811 research outputs found
Photometric Properties of Kiso Ultraviolet-Excess Galaxies in the Lynx-Ursa Major Region
We have performed a systematic study of several regions in the sky where the
number of galaxies exhibiting star formation (SF) activity is greater than
average. We used Kiso ultraviolet-excess galaxies (KUGs) as our SF-enhanced
sample. By statistically comparing the KUG and non-KUG distributions, we
discovered four KUG-rich regions with a size of . One of these regions corresponds spatially to a filament of length
Mpc in the Lynx-Ursa Major region (). We call this ``the Lynx-Ursa
Major (LUM) filament''. We obtained surface photometry of 11 of
the KUGs in the LUM filament and used these to investigate the integrated
colors, distribution of SF regions, morphologies, and local environments. We
found that these KUGs consist of distorted spiral galaxies and compact galaxies
with blue colors. Their star formation occurs in the entire disk, and is not
confined to just the central regions. The colors of the SF regions imply that
active star formation in the spiral galaxies occurred yr ago,
while that of the compact objects occurred yr ago. Though the
photometric characteristics of these KUGs are similar to those of interacting
galaxies or mergers, most of these KUGs do not show direct evidence of merger
processes.Comment: 39 pages LaTeX, using aasms4.sty, 20 figures, ApJS accepted. The
Title of the previous one was truncated by the author's mistake, and is
corrected. Main body of the paper is unchange
KIC 4150611: a rare multi-eclipsing quintuple with a hybrid pulsator
We present the results of our analysis of KIC 4150611 (HD 181469) - an
interesting, bright quintuple system that includes a hybrid
Sct/ Dor pulsator. Four periods of eclipses - 94.2, 8.65, 1.52 and 1.43
d - have been observed by the Kepler satellite, and three point sources (A, B,
and C) are seen in high angular resolution images.
From spectroscopic observations made with the HIDES spectrograph attached to
the 1.88-m telescope of the Okayama Astrophysical Observatory (OAO), for the
first time we calculated radial velocities (RVs) of the component B - a pair of
G-type stars - and combined them with Kepler photometry in order to obtain
absolute physical parameters of this pair. We also managed to directly measure
RVs of the pulsator, also for the first time. Additionally, we modelled the
light curves of the 1.52 and 1.43-day pairs, and measured their eclipse timing
variations (ETVs). We also performed relative astrometry and photometry of
three sources seen on the images taken with the NIRC2 camera of the Keck II
telescope. Finally, we compared our results with theoretical isochrones.
The brightest component Aa is the hybrid pulsator, transited every 94.2 days
by a pair of K/M-type stars (Ab1+Ab2), which themselves form a 1.52-day
eclipsing binary. The components Ba and Bb are late G-type stars, forming
another eclipsing pair with a 8.65 day period. Their masses and radii are
M, R for the
primary, and M, R
for the secondary. The remaining period of 1.43 days is possibly related to a
faint third star C, which itself is most likely a background object. The
system's properties are well-represented by a 35 Myr isochrone. There are also
hints of additional bodies in the system.Comment: 14 pages, 15 figures, 7 tables, to appear in A&A, abstract modified
in order to fit the arXiv limi
The star formation properties of disk galaxies: Halpha imaging of galaxies in the Coma supercluster
We present integrated H alpha measurements obtained from imaging observations
of 98 late-type galaxies, primarily selected in the Coma supercluster. These
data, combined with H alpha photometry from the literature, include a magnitude
selected sample of spiral (Sa to Irr) galaxies belonging to the "Great Wall"
complete up to mp=15.4, thus composed of galaxies brighter than Mp=-18.8
(H0=100 km Mpc^-1 s^-1). The frequency distribution of the H alpha E.W.,
determined for the first time from an optically complete sample, is
approximately gaussian peaking at E.W. ~25 A. We find that, at the present
limiting luminosity, the star formation properties of spiral+Irr galaxies
members of the Coma and A1367 clusters do not differ significantly from those
of the isolated ones belonging to the Great Wall. The present analysis confirms
the well known increase of the current massive star formation rate (SFR) with
Hubble type. Moreover perhaps a more fundamental anticorrelation exists between
the SFR and the mass of disk galaxies: low-mass spirals and dwarf systems have
present SFRs ~50 times higher than giant spirals. This result is consistent
with the idea that disk galaxies are coeval, evolve as "closed systems" with
exponentially declining SFR and that the mass of their progenitor protogalaxies
is the principal parameter governing their evolution. Massive systems having
high initial efficiency of collapse, or a short collapse time-scale, have
retained little gas to feed the present epoch of star formation. These findings
support the conclusions of Gavazzi & Scodeggio (1996) who studyed the
color-mass relation of a local galaxy sample and agree with the analysis by
Cowie et al. (1996) who traced the star formation history of galaxies up to
z>1.Comment: 13 pages (LateX) + 24 figures + 4 tables. To appear in Astronomical
Journal, April 1998 issu
Semantics and Proof Theory of the Epsilon Calculus
The epsilon operator is a term-forming operator which replaces quantifiers in
ordinary predicate logic. The application of this undervalued formalism has
been hampered by the absence of well-behaved proof systems on the one hand, and
accessible presentations of its theory on the other. One significant early
result for the original axiomatic proof system for the epsilon-calculus is the
first epsilon theorem, for which a proof is sketched. The system itself is
discussed, also relative to possible semantic interpretations. The problems
facing the development of proof-theoretically well-behaved systems are
outlined.Comment: arXiv admin note: substantial text overlap with arXiv:1411.362
Dynamical Generation of CKM Mixings by Broken Horizontal Gauge Interactions
The fermion mass matrices are calculated in the framework of the dynamical
mass generation by the broken horizontal gauge interactions. The
non-proportional mass spectra between up- and down-sectors and CKM mixings are
obtained solely by radiative corrections due to the ordinary gauge
interactions.Comment: 20 pages + 1 uuencoded eps figure, PHYZZ
IC 225: a dwarf elliptical galaxy with a peculiar blue core
We present the discovery of a peculiar blue core in the elliptical galaxy IC
225 by using images and spectrum from the Sloan Digital Sky Survey (SDSS). The
outer parts of the surface brightness profiles of u-, g-, r-, i- and z-band
SDSS images for IC 225 are well fitted with an exponential function. The
fitting results show that IC 225 follows the same relations between the
magnitude, scale length and central surface brightness for dwarf elliptical
galaxies. Its absolute blue magnitude (M_B) is -17.14 mag, all of which suggest
that IC 225 is a typical dwarf elliptical galaxy. The g-r color profile
indicates a very blue core with a radius of 2 arcseconds, which is also clearly
seen in the RGB image made of g-, r- and i-band SDSS images. The SDSS optical
spectrum exhibits strong and very narrow nebular emission lines. The metal
abundances derived by the standard methods, which are 12+log(O/H) = 8.98,
log(N/O) = -0.77 and 12+log(S+/H+) = 6.76, turn out to be significantly higher
than that predicted by the well-known luminosity-metallicity relation. After
carefully inspecting the central region of IC 225, we find that there are two
distinct nuclei, separated by 1.4 arcseconds, the off-nucleated one is even
bluer than the nucleus of IC 225. The asymmetric line profiles of higher-order
Balmer lines indicate that the emission lines are bluer shifted relative to the
absorption lines, suggesting that the line emission arises from the off-center
core, whose nature is a metal-rich Hii region. To the best of our knowledge, it
is the first high-metallicity Hii region detected in a dwarf elliptical galaxy.Comment: 7 figures, accepted for publication in A
Third Generation Familons, B Factories, and Neutrino Cosmology
We study the physics of spontaneously broken family symmetries acting on the
third generation. Massless familons (or Majorons) associated with such
broken symmetries are motivated especially by cosmological scenarios with
decaying tau neutrinos. We first note that, in marked contrast with the case
for the first two generations, constraints on third generation familon
couplings are poor, and are, in fact, non-existent at present in the hadronic
sector. We derive new bounds from -- mixing, , , and astrophysics. The resulting constraints on
familon decay constants are still much weaker than those for the first and
second generation. We then discuss the promising prospects for significant
improvements from searches for , , and with the current CLEO, ARGUS, and LEP data. Finally, we note that
future constraints from CLEO III and the factories will probe decay
constants beyond 10^8 GeV, well within regions of parameter space favored by
proposed scenarios in neutrino cosmology.Comment: ReVTeX, 33 pages, 6 figures, notation improved, references added,
revised to conform to pubished versio
Effective Lagrangian Approach to the Fermion Mass Problem
An effective theory is proposed, combining the standard gauge group
with a horizontal discrete
symmetry. By assigning appropriate charges under this discrete symmetry to the
various fermion fields and to (at least) two Higgs doublets, the broad spread
of the fermion mass and mixing angle spectrum can be explained as a result of
suppressed, non-renormalisable terms. A particular model is constructed which
achieves the above while simultaneously suppressing neutral Higgs-induced
flavour-changing processes.Comment: 21 pages, UM-P-93/81, latex file, 1 figure available on reques
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