Search Publications
Measurements of Sunspot Group Tilt Angles Based on SOHO/MDI and SDO/HMI Magnetograms
Zeng, Xiang-Yun; Zheng, Sheng; Huang, Yao +4 more
The tilt angle of sunspot groups plays a crucial role in solar dynamo models for the generation of the poloidal field, yet the statistical properties of the tilt angle are not fully comprehended. This study employs magnetograms from the Solar and Heliospheric Observatory/Michelson Doppler Imager and Solar Dynamics Observatory/Helioseismic and Magn…
Mid-term Periodicity of Coronal Mass Ejections during the Time Interval 1996–2022
Mei, Ying; Wang, Feng; Deng, Hui +3 more
Coronal mass ejections (CMEs) exhibit a wide range of quasiperiodic variations and are crucial for our understanding of the cyclical evolution of large-scale magnetic fields. However, the mid-term periodicities of different types of CMEs associated with different processes at the source location need to be clearly understood. Based on the CDAW cat…
BD+44°493: Chemo-dynamical Analysis and Constraints on Companion Planetary Masses from WIYN/NEID Spectroscopy
Placco, Vinicius M.; Logsdon, Sarah E.; Holmbeck, Erika M. +11 more
In this work, we present high-resolution (R ∼ 100,000), high signal-to-noise ratio (S/N ∼ 800) spectroscopic observations for the well-known, bright, extremely metal-poor, carbon-enhanced star BD+44°493. We determined chemical abundances and upper limits for 17 elements from WIYN/NEID data, complemented with 11 abundances redetermined from Subaru …
A Far-ultraviolet-detected Accretion Shock at the Star–Disk Boundary of FU Ori
Herczeg, Gregory J.; France, Kevin; Hillenbrand, Lynne A. +1 more
FU Ori objects are the most extreme eruptive young stars known. Their 4–5 mag photometric outbursts last for decades and are attributed to a factor of up to 10,000 increase in the stellar accretion rate. The nature of the accretion disk-to-star interface in FU Ori objects has remained a mystery for decades. To date, attempts to directly observe a …
SCExAO/CHARIS Spectroscopic Characterization of Cloudy L/T Transition Companion Brown Dwarf HIP 93398 B
Jensen-Clem, Rebecca; Salama, Maïssa; Lewis, Briley L. +10 more
Brown dwarfs with measured dynamical masses and spectra from direct imaging are benchmarks that anchor substellar atmosphere cooling and evolution models. We present Subaru SCExAO/CHARIS infrared spectroscopy of HIP 93398 B, a brown dwarf companion recently discovered by Y. Li et al. (2023), as part of an informed survey using the Hipparcos–Gaia C…
Near-infrared Spectroscopy for Remote Sensing of Porosity, Density, and Cubicity of Crystalline and Amorphous H2O Ices in Astrophysical Environments
Tonauer, Christina M.; Köck, Eva-Maria; Henn, Raphael +8 more
We present laboratory spectra of pure amorphous and crystalline H2O ices in the near-infrared (NIR, 1–2.5 µm/10,000–4000 cm‑1) at 80–180 K. The aim of this study is to provide spectroscopic reference data that allow remotely accessing ice properties for icy objects such as icy moons, cometary ice, or Saturn rings. Speci…
Evidence for Type Ib/c Origin of the Supernova Remnant G292.0+1.8
Katsuda, Satoru; Sato, Toshiki; Uchida, Hiroyuki +6 more
Circumstellar material (CSM) produced by mass loss from massive stars (≳10 M ⊙) through strong stellar winds or binary stripping provides rich information for understanding progenitors of core-collapse supernova remnants. In this paper we present a grating spectroscopy of a Galactic SNR G292.0+1.8, which is claimed to be a Type Ib/c rem…
Probing Velocity Dispersion Inside Coronal Mass Ejections: New Insights on Their Initiation
Mierla, Marilena; Reiss, Martin A.; Banerjee, Dipankar +4 more
This work studies the kinematics of the leading edge and the core of six coronal mass ejections (CMEs) in the combined field of view of Sun Watcher using Active Pixel System detector and Image Processing (SWAP) on board PRoject for On-Board Autonomy (PROBA-2) and the ground-based K-Cor coronagraph of the Mauna Loa Solar Observatory. We report, for…
Radial Distribution of Electron Quasi-thermal Noise in the Inner Heliosphere
Chen, Ling; Li, Yi-Lun; Wu, De-Jin
The electron population in the solar wind plasma can be described with three different components: a core, a halo, and a magnetic field aligned strahl. The electron quasi-thermal noise (QTN) is investigated by using an electron population model consisting of a core with a Maxwellian distribution and a halo with a kappa distribution, based on the e…
Soft X-Ray Energy Spectra in the Wide-field Galactic Disk Area Revealed with HaloSat
Kaaret, Philip; Angelini, Lorella; Mitsuishi, Ikuyuki +3 more
We analyzed data from HaloSat observations for five fields in the Galactic disk located far away from the Galactic center (135° < l < 254°) to understand the nature of soft X-ray energy emission in the Galactic disk. The fields have 14° diameter and were selected to contain no significant high-flux X-ray sources. All five HaloSat soft X-ray …