492 citations · 1.1k across the 16 of their papers we have counts for
16 papers
SN 2020uem: A Possible Thermonuclear Explosion within A Dense Circumstellar Medium (II) The Properties of The CSM from Polarimetry and Light Curve Modeling
Kohki Uno, Takashi Nagao, Keiichi Maeda +11
Type IIn/Ia-CSM supernovae (SNe IIn/Ia-CSM) are classified by their characteristic spectra, which exhibit narrow hydrogen emission lines originating from a strong interaction with…
SN 2020uem: A Possible Thermonuclear Explosion within A Dense Circumstellar Medium (I) The Nature of Type IIn/Ia-CSM SNe from Photometry and Spectroscopy
Kohki Uno, Keiichi Maeda, Takashi Nagao +18
We have performed intensive follow-up observations of a Type IIn/Ia-CSM SN (SN IIn/Ia-CSM), 2020uem, with photometry, spectroscopy, and polarimetry. In this paper, we report on the…
Calcium-rich Transient SN 2019ehk in A Star-Forming Environment: Yet Another Candidate for An Ultra-Stripped Envelope Supernova
Tatsuya Nakaoka, Keiichi Maeda, Masayuki Yamanaka +20
We present optical and near-infrared observations of SN~Ib~2019ehk. We show that it evolved to a Ca-rich transient according to its spectral properties and evolution in late phases…
SN 2018hna: 1987A-like supernova with a signature of shock breakout
Avinash Singh, D. K. Sahu, G. C. Anupama +22
High cadence ultraviolet, optical and near-infrared photometric and low-resolution spectroscopic observations of the peculiar Type II supernova (SN) 2018hna are presented. The earl…
Type Ia SN 2019ein: New Insights into the Similarities and diversities among High-Velocity SNe Ia
Miho Kawabata, Keiichi Maeda, Masayuki Yamanaka +38
We present optical observations of type Ia supernova (SN) 2019ein, starting at 2 days after the estimated explosion date. The spectra and the light curves show that SN 2019ein belo…
Multi-band polarization of Type IIP supernovae due to light echo from circumstellar dust
Takashi Nagao, Keiichi Maeda, Masaomi Tanaka
Type IIP supernovae (SNe IIP) often show relatively high continuum polarization (\%) in the late phase. This polarization feature is generally believed to be due to an inne…
Polarization as a probe of dusty environments around Type Ia supernovae: radiative transfer models for SN 2012dn
Takashi Nagao, Keiichi Maeda, Masayuki Yamanaka
Geometry of circumstellar (CS) medium around supernovae (SNe) provides important diagnostics to understand the nature of their progenitors. In this paper, properties of CS dust aro…
Circumstellar Light Echo as a Possible Origin of the Polarization of Type IIP Supernovae
Takashi Nagao, Keiichi Maeda, Masaomi Tanaka
Type IIP supernovae (SNe IIP) are the most common class of core-collapse SNe. They often show rapid increase of polarization degree in the late phase. This time evolution is genera…
The origin of the near-infrared excess in SN Ia 2012dn: Circumstellar dust around the super-Chandrasekhar supernova candidate
Takashi Nagao, Keiichi Maeda, Masayuki Yamanaka
The nature of progenitors of the so-called super-Chandrasekhar candidate Type Ia supernovae (SC-SNe Ia) has been actively debated. Recently, Yamanaka et al. (2016) reported a near-…
OISTER Optical and Near-Infrared Observations of the Super-Chandrasekhar Supernova Candidate SN 2012dn: Dust Emission from the Circumstellar Shell
Masayuki Yamanaka, Keiichi Maeda, Masaomi Tanaka +34
We present extensively dense observations of the super-Chandrasekhar supernova (SC SN) candidate SN 2012dn from to days after the date of its -band maximum in the o…
Extinction Laws toward Stellar Sources within a Dusty Circimstellar Medium and Implications for Type Ia Supernovae
T. Nagao, K. Maeda, T. Nozawa
Many astronomical objects are surrounded by dusty environments. In such dusty objects, multiple scattering processes of photons by circumstellar (CS) dust grains can effectively al…
Constraining the Amount of Circumstellar Matter and Dust around Type Ia Supernovae through Near-Infrared Echoes
Keiichi Maeda, Takaya Nozawa, Takashi Nagao +1
The circumstellar (CS) environment is key to understanding progenitors of type Ia supernovae (SNe Ia), as well as the origin of a peculiar extinction property toward SNe Ia for cos…
Superflares on Solar Type Stars Observed with Kepler I. Statistical Properties of Superflares
Takuya Shibayama, Hiroyuki Maehara, Shota Notsu +6
By extending our previous study by Maehara et al. (2012), we searched for superflares on G-type dwarfs (solar type stars) using Kepler data for a longer period (500 days) than that…
High Dispersion Spectroscopy of the Superflare Star KIC6934317
Shota Notsu, Satoshi Honda, Yuta Notsu +5
We conducted the high-resolution spectroscopic observation with Subaru/HDS for a G-type star (KIC6934317). We selected this star from the data of the Kepler spacecraft. This star p…
Superflares on Solar-Type Stars Observed with Kepler II. Photometric Variability of Superflare-Generating Stars : A Signature of Stellar Rotation and Starspots
Yuta Notsu, Takuya Shibayama, Hiroyuki Maehara +6
We performed simple spot-model calculations for quasi-periodic brightness variations of solar-type stars showing superflares, by using Kepler photometric data. Most of superflare s…
Can Superflares Occur on Our Sun?
Kazunari Shibata, Hiroaki Isobe, Andrew Hillier +9
Recent observations of solar type stars with the Kepler satellite by Maehara et al. have revealed the existence of superflares (with energy of 10^33 - 10^35 erg) on Sun-like stars,…