Search Publications
Zone of Preferential Heating for Minor Ions in the Solar Wind
Klein, Kristopher G.; Kasper, Justin; Lepri, Susan T. +2 more
The properties of minor ions in the solar wind are important indicators of the state of the solar corona and the heating processes it undergoes as it expands. Evidence of preferential heating of minor ions has been observed in the solar wind, and is believed to be active up to a certain radial boundary, beyond which thermalization due to Coulomb c…
Reevaluating the Origin of Detectable Cataclysmic Variables in Globular Clusters: Testing the Importance of Dynamics
Belloni, Diogo; Rivera Sandoval, Liliana; Ramos Arevalo, Miriam
Based on the current detectable cataclysmic variable (CV) population in Galactic globular clusters (GCs), we show that there is not a clear relation between the number of sources per unit of mass and the stellar encounter rate, the cluster mass, or the cluster central density. If any, only in the case of core-collapsed GCs could there be an antico…
Phase-dependent Spectral Shape Changes in the Ultraluminous X-Ray Pulsar NGC 5907 ULX1
Yamaguchi, Hiroya; Kobayashi, Shogo B.; Miura, Daiki
The discovery of coherent pulsations from several ultraluminous X-ray pulsars (ULXPs) has provided direct evidence of a supercritical accretion flow. However, the geometrical structure of such an accretion flow onto the central neutron star remains poorly understood. NGC 5907 ULX1 is one of the most luminous ULXPs, with a luminosity exceeding 10
Absolute Dimensions of the Interferometric Binary HD 174881: A Test of Stellar Evolution Models for Evolved Stars
Torres, Guillermo; Monnier, John D.; van Belle, Gerard T. +1 more
We report high-resolution spectroscopic monitoring and long-baseline interferometric observations with the Palomar Testbed Interferometer (PTI) of the 215 day binary system HD 174881 (K1 II-III), composed of two giant stars. The system is spatially resolved with the PTI, as well as in archival measurements with the CHARA Array. Our analysis of the…
The Magnetic Field in Quiescent Star-forming Filament G16.96+0.27
Pattle, Kate; Sanhueza, Patricio; Kwon, Woojin +20 more
We present 850 µm thermal dust polarization observations with a resolution of 14.″4 (∼0.13 pc) toward an infrared dark cloud G16.96+0.27 using James Clerk Maxwell Telescope/POL-2. The average magnetic field orientation, which roughly agrees with the larger-scale magnetic field orientation traced by the Planck 353 GHz data, is approximately p…
A Model of the C IV λ λ1548, 1550 Doublet Line in T Tauri Stars
France, Kevin; Calvet, Nuria; Espaillat, Catherine C. +7 more
The C IV doublet in the UV has long been associated with accretion in T Tauri stars. However, it is still unclear where and how the lines are formed. Here, we present a new C IV line model based on the currently available accretion shock and accretion flow models. We assume axisymmetric, dipolar accretion flows with different energy fluxes and cal…
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 …