The initial mass function and stellar birthrate in the solar neighborhood

AbstractOutskirts of spiral galaxies, including our own, and dwarf irregular galaxies are known to have a different environment from the solar neighborhood, e.g., low metallicities ( ~ − 1 dex). Among them, the outer Galaxy is the closest and hence is so far the only site suitable for population studies of resolved stars on the same basis as solar neighborhood. We have obtained NIR images of young clusters in the outer Galaxy, using the Subaru 8.2-m telescope, and clearly resolved cluster members with mass detection limits of ~ 0.1 M⊙. Based on the fitting of K-band luminosity functions (KLFs) for four clusters, we found that the initial mass function (IMF) in the outer Galaxy is consistent with that in the solar neighborhood in terms of the high-mass slope and IMF peak. Upcoming observations with a higher spatial resolution and sensitivity, using JWST, TMT, etc., will allow us to extend spatially-resolved studies of the IMF to Local Group galaxies.

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A New Approach to Determine the Initial Mass Function in the Solar Neighborhood

The Astrophysical Journal ◽

10.1086/304215 ◽

1997 ◽

Vol 483 (1) ◽

pp. 228-234 ◽

Cited By ~ 46

Author(s):

Takuji Tsujimoto ◽

Yuzuru Yoshii ◽

Ken'ichi Nomoto ◽

Francesca Matteucci ◽

Friedrich‐Karl Thielemann ◽

...

Keyword(s):

Mass Function ◽

Initial Mass Function ◽

Solar Neighborhood ◽

Initial Mass ◽

New Approach

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Stellar populations in starburst galaxies

Symposium - International Astronomical Union ◽

10.1017/s0074180900206281 ◽

1999 ◽

Vol 193 ◽

pp. 568-577 ◽

Cited By ~ 1

Author(s):

Robert D. Joseph

Keyword(s):

Star Formation ◽

Mass Function ◽

Small Mass ◽

Starburst Galaxies ◽

Initial Mass Function ◽

Solar Neighborhood ◽

Initial Mass ◽

Full Spectrum ◽

Bolometric Luminosity ◽

Normal Galaxies

Many galaxies emit a dominant fraction of their bolometric luminosity in the infrared. The small mass-luminosity ratios suggest that these infrared luminosities cannot be sustained by a normal stellar population over a Hubble time. The commonly held explanation is that there has been a burst of star formation sufficiently recently that the full spectrum of the initial mass function up to the highest mass stars is contributing to the luminosity. Starburst galaxies therefore provide laboratories for studying the upper end of the initial mass function.After a briefly summarizing studies of the IMF in the solar neighborhood and in nearby ‘normal’ galaxies, I will turn to studies of environments in which there appears to be evidence for a somewhat different IMF,viz., in starburst galaxies. I will discuss infrared spectroscopic diagnostics of a sample of the most luminous starburst galaxies and what this implies for the IMFs in these ‘violent’ star formation events.

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The Star Formation History and IMF in the LMC and SMC from Deep HST Imaging

Symposium - International Astronomical Union ◽

10.1017/s0074180900118200 ◽

1999 ◽

Vol 190 ◽

pp. 351-353

Author(s):

J. Holtzman ◽

J. R. Mould ◽

J. S. Gallagher

Keyword(s):

Star Formation ◽

Mass Function ◽

Initial Mass Function ◽

Solar Neighborhood ◽

Star Formation History ◽

Initial Mass ◽

Luminosity Functions ◽

Formation History

We present deep photometry to V ~ 27.5 obtained with the HST in several fields in the LMC and the SMC. We derive luminosity functions for the faintest stars which are consistent with an initial mass function similar to that of the solar neighborhood, although moderate variations are not excluded. We discuss implications of these observations for the star formation history in these regions of the LMC and SMC.

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