23 research outputs found
UBVRI photometry of Betelgeuse over 23 years since 1999
We report the results of our continuous UBVRI-band photometry of Betelgeuse
from 1999 to 2022 using the same photometric system. There are two advantages
in our observation: (1) we used a photodiode as a detector to avoid saturation,
and (2) our data set includes U-band light curve, which is not widely observed
in recent CCD photometries. Using our light curves, we conducted the
periodicity analysis, and found ~405- and ~2160-day periods. We also discuss
the tentative detection of a long-period variation over 20 years or longer.
Finally, we discuss the peculiar variation of the U-B color index during the
"Great Dimming" event between late 2019 and early 2020.Comment: 29 pages, 7 figures, 2 tables. Published in OEJV. Full tables
available as table1.dat and table2.da
Early Spectral Evolution of the Rapidly Expanding Type Ia SN 2006X
We present optical spectroscopic and photometric observations of Type Ia
supernova (SN) 2006X from --10 to +91 days after the -band maximum. This SN
exhibits one of the highest expansion velocity ever published for SNe Ia. At
premaximum phases, the spectra show strong and broad features of
intermediate-mass elements such as Si, S, Ca, and Mg, while the O{\sc
i}7773 line is weak. The extremely high velocities of Si{\sc ii} and
S{\sc ii} lines and the weak O{\sc i} line suggest that an intense
nucleosynthesis might take place in the outer layers, favoring a delayed
detonation model. Interestingly, Si{\sc ii}5972 feature is quite
shallow, resulting in an unusually low depth ratio of Si{\sc ii}5972
to 6355, (Si{\sc ii}). The low (Si{\sc ii}) is usually
interpreted as a high photospheric temperature. However, the weak Si{\sc
iii}4560 line suggests a low temperature, in contradiction to the low
(Si{\sc ii}). This could imply that the Si{\sc ii}5972 line
might be contaminated by underlying emission. We propose that (Si{\sc
ii}) may not be a good temperature indicator for rapidly expanding SNe Ia at
premaximum phases.Comment: 20 pages, 7 figures, (Received 2008 August 17; Accepted 2009 April
13
The Type Ia supernovae rate with Subaru/XMM-Newton Deep Survey
We present measurements of the rates of high-redshift Type Ia supernovae
derived from the Subaru/XMM-Newton Deep Survey (SXDS). We carried out repeat
deep imaging observations with Suprime-Cam on the Subaru Telescope, and
detected 1040 variable objects over 0.918 deg in the Subaru/XMM-Newton Deep
Field. From the imaging observations, light curves in the observed -band
are constructed for all objects, and we fit the observed light curves with
template light curves. Out of the 1040 variable objects detected by the SXDS,
39 objects over the redshift range are classified as Type Ia
supernovae using the light curves. These are among the most distant SN Ia rate
measurements to date. We find that the Type Ia supernova rate increase up to and may then flatten at higher redshift. The rates can be fitted by a
simple power law, with
(stat.)(syst.), and
(stat.)(syst.).Comment: 21 pages, 16 figures, accepted to PAS
中国上海市小児における乳歯列形態の検討 : 正常咬合児72例の模型から
To obtain the dimensional data of the dental casts of growing and developing Chinese children, and to compare the data to the Japanese, we have performed dental examinations on children in the kindergarten attached to Shanghai Teachers\u27 University in Shanghai since 1996. As study materials, dental casts obtained between 1996 and 1999 from 72 Chinese children aged 3 to 6 years with normal primary occlusion were used to evaluate the mesio-distal crown diameters of the primary teeth, the sizes of the primary dental arch, and the standard values and frequency distributions of primary occlusion. 1. Males showed higher values in mesio-distal crown diameters in deciduous teeth, and the size of dental arch than females. 2. In regard to the interdental spaces both in the maxilla and mandible, primate and developmental spaces together were most frequently observed. 3. In regard to the occlusal relationship, the incidence of terminal planes was higher in the order of Vertical type > Mesial step type > Distal step type, and the incidence of primary canine occlusal relationship was higher in the order of type I>type III>type II. 4. The items that were thought to be characteristic of Chinese children were the frequency of only primate spaces, and the incidence of the Mesial step type of terminal plane and type III primary canine occlusal relationship
First-year Sloan Digital Sky Survey-II (SDSS-II) Supernova Results: Hubble Diagram and Cosmological Parameters
We present measurements of the Hubble diagram for 103 Type Ia supernovae
(SNe) with redshifts 0.04 < z < 0.42, discovered during the first season (Fall
2005) of the Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey. These data
fill in the redshift "desert" between low- and high-redshift SN Ia surveys. We
combine the SDSS-II measurements with new distance estimates for published SN
data from the ESSENCE survey, the Supernova Legacy Survey, the Hubble Space
Telescope, and a compilation of nearby SN Ia measurements. Combining the SN
Hubble diagram with measurements of Baryon Acoustic Oscillations from the SDSS
Luminous Red Galaxy sample and with CMB temperature anisotropy measurements
from WMAP, we estimate the cosmological parameters w and Omega_M, assuming a
spatially flat cosmological model (FwCDM) with constant dark energy equation of
state parameter, w. For the FwCDM model and the combined sample of 288 SNe Ia,
we find w = -0.76 +- 0.07(stat) +- 0.11(syst), Omega_M = 0.306 +- 0.019(stat)
+- 0.023(syst) using MLCS2k2 and w = -0.96 +- 0.06(stat) +- 0.12(syst), Omega_M
= 0.265 +- 0.016(stat) +- 0.025(syst) using the SALT-II fitter. We trace the
discrepancy between these results to a difference in the rest-frame UV model
combined with a different luminosity correction from color variations; these
differences mostly affect the distance estimates for the SNLS and HST
supernovae. We present detailed discussions of systematic errors for both
light-curve methods and find that they both show data-model discrepancies in
rest-frame -band. For the SALT-II approach, we also see strong evidence for
redshift-dependence of the color-luminosity parameter (beta). Restricting the
analysis to the 136 SNe Ia in the Nearby+SDSS-II samples, we find much better
agreement between the two analysis methods but with larger uncertainties.Comment: Accepted for publication by ApJ
The Sloan Digital Sky Survey-II Supernova Survey: Search Algorithm and Follow-up Observations
The Sloan Digital Sky Survey-II Supernova Survey has identified a large
number of new transient sources in a 300 sq. deg. region along the celestial
equator during its first two seasons of a three-season campaign. Multi-band
(ugriz) light curves were measured for most of the sources, which include solar
system objects, Galactic variable stars, active galactic nuclei, supernovae
(SNe), and other astronomical transients. The imaging survey is augmented by an
extensive spectroscopic follow-up program to identify SNe, measure their
redshifts, and study the physical conditions of the explosions and their
environment through spectroscopic diagnostics. During the survey, light curves
are rapidly evaluated to provide an initial photometric type of the SNe, and a
selected sample of sources are targeted for spectroscopic observations. In the
first two seasons, 476 sources were selected for spectroscopic observations, of
which 403 were identified as SNe. For the Type Ia SNe, the main driver for the
Survey, our photometric typing and targeting efficiency is 90%. Only 6% of the
photometric SN Ia candidates were spectroscopically classified as non-SN Ia
instead, and the remaining 4% resulted in low signal-to-noise, unclassified
spectra. This paper describes the search algorithm and the software, and the
real-time processing of the SDSS imaging data. We also present the details of
the supernova candidate selection procedures and strategies for follow-up
spectroscopic and imaging observations of the discovered sources.Comment: Accepted for publication in The Astronomical Journal (66 pages, 13
figures); typos correcte
First-Year Spectroscopy for the SDSS-II Supernova Survey
This paper presents spectroscopy of supernovae discovered in the first season
of the Sloan Digital Sky Survey-II Supernova Survey. This program searches for
and measures multi-band light curves of supernovae in the redshift range z =
0.05 - 0.4, complementing existing surveys at lower and higher redshifts. Our
goal is to better characterize the supernova population, with a particular
focus on SNe Ia, improving their utility as cosmological distance indicators
and as probes of dark energy. Our supernova spectroscopy program features
rapid-response observations using telescopes of a range of apertures, and
provides confirmation of the supernova and host-galaxy types as well as precise
redshifts. We describe here the target identification and prioritization, data
reduction, redshift measurement, and classification of 129 SNe Ia, 16
spectroscopically probable SNe Ia, 7 SNe Ib/c, and 11 SNe II from the first
season. We also describe our efforts to measure and remove the substantial host
galaxy contamination existing in the majority of our SN spectra.Comment: Accepted for publication in The Astronomical Journal(47pages, 9
figures