1,764 research outputs found
The Virgo High-Resolution CO Survey. II. Rotation Curves and Dynamical Mass Distributions
Based on a high-resolution CO survey of Virgo spirals with the Nobeyama
Millimeter-wave Array, we determined the dynamical centers using velocity
fields, and derived position-velocity diagrams (PVDs) along the major axes of
the galaxies across their dynamical centers. We applied a new iteration method
to derive rotation curves (RCs), which reproduce the observed PVDs. The
obtained high-accuracy RCs generally show steep rise in the central 100 to 200
pc regions, followed by flat rotation in the disk. We applied a deconvolution
method to calculate the surface-mass density (SMD) using the RCs based on two
extreme assumptions that the mass distribution is either spherical or thin-disk
shaped. Both assumptions give nearly identical results, agreeing with each
other within a factor of two at any radii. The SMD distributions revealed
central massive cores with peak SMD of 10^4 - 10^5 Msun pc^-2 and total mass
within 200 pc radius of the order of about 10^9 Msun Correlation analysis among
the derived parameters show that the central CO-line intensity is positively
correlated with the central SMD, which suggests that the deeper is the
gravitational potential, the higher is the molecular gas concentration in the
nuclei regardless morphological types.Comment: PASJ 2003 in press, Latex 12 pages, 6 figures (Bigger gif/ps figures
available at http://www.ioa.s.u-tokyo.ac.jp/radio/virgo2
Magnetic Phase Diagrams with Possible Field-induced Antiferroquadrupolar Order in TbBC
Magnetic phase diagrams of a tetragonal antiferromagnet TbBC were
clarified by temperature and field dependence of magnetization. It is
noticeable that the N{\'e}el temperature in TbBC is anomalously
enhanced with magnetic fields, in particular the enhancement reaches 13.5 K for
the direction at 10 T. The magnetization processes as well as the
phase diagrams are well interpreted assuming that there appear field-induced
antiferroquadrupolar ordered phases in TbBC. The phase diagrams of the
AFQ compounds in RBC are systematically understood in terms of the
competition with AFQ and AFM interactions.Comment: 4 pages, 4 figures, RevTeX
A Study of Dopamine Metabolism in a Patient with Juvenile Parkinsonism by Positron Emission Tomography
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