(ORDO NEWS) — Recently, a joint research team from the Chinese Academy of Sciences (CAS) National Time Service Center (NTSC), CAS Shanghai Astronomical Observatory (SHAO) and SKA Observatory used the Shanghai Tianma radio telescope to search for 4.7 GHz OH masers in 155 northern star forming regions and found eight new sources.
OH masers are typically found in star-forming regions of high mass (eight times the mass of the Sun). “Observing OH masers at different transitions at the same location can impose strong restrictions on the physical conditions at the site, such as H2 density, temperature, and velocity gradients,” said Qiao Haihua, first author of the study.
The researchers studied associations between 18 detected OH masers at 4.7 GHz with ground-state OH masers around 1.7 GHz, methanol masers at 6.7 GHz, and water masers at 22 GHz.
They found that the presence of OH masers at 1665 MHz is a better indicator of the presence of OH masers at 4.7 GHz than OH masers at 1720 MHz, and most OH masers at 4.7 GHz were associated with methanol masers at 6 .7 GHz and/or water masers at 22 GHz.
The process of formation of large mass stars is a fundamental and topical topic in astrophysics. Observations of the processes of formation of stars of large mass are hindered by their large distances, high extinction, and short time frames of critical evolutionary phases.
However, OH maser emission occurs at radio frequency and is not affected by the dense optically bleaching gas and dust that exists in the early stages of high-mass star formation. In this way, researchers can use OH masers to study high-mass stars at their earliest stages.
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