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Otsuka, Masaaki,Hyung, Siek,Tajitsu, Akito IOP Publishing 2015 The Astrophysical journal Supplement series Vol.217 No.2
<P>We report on an investigation of the extremely metal-poor and C-rich planetary nebula (PN) K648 in M15 using the UV to far-infrared data obtained using Subaru, the Hubble Space Telescope, the Far Ultraviolet Spectroscopic Explorer, Spitzer, and Herschel. We determined the nebular abundances of 10 elements. The enhancement of F ([F/H] = +0.96) is comparable to that of the halo PN BoBn1. The central stellar abundances of seven elements are determined. The stellar C/O ratio is similar to the nebular C/O ratios from recombination lines and from collisionally excited lines (CELs) within error, and the stellar Ne/O ratio is also close to the nebular CEL Ne/O ratio. We found evidence of carbonaceous dust grains and molecules including Class B 6-9 and 11.3 mu m polycyclic aromatic hydrocarbons and the broad 11 mu m feature. The profiles of these bands are similar to those of the C-rich halo PNe H4-1 and BoBn1. Based on the theoretical model, we determined the physical conditions of the gas and dust and their masses, i.e., 0.048 and 4.95 X 10(-7) M-circle dot, respectively. The observed chemical abundances and gas mass are in good agreement with an asymptotic giant branch nucleosynthesis model prediction for stars with an initial 1.25 M-circle dot plus a 2.0 X 10(-3) M-circle dot partial mixing zone (PMZ) and stars with an initial mass of 1.5 M-circle dot without a PMZ. The core mass of the central star is approximately 0.61-0.63 M-circle dot. K648 is therefore likely to have evolved from a progenitor that experienced coalescence or tidal disruption during the early stages of evolution, and became a similar to 1.25-1.5 M-circle dot blue straggler.</P>
DUST AND CHEMICAL ABUNDANCES OF THE SAGITTARIUS DWARF GALAXY PLANETARY NEBULA Hen2-436
Otsuka, Masaaki,Meixner, Margaret,Riebel, David,Hyung, Siek,Tajitsu, Akito,Izumiura, Hideyuki IOP Publishing 2011 The Astrophysical journal Vol.729 No.1
<P>We have estimated elemental abundances of the planetary nebula (PN) Hen2-436 in the Sagittarius (Sgr) spheroidal dwarf galaxy using ESO/VLT FORS2, Magellan/MMIRS, and Spitzer/IRS spectra. We have detected candidates of fluorine [F II] lambda 4790, krypton [Kr III] lambda 6826, and phosphorus [P II] lambda 7875 lines and successfully estimated the abundances of these elements ([F/H] = +1.23, [Kr/H] = +0.26, [P/H] = +0.26) for the first time. These elements are known to be synthesized by the neutron capture process in the He-rich intershell during the thermally pulsing asymptotic giant branch (AGB) phase. We present a relation between C, F, P, and Kr abundances among PNe and C-rich stars. The detections of these elements in Hen2-436 support the idea that F, P, Kr together with C are synthesized in the same layer and brought to the surface by the third dredge-up. We have detected N II and O II optical recombination lines (ORLs) and derived the N2+ and O2+ abundances. The discrepancy between the abundance derived from the oxygen ORL and that derived from the collisionally excited line is > 1 dex. To investigate the status of the central star of the PN, nebula condition, and dust properties, we construct a theoretical spectral energy distribution (SED) model to match the observed SED with Cloudy. By comparing the derived luminosity and temperature of the central star with theoretical evolutionary tracks, we conclude that the initial mass of the progenitor is likely to be similar to 1.5-2.0M(circle dot) and the age is similar to 3000 yr after the AGB phase. The observed elemental abundances of Hen2-436 can be explained by a theoretical nucleosynthesis model with a star of initial mass 2.25 M-circle dot, Z = 0.008, and LMC compositions. We have estimated the dust mass to be 2.9x10(-4) M-circle dot (amorphous carbon only) or 4.0x10(-4) M-circle dot (amorphous carbon and polycyclic aromatic hydrocarbon). Based on the assumption that most of the observed dust is formed during the last two thermal pulses and the dust-to-gas mass ratio is 5.58 x 10(-3), the dust mass-loss rate and the total mass-loss rate are < 3.1x10(-8) M-circle dot yr(-1) and < 5.5x10(-6) M-circle dot yr(-1), respectively. Our estimated dust mass-loss rate is comparable to a Sgr dwarf galaxy AGB star with similar metallicity and luminosity.</P>
Hiroki Monjo,Yoshihiro Fukumoto,Tsuyoshi Asai,Kensuke Ohshima,Hirotsugu Tajitsu,Shota Koyama 대한신경과학회 2022 Journal of Clinical Neurology Vol.18 No.3
Background and Purpose The objective of this study was to identify 2-year longitudinal changes in the muscle thickness (MT) and echo intensity (EI) of the abdominal, thigh, and lower limb muscles in chronic stroke survivors. Methods This study included 15 chronic stroke survivors aged 74.1±9.9 years. The MT, EI, and subcutaneous fat thickness values of the following muscles on the paretic and nonparetic sides were assessed on transverse ultrasound images: rectus abdominis, external oblique, internal oblique, transversus abdominis, rectus femoris (RF), vastus intermedius, vastus lateralis (VL), vastus medialis, tibialis anterior, gastrocnemius, and soleus. The ultrasound measurements were performed both at baseline and 2 years later. Results After 2 years, the VL on the paretic side showed a significant decrease in MT (p= 0.031) and increase in EI (p=0.002), whereas the RF on the nonparetic side showed a significant decrease in EI (p=0.046). Correlation coefficient analyses showed that changes in MT (r= 0.668, p=0.012) and EI (r=0.597, p=0.018) of the VL on the paretic side were significantly associated with a change in the body mass index. Conclusions The findings of this longitudinal study suggest that the VL on the paretic side is subject to deteriorations in muscle quantity and quality, and conversely that the RF on the nonparetic side shows an improvement in muscle quality after 2 years in chronic stroke survivors.