along IRS 1A

Abstract

S140 IRS1 is a remarkable source where the radio source at the center of the main bipolar molecular outflow in the region is elongated perpendicular to the axis of the outflow, an orientation opposite to that expected if the radio source is a thermal jet exciting the outflow. We present results of 1.3 cm continuum and H2O maser emission observations made with the VLA in its A configuration toward this region. In addition, we also present results of continuum observations at 7 mm and re-analyse observations at 2, 3.5 and 6 cm (previously published). IRS 1A is detected at all wavelengths, showing an elongated structure. Three water maser spots are detected along the major axis of the radio source IRS 1A. We have also detected a new continuum source at 3.5 cm (IRS 1C) located ~0.6'' northeast of IRS 1A. The presence of these two YSOs (IRS 1A and 1C) could explain the existence of the two bipolar molecular outflows observed in the region. In addition, we have also detected three continuum clumps (IRS 1B, 1D and 1E) located along the major axis of IRS 1A. We discuss two possible models to explain the nature of IRS 1A: a thermal jet and an equatorial wind.