相关论文: Star Formation in the Extreme Outer Galaxy: the IM…
As a first step for studying star formation in the extreme outer Galaxy (EOG), we obtained deep near-infrared images of two embedded clusters at the northern and southern CO peaks of Cloud 2, which is one of the most distant star forming…
The extreme outer Galaxy (EOG) has a very different environment from that in the solar neighborhood, with low metallicity (less than -0.5 dex), much lower gas density, and small or no perturbation from spiral arms. The EOG is an excellent…
We report the discovery of active star formation in Digel's Cloud 2, which is one of the most distant giant molecular clouds known in the extreme outer Galaxy (EOG). At the probable Galactic radius of ~20 kpc, Cloud 2 has a quite different…
To study star formation in low metallicity environments ([M/H] ~ -1 ,dex), we obtained deep near-infrared (NIR) images of Sh 2-207 (S207), which is an HII region in the outer Galaxy with spectroscopically determined metallicity of [O/H] ~=…
The extreme outer Galaxy (EOG), which we define as the region of the Milky Way with a galactocentric radius of more than 18 kpc, provides an excellent opportunity to study star formation in an environment significantly different from that…
We have been investigating the metallicity dependence of star and planet formation, particularly focusing on the outer Galaxy with a Galactocentric distance ($R_g$) of $\gtrsim$15 kpc, where the metallicity is determined to be as low as…
The extreme outer Galaxy (EOG), the region with a Galactic radius of more than 18 kpc, is known to have very low metallicity, about one-tenth that of the solar neighborhood. We obtained deep near-infrared (NIR) images of two very young…
While conducting a near-infrared (NIR) survey of ``Digel Clouds'', which are thought to be located in the extreme outer Galaxy (EOG), Kobayashi & Tokunaga found star formation activity in ``Cloud 2'', a giant molecular cloud at the Galactic…
We review our current knowledge on the IMF in nearby environments, massive star forming regions, super star clusters, starbursts and alike objects from studies of integrated light, and discuss the various techniques used to constrain the…
We obtained deep near-infrared images of Sh 2-208, one of the lowest-metallicity HII regions in the Galaxy, [O/H] = -0.8 dex. We detected a young cluster in the center of the HII region with a limiting magnitude of K = 18.0 mag (10sigma),…
In the star formation process, the vital impact of environmental factors such as feedback from massive stars and stellar density on the form of the initial mass function (IMF) at low-mass end is yet to be understood. Hence a systematic,…
We present the substellar mass function of star-forming clusters ($\simeq$0.1 Myr old) in a low-metallicity environment ($\simeq$$-$0.7 dex). We performed deep JWST/NIRCam and MIRI imaging of two star-forming clusters in Digel Cloud 2, a…
We present deep near-infrared (NIR) imaging of Sh 2-209 (S209), a low-metallicity (${\rm [O/H]} = - 0.5$ dex) HII region in the Galaxy. From the NIR images, combined with astrometric data from Gaia EDR3, we estimate the distance to S209 to…
Using new long-slit spectroscopy obtained with X-Shooter at ESO-VLT, we study, for the first time, radial gradients of optical and Near-Infrared IMF-sensitive features in a representative sample of galaxies at the very high-mass end of the…
Any predictive theory of star formation must explain observed variations (or lack thereof) in the initial mass function. Recent work suggests that we might expect quantitative variations in the IMF as a function of metallicity (Larson 2005)…
We report the discovery of star formation activity in perhaps the most distant molecular cloud in the extreme outer galaxy. We performed deep near infrared imaging with the Subaru 8.2 m telescope, and found two young embedded clusters at…
The low metallicity interstellar medium of dwarf galaxies gives a different picture in the far infrared(FIR)/submillimetre(submm)wavelengths than the more metal-rich galaxies. Excess emission is often found in the submm beginning at or…
Recent results indicate the stellar initial mass function is not a strong function of star-forming environment or ``initial conditions'' (e.g. Meyer et al. 2000). Some studies suggest that a universal IMF may extend to sub-stellar masses…
To fully understand the star formation process, we are compelled to study it in a variety of environments. Of particular interest are how star formation and the resulting initial mass function (IMF) vary as a function of metallicity. We…
We demonstrate the feasibility of detecting directly low mass stars in unresolved super-star clusters with ages < 10 Myr using near-infrared spectroscopy at modest resolution (R ~ 1000). Such measurements could constrain the ratio of high…