Publications (22)
Multiwavelength Campaign Observations of a Young Solar-type Star, EK Draconis. II. Understanding Prominence Eruption through Data-Driven Modeling and Observed Magnetic Environment
Kosuke Namekata, Kai Ikuta, Pascal Petit +15
EK Draconis, a nearby young solar-type star (G1.5V, 50-120 Myr), is known as one of the best proxies for inferring the environmental conditions of the young Sun. The star frequentl…
Rising Near-Ultraviolet Spectra in Stellar Megaflares
Adam F. Kowalski, Rachel A. Osten, Yuta Notsu +5
Flares from M-dwarf stars can attain energies up to times larger than solar flares but are generally thought to result from similar processes of magnetic energy release and…
Origin of the stellar Fe Kα line clarified with FUV and X-ray observations of a superflare on the RS Canum Venaticorum-type Star UX Arietis
Shun Inoue, Wataru Buz Iwakiri, Tomoki Kimura +11
Fluorescence line diagnostics of the Fe Kα line at keV observed in both solar and stellar flares can constrain the latitude and size of the flare loop, even in the abse…
APO & SMARTS flare star campaign observations I. Blue wing asymmetries in chromospheric lines during mid M dwarf flares from simultaneous spectroscopic and photometric observation data
Yuta Notsu, Adam F. Kowalski, Hiroyuki Maehara +12
We conducted the time-resolved simultaneous optical spectroscopic and photometric observations of mid M dwarf flare stars YZ CMi, EV Lac, and AD Leo. Spectroscopic observations wer…
Multiwavelength Campaign Observations of a Young Solar-type Star, EK Draconis. I. Discovery of Prominence Eruptions Associated with Superflares
Kosuke Namekata, Vladimir S. Airapetian, Pascal Petit +14
Young solar-type stars frequently produce superflares, serving as a unique window into the young Sun-Earth environments. Large solar flares are closely linked to coronal mass eject…
XRISM observations of solar flare X-ray emission reflected in the Earth's atmosphere
Hiromasa Suzuki, Jun Kurashima, Koji Mori +13
The X-ray Imaging and Spectroscopy Mission (XRISM), launched into low-Earth orbit in 2023, observes the reflection of solar flare X-rays in the Earth's atmosphere as a by-product o…
Systematic NICER study of the low-ionized Fe K line on RS Canum Venaticorum type stars
Shun Inoue, Teruaki Enoto, Yuta Notsu +4
The Fe K fluorescence line ( keV) has been observed during solar and stellar flares. Two emission mechanisms of the Fe K line, photoionization and collisional ion…
Multiwavelength observation of an active M-dwarf star EV Lac and its stellar flare accompanied by a delayed prominence eruption
Shun Inoue, Teruaki Enoto, Kosuke Namekata +9
We conducted 4-night multiwavelength observations of an active M-dwarf star EV Lac on 2022 October 2427 with simultaneous coverage of soft X-rays (NICER; 0.212 …
High-Resolution Modelling of Coronae and Winds in Solar-type Stars with Varying Rotation Rates I. X-ray Coronae
Yue-Hong Chen, Julián D. Alvarado-Gómez, Xin Cheng +8
Stellar coronae are believed to be the main birthplace of various stellar magnetic activities. However, the structures and properties of stellar coronae remain poorly understood. U…
A long-duration superflare on the K giant HD 251108
Hans Moritz Günther, Dheeraj Pasham, Alexander Binks +10
Many giant stars are magnetically active, which causes rotational variability, chromospheric emission lines, and X-ray emission. Large outbursts in these emission features can set…
High Spectral Resolution X-ray Observations of the Evolved Supermassive Stellar Binary System Carinae - Iron K Band Profile Revealed with XRISM
XRISM Collaboration, Marc Audard, Hisamitsu Awaki +138
The supermassive binary system, Carinae, is experiencing enormous wind-driven mass loss at a rate unparalleled in the rest of the Galaxy. Their wind-wind collision (WWC) conti…
Detection of extended X-ray emission around the PeVatron microquasar V4641 Sgr with XRISM
Hiromasa Suzuki, Naomi Tsuji, Yoshiaki Kanemaru +26
A recent report on the detection of very-high-energy gamma rays from V4641 Sagittarii (V4641 Sgr) up to ~0.8 peta-electronvolt has made it the second confirmed "PeVatron" microquas…
XRISM view of a stellar flare: High-resolution Fe K spectra of HR 1099, an RS CVn-type star
Miki Kurihara, Masahiro Tsujimoto, Michael Loewenstein +21
A high-resolution X-ray spectroscopic observation was made of the RS CVn-type binary star HR 1099 using the Resolve instrument onboard XRISM for its calibration purposes. During th…
Fe Kα equivalent-width mapping with 3D radiative transfer calculation: A general model and application to the RS Canum Venaticorum-type stars with XRISM/Resolve
Shun Inoue, Masahiro Tsujimoto, Takayuki Hayashi +4
The Fe K fluorescence line at 6.4 keV has long been used to probe the relative geometry between photoionizing X-ray sources and surrounding cold material in a wide range of as…
High-velocity blue-shifted Fe XXV He line during a superflare of the RS CVn-type star IM Peg
Shun Inoue, Wataru Buz Iwakiri, Teruaki Enoto +8
Monitor of All-sky X-ray Image (MAXI) detected a superflare, releasing erg in 210 keV, of the RS CVn-type star IM Peg at 10:41 UT on 2023 July 23 with its Gas…
In-orbit Performance of the Soft X-ray Imaging Telescope Xtend aboard XRISM
Hiroyuki Uchida, Koji Mori, Hiroshi Tomida +62
We present a summary of the in-orbit performance of the soft X-ray imaging telescope Xtend onboard the XRISM mission, based on in-flight observation data, including first-light cel…
Defect-Mediated Aggregation and Motility-Induced Phase Separation in Self-Propelled Lattice-Gas Active XY Model
Shun Inoue, Satoshi Yukawa
We propose an ``active XY model'' that incorporates key elements of both the classical XY model and the Vicsek model to study the role of topological defects in active matter syste…
Initial operations of the Soft X-ray Imager onboard XRISM
Hiromasa Suzuki, Tomokage Yoneyama, Shogo B. Kobayashi +52
XRISM (X-Ray Imaging and Spectroscopy Mission) is an astronomical satellite with the capability of high-resolution spectroscopy with the X-ray microcalorimeter, Resolve, and wide f…
Detection of a high-velocity prominence eruption leading to a CME associated with a superflare on the RS CVn-type star V1355 Orionis
Shun Inoue, Hiroyuki Maehara, Yuta Notsu +5
Stellar coronal mass ejections (CMEs) have recently received much attention for their impacts on exoplanets and stellar evolution. Detecting prominence eruptions, the initial phase…
Status of Xtend telescope onboard X-Ray Imaging and Spectroscopy Mission (XRISM)
Koji Mori, Hiroshi Tomida, Hiroshi Nakajima +59
Xtend is one of the two telescopes onboard the X-ray imaging and spectroscopy mission (XRISM), which was launched on September 7th, 2023. Xtend comprises the Soft X-ray Imager (SXI…
Eclipsing Stellar Flare on the Demon Star Algol Binary System Observed during the MAXI-NICER Follow-up Campaign in 2018
Kazuya Nakayama, Wataru Buz Iwakiri, Teruaki Enoto +6
Algol is a well-known eclipsing binary hosting an active and variable star that exhibits frequent stellar flares. Here, we report our pre-planned and coordinated rapid X-ray follow…
Soft X-ray Imager of the Xtend system onboard XRISM
Hirofumi Noda, Koji Mori, Hiroshi Tomida +57
The Soft X-ray Imager (SXI) is the X-ray charge-coupled device (CCD) camera for the soft X-ray imaging telescope Xtend installed on the X-ray Imaging and Spectroscopy Mission (XRIS…