ABSTRACT We present a detailed investigation of the Large Magellanic Cloud (LMC) disk using classical Cepheids. Our analysis is based on optical (I, V; OGLE-IV), near-infrared (NIR: J, H, ) and ...mid-infrared (MIR: w1; WISE) mean magnitudes. By adopting new templates to estimate the NIR mean magnitudes from single-epoch measurements, we build the currently most accurate, largest, and homogeneous multi-band data set of LMC Cepheids. We determine Cepheid individual distances using optical and NIR Period-Wesenheit relations (PWRs), to measure the geometry of the LMC disk and its viewing angles. Cepheid distances based on optical PWRs are precise at 3%, but accurate to 7%, while the ones based on NIR PWRs are more accurate (to 3%), but less precise (2%-15%), given the higher photometric error on the observed magnitudes. We found an inclination of i = 25.05 0.02 (stat.) 0.55 (syst.) deg, and a position angle of the lines of nodes P.A. = 150.76 0.02 (stat.) 0.07 (syst.) deg. These values agree well with estimates based either on young (Red Supergiants) or on intermediate-age (Asymptotic Giant Branch, Red Clump) stellar tracers, but they significantly differ from evaluations based on old (RR Lyrae) stellar tracers. This indicates that young/intermediate and old stellar populations have different spatial distributions. Finally, by using the reddening-law fitting approach, we provide a reddening map of the LMC disk, which is 10 times more accurate and 2 times larger than similar maps in the literature. We also found an LMC true distance modulus of (stat. and syst.) mag, in excellent agreement with the currently most accurate measurement.
ABSTRACT
This paper is a revised abundance analysis of four yellow supergiant stars Cepheids which are located in the Galactic nucleus. The results are based on the spectra secured with the help of ...Subaru telescope, which are of the better quality comparing to previously analysed spectra taken with the Infrared Telescope Facility. A significantly improved method of the effective temperature determination of program stars, which is based on the calibrating relations between the temperature and line depth ratios, was applied. The present results confirmed our previous finding about the solar metallicity level at the Galaxy centre. It is very likely that the four stars of our program were born from an interstellar medium having homogeneous chemical properties, since all the stars are located close to each other, have close pulsation periods, and hence the age. However, one of the stars has a somewhat increased abundance of all studied elements compared to the abundance in the other three stars. A possible reason of this fact is discussed.
Abstract
Terzan 5 is a complex stellar system in the Galactic bulge, harboring stellar populations (SPs) with very different iron content (ΔFe/H ∼ 1 dex) and with ages differing by several gigayears. ...Here we present an investigation of its variable stars. We report on the discovery and characterization of three RR Lyrae stars. For these newly discovered RR Lyrae and for six Miras of known periods we provide radial velocity (RV) and chemical abundances from spectra acquired with X-SHOOTER at the Very Large Telescope. We find that the three RR Lyrae and the three short-period Miras (
P
< 300 days) have RV consistent with being Terzan 5 members. They have subsolar iron abundances and enhanced
α
/Fe, well matching the age and abundance patterns of the 12 Gyr metal-poor SPs of Terzan 5. Only one, out of the three long-period (
P
> 300 days) Miras analyzed in this study, has an RV consistent with being a Terzan 5 member. Its super-solar iron abundance and solar-scaled
α
/Fe nicely match the chemical properties of the metal-rich SP of Terzan 5 and its derived mass nicely agrees with being several gigayears younger than the short-period Miras. This young variable is an additional proof of the surprisingly young subpopulation discovered in Terzan 5.
SnO2 nanotubular materials were prepared by using a natural cellulosic substance (filter paper) as template, and their morphologies were determined by scanning electron microscopy (SEM) and ...transmission electron microscopy (TEM). Cellulose fibers were first coated with SnO2 gel layers by the surface sol−gel process using Sn(O i Pr)4 as precursor, followed by calcination in air to give SnO2 nanotubular materials as hollow replicas of natural cellulose fibers. The nanotubes obtained by calcination at 450 °C were amorphous-like and composed of fine particles with sizes smaller than ca. 5 nm. The outer diameters are tens to two hundred nanometers, and wall thicknesses are 10−15 nm. Calcination at 1100 °C yielded tubelike polycrystalline SnO2 nanocages (outer diameter 100−200 nm), which were composed of rutile-phase SnO2 nanocrystallites with sizes of 10−20 nm. The thermal behavior and the crystalline property of the powder obtained from calcination of the as-prepared SnO2 sheet were examined in the temperature range of 300−900 °C. The sizes of the nanoparticle obtained by calcination at 300 and 900 °C were 2.0 and 9.2 nm, respectively, in fair agreement with TEM observation. Calcination temperatures above 500 °C are needed to obtain pure SnO2. A sensor setup was fabricated from the SnO2 nanotube sheet, and the sensor performance was measured for H2, CO, and ethylene oxide. The sensor signal, S, was 16.5 at 450 °C to 100 ppm H2, and was comparable to that of the conventional SnO2 sensor. Finally, the sensor characteristics were discussed in relation to the morphology of the nanotube sheet.
We present homogeneous and accurate iron abundances for 42 Galactic Cepheids based on high resolution (R ~ 38 000) high signal-to-noise ratio (S/N ≥ 100) optical spectra collected with UVES at VLT ...(128 spectra). The above abundances were complemented with high-quality iron abundances provided either by our group (86) or available in the literature. We were careful to derive a common metallicity scale and ended up with a sample of 450 Cepheids. We also estimated accurate individual distances for the entire sample by using homogeneous near-infrared photometry and the reddening free period-Wesenheit relations. The new metallicity gradient is linear over a broad range of Galactocentric distances (RG ~ 5–19 kpc) and agrees quite well with similar estimates available in the literature (–0.060 ± 0.002 dex/kpc). We also uncover evidence that suggests that the residuals of the metallicity gradient are tightly correlated with candidate Cepheid groups (CGs). The candidate CGs have been identified as spatial overdensities of Cepheids located across the thin disk. They account for a significant fraction of the residual fluctuations, and also for the large intrinsic dispersion of the metallicity gradient. We performed a detailed comparison with metallicity gradients based on different tracers: OB stars and open clusters. We found very similar metallicity gradients for ages younger than 3 Gyr, while for older ages we found a shallower slope and an increase in the intrinsic spread. The above findings rely on homogeneous age, metallicity, and distance scales. Finally, by using a large sample of Galactic and Magellanic Cepheids for which accurate iron abundances are available, we found that the dependence of the luminosity amplitude on metallicity is vanishing.
To examine the length of stay, hospitalisation costs and case fatality of methicillin-susceptible and -resistant Staphylococcus aureus (MSSA and MRSA) bacteremia in Japan.
Retrospective cohort study. ...Patients with a diagnosis of S. aureus bacteremia who were admitted to a tertiary care hospital (the National Centre for Global Health and Medicine NCGM) in Tokyo, Japan, between 1st January 2016 and 31st December 2020 were included in the study.
We combined Japan Nosocomial Infections Surveillance data and Diagnosis Procedure Combination data at NCGM from 2016 to 2020. The data were stratified into MSSA and MRSA groups. Length of stay (LoS), LoS after submission of a blood culture specimen (LoS-after), hospitalisation cost, hospitalisation costs per day and clinical outcome were compared after propensity score matching.
Median LoS was 46 (interquartile range IQR 28.5–64.5) days in the MSSA group and 66 (IQR 40–91) days in the MRSA group (P = 0.020). Median LoS-after was 38 (IQR 25–62.5) days and 45 (IQR 24–63) days (P = 0.691) in the MSSA and MRSA groups, respectively. Median hospitalisation cost was significantly higher in the MRSA group (26,035 IQR 18,154–47,362 USD) than in the MSSA group (19,823 IQR 13,764–32,042 USD) (P = 0.036), but cost per day was not (MRSA: 528.9 IQR 374.9–647.4 USD; MSSA: 455.6 IQR 359.2–701.7 USD; P = 0.990). Case fatality rate was higher in the MRSA group than in the MSSA group (22/60 vs 9/60, P = 0.012).
Patients with MRSA bacteremia had longer LoS and higher costs than those with MSSA bacteremia. However, LoS-after and hospitalisation costs per day were not different. The longer LoS of patients in Japan compared with other countries might contribute to the higher disease burden of S. aureus bacteremia in Japan.
Context. Cepheids are excellent tracers of young stellar populations. They play a crucial role in astrophysics as standard candles. The chemistry of classical Cepheids in the Milky Way is now quite ...well-known, however despite a much larger sample, the chemical composition of Magellanic Cepheids has been only scarcely investigated. Aims. For the first time, we study the chemical composition of several Cepheids located in the same populous cluster: NGC 1866, in the Large Magellanic Cloud (LMC). To also investigate the chemical composition of Cepheids at lower metallicity, we look at four targets located in the Small Magellanic Cloud (SMC). Our sample allows us to increase the number of Cepheids with known metallicities in the LMC/SMC by 20%/25% and the number of Cepheids with detailed chemical composition in the LMC/SMC by 46%/50%. Methods. We use canonical spectroscopic analysis to determine the chemical composition of Cepheids and provide abundances for a good number of α, iron-peak, and neutron-capture elements. Results. We find that six Cepheids in the LMC cluster NGC 1866 have a very homogeneous chemical composition, also consistent with red giant branch (RGB) stars in the cluster. Period–age relations that include no or average rotation indicate that all the Cepheids in NGC 1866 have a similar age and therefore belong to the same stellar population. Our results are in good agreement with theoretical models accounting for luminosity and radial velocity variations. Using distances based on period-luminosity relations in the near- or mid-infrared, we investigate for the first time the metallicity distribution of the young population in the SMC in the depth direction. Preliminary results show no metallicity gradient along the SMC main body, but our sample is small and does not contain Cepheids in the inner few degrees of the SMC.
Abstract
We collected the largest spectroscopic catalog of RR Lyrae (RRLs) including ≈20,000 high-, medium-, and low-resolution spectra for ≈10,000 RRLs. We provide the analytical forms of radial ...velocity curve (RVC) templates. These were built using 36 RRLs (31 fundamental—split into three period bins—and five first-overtone pulsators) with well-sampled RVCs based on three groups of metallic lines (Fe, Mg, Na) and four Balmer lines (H
α
, H
β
, H
γ
, H
δ
). We tackled the long-standing problem of the reference epoch to anchor light-curve and RVC templates. For the
V
-band, we found that the residuals of the templates anchored to the phase of the mean magnitude along the rising branch are ∼35% to ∼45% smaller than those anchored to the phase of maximum light. For the RVC, we used two independent reference epochs for metallic and Balmer lines and we verified that the residuals of the RVC templates anchored to the phase of mean RV are from 30% (metallic lines) up to 45% (Balmer lines) smaller than those anchored to the phase of minimum RV. We validated our RVC templates by using both the single-point and the three phase point approaches. We found that barycentric velocities based on our RVC templates are two to three times more accurate than those available in the literature. We applied the current RVC templates to Balmer lines RVs of RRLs in the globular NGC 3201 collected with MUSE at VLT. We found the cluster barycentric RV of
V
γ
= 496.89 ± 8.37(error) ± 3.43 (standard deviation) km s
−1
, which agrees well with literature estimates.
The present study was conducted to prepare precursors by rapid hydrolysis method for realizing lower temperature formation of NiFe
2
O
4
under hydrothermal conditions. The precursor, obtained from a ...lower concentration of NiCl
2
–FeCl
2
mixed solution, was almost amorphous and could be easily converted to NiFe
2
O
4
crystal phase at around 130°C by hydrothermal treatment. On the other hand, when a higher concentration of NiCl
2
–FeCl
2
solution or trivalent iron salt (FeCl
3
) was used as starting reagents, individual crystal phases such as α-Ni(OH)
2
, γ-Fe
2
O
3
and α-FeOOH were recognized in precursors owing to the difference in hydrolysis rates between Ni
2+
and Fe
2+
(or Fe
3+
). These individual crystal phases involved precursors that could not be converted easily to NiFe
2
O
4
crystal phase, but needed to treat at higher temperatures for forming NiFe
2
O
4
at least 200°C. Thus, the co-existence of individual crystal phases in precursors might prevent the amorphous precursor from forming NiFe
2
O
4
crystal phase. The formation of NiFe
2
O
4
at lower temperatures is considered to be taken place preferentially from amorphous precursors than individual certain crystal phases.
We determine the metallicity and detailed chemical abundances (α, iron-peak and neutron-capture elements) for the almost complete (18/24) sample of Galactic double mode Cepheids (also called beat ...Cepheids). Double mode Cepheids are Cepheids that pulsate in two modes simultaneously. We calibrate a new relation between their metallicity and their period ratio P
1/P
0. This linear relation allows to determine the metallicity of bimodal Cepheids with an accuracy of 0.03 dex in the range of Fe/H from +0.2 to −0.5 dex. By extrapolating the relation to Magellanic Clouds beat Cepheids, we provide their metallicity distribution function. Moreover, by using this relation, we also provide the first metallicity estimate for two double-mode F/1O Cepheids located in and beyond the Galactic bulge. Finally, we report the discovery of a super-Lithium rich double mode Cepheid V371 Per which has a Lithium abundance of logA(Li) = 3.54 ± 0.09 dex. Along with V1033 Cyg (which is an ordinary classical Cepheid), it is the second known Cepheid of such type in the Galaxy.
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