Two New SiO Maser Sources in High-Mass Star-Forming Regions

We present the ALMA Cycle 2 results "Two New SiO Maser Sources in High-Mass Star-Forming Regions" which was published in the Astrophysical Journal (Vol. 826, P157, 2016). Silicon monoxide (SiO) masers are rare in star forming regions, with the exception of five known SiO maser sources. However, we detected two new SiO maser sources from infrared loud clumps of the high-mass star forming regions G19.61-0.23 and G75.78+0.34 using the KVN single dish. High angular resolution observations with ALMA and JVLA toward G19.61-0.23 suggest that the deeply embedded young stellar object (YSO) of SMA 1 is powering the SiO masers. In addition, the SiO v=1, J=1-0 line shows four spike features while the v=2 maser shows combined features of one spike and broad wing components, implying energetic activities of the YSO of SMA 1 in the G19.61-0.23 hot molecular core. The SiO v=0, J=2-1 emission shows bipolar outflows in NE-SW direction with respect to the center of the SiO maser source. A high angular resolution map of the SiO v=1, J=2-1 maser in G75.78+0.34 shows that the SiO maser is associated with the CORE source at the earliest stage of high-mass star formation. Therefore, the newly detected SiO masers and their associated outflows will provide good probes for investigating this early high-mass star formation.