Modelled 3D distribution of OH/IR stars in the Galactic disc

We have modelled the 3D distribution of OH/IR stars in the Galactic plane, traced by 1612 MHz OH maser sources with classic double horned spectral profiles. We statistically analysed over 700 maser sources detected by the HI/OH/Recombination line survey of the Milky Way (THOR) and the Australia Telescope Compact Array interferometric follow-up observations of the Southern Parkes Large-Area Survey in Hydroxyl (SPLASH). With a simple model constructed from a classical density distribution of stars and luminosity functions of OH maser sources in the Galaxy, we estimate the scale height, or the half thickness of the OH/IR star distribution along the Galactic disc to be 90–290 pc. The simple model also implies that there are ∼4000 OH/IR stars hosting 1612 MHz OH masers along the Galactic Plane. Therefore, next generation telescopes such as the Australian Square Kilometre Array Pathfinder (ASKAP) and SKA Phase 1 will detect about 80 per cent of such OH/IR stars in the Galaxy at a 10 mJy detection limit. Comparing the data of previously detected circumstellar 1612 MHz OH maser sources with those of THOR and SPLASH, the maser source lifetime is estimated to be ∼300 yr. This is likely a lower limit, since non-detections of masers in some cases could be affected by the flux variation of the maser source. © 2021 The Author(s).For deriving a kinematic distance, we used a python library provided by Trey Wenger (https://github.com/tvwenger/kd). This research has made use of: NASA’s Astrophysics Data System Abstract Service; NASA/IPAC Infrared Science Archive, which is funded by the National Aeronautics and Space Administration and operated by the California Institute of Technology; and Database of Circumstellar Masers. HI was supported by the Bilateral Collaboration Program by the Japan Society for Promotion of Science (JSPS) and KAKENHI programs 25610043 and 16H02167 by the Ministry of Education, Culture, Sports, Science and Technology (MEXT). JFG and HI were supported by the Invitation Program for Foreign Researcher by JSPS (S14128), by Amanogawa Galaxy Astronomy Research Center (AGARC), and the State Agency for Research of the Spanish MCIU through the ’Center of Excellence Severo Ochoa’ award for the Instituto de Astrofísica de Andalucía (SEV-2017-0709). JFG also acknowledges support by MCIU-AEI (Spain) grant AYA2017-84390-C2-R (co-funded by FEDER). JRD acknowledges the support of an Australian Research Council (ARC) DECRA Fellowship (project number DE170101086). H-HQ is partially supported by the Special Funding for Advanced Users, budgeted and administrated by Center for Astronomical Mega-Science, Chinese Academy of Sciences (CAMS-CAS), CAS ‘Light of West China’ Program and the National Natural Science Foundation of China (Grant No. 11903038).Peer reviewe