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Reserch Results

2008

Prediction of The Mass of a Star to be Born

2008-12-16

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Figure: Mass distribution of the cores (Left), the predicted and observed stellar mass distribution (Right).

The evolution of a star is determined by its mass. A new star is born in a dense molecular cloud core, and therefore the core has been thought to be a key to reveal how the stellar mass is determined. N. Ikeda (NRO/GUAS) and his colleagues have surveyed molecular cloud coresin the Orion A region using the 45 m telescope, and succeeded in detecting 236 cores. The mass distribution of the cores is found to be quite similar to that of stars. Furthermore, the stellar mass distribution can be well reproduced from the core mass one, by correcting for the overlap among the cores and by assuming that 40 % of the core mass turns into stellar mass. In conclusion, the stellar mass distribution is most likely to originate from the core mass one (Ikeda, Sunada and Kitamura 2007, ApJ, 665, 1194).

A New Single-Beam 100-GHz Band Receiver for The 45-m Telescope

2008-04-04

Figure: The new receiver system installed in the 45-m telescope.

T. Nakajima (Osaka Prefecture University) and collaborators have developed a waveguide-type dual-polarization sideband-separating SIS receiver system of the 100-GHz band for the 45-m radio telescope. This receiver is composed of an ortho-mode transducer and two sideband-separating SIS mixers, which are both based on the waveguide technique. The new receiver system was installed in the telescope, and we successfully test observations. The SSB receiver noise temperature of the system including the atmosphere became approximately half of that of the previous receiver system. (Nakajima et al. 2008, PASJ, 60, 435)

Detection of C8H- Toward a Late - Type Star

2008-02-15

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Figure: Spectra of the C8H- ion observed with the 45-m telescope.

In the envelope of the late-type star IRC+0216 many carbon-chain molecules have been detected. The first negative ion C6H- in space was identified in this source. A research group of Okayama University, National Astronomical Observatory, Shizuoka University, and Harvard University observed five rotational transitions of C8H- (the third negative ion in space) with the Nobeyama 45-m telescope. Two observed spectral features are shown in Figure. The abundance was estimated from the observed line intensities and found to be 37 % of the C8H radical. (Kawaguchi et al. 2007, PASJ, 59, L47)