The First VERA Astrometry Catalog collaboration, VERA; Hirota, Tomoya; Nagayama, Takumi ...
arXiv.org,
02/2020
Paper, Journal Article
Odprti dostop
We present the first astrometry catalog from the Japanese VLBI (very long baseline interferometer) project VERA (VLBI Exploration of Radio Astrometry). We have compiled all the astrometry results ...from VERA, providing accurate trigonometric annual parallax and proper motion measurements. In total, 99 maser sources are listed in the VERA catalog. Among them, 21 maser sources are newly reported while the rest of 78 sources are referred to previously published results or those in preparation for forthcoming papers. The accuracy in the VERA astrometry are revisited and compared with those from the other VLBI astrometry projects such as BeSSeL (The Bar and Spiral Structure Legacy) Survey and GOBELINS (the Gould's Belt Distances Survey) with the VLBA (Very Long Baseline Array). We have confirmed that most of the astrometry results are consistent with each other, and the largest error sources are due to source structure of the maser features and their rapid variation, along with the systematic calibration errors and different analysis methods. Combined with the BeSSeL results, we estimate the up-to-date fundamental Galactic parameter of \(R_{0}=7.92\pm0.16_{\rm{stat.}}\pm0.3_{\rm{sys.}}\)~kpc and \(\Omega_{\odot}=30.17\pm0.27_{\rm{stat.}}\pm0.3_{\rm{sys.}}\)~km~s\(^{-1}\)~kpc\(^{-1}\), where \(R_{0}\) and \(\Omega_{\odot}\) are the distance from the Sun to the Galactic center and the Sun's angular velocity of the Galactic circular rotation, respectively.
We present monitoring campaign observations at optical and near-infrared (NIR) wavelengths for a radio-loud active galactic nucleus (AGN) at z=0.840, SDSS~J110006.07+442144.3 (hereafter, J1100+4421), ...which was identified during a flare phase in late February, 2014. The campaigns consist of three intensive observing runs from the discovery to March, 2015, mostly within the scheme of the OISTER collaboration. Optical-NIR light curves and simultaneous spectral energy distributions (SEDs) are obtained. Our measurements show the strongest brightening in March, 2015. We found that the optical-NIR SEDs of J1100+4421 show an almost steady shape despite the large and rapid intranight variability. This constant SED shape is confirmed to extend to \(\sim5~\mu\)m in the observed frame using the archival WISE data. Given the lack of absorption lines and the steep power-law spectrum of \(\alpha_{\nu}\sim-1.4\), where \(f_{\nu}\propto\nu^{\alpha_{\nu}}\), synchrotron radiation by a relativistic jet with no or small contributions from the host galaxy and the accretion disk seems most plausible as an optical-NIR emission mechanism. The steep optical-NIR spectral shape and the large amplitude of variability are consistent with this object being a low \(\nu_{\rm{peak}}\) jet-dominated AGN. In addition, sub-arcsec resolution optical imaging data taken with Subaru Hyper Suprime-Cam does not show a clear extended component and the spatial scales are significantly smaller than the large extensions detected at radio wavelengths. The optical spectrum of a possible faint companion galaxy does not show any emission lines at the same redshift and hence a merging hypothesis for this AGN-related activity is not supported by our observations.
We present analyses to determine the fundamental parameters of the Galaxy based on VLBI astrometry of 52 Galactic maser sources obtained with VERA, VLBA and EVN. We model the Galaxy's structure with ...a set of parameters including the Galaxy center distance R_0, the angular rotation velocity at the LSR Omega_0, mean peculiar motion of the sources with respect to Galactic rotation (U_src, V_src, W_src), rotation-curve shape index, and the V component of the Solar peculiar motions V_sun. Based on a Markov chain Monte Carlo method, we find that the Galaxy center distance is constrained at a 5% level to be R_0 = 8.05 +/- 0.45 kpc, where the error bar includes both statistical and systematic errors. We also find that the two components of the source peculiar motion U_src and W_src are fairly small compared to the Galactic rotation velocity, being U_src = 1.0 +/- 1.5 km/s and W_src = -1.4 +/- 1.2 km/s. Also, the rotation curve shape is found to be basically flat between Galacto-centric radii of 4 and 13 kpc. On the other hand, we find a linear relation between V_src and V_sun as V_src = V_sun -19 (+/- 2) km/s, suggesting that the value of V_src is fully dependent on the adopted value of V_sun. Regarding the rotation speed in the vicinity of the Sun, we also find a strong correlation between Omega_0 and V_sun. We find that the angular velocity of the Sun, Omega_sun, which is defined as Omega_sun = Omega_0 + V_sun/R_0, can be well constrained with the best estimate of Omega_sun = 31.09 +/- 0.78 km/s/kpc. This corresponds to Theta_0 = 238 +/- 14 km/s if one adopts the above value of R_0 and recent determination of V_sun ~ 12 km/s.
Out of 23 cases of an anomalous arrangement of pancreatico-biliary duct encountered in our department and the affiliated institutions during the last 8 years, 2 cases (9%) were complicated with acute ...pancreatitis and 3 cases (13%) with chronic pancreatitis. In view of these findings, the relationship between anomalous arrangement of pancreatico-biliary duct and pancreatitis was clinically investigated from various aspects. The subjects included a total of 23 cases of the anomalous arrangement of pancreatico-biliary duct. They consisted of 3 male cases and 20 female cases. According to Kimura's criteria, the anastomotic pattern was classified as typeI (pancreatic duct anatomotic type) in 11 cases and as type II (bile duct anatomotic type) in 12 cases. All 5 cases with complication of pancreatitis had a congenital biliary dilatation. Two patients who had acute pancreatitis were girls of 5 years and 14 years of age, respectively, and both were diagnosed as having the type I anastomotic pattern. Chronic pancreatitis was seen in 3 patients consisting of a 46-year-old woman, a 49-year-old woman and a 50-year-old man, in all of whom the anastomotic pattern was classified as type II. In these patients, the chronic pancreatitis was considered X-ray-positive pancreatolithiasis, mass forming pancreatitis and alcoholic pancreatitis, respectively. The results in these 5 patients showed that a complication of acute pancreatitis was seen more frequently in younger patients and took a relatively mild course, while chronic pancreatitis is a more frequent complication in patients having the type II anastomotic pattern. These findings suggest the presence of causal relationship between the development of pancreatitis and an anomalous arrangement of pancreaticobiliary duct.
