7,932 research outputs found
Three-dimensional orbits of metal-poor halo stars and the formation of the Galaxy
We present the three-dimensional orbital motions of metal-poor stars in
conjunction with their metal abundances, for the purpose of getting insight
into the formation process of the Galaxy. Our sample stars, which include
metal-deficient red giants and RR Lyrae variables observed by the Hipparcos
satellite, are least affected by known systematics, stemmed from kinematic
bias, metallicity calibration, and secondary metal contamination of stellar
surface. We find, for the stars in the metallicity range of [Fe/H]<-1, that
there is no evidence for the correlation between [Fe/H] and their orbital
eccentricities e. Even for [Fe/H]<-1.6, about 16% of the stars have e less than
0.4. We show that the e distribution of orbits for [Fe/H]<-1.6 is independent
of the height |z| away from the Galactic plane, whereas for [Fe/H]>-1.6 the
stars at |z|>1 kpc are systematically devoid of low-e orbits with e<0.6. This
indicates that low-e stars with [Fe/H]<-1.6 belong to the halo component,
whereas the rapidly-rotating thick disk with a scale height about 1 kpc has a
metal-weak tail in the range of -1.6<[Fe/H]<-1. The fraction of this metal-weak
thick disk appears to be only less than 20%. The significance of these results
for the early evolution of the Galaxy is briefly discussed.Comment: 11 pages, 3 figures, AASTeX, to appear in ApJ Letter
Rebuild to Preserve: renewal of the historical buildings along the alleyways in Kyoto (Japan)
Ponència presentada a: Session 9: Forma urbana y relaciones entre historia y proyecto: el medio ambiente como patrimonio / Urban form and relationships between design and history: environmental heritage, arquitecture and plannin
A Technique Fof Determining the Extragalactic Distance Scale
We propose a method of distance determination based on the internal structure
and dynamics of disk galaxies. The method relies on the universal luminosity
profile of a stellar disk represented by an exponential law. Calibrating nearby
galaxies with known distances, it is found that the scale length of the disk is
tightly correlated with the specific combination of central surface brightness
{\it and} rotational velocity at a characteristic radius of 2.15 scale lengths
from the center. This suggests that the scale length of the disk may be used as
an indicator for extragalactic distance scale. The application of this relation
to M51 and M100 allows us to arrive at the distances of about 6 Mpc and 14 Mpc,
respectively, implying a Hubble constant of km s
Mpc.Comment: 12pp + 2 figures, included as uuencoded postscript file, to appear in
ApJ (Part1), TH94092
Self-consistent Analytic Solutions in Twisted Model in the Large- Limit
We construct self-consistent analytic solutions in the
model in the large- limit, in which more than one Higgs scalar component
take values inside a single or multiple soliton on an infinite space or on a
ring, or around boundaries of a finite interval.Comment: 16 pages, 5 figures. Updates in v2: References added, Minor typos
corrected. v3: Published versio
Nambu-Jona Lasinio and Nonlinear Sigma Models in Condensed Matter Systems
We review various connections between condensed matter systems with the
Nambu-Jona Lasinio model and nonlinear sigma models. The field theoretical
description of interacting systems offers a systematic framework to describe
the dynamical generation of condensates. Resent findings of a duality between
the Nambu-Jona Lasinio model and the nonlinear sigma model enables us to
investigate various properties underlying both theories. In this review we
mainly focus on inhomogeneous condensations in static situations. The various
methods developed in the Nambu-Jona Lasinio model reveal the inhomogeneous
phase structures and also yield new inhomogeneous solutions in the nonlinear
sigma model owing to the duality. The recent progress on interacting systems in
finite systems is also reviewed.Comment: 24pages, 10 figures, Invited review paper commissioned by Symmetry.
Comments warmly welcom
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