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| Paper: |
Interferometer CO Survey of Early-type Spiral Galaxies |
| Volume: |
320, The Neutral ISM in Starburst Galaxies |
| Page: |
42 |
| Authors: |
Koda, J.; Okuda, T.; Nakanishi, K.; Kuno, N.; Okumura, S.; Kohno, K.; Ishizuki, S. |
| Abstract: |
We report an on-going interferometer CO survey of early-type spiral galaxies (S0-Sab). We have observed 5 targets with HII region-like nuclei. Distinct nature of nuclear star formation from global ones in disk galaxies has been reported in many studies (Kennicutt 1998 for review). In contrast to low global star formation in early-type disks, vigorous circumnuclear star formation is sometimes found in early-type spiral galaxies. Ho, Filippenko, & Sargent (1997a) reported (1) that the occurrence for hosting HII-nuclei (HII regionslike spectra) is less frequent in early-type spirals than in late-type spirals, (2) however that among the galaxies with HII-nuclei, the average Hα-luminosity in early-type spirals is higher than that in late-types. Therefore, assuming a constant star formation efficiency, it is expected that early-type spirals would have larger gas mass in circumnuclear regions than late-types. However, our survey so far indicates the opposite trend: our early-type samples have smaller gas masses than the late-types (collected from the literature), although both samples shows similar dynamical masses and star formation rates. |
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