Abstract
Observing star-forming regions in the outer Galaxy with JWST
Natsuko Izumi (National Astronomical Observatory of Japan)
Naoto Kobayashi (University of Tokyo), Chikako Yasui (NAOJ), Masao Saito (NAOJ), Satoshi Hamano (Kyoto Sangyo University)
The outer Galaxy beyond the outer arm (Rg ≧ 13.5 kpc) offers an interesting opportunity to study star formation in a significantly different environment from that in the solar neighborhood with much lower gas density (< 1/10) and lower metallicity (~ 1/10). However, star-forming regions in the outer Galaxy have never been comprehensively surveyed and listed due to the difficulties in detecting them at such large distances. Therefore, we searched for star-forming regions with WISE MIR all-sky survey data and FCRAO CO outer Galaxy survey data to identify new 711 star-forming regions in 240 molecular clouds up to Rg ~ 20 kpc (Izumi et al., in prep, 2016). Our new sample star-forming regions enable statistical studies of star formation processes up to extreme outer Galaxy for the first time. We estimated star-formation efficiency per molecular clouds for converting H2 gas to stars to find that the efficiency may not depend on environmental parameters including gas density and metallicity. However, the internal structure of those star-forming regions cannot be spatially resolved with the WISE resolution. We need to understand detailed properties of star-formation activity such as initial mass function, apparent age spread, and triggering mechanisms in the outer Galaxy with JWST. Individual young stellar objects (YSOs) less than 0.1 Msun can be detected using JWST because of its high spatial resolution and sensitivity. We are also able to estimate spectral energy distribution for each YSOs with both near and mid-infrared data, which enable us to classify their evolutional state accurately. Furthermore, combining with data from ALMA, we would be able to study the relationship between dense core formation and star formation processes in the outer Galaxy. Investigating the large number of YSOs in our sample star-forming regions and their surrounding structures is probably related to reveal environmental dependence of star formation processes.
Talk