Publications of the Astronomical Society of Japan最新文献

{"title":"Solar horizontal flow evaluation using neural network and numerical simulations with snapshot data","authors":"Hiroyuki Masaki, Hideyuki Hotta, Yukio Katsukawa, Ryohtaroh T Ishikawa","doi":"10.1093/pasj/psad063","DOIUrl":"https://doi.org/10.1093/pasj/psad063","url":null,"abstract":"Abstract We suggest a method that evaluates the horizontal velocity in the solar photosphere with easily observable values using a combination of neural network and radiative magnetohydrodynamics simulations. All three-component velocities of thermal convection on the solar surface have important roles in generating waves in the upper atmosphere. However, the velocity perpendicular to the line of sight (LoS) is difficult to observe. To deal with this problem, the local correlation tracking (LCT) method, which employs the difference between two images, has been widely used, but this method has several disadvantages. We develop a method that evaluates the horizontal velocity from a snapshot of the intensity and the LoS velocity with a neural network. We use data from numerical simulations for training the neural network. While two consecutive intensity images are required for LCT, our network needs just one intensity image at only a specific moment for input. From these input arrays, our network outputs a same-size array of a two-component velocity field. With only the intensity data, the network achieves a high correlation coefficient between the simulated and evaluated velocities of 0.83. In addition, the network performance can be improved when we add LoS velocity for input, enabling us to achieve a correlation coefficient of 0.90. Our method is also applied to observed data.","PeriodicalId":20733,"journal":{"name":"Publications of the Astronomical Society of Japan","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135957973","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Water maser distributions and their internal motions in the Sagittarius B2 complex","authors":"Daisuke Sakai, Tomoaki Oyama, Takumi Nagayama, Mareki Honma, Hideyuki Kobayashi","doi":"10.1093/pasj/psad052","DOIUrl":"https://doi.org/10.1093/pasj/psad052","url":null,"abstract":"Abstract We conducted a multi-epoch very long baseline interferometry (VLBI) observation of 22 GHz H2O maser sources, which are associated with the Sagittarius B2 (Sgr B2) complex, one of the most active star-forming regions in the Galactic center. Using the VLBI exploration of radio astrometry (VERA) array, we detected 29, 90, and seven maser features in Sgr B2(North), (Main), and (South), respectively. We also discovered two H2O maser features in Sgr B2 (Mid-North). Moreover, we successfully measured spatial distributions and internal motions of the H2O maser sources in Sgr B2(M). We then discovered that the H2O maser features in Sgr B2(M) are located at the outer edge of H ii regions detected by using the centimeter radio continuum emission, and observationally demonstrated that they have outward motions from the two H ii regions separated by 1′. We obtained an absolute proper motion of (μαcos δ, μδ) = (−2.17 ± 0.03, −2.63 ± 0.06) mas yr−1 and marginally detected a parallax of Sgr B2, which is consistent with other measurements. The absolute proper motion corrected by the internal motions of the H2O maser features implies that the Sgr B2 complex is located at the near side of the Galactic center and is moving toward the positive galactic longitude. We estimate that Sgr B2 is at 160 ± 10 pc in front of Sgr A* by assuming a simple circular orbit of the central molecular zone (CMZ).","PeriodicalId":20733,"journal":{"name":"Publications of the Astronomical Society of Japan","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136314002","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Photometric and spectroscopic properties of the eclipsing system V864 Monocerotis","authors":"Jang-Ho Park, Jae Woo Lee, Kyeongsoo Hong","doi":"10.1093/pasj/psad061","DOIUrl":"https://doi.org/10.1093/pasj/psad061","url":null,"abstract":"Abstract We present the orbital period variability and evolutionary status of the W UMa-type binary system V864 Mon from accurately measured fundamental parameters. New BV photometric observations of this system were performed in 2019 January and 2022 January, and the first high-resolution spectroscopic observations were carried out on three nights between 2019 January and March. A total of 29 times of minimum light were collected to examine the behavior of the orbital period. Our analysis of these timings indicates a continuous period increase at a rate of +2.62 × 10−7 d yr−1 over the past 20 years, which can be interpreted as a mass transfer from the less massive primary to the secondary component with a rate of 1.22 × 10−7 M⊙ yr−1. We measured the radial velocities (RVs) for both components, and determined the effective temperature and projected rotational velocity of the more massive secondary star to be Teff,2 = 5450 ± 94 K and v2sin i = 192 ± 40 km s−1, respectively, from the comparison of the observed spectrum at the primary minimum and the theoretical models. The individual masses and radii of both components were determined from a simultaneous analysis of the light and RV curves, which are M1 = 0.34 ± 0.02 M⊙, R1 = 0.69 ± 0.01 R⊙, and M2 = 1.06 ± 0.04 M⊙, R2 = 1.16 ± 0.02 R⊙, respectively. Our results indicate that V864 Mon is a W-subtype of W UMa stars with time-varying spot activity. The positions in the mass-luminosity and mass-radius diagrams indicate that the secondary star belongs to the main-sequence region, while the hotter primary is located beyond the terminal-age main sequence.","PeriodicalId":20733,"journal":{"name":"Publications of the Astronomical Society of Japan","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135394468","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Statistical X-ray analysis of gamma-ray-emitting radio galaxies","authors":"Hiroto Matake, Yasushi Fukazawa","doi":"10.1093/pasj/psad060","DOIUrl":"https://doi.org/10.1093/pasj/psad060","url":null,"abstract":"Abstract We systematically analyzed Swift/XRT X-ray data of gamma-ray-emitting radio galaxies (RGs) to study the origin of X-ray radiation. We studied the short-duration variability of spectra by using Swift/XRT data for 20 RGs. We found that gamma-ray-emitting RGs with a higher gamma-ray-to-X-ray flux ratio show a strong harder-when-brighter behavior. In addition, gamma-ray-emitting RGs with soft gamma-ray spectral index tend to have a hard X-ray spectral index and vice versa. Based on these properties, we imply a trend that gamma-ray-emitting RGs could be roughly classified into three types of X-ray emission: jet-dominated type, disk/corona-dominated type, and intermediate type. This classification is quite consistent with the optical and radio classification of RGs. In addition, we also discuss this result in terms of the Eddington luminosity ratio. These interpretations should be confirmed using larger samples of RGs in the future.","PeriodicalId":20733,"journal":{"name":"Publications of the Astronomical Society of Japan","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135394459","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Kinematic signatures of a low-mass planet with a moderately inclined orbit in a protoplanetary disk","authors":"Kazuhiro D Kanagawa, Tomohiro Ono, Munetake Momose","doi":"10.1093/pasj/psad059","DOIUrl":"https://doi.org/10.1093/pasj/psad059","url":null,"abstract":"Abstract A planet embedded in a protoplanetary disk produces a gap by disk–planet interaction. It also generates velocity perturbation of gas, which can also be observed as deviations from the Keplerian rotation in the channel map of molecular line emission, called kinematic planetary features. These observed signatures provide clues to determine the mass of the planet. We investigated the features induced by a planet with an inclined orbit through three-dimensional hydrodynamic simulations. We found that a smaller planet, with an inclination of ∼10○–20○, can produce kinematic features as prominent as those induced by a massive coplanar planet. Despite the kinematic features being similar, the gap is shallower and narrower compared with the case in which the kinematic features are formed by a coplanar planet. We also found that the kinematic features induced by an inclined planet were fainter for rarer CO isotopologues because the velocity perturbation is weaker at the position closer to the midplane, which was different in the case with a coplanar massive planet. This dependence on the isotopologues is distinguished if the planet has an inclined orbit. We discussed two observed kinematic features in the disk of HD 163296. We concluded that the kink observed at 220 au can be induced by an inclined planet, while the kink at 67 au is consistent to that induced by a coplanar planet.","PeriodicalId":20733,"journal":{"name":"Publications of the Astronomical Society of Japan","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135552843","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Revisiting planetary systems in the Okayama Planet Search Program: A new long-period planet, RV astrometry joint analysis, and a multiplicity-metallicity trend around evolved stars","authors":"Huan-Yu Teng, Bun’ei Sato, Masayuki Kuzuhara, Takuya Takarada, Masashi Omiya, Hiroki Harakawa, Hideyuki Izumiura, Eiji Kambe, Mesut Yilmaz, Ilfan Bikmaev, Selim O Selam, Timothy D Brandt, Guang-Yao Xiao, Michitoshi Yoshida, Yoichi Itoh, Hiroyasu Ando, Eiichiro Kokubo, Shigeru Ida","doi":"10.1093/pasj/psad056","DOIUrl":"https://doi.org/10.1093/pasj/psad056","url":null,"abstract":"Abstract In this study, we revisit 32 planetary systems around evolved stars observed within the framework of the Okayama Planet Search Program (OPSP) and its collaborative framework of the East Asian Planet Search Network to search for additional companions and investigate the properties of stars and giant planets in multiple-planet systems. With our latest radial velocities obtained from Okayama Astrophysical Observatory, we confirm an additional giant planet in the wide orbit of the 75 Cet system ($P_{rm {c}} = 2051.62_{-40.47}^{+45.98} rm {d}$, $M_{rm {c}}sin i=0.912_{-0.090}^{+0.088},,M_{rm {J}}$, and $a_{rm {c}}=3.929_{-0.058}^{+0.052} rm {au}$), along with five stars exhibiting long-term radial velocity accelerations, which indicates massive companions in the wide orbits. We also find that the radial velocity variations of several planet-harboring stars may indicate additional planet candidates, stellar activities, or other understudied sources. These stars include ϵ Tau, 11 Com, 24 Boo, 41 Lyn, 14 And, HD 32518, and ω Ser. We further constrain the orbital configuration of the HD 5608, HD 14067, HD 120084, and HD 175679 systems by combining radial velocities with astrometry, as their host central stars exhibit significant astrometric accelerations. For other systems, we simply refine their orbital parameters. Moreover, our study indicates that the OPSP planet-harboring stars are more metal poor compared to the currently known planet-harboring stars, and this is likely due to the B − V color upper limit at 1.0 for star selection in the beginning of the survey. Finally, by investigating the less massive giant planets (<5 MJ) around currently known planet-harboring evolved stars, we find that metallicity positively correlates with the multiplicity and total planet mass of the system, which can be evidence for the core-accretion planet formation model.","PeriodicalId":20733,"journal":{"name":"Publications of the Astronomical Society of Japan","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135690047","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Transition luminosities of Galactic black hole transients with Swift/XRT and NICER/XTI observations","authors":"Sili Wang, Nobuyuki Kawai, Megumi Shidatsu, Yoshiki Matsuoka","doi":"10.1093/pasj/psad057","DOIUrl":"https://doi.org/10.1093/pasj/psad057","url":null,"abstract":"Abstract The X-ray spectral state transitions of Galactic black hole transients (GBHTs) are often linked to the changes in the mass accretion rate. A narrow distribution of transition luminosity in terms of the Eddington ratio has been found in previous studies of GBHTs based on RXTE data (Maccarone, 2003, A&A, 409, 697; Vahdat Motlagh et al., 2019, MNRAS, 485, 2744) and this Eddington ratio at the transition is often used in recent studies with instruments such as Swift/XRT and NICER/XTI, covering soft energies below 1 to 10 keV. However, the X-ray states characterized by spectral parameters may have different definitions depending on the energy ranges adopted in the spectral analysis, leaving the question of whether the distribution of transition luminosity obtained with RXTE remains the same when we use the instruments covering softer energy bands. In this work, we investigated the X-ray state evolutions and the variations of luminosities of eight outbursts of seven GBHTs. We found that the bolometric luminosity of the power-law component was tightly constrained to $sim! 1.3%$ Eddington luminosity at index transition when the photon index starts to decrease towards the hard state, which is consistent with the previous RXTE results (Vahdat Motlagh et al. 2019, MNRAS, 485, 2744; Kalemci et al. 2013, ApJ, 779, 95). Moreover, the tightest clustering was found to be the power-law luminosity right after the start of disk recession, with a mean logarithmic Eddington ratio of −1.84 ± 0.28. In addition, our results suggest that the disk recession starts after the bolometric disk luminosity drops below 1% Eddington luminosity.","PeriodicalId":20733,"journal":{"name":"Publications of the Astronomical Society of Japan","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135982378","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"<i>N</i>-body simulation of planetary formation through pebble accretion in a radially structured protoplanetary disk","authors":"Tenri Jinno, Takayuki R Saitoh, Yota Ishigaki, Junichiro Makino","doi":"10.1093/pasj/psad053","DOIUrl":"https://doi.org/10.1093/pasj/psad053","url":null,"abstract":"Abstract In the conventional theory of planet formation, it is assumed that protoplanetary disks are axisymmetric and have a smooth radial profile. However, recent radio observations of protoplanetary disks have revealed that many of them have complex radial structures. In this study, we perform a series of N-body simulations to investigate how planets are formed in protoplanetary disks with radial structures. For this purpose, we consider the effect of continuous pebble accretion onto the discontinuity boundary within the terrestrial planet-forming region (∼0.6 au). We find that protoplanets grow efficiently at the discontinuity boundary, reaching the Earth mass within ∼104 yr. We confirm that giant collisions of protoplanets occur universally in our model. Moreover, we find that multiple planet-sized bodies form at regular intervals in the vicinity of the discontinuity boundary. These results indicate the possibility of the formation of solar system-like planetary systems in radially structured protoplanetary disks.","PeriodicalId":20733,"journal":{"name":"Publications of the Astronomical Society of Japan","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135048159","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Discovery of a molecular cloud possibly associated with the youngest Galactic SNR G1.9+0.3","authors":"Rei Enokiya, Hidetoshi Sano, Miroslav D Filipović, Rami Z E Alsaberi, Tsuyoshi Inoue, Tomoharu Oka","doi":"10.1093/pasj/psad054","DOIUrl":"https://doi.org/10.1093/pasj/psad054","url":null,"abstract":"Abstract The youngest known Galactic supernova remnant (SNR) G1.9+0.3 has high-velocity supernova shock beyond 10000 km s−1, and it is considered to be one of the major candidates of a PeVatron. Despite these outstanding properties, the surrounding interstellar matter of this object is poorly understood. We investigated the interstellar gas toward G1.9+0.3 using the 12CO(J = 3−2) data with the angular resolution of 15″ obtained by the CHIMPS2 survey by the James Clerk Maxwell Telescope, and discovered three individual clouds at −1, 7, and 45 km s−1. From its morphological and velocity structures, the −1 km s−1 cloud, having the largest velocity width &amp;gt;20 km s−1 and located at the distance of the Galactic Center, is possibly associated with the SNR. The associated cloud shows a cavity structure both in space and velocity and coincides well with the SNR. We found that the associated cloud has higher column densities toward three bright, radio synchrotron-emitted rims where the radial expansion velocity of the supernova shock is decelerated, and the cloud is faint in the other parts of the SNR. This is the first direct evidence indicating that the highly anisotropic expansion of G1.9+0.3 observed by previous studies results from the deceleration by the interaction between the supernova shock and surrounding dense interstellar medium.","PeriodicalId":20733,"journal":{"name":"Publications of the Astronomical Society of Japan","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135369645","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bright Type II supernova 2023ixf in M 101: A quick analysis of the early-stage spectra and near-infrared light curves","authors":"M. Yamanaka, M. Fujii, T. Nagayama","doi":"10.1093/pasj/psad051","DOIUrl":"https://doi.org/10.1093/pasj/psad051","url":null,"abstract":"\u0000 We present early-stage analyses of low-resolution (R = 1000) optical spectra and near-infrared light curves of the bright Type II supernova (SN II) 2023ixf in the notable nearby face-on spiral galaxy M 101, which were obtained from t = 1.7 to 8.0 d. Our first spectrum showed remarkable emission features of the Balmer series, He ii, N iii, C iv, and N iv with a strong blue continuum. Compared with the SNe II which show flash-ionized features, we suggest that this SN could be categorized as a high-luminosity SN II with a nitrogen/helium-rich circumstellar material (CSM), e.g., SNe 2014G, 2017ahn, and 2020pni. The Hα emission line can be tentatively explained by a narrower component with a velocity of <300 km s−1 and a broader one with ∼2200 km s−1. The near-infrared light curves were well consistent with those of the another luminous SN 2017ahn, and its absolute magnitudes are located at the bright end of the luminosity distribution of SNe II. These observational facts support that SN 2023ixf is well consistent with high-luminosity SNe II showing evidence of a dense nitrogen/helium-rich CSM.","PeriodicalId":20733,"journal":{"name":"Publications of the Astronomical Society of Japan","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2023-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84105880","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}