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  2. Katsura Matsumoto

Katsura Matsumoto

  (松本 桂)

Profile Information

Affiliation
Associate Professor, Division of Math, Sciences, and Information Technology in Education, Osaka Kyoiku University
Degree
Doctor of Science(2000, Kyoto University)
Contact information
katsuracc.osaka-kyoiku.ac.jp
Researcher number
90362748
ORCID ID
 https://orcid.org/0000-0002-5277-568X
J-GLOBAL ID
200901049121591542
researchmap Member ID
6000005612
External link

Research Areas

 2

Papers

 178
  • 吉田玲菜, 松本桂
    天文教育, 38(2) 94-98, Mar, 2026  Corresponding author
  • Naoto Kojiguchi, Keisuke Isogai, Yusuke Tampo, Taichi Kato, Hiroshi Itoh, Berto Monard, Franz-Josef Hambsch, Yasuyuki Wakamatsu, Tomohito Ohshima, Junpei Ito, Masaaki Shibata, Ryuhei Ohnishi, Mariko Kimura, Pavol A Dubovsky, Tomas Medulka, Enrique De Miguel, Yuki Sugiura, Daiki Ito, Hanami Matsumoto, Sho Sumiya, Kengo Nikai, Yuki Zenko, Ryota Matsumura, Daiti Fujii, Taiti Kato, Katsura Matsumoto, Tonny Vanmunster, William Stein, Katsuaki Kubotera, Tamás Tordai, Kirill Antonyuk, Oksana Antonyuk, Nikolaj Pit, Aleksei Sosnovskij, Alex Baklanov, Julia Babina, Elena P Pavlenko, Marlin Costello, Kazunari Masumoto, Daiki Fukushima, Megumi Takenaka, Miho Kawabata, Daisuke Sakai, Kazuki Maeda, Risa Matsuda, Gianluca Masi, Peter Starr, Shawn Dvorak, John W Rock, Michael J Cook, Joseph H Ulowetz, Yutaka Maeda, Raúl Michel, Sergey Yu Shugarov, Drahomir Chochol, Lewis M Cook, Domenico Licchelli, Sjoerd Dufoer, Kenneth Menzies, Rudolf Novák, Stephen M Brincat, Graeme Coates, Filipp D Romanov, David J Lane, Eddy Muyllaert, Geoffrey Stone, Stephen Hovell, Rod Stubbings, Daisaku Nogami
    Publications of the Astronomical Society of Japan, 78(1) 199-219, Feb, 2026  Peer-reviewed
    Abstract We present an observational study of superoutbursts in six AM CVn systems with orbital periods longer than 35 min. We focused on this range because such systems are expected to have very low mass ratios, making them particularly likely to exhibit double superoutbursts and fading-tail profiles. Using time-resolved photometry from the Variable Star Network and the American Association of Variable Star Observers campaigns, complemented by survey data from the Zwicky Transient Facility, the All-Sky Automated Survey for Supernovae, the Asteroid Terrestrial-impact Last Alert System, Gaia, and the Transiting Exoplanet Survey Satellite, we analyzed nine superoutbursts observed between 2014 and 2021. Among them, four events exhibited clear double superoutburst profiles, analogous to those seen in hydrogen-rich WZ Sge-type dwarf novae. We characterized the fading tail following the second superoutburst and found that it can be divided into three distinct phases (tails A, B, and C) with different power-law fading indices. The effective superoutburst durations were typically 7–13 d, while the dip duration is significantly different among systems. Notably, the effective durations of the second superoutbursts in the double superoutburst were consistently around 5 d. These results highlight the importance of thermal–tidal instabilities in explaining the outbursts of long-orbital-period AM CVn stars. They also suggested that the three-phase fading-tail structure may be a universal feature of the systems and further imply that in systems with short supercycles the effective viscosity during quiescence could be higher than expected from a true quiescent state.
  • Y Tampo, N Kojiguchi, K Isogai, D Nogami, H Itoh, F -J Hambsch, K Matsumoto, R Matsumura, D Fujii, T Tordai, Y Sano, B Monard, P A Dubovsky, T Medulka, D A H Buckley, N Rawat, S B Potter, A van Dyk, P J Groot, P Woudt, S Kiyota, G Bolt, T Vanmunster, J Pietz, P Starr, S Y Shugarov, K Kasai, K Menzies, S M Brincat, E P Pavlenko, A Baklanov, J Ito, T Kato
    Monthly Notices of the Royal Astronomical Society, 545(2) staf1964, Jan, 2026  Peer-reviewed
    ABSTRACT Dwarf nova (DN) superoutbursts are accompanied by superhumps, which change their periods and profiles over a superoutburst. We present the TESS and ground-based observations of nine WZ Sge-type DNe and candidates in superoutburst. In TCP J23580961$+$5502508, ASASSN-23ba, PNV J19030433$-$3102187, V748 Hya, and ASASSN-25ci, we confirmed double-peaked oscillations called early superhumps, which are regarded as the unambiguous feature of WZ Sge-type DNe. On the other hand, the superhump and outburst properties of MO Psc and V1676 Her suggest that they may not be a member of WZ Sge-type DNe. The 2022 superoutburst of a confirmed WZ Sge-type DN TCP J05515391$+$6504346, however, lacked an early superhump phase. We find superhumps in a WZ Sge-type DN ASASSN-20mq during its rebrightening outburst. Due to the continuous coverage of TESS, we find the broken-power-law rise of the outburst light curve in V748 Hya and PNV J19030433$-$3102187, previously found in only one WZ Sge-type DN observed by Kepler. Early superhumps appeared when the system reached $\simeq 40$ per cent of the outburst peak flux. No orbital modulation from a hot spot is detected before and after this. This non-detection of orbital humps on the early rise of V748 Hya constrains that the corresponding mass transfer rate should be below $\simeq 1\times 10^{16}$ g s$^{-1}$, disfavouring an enhancement of a mass transfer rate by an order of magnitude or larger, even if it occurs. The contentious TESS observations also confirm the coexistence of early and ordinary superhumps during their transition and $\le$2-cycle duration of stage A–B superhump transition in V748 Hya.
  • Mauri J. Valtonen, Lankeswar Dey, Staszek Zola, Alok C. Gupta, Shubham Kishore, Achamveedu Gopakumar, Paul J. Wiita, Minfeng Gu, Kari Nilsson, Zhongli Zhang, Rene Hudec, Katsura Matsumoto, Marek Drozdz, Waldemar Ogloza, Andrei V. Berdyugin, Daniel E. Reichart, Markus Mugrauer, Tapio Pursimo, Stefano Ciprini, Tatsuya Nakaoka, Makoto Uemura, Ryo Imazawa, Michal Zejmo, Vladimir V. Kouprianov, James W. Davidson, Alberto Sadun, Jan Štrobl, Martin Jelínek, Abhimanyu Susobhanan
    Astrophysical Journal, 992(1) 110, Oct, 2025  Peer-reviewed
    Abstract The 136 yr long optical light curve of OJ 287 is explained by a binary black hole model where the secondary is in a 12 yr orbit around the primary. Impacts of the secondary on the accretion disk of the primary generate a series of optical flares that follow a quasi-Keplerian relativistic mathematical model. The orientation of the binary in space is determined from the behavior of the primary jet. Here, we ask how the jet of the secondary black hole projects onto the sky plane. Assuming that the jet is initially perpendicular to the disk, and that it is ballistic, we follow its evolution after the Lorentz transformation to the observer’s frame. Since the orbital speed of the secondary is of the order of one-tenth of the speed of light, the result is a change in the jet direction by more than a radian during an orbital cycle. We match the theoretical jet line with the recent 12 μas resolution RadioAstron map of OJ 287 and determine the only free parameter of the problem, the apparent speed of the jet relative to speed of light. It turns out that the Doppler factor of the jet, δ ∼ 5, is much lower than in the primary jet. Besides following a unique shape of the jet path, the secondary jet is also distinguished by a different spectral shape than in the primary jet. The present result on the spectral shape agrees with the huge optical flare of 2021 November 12, also arising from the secondary jet.
  • Yusuke Tampo, Taichi Kato, Keisuke Isogai, Mariko Kimura, Naoto Kojiguchi, Daisaku Nogami, Junpei Ito, Masaaki Shibata, Masayuki Yamanaka, Kenta Taguchi, Hiroyuki Maehara, Hiroshi Itoh, Katsura Matsumoto, Momoka Nakagawa, Yukitaka Nishida, Shawn Dvorak, Katsuhiro L Murata, Ryohei Hosokawa, Yuri Imai, Naohiro Ito, Masafumi Niwano, Shota Sato, Ryotaro Noto, Ryodai Yamaguchi, Malte Schramm, Yumiko Oasa, Takahiro Kanai, Yu Sasaki, Tamás Tordai, Tonny Vanmunster, Seiichiro Kiyota, Nataly Katysheva, Sergey Yu Shugarov, Alexandra M Zubareva, Sergei Antipin, Natalia Ikonnikova, Alexandr Belinski, Pavol A Dubovsky, Tomáš Medulka, Jun Takahashi, Masaki Takayama, Tomohito Ohshima, Tomoki Saito, Miyako Tozuka, Shigeyuki Sako, Masaomi Tanaka, Nozomu Tominaga, Takashi Horiuchi, Hidekazu Hanayama, Daniel E Reichart, Vladimir V Kouprianov, James W Davidson Jr, Daniel B Caton, Filipp D Romanov, David J Lane, Franz-Josef Hambsch, Norio Narita, Akihiko Fukui, Masahiro Ikoma, Motohide Tamura, Koji S Kawabata, Tatsuya Nakaoka, Ryo Imazawa
    Publications of the Astronomical Society of Japan, 76(6) 1228-1245, Dec, 2024  Peer-reviewed
    Abstract We present a detailed study of the MASTER OT J030227.28$+$191754.5 outburst in 2021–2022, which reached an amplitude of $10.2\:$mag and a duration of $60\:$d. The detections of (1) the double-peaked optical emission lines, and (2) the early and ordinary superhumps, established that MASTER OT J030227.28$+$191754.5 is an extremely energetic WZ Sge-type dwarf nova (DN). Based on the superhump observations, we obtained its orbital period and mass ratio as $0.05986(1)\:$d and 0.063(1), respectively. These values are within a typical range for low-mass-ratio DNe. According to the binary parameters derived based on the thermal–tidal instability model, our analyses showed that (1) the standard disk model requires an accretion rate $\simeq\!\! 10^{20}\:$g$\:$s$^{-1}$ to explain its peak optical luminosity, and (2) large mass was stored in the disk at the outburst onset. These factors cannot be explained solely by the impact of its massive ($\gtrsim\!\! 1.15\, M_{\odot }$) primary white dwarf implied by Kimura et al. (2023, ApJ, 951, 124). Instead, we propose that the probable origin of this enormously energetic DN outburst is the even lower quiescence viscosity than other WZ Sge-type DNe. This discussion is qualitatively valid for most possible binary parameter spaces unless the inclination is low enough ($\lesssim\!\! 40^\circ$) for the disk to be bright, explaining the outburst amplitude. Such low inclinations, however, would not allow detectable amplitude of early superhumps in the current thermal–tidal instability model. The optical spectra at outburst maximum showed strong emission lines of the Balmer, He i, and He ii series, the core of which is narrower than $\sim \! 800\:$km$\:$s$^{-1}$. Considering its binary parameters, a Keplerian disk cannot explain this narrow component, but the presumable origin is disk winds.
More

Misc.

 36
  • K. Taguchi, H. Naito, Y. Sano, K. Matsumoto, H. Maehara, A. Arai, K. Itagaki, M. Kato, S. Kiyota, K. Nishiyama, F. Kabashima, A. Tajitsu, S. Takagi, F. Watanabe
    Astronomer's Telegram, (17530), Dec 8, 2025  
  • 西村昌能, 時政典孝, 山田隆文, 松浦美波, 松本桂
    天文教育, 37(6) 21-24, Nov, 2025  
  • 西村昌能, 時政典孝, 山田隆文, 松浦美波, 松本基希, 松本桂
    天文教育, 36(6) 41-43, Nov, 2024  
  • H. Naito, Y. Sano, K. Matsumoto, H. Maehara, A. Arai, K. Itagaki, M. Kato, S. Kiyota, K. Nishiyama, F. Kabashima, H. Saito, K. Taguchi, A. Tajitsu, F. Watanabe
    Astronomer's Telegram, (16386), Dec 19, 2023  
    We report additional multicolor photometry of the 2023 eruption of the remarkable recurrent nova M31N 2008-12a (ATels #16361, #16362, #16364, #16365, #16367, #16370, #16382, also see Darnley et al. 2014, 2015, 2016 and Henze et al. 2014, 2015a, 2015b, 2018, for comprehensive multi-wavelength light curves of previous eruptions)....
  • 西村昌能, 松本桂, 松本基希, 松浦美波, 時政典孝, 山田隆文, 有本淳一, 福江純, 定金晃三
    天文教育, 35(6) 22-26, Nov, 2023  
  • Publications of the Japanese Society for Education and Popularization of Astronomy, 34(6) 41-45, Nov, 2022  
  • H. Naito, S. Kiyota, Y. Sano, K. Taguchi, H. Maehara, A. Arai, K. Itagaki, M. Kato, K. Matsumoto, K. Nishiyama, F. Kabashima, A. Tajitsu, S. Takagi, F. Watanabe
    Astronomer's Telegram, (15068), Nov 28, 2021  
    We report additional multicolor photometry of the 2021 eruption of the remarkable recurrent nova M31N 2008-12a (ATels #15034, #15036, #15037, #15038, #15039, #15040, #15045, #15050, see Darnley et al. 2014, 2015, 2016 and Henze et al. 2014, 2015a, 2015b, 2018 for comprehensive multi-wavelength light curves of previous eruptions)....
  • K. Itagaki, T. Vanmunster, F. Watanabe, J.-L. G. Carballo, K. Matsumoto, H. Naito, M. W. Healy, M. J. Darnley, S. C. Williams, S. Kafka, W. Shafter, M. Henze
    Astronomer's Telegram, (15034), Nov 14, 2021  
    We report the discovery of the predicted 2021 eruption of the remarkable recurrent M31 nova M31N 2008-12a (see ATels #5607, #6527, #7964, #9848, #11116, #12177, #13269, #14130 for earlier detections as well as Darnley et al. 2014, 2015, 2016 and Henze et al. 2014, 2015a, 2015b, 2018, for comprehensive multi-wavelength studies of previous eruptions)....
  • 西村昌能, 松本基希, 松浦美波, 松本桂
    Publications of the Japanese Society for Education and Popularization of Astronomy, 33(6) 2-6, Nov, 2021  
  • 西村昌能, 成田直, 有本淳一, 時政典孝, 山田隆文, 松浦美波, 松本桂, 福江純, 定金晃三
    天文教育, 30(5) 15-18, Sep, 2018  
  • H. Naito, F. Watanabe, Y. Sano, K. Kuramoto, K. Itagaki, S. Kiyota, A. Arai, H. Maehara, K. Matsumoto, A. Fukui, K. Nishiyama, F. Kabashima, M. Henze, M. J. Darnley, A. W. Shafter, M. Kato
    Astronomer's Telegram, (11133), Jan 6, 2018  
    We report additional multicolor photometry of the 2017 outburst of the remarkable recurrent nova M31N 2008-12a (ATels #11116, #11117, #11118, #11121, #11124, #11125, #11126, #11130, see Darnley et al. 2014, 2015, 2016 and Henze et al. 2014, 2015a, 2015b for comprehensive multi-wavelength light curves of previous eruptions)....
  • H. Naito, F. Watanabe, Y. Sano, K. Kuramoto, K. Itagaki, S. Kiyota, A. Arai, K. Matsumoto, N. Kojiguchi, Y. Sugiura, H. Maehara, K. Nishiyama, F. Kabashima, M. Henze, M. J. Darnley, A. W. Shafter, M. Kato
    Astronomer's Telegram, (9891), Dec 22, 2016  
    We report additional multicolor photometry of the 2016 outburst of the remarkable recurrent nova M31N 2008-12a (ATel #9848, #9852, #9853, #9857, #9861, #9864, #9865, #9872, #9874, #9881 see Darnley et al. 2014, 2015, 2016 and Henze et al. 2014, 2015a, 2015b for comprehensive multi-wavelength light curves of previous eruptions)....
  • 西村昌能, 山田隆文, 成田直, 有本淳一, 時政典孝, 野口亮, 梅津寛明, 柳澤洋文, 松本桂, 福江純, 定金晃三
    天文教育, 28(5) 20-23, Sep, 2016  
  • S. Zola, M. Valtonen, S. Ciprini, D. E. Reichart, J. P. Moore, A. P. LaCluyze, K. M. Ivarsen, R. Groom, K. Stranger, K. Sadakane, K. Matsumoto, M. Kagitani, S. Okano, T. Sakanoi, J. Provencal, J. Dalessio, M. Drozdz, M. Siwak, K. Gazeas, V. Fallah Ramazani, M. Kidger, R. Naves, Montse Campas, H. Jermak, I. A. Steele, E. Sonbas, H. Er, M. Zejmo, D. B. Caton, G. Poyner
    Astronomer's Telegram, (8768), Mar 3, 2016  
    We have continued monitoring the blazar OJ287 in the optical at several sites after its November/December, 2015 outburst. After a further large outburst that started in the beginning of February, 2016 (Atels #8667, #8697, #8705) OJ287 remained brighter than 14th magnitude [in R] for the rest of the month....
  • S. Zola, B. Debski, A. Goyal, M. Valtonen, S. Ciprini, W. Ogloza, M. Drozdz, M. Siwak, K. Sadakane, K. Matsumoto, M. Kagitani, S. Okano, T. Sakanoi, K. Gazeas, H. Jermak, I. A. Steele, J. Dalessio, J. Provencal, D. E. Reichart, J. P. Moore, A. P. LaCluyze, K. M. Ivarsen, A. Erdem, F. Alicavus, D. B. Caton, W. C. Keel, M. Kidger, R. Naves
    Astronomer's Telegram, (8667), Feb 10, 2016  
    OJ287 has been monitored in the optical wavelength with small telescopes since the beginning of September, 2015. In November and December, an unprecedented outburst in the optical band was noticed (ATels: 8382, 8395, 8401, 8411, 8438), with OJ287 reaching 12.9 mag in the R filter....
  • 西村昌能, 成田直, 有本淳一, 時政典孝, 山田隆文, 梅津寛明, 柳澤洋文, 松本桂, 福江純, 定金晃三
    天文教育, 27(6) 46-49, Nov, 2015  
  • 西村昌能, 梅津寛明, 成田直, 有本淳一, 時政典孝, 山田隆文, 柳澤洋文, 松本桂, 福江純, 定金晃三
    天文教育, 26(6) 34-38, Nov, 2014  
  • M. Uemura, Y. Moritani, R. Itoh, H. Akitaya, A. Arai, K. Morihana, S. Honda, K. Matsumoto
    Astronomer's Telegram, (5836), Jan 30, 2014  
    We performed optical imaging of the black hole X-ray binary, V4641 Sgr which is now active in X-rays (ATel #5803)....
  • 柳澤洋文, 成田直, 山田隆文, 有本淳一, 西村昌能, 時政典孝, 松本桂, 福江純, 定金晃三
    天文教育, 25(5) 32-35, Sep, 2013  
  • 成田直, 渡部義弥, 時政典孝, 西村昌能, 有本淳一, 柳澤洋文, 福江純, 松本桂, 定金晃三
    天文教育, 24(5) 61-64, Sep, 2012  
  • 成田直, 時政典孝, 有本淳一, 西村昌能, 福江純, 松本桂, 定金晃三
    天文月報, 104 731-733, Oct, 2011  
  • Kazuya Ayani, Katsura Matsumoto
    Central Bureau Electronic Telegrams, (1334), Apr 11, 2008  Peer-reviewed
    K. Ayani, Bisei Astronomical Observatory (BAO); and K. Matsumoto, Osaka Kyoiku University, write that low-resolution spectra (range 400-800 nm; resolution 0.5 nm at H-alpha) of V2491 Cyg (cf. IAUC 8934), obtained with the BAO 1.01-m telescope on Apr. 11.72 UT, show prominent broad Balmer emission lines, which indicate that the object is a nova in its early phase of outburst. Fe II emission may be present. The H-alpha line has a FWHM of 4500 km/s and an equivalent width of about 36 nm....
  • K. Matsumoto, T. Kawabata, K. Ayani, Y. Urata, H. Yamaoka, N. Kawai
    GRB Coordinates Network Circulars, (1594), Oct 7, 2002  
    ...
  • K. Matsumoto, T. Kawabata, K. Ayani, Y. Urata, H. Yamaoka
    GRB Coordinates Network Circulars, (1567), Oct 4, 2002  
    ...
  • T. Kato, H. Ohashi, R. Ishioka, M. Uemura, K. Matsumoto, G. Masi, F. Mallia, D. Starkey, J. Pietz, B. Martin, G.A. Good, M. Richmond, S. Davis, T. Davis
    IAU Circular, (7680), Aug 11, 2001  Peer-reviewed
  • T. Kato, H. Ohashi, R. Ishioka, M. Uemura, K. Matsumoto, G. Masi, D. Starkey, J. Pietz, B. Martin
    IAU Circular, (7678), Aug 6, 2001  Peer-reviewed
  • H. Baba, K. Sadakane, Y. Norimoto, D. Nogami, K. Matsumoto, M. Makita, T. Kato
    IAU Circular, (7678), Aug 6, 2001  Peer-reviewed
    R. Ishioka, M. Uemura, K. Matsumoto, and T. Kato, Kyoto University; K. Ayani, Bisei Astronomical Observatory (BAO); and H. Yamaoka, Kyushu University, on behalf of the VSNET collaboration team and the Variable Star Observers League in Japan, report: "WZ Sge is undergoing its first outburst since 1978 (cf. IAUC 3311), as indicated by the following visual magnitude estimates: July 23.565 UT, 9.7 (T. Ohshima, Gifu, Japan); 23.597, 9.4 (H. Itoh, Tokyo, Japan); 23.600, 9.6 (H. Maehara, Saitama, Japan); 23.622, 9.8 (T. Watanabe, Shizuoka, Japan); 23.716, 8.6 (Itoh); 23.843, 8.7. CCD time-resolved photometry at Kyoto University on July 23.6-23.8 showed a rapid brightening from mag 9.7 to 8.7 within 5 hr. Short- term modulations with timescales of 0.01-0.03 day were superimposed on the rapidly rising trend. These modulations will grow into 'early superhumps', which are observed in early stages of the outburst of WZ Sge-type stars (cf. IAUC 6164, 6517, 7552). A preliminary spectrum (range 450-670 nm) of WZ Sge on July 23.74 (taken by Ayani with the BAO 1.01-m telescope) shows H-alpha and H-beta lines in absorption on a blue continuum. This feature differs from one at 1978 outburst (Brosch et al. 1980, Ap.J. 236, L29; Oltorani et al. 1980, A.Ap. 87, 31), when the H-alpha line was observed as emission (on the day that the outburst was detected) and became stronger in its intensity with time."...
  • T. Kato, R. Ishioka, M. Uemura, K. Matsumoto, H. Ohashi, G. Masi, G.A. Good, J. Pietz, M. Moilanen
    IAU Circular, (7672), Jul 27, 2001  Peer-reviewed
    T. Kato, H. Ohashi, R. Ishioka, M. Uemura and K. Matsumoto, Kyoto University; G. Masi, Ceccano, Italy; D. Starkey, Auburn, Indiana; J. Pietz, Erftstadt, Germany; and B. Martin, The King's University College, Edmonton, Alberta, on behalf of the VSNET collaboration team, report: "Our time-resolved CCD photometry revealed that WZ Sge started to show a different type of prominent modulations (amplitude 0.10 mag) on Aug. 4.53 UT. Between Aug. 4.44 and 5.08 the oscillations had an initial period of 0.057143 +/- 0.000046 day, which is 0.8 percent longer than the orbital period (0.05669 day). Earlier observations, starting on Aug. 4.163, also showed a suggestion of the growing signal. Later observations, between Aug. 5.166 and 6.074, have shown further development of superhumps up to 0.23 mag and give a mean period of 0.058876 +/- 0.000025 day. The sharply defined profile and the period excess qualify the present variations as genuine superhumps. The superhumps developed from the secondary hump structure of the early superhumps (IAUC 7672). The 12-day delay of superhump evolution since the start of the outburst is the longest one measured among all known SU UMa-type dwarf novae. The observed delay is consistent with the earliest time of detection of a similar, but less distinct, signal during the 1978 outburst (Heiser and Henry, IBVS 1559)." H. Baba, National Astronomical Observatory of Japan; K. Sadakane, Osaka-Kyoiku University; Y. Norimoto, Okayama Astrophysical Observatory (OAO); and D. Nogami, K. Matsumoto, M. Makita and T. Kato, Kyoto University, report: "We constructed Doppler tomograms of WZ Sge using time-resolved spectra (resolution about 3000) covering two binary orbits between July 24.576 and 24.701 UT with the OAO 0.91-m telescope (IAUC 7672). The He II (468.6 nm) map shows that the emitting region on the accretion disk is elongated along the ballistic stream, which constitutes an asymmetric 'boomerang-like' one-armed spiral structure. The present observation shows the earliest detection of presence of the spiral structure of the emission line. Since Steeghs et al. (IAUC 7675) reported that the He II and C III emission lines were dominated by a two-armed spiral pattern four days after the maximum, there must have been a dramatic change in the emission pattern between our earlier observation and theirs. Such a totally unprecedented, unexpected change may be responsible for the growth of early superhumps."...
  • R. Ishioka, M. Uemura, K. Matsumoto, T. Kato, K. Ayani, H. Yamaoka
    IAU Circular, (7669), Jul 24, 2001  Peer-reviewed
  • R. Ishioka, M. Uemura, K. Matsumoto, H. Iwamatsu, T. Kato, H. Yamaoka
    GRB Coordinates Network Circulars, (902), Dec, 2000  
    ...
  • R. Ishioka, M. Uemura, T. Kato, H. Iwamatsu, K. Matsumoto, G. Billings, G. Masi, S. Kiyota
    IAU Circular, (7552), Dec, 2000  Peer-reviewed
    R. Ishioka, M. Uemura, T. Kato, H. Iwamatsu, and K. Matsumoto, Kyoto University, report on behalf of the VSNET collaboration team: "Unfiltered and V-band CCD photometry of RZ Leo (cf. IAUC 7547) since Dec. 20.37 UT by G. Billings, G. Masi, S. Kiyota, and us shows a complex feature with amplitude about 0.2 mag and period 0.07616 +/- 0.00021 day (close to the quiescent photometric period of 0.0756 +/- 0.0012 day; Mennickent et al. 1999, A.Ap. 352, 239) on Dec. 21 and 22 and a normal superhump feature (rapid rise; slower decline) with amplitude about 0.4 mag and period 0.07857 +/- 0.00022 day on Dec. 23 and 24. This suggests that the early modulations are 'early superhumps' observed in WZ Sge-type dwarf novae (cf. IAUC 6164, 6517) and current modulations are genuine superhumps."...
  • K. Matsumoto, T. Kato
    IAU Circular, (7528), Nov, 2000  Peer-reviewed
    K. Matsumoto and T. Kato, Kyoto University, report: "R-band CCD photometry using a 0.25-m telescope reveals that this recurrent nova has apparently entered the final rapid-decline stage. Nightly averaged R_c magnitudes: Nov. 19.378 UT, 13.01 +/- 0.05; 22.441, 13.68 +/- 0.28; 23.401, 15.13 +/- 0.61; 25.382, 14.48 +/- 0.28. These observations correspond to the orbital phases of 0.60, 0.51, 0.05, and 0.27, respectively, based on our refined eclipse ephemeris. The deep fading on Nov. 23 reflects the primary eclipse."...
  • M. Uemura, T. Kato, K. Matsumoto, M. Honkawa, L. Cook, B. Martin, G. Masi, A. Oksanen, M. Moilanen, R. Novak, Y. Sano, Y. Ueda
    IAU Circular, (7418), May 9, 2000  Peer-reviewed
    M. Uemura, Kyoto University, reports on behalf of the VSNET XTE J1118+480 collaboration team: "Unfiltered CCD photometry of this x-ray transient (cf. IAUC 7389) has been undertaken since Mar. 30 by numerous observers around the world (M. Uemura, T. Kato, K. Matsumoto, M. Honkawa, L. Cook, B. Martin, G. Masi, A. Oksanen, M. Moilanen, R. Novak, and Y. Sano). Analysis of the combined light curve (covering 37 days) revealed the growth of the periodic variation profile from sinusoidal to 'asymmetric humplike'. The period has significantly changed from 0.1709(3) day during Mar. 30.7-Apr. 1.4 UT to 0.1703(1) day during Apr. 26.8-May 5.7. The period change strongly suggests that the optical modulation not only reflects the orbital modulation but also shows for the first time ongoing development of superhumps in a blackhole transient (e.g., Bailyn 1992, Ap.J. 391, 298; Mineshige et al. 1992, PASJ 44, L15; O'Donoghue and Charles 1996, MNRAS 282, 191). We invite worldwide observers to join the VSNET collaboration team as part of a simultaneous multiwavelength campaign. An ASCA x-ray pointing observation (led by Y. Ueda) in the band 0.5-10 keV is planned between May 11.5 and 12.0. More detailed information can be seen at http://www.kusastro.kyoto-u.ac.jp/vsnet/Xray/xtej1118-camp.html."...
  • T. Kato, M. Uemura, K. Matsumoto, G. Masi, A. Cassetti, L. Cook, L.T. Jensen, B. Martin, T. Vanmunster, D. Buczynski
    IAU Circular, (7343), Jan 10, 2000  Peer-reviewed
    T. Kato, Kyoto University, reports on behalf of the VSNET QY Per collaboration team: ''Unfiltered CCD photometry of QY Per has been undertaken since 1999 Dec. 29.356 UT by numerous observers around the world (T. Kato, M. Uemura, K. Matsumoto, G. Masi, A. Cassetti, L. Cook, L. T. Jensen, B. Martin, T. Vanmunster, and D. Buczynski). Analysis of the combined light curve (covering 8 days) revealed the clear existence of superhumps, with an average period of 0.07861 day, including the prominent growth of superhumps starting around Dec. 29.7. The fairly long outburst interval and the long superhump period suggest that QY Per does indeed belong (cf. IAUC 7340) to a relatively rare class of long-period SU UMa- type dwarf novae. The light curve can be seen at http://www.kusastro.kyoto-u.ac.jp/vsnet/DNe/qyper.html."...
  • 松本 桂
    天文月報, 91(8) 381, Jul, 1998  Lead author
  • K. Matsumoto
    IAU Circular, (6517), Dec 9, 1996  Peer-reviewed
    K. Matsumoto, Osaka Kyoiku University, reports: "We obtained continuous CCD V-band lightcurves of EG Cnc on Dec. 2.625-2.791 UT and Dec. 3.625-3.708 UT with a 0.51-m reflector at Osaka Kyoiku University. The observed lightcurves revealed superhumps with a low (0.03-0.04 mag) amplitude. A preliminary analysis for combined lightcurves yielded a period of 0.0582 day, which is one of the shortest known among dwarf novae. The long interval since the last outburst and large amplitude (> 7 mag) of the outbursts, together with the short superhump period, support the WZ Sge-type classification for this star." Visual magnitude estimates by P. Schmeer, Bishmisheim, Germany: Dec. 2.991 UT, 11.8; 5.972, 12.8; 6.072, 12.8; 6.154, 12.8....

Books and Other Publications

 5

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 3
  • 松本 桂
    国立天文台談話会, Nov 18, 2016, 国立天文台  Invited
    OJ 287 の活動銀河核における連星ブラックホールの性質は，少なくとも過去120年間，平均すれば約12年でくりかえされている準周期的な増光の形で現れており，さらに1公転につき2回生じる熱的フレアによる極大で特徴付けられます．このような性質を説明する仮説として，Mauri Valtonen らの歳差連星ブラックホールモデルが有力視されています．これは2005年およびそれ以降の増光の時期を事前に予測できた唯一のモデルであり，OJ 287 の理論モデルにおいては増光間隔の変化を考慮する必要があることが明らかとなりました．また同モデルによると，現在の OJ 287 の公転軌道の長軸は主ブラックホールの降着円盤に対し平行に近くなっていると考えられ，熱的フレアの間隔が12年周期から大きく乖離してくる時期にあると推測されています．したがって，今後の増光時期の観測的決定は同モデルの妥当性に対する試金石となります．その一環として，2015年12月に極大を迎えると予測されたフレアの時期の検証を国際共同観測により行いました．その結果や2016年以降のことなどについて紹介します．
  • 松本 桂
    第3回美星天文台ユーザーズミーティング, Mar 3, 2002  Invited
  • 松本 桂
    第6回天体スペクトル研究会, Jun 24, 2000  Invited

Teaching Experience

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Professional Memberships

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