Long-term with short-intervals monitor of 6.7 GHz CH3OH masers using Hitachi 32-m radio telescope to statistically research the periodic flux variability around high-mass protostars

• Main Authors: Sugiyama, K, Yonekura, Y, Motogi, K, Saito, Y, Momose, M, Honma, M, Hirota, T, Uchiyama, M, Tanaka, K E I, Kramer, B H, Asanok, K, Jaroenjittichai, P, Fujisawa, K
• Format: Conference Proceeding
• Language: English
• Subjects: Intervals; Masers; Monitoring; Periodic variations; Physics; Protostars; Radio telescopes; Telescopes
• ISSN: 1742-6588; 1742-6596
• DOI: 10.1088/1742-6596/1380/1/012057

We initiated a long-term with short-intervals monitoring project toward 442 CH3OH masers at 6.7 GHz (Dec > -30 deg) using Hitachi 32-m radio telescope of Japan in Dec 2012. Our observations have been carried out daily, monitoring a spectrum of each source with intervals of 9-10 days. In Sep 2015, the number of the targets sources and intervals were redesigned into 143 and 4-5 days to detect periodic variations with periods shorter than 30 days. We have so far obtained new detections of periodic flux variations in 31 CH3OH sources with periods of 22-409 days. These periodic flux variability with timescale between a few months and a few years must be a unique tool to study high-mass protostars themselves and their circumstellar structures on a tiny spatial scale of 0.1-1 au (∼1.5 x 107-8 km). We will also present the future prospect via monitoring of OH and H2O masers in these periodic sources using 40-m Thai National Radio Telescope that is under construction by NARIT.