Massive protocluster of a periodic maser source G188.95+0.89

Abstract

ABSTRACT We report the results of ongoing monitoring of the 6.7 GHz CH3OH 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 two continuum cores (separated by 0.1 arcsec) in ALMA band 7 observations. Also, CH3OH (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 exhibits a bow-shock morphology in MM2 while strong emission of 12CO at the east and west of MM2 suggests the presence of an east–west bipolar outflow.