The Caltech Submillimeter Observatory telescope was completely disassembled in 2023 October and will be shipped from Hawaii, USA to the new site at Chajnantor Plateau, Chile in 2024, where it is expected to be refurbished and renamed the Leighton Chajnantor Telescope (LCT). Since the much stronger wind load at the new site will provide a great challenge for LCT’s realization of a higher pointing and tracking accuracy, an active disturbance rejection controller (ADRC) is designed for LCT’s pointing control system. Due to the unavailability of LCT during its relocation process, it is necessary to develop a testbed to verify the performance of ADRC by constructing a synthesized simulation model of LCT’s pointing control system, including a mechanical dynamics model of the antenna, an analog circuit model of the motor drive system, a mathematical model of the direct current motors and the reducers, and a wind disturbance model. On the testbed, ADRC undergoes simulations to verify its capability to eliminate the negative impact of strong wind disturbance on LCT’s pointing control performance. The simulation results show that ADRC can bring benefits in improving LCT’s pointing and tracking accuracy when facing strong wind disturbance.
{"title":"Synthesized modeling and active disturbance rejection control for the Leighton Chajnantor Telescope","authors":"Weirui Chen, Yiwei Yao, Zheng Wang","doi":"10.1093/pasj/psad087","DOIUrl":"https://doi.org/10.1093/pasj/psad087","url":null,"abstract":"The Caltech Submillimeter Observatory telescope was completely disassembled in 2023 October and will be shipped from Hawaii, USA to the new site at Chajnantor Plateau, Chile in 2024, where it is expected to be refurbished and renamed the Leighton Chajnantor Telescope (LCT). Since the much stronger wind load at the new site will provide a great challenge for LCT’s realization of a higher pointing and tracking accuracy, an active disturbance rejection controller (ADRC) is designed for LCT’s pointing control system. Due to the unavailability of LCT during its relocation process, it is necessary to develop a testbed to verify the performance of ADRC by constructing a synthesized simulation model of LCT’s pointing control system, including a mechanical dynamics model of the antenna, an analog circuit model of the motor drive system, a mathematical model of the direct current motors and the reducers, and a wind disturbance model. On the testbed, ADRC undergoes simulations to verify its capability to eliminate the negative impact of strong wind disturbance on LCT’s pointing control performance. The simulation results show that ADRC can bring benefits in improving LCT’s pointing and tracking accuracy when facing strong wind disturbance.","PeriodicalId":20733,"journal":{"name":"Publications of the Astronomical Society of Japan","volume":"1 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139754303","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}
Mikio Morii, Yoshitomo Maeda, Hisamitsu Awaki, Kouichi Hagino, Manabu Ishida, Koji Mori
We develop a new deconvolution method to recover the precise Crab Nebula image taken by the Hitomi HXT, suppressing the artifact due to the bright Crab pulsar. We extend the Richardson–Lucy method, introducing two components corresponding to the nebula and pulsar with regularization for smoothness and flux, respectively, and performing simultaneous deconvolution of multi-pulse-phase images. The structures, including the torus and jets, seen in the deconvolved nebula image at the lowest energy band of 3.6–15 keV appear consistent with those identified in the high-resolution Chandra X-ray image. Above 15 keV, we confirm NuSTAR’s findings that the nebula size decreases in higher energy bands. We find that the north-east side of the nebula is fainter in higher energy bands. Our deconvolution method is applicable for any telescope images of faint diffuse objects containing a bright point source.
{"title":"Hitomi HXT deconvolution imaging of the Crab Nebula dazzled by the Crab pulsar","authors":"Mikio Morii, Yoshitomo Maeda, Hisamitsu Awaki, Kouichi Hagino, Manabu Ishida, Koji Mori","doi":"10.1093/pasj/psae008","DOIUrl":"https://doi.org/10.1093/pasj/psae008","url":null,"abstract":"We develop a new deconvolution method to recover the precise Crab Nebula image taken by the Hitomi HXT, suppressing the artifact due to the bright Crab pulsar. We extend the Richardson–Lucy method, introducing two components corresponding to the nebula and pulsar with regularization for smoothness and flux, respectively, and performing simultaneous deconvolution of multi-pulse-phase images. The structures, including the torus and jets, seen in the deconvolved nebula image at the lowest energy band of 3.6–15 keV appear consistent with those identified in the high-resolution Chandra X-ray image. Above 15 keV, we confirm NuSTAR’s findings that the nebula size decreases in higher energy bands. We find that the north-east side of the nebula is fainter in higher energy bands. Our deconvolution method is applicable for any telescope images of faint diffuse objects containing a bright point source.","PeriodicalId":20733,"journal":{"name":"Publications of the Astronomical Society of Japan","volume":"19 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139754416","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}
Recent studies of supernova remnants (SNRs) have revealed that some SNRs exhibit a neutral iron line emission at 6.4 keV. This line has been proposed to originate from the interaction of high-energy particles formed in the SNR shell with the surrounding cold matter. We searched for the neutral iron line emission in the SNR W 49 B. Significant detection of the 6.4 keV line is found in the north-west region, close to the molecular cloud interacting with the SNR shell. In addition, an excess emission at 8–9 keV, in which Kγ, Kδ, and Kϵ lines of He-like iron exist, is also significantly found in the region where the radio shell is not bright. We discuss the origin of the 6.4 keV line and the excess emission at 8–9 keV.
{"title":"Detection of the neutral iron line from the supernova remnant W 49 B with Suzaku","authors":"Nari Suzuki, Shigeo Yamauchi, Kumiko K Nobukawa, Masayoshi Nobukawa, Satoru Katsuda","doi":"10.1093/pasj/psae006","DOIUrl":"https://doi.org/10.1093/pasj/psae006","url":null,"abstract":"Recent studies of supernova remnants (SNRs) have revealed that some SNRs exhibit a neutral iron line emission at 6.4 keV. This line has been proposed to originate from the interaction of high-energy particles formed in the SNR shell with the surrounding cold matter. We searched for the neutral iron line emission in the SNR W 49 B. Significant detection of the 6.4 keV line is found in the north-west region, close to the molecular cloud interacting with the SNR shell. In addition, an excess emission at 8–9 keV, in which Kγ, Kδ, and Kϵ lines of He-like iron exist, is also significantly found in the region where the radio shell is not bright. We discuss the origin of the 6.4 keV line and the excess emission at 8–9 keV.","PeriodicalId":20733,"journal":{"name":"Publications of the Astronomical Society of Japan","volume":"17 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139754512","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}
We present the rest-frame optical and UV surface brightness (SB) profiles for 149 galaxies with Mopt < −19.4 mag at z = 4–10 (29 of which are spectroscopically confirmed with JWST NIRSpec), securing high signal-to-noise ratios of 10–135 with deep JWST NIRCam 1–$5, mu$m images obtained by the CEERS survey. We derive morphologies of our high-z galaxies, carefully evaluating the systematics of SB profile measurements with Monte Carlo simulations as well as the impacts of a) AGNs, b) multiple clumps including galaxy mergers, c) spatial resolution differences with previous HST studies, and d) strong emission lines, e.g., Hα and [O iii], on optical morphologies with medium-band F410M images. Conducting Sérsic profile fitting for our high-z galaxy SBs with GALFIT, we obtain effective radius ranges for optical re,opt and UV re,UV wavelengths of re, opt = 0.05–1.6 kpc and re,UV = 0.03–1.7 kpc that are consistent with previous results within large scatters in the size–luminosity relations. However, we find that the effective radius ratio, re,opt$/$re,UV, is almost unity, $1.01^{+0.35}_{-0.22}$, over z = 4–10 with no signatures of past inside-out star formation such as found at z ∼ 0–2. There are no spatial offsets exceeding 3σ between the optical and UV morphology centers in cases of no mergers, indicative of major star-forming activity only being found near mass centers of galaxies at z ≳ 4 probably experiencing the first phase of inside-out galaxy formation.
{"title":"Census for the rest-frame optical and UV morphologies of galaxies at z = 4–10: First phase of inside-out galaxy formation","authors":"Yoshiaki Ono, Yuichi Harikane, Masami Ouchi, Kimihiko Nakajima, Yuki Isobe, Takatoshi Shibuya, Minami Nakane, Hiroya Umeda, Yi Xu, Yechi Zhang","doi":"10.1093/pasj/psae004","DOIUrl":"https://doi.org/10.1093/pasj/psae004","url":null,"abstract":"We present the rest-frame optical and UV surface brightness (SB) profiles for 149 galaxies with Mopt &lt; −19.4 mag at z = 4–10 (29 of which are spectroscopically confirmed with JWST NIRSpec), securing high signal-to-noise ratios of 10–135 with deep JWST NIRCam 1–$5, mu$m images obtained by the CEERS survey. We derive morphologies of our high-z galaxies, carefully evaluating the systematics of SB profile measurements with Monte Carlo simulations as well as the impacts of a) AGNs, b) multiple clumps including galaxy mergers, c) spatial resolution differences with previous HST studies, and d) strong emission lines, e.g., Hα and [O iii], on optical morphologies with medium-band F410M images. Conducting Sérsic profile fitting for our high-z galaxy SBs with GALFIT, we obtain effective radius ranges for optical re,opt and UV re,UV wavelengths of re, opt = 0.05–1.6 kpc and re,UV = 0.03–1.7 kpc that are consistent with previous results within large scatters in the size–luminosity relations. However, we find that the effective radius ratio, re,opt$/$re,UV, is almost unity, $1.01^{+0.35}_{-0.22}$, over z = 4–10 with no signatures of past inside-out star formation such as found at z ∼ 0–2. There are no spatial offsets exceeding 3σ between the optical and UV morphology centers in cases of no mergers, indicative of major star-forming activity only being found near mass centers of galaxies at z ≳ 4 probably experiencing the first phase of inside-out galaxy formation.","PeriodicalId":20733,"journal":{"name":"Publications of the Astronomical Society of Japan","volume":"26 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139754513","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}
We analyze the photometric data in the Wide layer of the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) over ∼1200 deg2 to uncover new halo substructures beyond the distance, D⊙ ∼ 30 kpc, from the Sun. For this purpose, we develop an isochrone filter for an old, metal-poor stellar system to extract the faint main-sequence stars at a range of distances. With this method, we detect not only the previously discovered substructures such as the Orphan Stream, but also a new overdensity toward Boötes at about D⊙ ∼ 60 kpc and a new stream-like feature toward Pisces at around D⊙ ∼ 60 kpc. It has been suggested that a small-scale overdensity exists in this direction of Pisces (the so-called Pisces Overdensity), but our results show that the overdensity is widely spread with a tidally elongated feature. Combining our results with the ongoing Hyper Suprime-Cam narrow-band survey and the near-future spectroscopic survey with Prime Focus Spectrograph (PFS) will allow us to place strong constraints on the origin of these halo substructures.
{"title":"The Milky Way tomography with Subaru Hyper Suprime-Cam. I. Halo substructures","authors":"Yoshihisa Suzuki, Masashi Chiba, Yutaka Komiyama, Kohei Hayashi, Masayuki Tanaka, Tetsuya Fukushima, Scott G Carlsten, Akira Tokiwa, Tian Qiu, Masahiro Takada","doi":"10.1093/pasj/psae003","DOIUrl":"https://doi.org/10.1093/pasj/psae003","url":null,"abstract":"We analyze the photometric data in the Wide layer of the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) over ∼1200 deg2 to uncover new halo substructures beyond the distance, D⊙ ∼ 30 kpc, from the Sun. For this purpose, we develop an isochrone filter for an old, metal-poor stellar system to extract the faint main-sequence stars at a range of distances. With this method, we detect not only the previously discovered substructures such as the Orphan Stream, but also a new overdensity toward Boötes at about D⊙ ∼ 60 kpc and a new stream-like feature toward Pisces at around D⊙ ∼ 60 kpc. It has been suggested that a small-scale overdensity exists in this direction of Pisces (the so-called Pisces Overdensity), but our results show that the overdensity is widely spread with a tidally elongated feature. Combining our results with the ongoing Hyper Suprime-Cam narrow-band survey and the near-future spectroscopic survey with Prime Focus Spectrograph (PFS) will allow us to place strong constraints on the origin of these halo substructures.","PeriodicalId":20733,"journal":{"name":"Publications of the Astronomical Society of Japan","volume":"5 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139658868","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}
This paper presents a morphology classification catalog of spiral and ring features of 59854 magnitude-limited galaxies (r < 17.8 mag, and additional 628005 subsamples down to r = 20 mag) at z = 0.01–0.3 based on the Third Public Data Release of the Hyper Suprime-Cam Subaru Strategic Program. We employ two deep-learning classifiers to determine the spiral and ring structures separately based on GALAXY CRUISE Data Release 1, which is dedicated to Hyper Suprime-Cam data. The number of spiral and ring galaxies contain 31864 and 8808 sources, respectively, which constitute 53% and 15% of the sample. A notable result of this study is the construction of a large sample of ring galaxies utilizing high-quality imaging data delivered by the Subaru Hyper Suprime-Cam. However, the accurate identification of ring galaxies remains difficult at a limited seeing resolution. Additionally, we confirm that most spiral galaxies are located on the star-forming main sequence, whereas ring galaxies preferentially reside in the green valley at stellar masses of 1010.5–1011 solar mass. Furthermore, decreasing fractions of spiral and ring galaxies are observed toward the centers of the galaxy clusters. The obtained morphology catalog is publicly available on the GALAXY CRUISE website.
{"title":"GALAXY CRUISE: Spiral and ring classifications for bright galaxies at z = 0.01–0.3","authors":"Rhythm Shimakawa, Masayuki Tanaka, Kei Ito, Makoto Ando","doi":"10.1093/pasj/psae002","DOIUrl":"https://doi.org/10.1093/pasj/psae002","url":null,"abstract":"This paper presents a morphology classification catalog of spiral and ring features of 59854 magnitude-limited galaxies (r &lt; 17.8 mag, and additional 628005 subsamples down to r = 20 mag) at z = 0.01–0.3 based on the Third Public Data Release of the Hyper Suprime-Cam Subaru Strategic Program. We employ two deep-learning classifiers to determine the spiral and ring structures separately based on GALAXY CRUISE Data Release 1, which is dedicated to Hyper Suprime-Cam data. The number of spiral and ring galaxies contain 31864 and 8808 sources, respectively, which constitute 53% and 15% of the sample. A notable result of this study is the construction of a large sample of ring galaxies utilizing high-quality imaging data delivered by the Subaru Hyper Suprime-Cam. However, the accurate identification of ring galaxies remains difficult at a limited seeing resolution. Additionally, we confirm that most spiral galaxies are located on the star-forming main sequence, whereas ring galaxies preferentially reside in the green valley at stellar masses of 1010.5–1011 solar mass. Furthermore, decreasing fractions of spiral and ring galaxies are observed toward the centers of the galaxy clusters. The obtained morphology catalog is publicly available on the GALAXY CRUISE website.","PeriodicalId":20733,"journal":{"name":"Publications of the Astronomical Society of Japan","volume":"280 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139586989","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}
We conducted four-night multiwavelength observations of an active M-dwarf star EV Lacertae on 2022 October 24–27 with simultaneous coverage of soft X-rays (NICER; 0.2–12 keV, Swift XRT; 0.2–10 keV), near-ultraviolet (Swift UVOT/UVW2; 1600–3500 Å), optical photometry (TESS; 6000–10000 Å), and optical spectroscopy (Nayuta/MALLS; 6350–6800 Å). During the campaign, we detected a flare starting at 12:28 UTC on October 25 with a white-light bolometric energy of 3.4 × 1032 erg. At about 1 h after this flare peak, our Hα spectrum showed a blueshifted excess component at a corresponding velocity of ∼100 km s−1. This may indicate that the prominence erupted with a 1 h delay of the flare peak. Furthermore, the simultaneous 20 s cadence near-ultraviolet (NUV) and white-light curves show gradual and rapid brightening behaviors during the rising phase at this flare. The ratio of flux in NUV to white light at the gradual brightening was ∼0.49, which may suggest that the temperature of the blackbody is low (<9000 K) or the maximum energy flux of a non-thermal electron beam is less than 5 × 1011 erg cm−2 s−1. Our simultaneous observations of the NUV and white-light flare raise the issue of a simple estimation of UV flux from optical continuum data by using a blackbody model.
{"title":"Multiwavelength observation of an active M-dwarf star EV Lacertae and its stellar flare accompanied by a delayed prominence eruption","authors":"Shun Inoue, Teruaki Enoto, Kosuke Namekata, Yuta Notsu, Satoshi Honda, Hiroyuki Maehara, Jiale Zhang, Hong-Peng Lu, Hiroyuki Uchida, Takeshi Go Tsuru, Daisaku Nogami, Kazunari Shibata","doi":"10.1093/pasj/psae001","DOIUrl":"https://doi.org/10.1093/pasj/psae001","url":null,"abstract":"We conducted four-night multiwavelength observations of an active M-dwarf star EV Lacertae on 2022 October 24–27 with simultaneous coverage of soft X-rays (NICER; 0.2–12 keV, Swift XRT; 0.2–10 keV), near-ultraviolet (Swift UVOT/UVW2; 1600–3500 Å), optical photometry (TESS; 6000–10000 Å), and optical spectroscopy (Nayuta/MALLS; 6350–6800 Å). During the campaign, we detected a flare starting at 12:28 UTC on October 25 with a white-light bolometric energy of 3.4 × 1032 erg. At about 1 h after this flare peak, our Hα spectrum showed a blueshifted excess component at a corresponding velocity of ∼100 km s−1. This may indicate that the prominence erupted with a 1 h delay of the flare peak. Furthermore, the simultaneous 20 s cadence near-ultraviolet (NUV) and white-light curves show gradual and rapid brightening behaviors during the rising phase at this flare. The ratio of flux in NUV to white light at the gradual brightening was ∼0.49, which may suggest that the temperature of the blackbody is low (&lt;9000 K) or the maximum energy flux of a non-thermal electron beam is less than 5 × 1011 erg cm−2 s−1. Our simultaneous observations of the NUV and white-light flare raise the issue of a simple estimation of UV flux from optical continuum data by using a blackbody model.","PeriodicalId":20733,"journal":{"name":"Publications of the Astronomical Society of Japan","volume":"17 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139586900","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}
We successfully measured the trigonometric parallax of Sagittarius A* (Sgr A*) to be 117 ± 17 micro-arcseconds ($, mu mbox{as}$) using the VLBI Exploration of Radio Astrometry (VERA) with the newly developed broad-band signal-processing system named “OCTAVE-DAS.” The measured parallax corresponds to a Galactocentric distance at the Sun of $R_0 = 8.5^{+1.5}_{-1.1}:$kpc. By combining the astrometric results with VERA and the Very Long Baseline Array (VLBA) over a monitoring period of 25 yr, the proper motion of Sgr A* is obtained to be (μα, μδ) = (−3.133 ± 0.003, −5.575 ± 0.005) mas yr−1 in equatorial coordinates, corresponding to (μl, μb) = (−6.391 ± 0.005, −0.230 ± 0.004) mas yr−1 in Galactic coordinates. This gives an angular orbital velocity of the Sun of Ω⊙ = 30.30 ± 0.02 km s−1 kpc−1. We find upper limits to the core wander, Δθ < 0.20 mas (1.6 au), peculiar motion, Δμ < 0.10 mas yr−1 (3.7 km s−1), and acceleration, a < 2.6 $, mu mbox{as} :$yr−2 (0.10 km s−1 yr−1) for Sgr A*. Thus, we obtained upper mass limits of $approx 3 times 10^{4}, M_{odot }$ and $approx 3 times 10^{3}, M_{odot }$ for the supposed intermediate-mass black holes at 0.1 and 0.01 pc from the Galactic center, respectively.
我们利用新开发的宽波段信号处理系统 "OCTAVE-DAS "进行了射电天体测量的VLBI探索（VERA），成功地测量出人马座A*（Sgr A*）的三角视差为117 ± 17微弧秒（$, mu mbox{as}$）。测得的视差对应于太阳的银河中心距为$R_0 = 8.5^{+1.5}_{-1.1}:$kpc 。通过将天体测量结果与VERA和超长基线阵列（VLBA）25年的监测期结合起来，得到Sgr A*的正确运动在赤道坐标上为（μα, μδ) = (-3.133 ± 0.003, -5.575 ± 0.005) mas yr-1，在银河坐标上对应于（μl, μb) = (-6.391 ± 0.005, -0.230 ± 0.004) mas yr-1。由此得出太阳的角轨道速度为 Ω⊙ = 30.30 ± 0.02 km s-1 kpc-1。我们找到了核心漂移（Δθ < 0.20 mas (1.6 au)）、奇特运动（Δμ < 0.10 mas yr-1 (3.7 km s-1)）和加速度（a < 2.6 $, mu mbox{as} ）的上限。:$yr-2 (0.10 km s-1 yr-1)。因此，我们得到了距离银河系中心0.1 pc和0.01 pc的假定中等质量黑洞的质量上限，分别为$approx 3 times 10^{4}, M_{odot }$和$approx 3 times 10^{3}, M_{odot }$。
{"title":"Trigonometric parallax and proper motion of Sagittarius A* measured by VERA using the new broad-band back-end system OCTAVE-DAS","authors":"Tomoaki Oyama, Takumi Nagayama, Aya Yamauchi, Daisuke Sakai, Hiroshi Imai, Mareki Honma, Yu Asakura, Kazuhiro Hada, Yoshiaki Hagiwara, Tomoya Hirota, Takaaki Jike, Yusuke Kono, Syunsaku Suzuki, Hideyuki Kobayashi, Noriyuki Kawaguchi","doi":"10.1093/pasj/psad088","DOIUrl":"https://doi.org/10.1093/pasj/psad088","url":null,"abstract":"We successfully measured the trigonometric parallax of Sagittarius A* (Sgr A*) to be 117 ± 17 micro-arcseconds ($, mu mbox{as}$) using the VLBI Exploration of Radio Astrometry (VERA) with the newly developed broad-band signal-processing system named “OCTAVE-DAS.” The measured parallax corresponds to a Galactocentric distance at the Sun of $R_0 = 8.5^{+1.5}_{-1.1}:$kpc. By combining the astrometric results with VERA and the Very Long Baseline Array (VLBA) over a monitoring period of 25 yr, the proper motion of Sgr A* is obtained to be (μα, μδ) = (−3.133 ± 0.003, −5.575 ± 0.005) mas yr−1 in equatorial coordinates, corresponding to (μl, μb) = (−6.391 ± 0.005, −0.230 ± 0.004) mas yr−1 in Galactic coordinates. This gives an angular orbital velocity of the Sun of Ω⊙ = 30.30 ± 0.02 km s−1 kpc−1. We find upper limits to the core wander, Δθ &lt; 0.20 mas (1.6 au), peculiar motion, Δμ &lt; 0.10 mas yr−1 (3.7 km s−1), and acceleration, a &lt; 2.6 $, mu mbox{as} :$yr−2 (0.10 km s−1 yr−1) for Sgr A*. Thus, we obtained upper mass limits of $approx 3 times 10^{4}, M_{odot }$ and $approx 3 times 10^{3}, M_{odot }$ for the supposed intermediate-mass black holes at 0.1 and 0.01 pc from the Galactic center, respectively.","PeriodicalId":20733,"journal":{"name":"Publications of the Astronomical Society of Japan","volume":"174 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139586870","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}
Jae Woo Lee, Kyeongsoo Hong, Hye-Young Kim, Marek Wolf, Jang-Ho Park, Pakakaew Rittipruk
It is known from archival TESS data that the semi-detached Algol system XZ Ursae Majoris (UMa) is one of the candidate binary stars exhibiting short-period oscillations. We secured new high-resolution spectroscopic observations for the program target to better understand its binary and pulsation properties. From the echelle spectra, the radial velocities (RVs) of the eclipsing pair were derived, and the atmosphere parameters of the primary component were measured to be vAsin i = 80 ± 7 km s−1, Teff, A = 7940 ± 120 K, and [M/H] = −0.15 ± 0.20. The combined solution of our double-lined RVs and the TESS data provides robust physical parameters for XZ UMa with mass and radius measurement precision of better than 2%. The outside-eclipse residuals from a mean light curve in the 0.002 phase bin were used for multifrequency analyses, and we extracted 32 significant frequencies (22 in <5.0 d−1 and 10 in 39–52 d−1). The low frequencies may be mostly aliasing sidelobes, while six of the high frequencies may be pulsation signals arising from the detached primary located inside the δ Sct domain. Their periods, pulsation constants, and pulsational–orbital-period ratios indicate that the mass-accreting primary star is a δ Sct pulsator and, hence, XZ UMa is an oscillating eclipsing Algol.
{"title":"Absolute properties of the oscillating eclipsing Algol XZ Ursae Majoris","authors":"Jae Woo Lee, Kyeongsoo Hong, Hye-Young Kim, Marek Wolf, Jang-Ho Park, Pakakaew Rittipruk","doi":"10.1093/pasj/psad085","DOIUrl":"https://doi.org/10.1093/pasj/psad085","url":null,"abstract":"It is known from archival TESS data that the semi-detached Algol system XZ Ursae Majoris (UMa) is one of the candidate binary stars exhibiting short-period oscillations. We secured new high-resolution spectroscopic observations for the program target to better understand its binary and pulsation properties. From the echelle spectra, the radial velocities (RVs) of the eclipsing pair were derived, and the atmosphere parameters of the primary component were measured to be vAsin i = 80 ± 7 km s−1, Teff, A = 7940 ± 120 K, and [M/H] = −0.15 ± 0.20. The combined solution of our double-lined RVs and the TESS data provides robust physical parameters for XZ UMa with mass and radius measurement precision of better than 2%. The outside-eclipse residuals from a mean light curve in the 0.002 phase bin were used for multifrequency analyses, and we extracted 32 significant frequencies (22 in &lt;5.0 d−1 and 10 in 39–52 d−1). The low frequencies may be mostly aliasing sidelobes, while six of the high frequencies may be pulsation signals arising from the detached primary located inside the δ Sct domain. Their periods, pulsation constants, and pulsational–orbital-period ratios indicate that the mass-accreting primary star is a δ Sct pulsator and, hence, XZ UMa is an oscillating eclipsing Algol.","PeriodicalId":20733,"journal":{"name":"Publications of the Astronomical Society of Japan","volume":"37 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139586868","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}
Comets are believed to have amorphous rather than crystalline ice at the epoch of their accretion. Cometary ice contains some impurities that govern the latent heat of ice crystallization, Lcry. However, it is still controversial whether the crystallization process is exothermic or endothermic. In this study, we perform one-dimensional simulations of the thermal evolution of kilometer-sized comets and investigate the effect of the latent heat. We find that the depth at which amorphous ice can survive significantly depends on the latent heat of ice crystallization. Assuming the cometary radius of 2 km, the depth of the amorphous ice mantle is approximately 100 m when the latent heat is positive (i.e., the exothermic case with Lcry = +9 × 104 J kg−1). In contrast, when we consider the impure ice representing the endothermic case with Lcry = −9 × 104 J kg−1, the depth of the amorphous ice mantle could exceed 1 km. Although our numerical results indicate that these depths depend on the size and the accretion age of comets, the depth in a comet with the negative latent heat is a few to several times larger than in the positive case for a given comet size. This work suggests that the spatial distribution of the ice crystallinity in a comet nucleus depends on the latent heat, which can be different from the previous estimates assuming pure water ice.
{"title":"Survivability of amorphous ice in comets depends on the latent heat of crystallization of impure water ice","authors":"Sota Arakawa, Shigeru Wakita","doi":"10.1093/pasj/psad086","DOIUrl":"https://doi.org/10.1093/pasj/psad086","url":null,"abstract":"Comets are believed to have amorphous rather than crystalline ice at the epoch of their accretion. Cometary ice contains some impurities that govern the latent heat of ice crystallization, Lcry. However, it is still controversial whether the crystallization process is exothermic or endothermic. In this study, we perform one-dimensional simulations of the thermal evolution of kilometer-sized comets and investigate the effect of the latent heat. We find that the depth at which amorphous ice can survive significantly depends on the latent heat of ice crystallization. Assuming the cometary radius of 2 km, the depth of the amorphous ice mantle is approximately 100 m when the latent heat is positive (i.e., the exothermic case with Lcry = +9 × 104 J kg−1). In contrast, when we consider the impure ice representing the endothermic case with Lcry = −9 × 104 J kg−1, the depth of the amorphous ice mantle could exceed 1 km. Although our numerical results indicate that these depths depend on the size and the accretion age of comets, the depth in a comet with the negative latent heat is a few to several times larger than in the positive case for a given comet size. This work suggests that the spatial distribution of the ice crystallinity in a comet nucleus depends on the latent heat, which can be different from the previous estimates assuming pure water ice.","PeriodicalId":20733,"journal":{"name":"Publications of the Astronomical Society of Japan","volume":"16 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139552707","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：