144 citations · 1.1k across the 67 of their papers we have counts for
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Conspicuous Gas, Cryptic Dust: Spectroscopy and Chromaticity of Complex Periodic Variables
Luke G. Bouma, Facundo Perez Paolino, Lynne A. Hillenbrand +17
Complex periodic variables (CPVs) are young low-mass stars whose light curves show periodic dips indicative of transiting corotating material. The origin and composition of this ma…
Spectral evolution of the narrow emission line components in optical during the 2022 nova eruption of U Scorpii
Katsuki Muraoka, Naoto Kojiguchi, Junpei Ito +20
There remains debate over whether the accretion disk survives or is entirely disrupted after the nova eruption. In our previous paper, Muraoka et al. (2024, PASJ, 76, 293) have pho…
Smart Kanata: A Framework for Autonomous Decision Making in Rapid Follow-up Observations of Cataclysmic Variables
Makoto Uemura, Yuzuki Koga, Ryosuke Sazaki +11
Studying the early stages of transient events provides crucial information about the fundamental physical processes in cataclysmic variables (CVs). However, determining an appropri…
MASTER OT J030227.28+191754.5: an unprecedentedly energetic dwarf nova outburst
Yusuke Tampo, Taichi Kato, Keisuke Isogai +60
We present a detailed study of the MASTER OT J030227.28+191754.5 outburst in 2021-2022, reaching an amplitude of 10.2 mag and a duration of 60 d. The detections of (1) the double-p…
Optical and soft X-ray light-curve analysis during the 2022 eruption of U Scorpii: structural changes in the accretion disk
Katsuki Muraoka, Naoto Kojiguchi, Junpei Ito +52
We present our optical photometric observations of the 2022 eruption of the recurrent nova U Scorpii (U Sco) using 49,152 data points over 70 d following the optical peak. We have…
Spectra of V1405 Cas at the very beginning indicate a low-mass ONeMg white dwarf progenitor
Kenta Taguchi, Keiichi Maeda, Hiroyuki Maehara +9
The lowest possible mass of ONeMg white dwarfs (WDs) has not been clarified despite its importance in the formation and evolution of WDs. We tackle this issue by studying the prope…
PNV J00444033+4113068: early superhumps with 0.7 mag amplitude and non-red color
Yusuke Tampo, Keisuke Isogai, Naoto Kojiguchi +13
In the first days of WZ Sge-type dwarf nova (DN) outbursts, the 2:1 resonance induces a spiral arm structure in the accretion disk, which is observed as early superhumps in optical…
TESS Hunt for Young and Maturing Exoplanets (THYME) VII : Membership, rotation, and lithium in the young cluster Group-X and a new young exoplanet
Elisabeth R. Newton, Rayna Rampalli, Adam L. Kraus +36
The public, all-sky surveys Gaia and TESS provide the ability to identify new young associations and determine their ages. These associations enable study of planetary evolution by…
Discovery of a Long-Duration Superflare on a Young Solar-Type Star EK Draconis with Nearly Similar Time Evolution for H and White-Light Emissions
Kosuke Namekata, Hiroyuki Maehara, Satoshi Honda +17
Young solar-type stars are known to show frequent "superflares", which may severely influence the habitable worlds on young planets via intense radiations and coronal mass ejection…
Probable detection of an eruptive filament from a superflare on a solar-type star
Kosuke Namekata, Hiroyuki Maehara, Satoshi Honda +20
Solar flares are often accompanied by filament/prominence eruptions ( K and cm), sometimes leading to coronal mass ejections (CMEs) that direct…
On the nature of the anomalous event in 2021 in the dwarf nova SS Cygni and its multi-wavelength transition
Mariko Kimura, Shinya Yamada, Nozomi Nakaniwa +20
SS Cyg has long been recognized as the prototype of a group of dwarf novae that show only outbursts. However, this object has entered a quite anomalous event in 2021, which at firs…
BO Ceti: Dwarf Nova Showing Both IW And and SU UMa-Type Features
Taichi Kato, Yusuke Tampo, Naoto Kojiguchi +13
IW And stars are a recently recognized subgroup of dwarf novae which are characterized by (often repetitive) slowly rising standstills terminated by brightening, but the exact mech…
Spectroscopic and Photometric Observations of Dwarf Nova Superoutbursts by the 3.8 m Telescope Seimei and the Variable Star Network
Yusuke Tampo, Keisuke Isogai, Naoto Kojiguchi +59
We present spectroscopic and photometric observations of 17 dwarf-nova superoutbursts obtained by KOOLS-IFU mounted on the 3.8 m telescope Seimei at Okayama Observatory of Kyoto Un…
ASASSN-18aan: An Eclipsing SU UMa-type Cataclysmic Variable with a 3.6-hour Orbital Period and a Late G-type Secondary Star
Yasuyuki Wakamatsu, John R. Thorstensen, Naoto Kojiguchi +41
We report photometric and spectroscopic observations of the eclipsing SU UMa-type dwarf nova ASASSN-18aan. We observed the 2018 superoutburst with 2.3 mag brightening and found the…
Multi-wavelength photometry during the 2018 superoutburst of the WZ Sge-type dwarf nova EG Cancri
Mariko Kimura, Keisuke Isogai, Taichi Kato +45
We report on the multi-wavelength photometry of the 2018 superoutburst in EG Cnc. We have detected stage A superhumps and long-lasting late-stage superhumps via the optical photome…
Optical and X-ray observations of stellar flares on an active M dwarf AD Leonis with Seimei Telescope, SCAT, NICER and OISTER
Kosuke Namekata, Hiroyuki Maehara, Ryo Sasaki +24
We report multi-wavelength monitoring observations of an M-dwarf flare star AD Leonis with Seimei Telescope (6150--7930 Å), SCAT (Spectroscopic Chuo-university Astronomical Telesco…
First Detection of Two Superoutbursts during Rebrightening Phase of a WZ Sge-type Dwarf Nova: TCP J21040470+4631129
Yusuke Tampo, Kojiguchi Naoto, Keisuke Isogai +51
We report photometric and spectroscopic observations and analysis of the 2019 superoutburst of TCP J21040470+4631129. This object showed a 9-mag superoutburst with early superhumps…
IW And-Type State in IM Eridani
Taichi Kato, Yasuyuki Wakamatsu, Naoto Kojiguchi +20
IW And stars are a recently recognized group of dwarf novae which are characterized by a repeated sequence of brightening from a standstill-like phase with damping oscillations fol…
ASASSN-18fk: A new WZ Sge-type dwarf nova with multiple rebrightenings and a new candidate for a superhumping intermediate polar
E. Pavlenko, K. Niijima, P. Mason +23
We present the result of a multi-longitude campaign on the photometric study of the dwarf nova ASASSN-18fk during its superoutburst in 2018. It was observed with 18 telescopes at 1…
NSV 1440: First WZ Sge-type Object in AM CVn stars and candidates
Keisuke Isogai, Taichi Kato, Berto Monard +5
In 2015 and 2017, the AM CVn candidate NSV 1440 showed superoutbursts having the characteristic features of WZ Sge-type dwarf novae (DNe). By analogy with hydrogen-rich cataclysmic…
Discovery of Standstills in the SU UMa-Type Dwarf Nova NY Serpentis
Taichi Kato, Elena P. Pavlenko, Nikolaj V. Pit +40
We found that the SU UMa-type dwarf nova NY Ser in the period gap [orbital period 0.097558(6) d] showed standstills twice in 2018. This is the first clear demonstration of a stands…
Third Nearest WZ Sge-Type Dwarf Nova candidate ASASSN-14dx Classified on the Basis of Gaia Data Release 2
Keisuke Isogai, Taichi Kato, Akira Imada +8
ASASSN-14dx showed an extraordinary outburst whose features are the small outburst amplitude (~ 2.3 mag) and long duration (> 4 years). Because we found a long observational gap of…
OAO/MITSuME Photometry of Dwarf Novae. III. CSS130418:174033+414756
Akira Imada, Keisuke Isogai, Kenshi Yanagisawa +1
We report on multicolour photometry of the short period dwarf nova CSS130418:174033+414756 during the 2013 superoutburst. The system showed an unusually short superhump period with…
ASASSN-16dt and ASASSN-16hg: Promising Candidates for a Period Bouncer
Mariko Kimura, Keisuke Isogai, Taichi Kato +13
We present optical photometry of superoutbursts in 2016 of two WZ Sge-type dwarf novae (DNe), ASASSN-16dt and ASASSN-16hg. Their light curves showed a dip in brightness between the…