Massive Protocluster of a Periodic Maser Source G188.95+0.89

TL;DR

This study monitors periodic methanol masers in G188.95+0.89, revealing variable features, velocity drifts, and multiple young stellar objects through combined maser and ALMA observations, indicating complex star formation activity.

Contribution

It provides the first detailed analysis of periodic maser variability and high-resolution ALMA imaging revealing multiple protostars and outflows in G188.95+0.89.

Findings

Five maser features show periodic variation.

Detection of multiple continuum cores, including a binary system.

Evidence of bipolar outflows and multiple young stellar objects.

Abstract

We report the results of ongoing monitoring of the 6.7 GHz CH$_3$OH masers associated with G188.95+0.89. In these observations five features are periodically varying and at least two exhibit evidence of velocity drifts. It is not clear the cause of these velocity drifts. The spectra have varied significantly since detection in 1991. The 11.45 km s$^1$ feature has decreased exponentially from 2003. Complementary ALMA 1.3 mm continuum and line observational results are also presented. Eight continuum cores (MM1 - MM8) were detected in G188.95+0.89. We derived the masses of the detected cores. G188.95+0.89 MM2 was resolved into 2 continuum cores (separated by 0.1 arcsec) in ALMA band 7 observations. Also CH$_3$OH (4$_{(2,2)}$-3$_{(1,2)})$ thermal emission associated with MM2 is double peaked. We propose the presence of multiple (at least binary) young stellar objects in MM2. SiO emission exhibit a bow-shock morphology in MM2 while strong emission of $^{12}$CO at the east and west of MM2 suggest the presence of an east-west bipolar outflow.