129 research outputs found
A New 100-GHz Band Front-End System with a Waveguide-Type Dual-Polarization Sideband-Separating SIS Receiver for the NRO 45-m Radio Telescope
We developed a waveguide-type dual-polarization sideband-separating SIS
receiver system of the 100-GHz band for the 45-m radio telescope at the
Nobeyama Radio Observatory, Japan. This receiver is composed of an ortho-mode
transducer and two sideband-separating SIS mixers, which are both based on the
waveguide technique. The receiver has four intermediate frequency bands of
4.0--8.0 GHz. Over the radio frequency range of 80--120 GHz, the
single-sideband receiver noise temperatures are 50--100 K and the image
rejection ratios are greater than 10 dB. We developed new matching optics for
the telescope beam as well as new IF chains for the four IF signals. The new
receiver system was installed in the telescope, and we successfully observed
the 12CO, 13CO and C18O emission lines simultaneously toward the Sagittarius B2
region to confirm the performance of the receiver system. The SSB noise
temperature of the system, including the atmosphere, became approximately half
of that of the previous receiver system. The Image Rejection Ratios (IRRs) of
the two 2SB mixers were calculated from the 12CO and HCO+ spectra from the W51
giant molecular cloud, resulting in > 20 dB for one polarization and > 12 dB
for the other polarization.Comment: 10 pages, 13 figures, Accepted for publication in PASJ, version with
high resolution figures is available via
http://www.nro.nao.ac.jp/library/report/list.htm
ASTE CO(3-2) Observations of the Barred Spiral Galaxy M 83: I. Correlation between CO(3-2)/CO(1-0) Ratios and Star Formation Efficiencies
We present CO(J=3-2) emission observations with the Atacama Submillimeter
Telescope Experiment (ASTE) toward the 5' x 5' (or 6.6 x 6.6 kpc at the
distance D = 4.5 Mpc) region of the nearby barred spiral galaxy M 83. We
successfully resolved the major structures, i.e., the nuclear starburst region,
bar, and inner spiral arms in CO(J=3-2) emission at a resolution of 22'' (or
480 pc), showing a good spatial coincidence between CO(J=3-2) and 6 cm
continuum emissions. We found a global CO(J=3-2) luminosity L'_CO(3-2) of 5.1 x
10^8 K km s^-1 pc^2 within the observed region. We also found L'_CO(3-2) in the
disk region (0.5 < r < 3.5 kpc) of 4.2 x 10^8 K km s^-1 pc^2, indicating that
CO(J=3-2) emission in the disk region significantly contributes to the global
L'_CO(3-2). From a comparison of a CO(J=3-2) data with CO(J=1-0) intensities
measured with Nobeyama 45-m telescope, we found that the radial profile of
CO(J=3-2)/CO(J=1-0) integrated intensity ratio R_3-2/1-0 is almost unity in the
central region (r < 0.25 kpc), whereas it drops to a constant value, 0.6--0.7,
in the disk region. The radial profile of star formation efficiencies (SFEs),
determined from 6 cm radio continuum and CO(J=1-0) emission, shows the same
trend as that of R_3-2/1-0. At the bar-end (r ~ 2.4 kpc), the amounts of
molecular gas and the massive stars are enhanced when compared with other disk
regions, whereas there is no excess of R_3-2/1-0 and SFE in that region. This
means that a simple summation of the star forming regions at the bar-end and
the disk cannot reproduce the nuclear starburst of M 83, implying that the
spatial variation of the dense gas fraction traced by R_3-2/1-0 governs the
spatial variation of SFE in M 83.Comment: 13 pages, 11 figures, PASJ in press, version with high resolution
figures is available via http://www.nro.nao.ac.jp/~z5001km/m83-aste.pd
Assignment of CPS1, OTC, CRYD2, ARG2 and ASS genes to the chicken RH map
An attempt was made to assign five genes, CPS1, OTC, ASS, CRYD2, and ARG2, to chicken chromosomes (GGA) by radiation-hybrid mapping. OTC was assigned to GGA1; ARG2 to GGA5; CPS1 to GGA7; and CRYD2 to GGA19. ASS was not, however, assigned to a specific chromosomal position
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