Search Publications
Estimating Ion Temperatures at the Polar Coronal Hole Boundary
Landi, Enrico; Zhu, Yingjie; Szente, Judit
The temperatures of the heavy ions (T i ) in the solar corona provide critical information about the heating mechanism of the million-degree corona. However, the measurement of T i is usually challenging due to the nonthermal motion, instrumental limitations, and optically thin nature of the coronal emissions. We present t…
Ba-enhanced Dwarf and Subgiant Stars in the LAMOST Galactic Surveys
Xiang, Maosheng; Ting, Yuan-Sen; Zhang, Meng +3 more
Ba-enhanced stars are interesting probes of stellar astrophysics and Galactic formation history. In this work, we investigate the chemistry and kinematics of a large sample of Ba-enhanced ([Ba/Fe]>1.0) dwarf and subgiant stars with 5000 < T eff < 6700 K from LAMOST. We find that both stellar internal evolution processes and ext…
The Search for Thermonuclear Transients from the Tidal Disruption of a White Dwarf by an Intermediate-mass Black Hole
Gezari, Suvi; Gomez, Sebastian
The close encounter of a white dwarf (WD) with a black hole (BH) could result in the tidal disruption of the WD. During this encounter, the WD can undergo a thermonuclear explosion due to its tidal compression, resulting in an optical transient similar to a Type Ia supernova, hereafter a Ia-TDE. Nevertheless, this will only be physically observabl…
DiskMINT: A Tool to Estimate Disk Masses with CO Isotopologues
Pascucci, Ilaria; Gorti, Uma; Ruaud, Maxime +1 more
CO is one of the most abundant molecules in protoplanetary disks, and optically thin emission from its isotopologues has been detected in many of them. However, several past works have argued that reproducing the relatively low emission of CO isotopologues requires a very low disk mass or significant CO depletion. Here, we present a Python code, D…
Accretion-modified Stars in Accretion Disks of Active Galactic Nuclei: The Low-luminosity Cases and an Application to Sgr A*
Ho, Luis C.; Wang, Jian-Min; Li, Yan-Rong +3 more
In this paper, we investigate the astrophysical processes of stellar-mass black holes (sMBHs) embedded in advection-dominated accretion flows (ADAFs) of supermassive black holes (SMBHs) in low-luminosity active galactic nuclei. The sMBH is undergoing Bondi accretion at a rate lower than the SMBH. Outflows from the sMBH-ADAF dynamically interact wi…
Theoretical Light-curve Models of the Symbiotic Nova CN Cha-Optical Flat Peak for 3 Yr
Kato, Mariko; Hachisu, Izumi
CN Cha is a slow symbiotic nova characterized by a 3 yr long optical flat peak followed by a rapid decline. We present theoretical light curves for CN Cha, based on hydrostatic approximation, and estimate the white-dwarf (WD) mass to be ~0.6 M ⊙ for a low metal abundance of Z = 0.004. These kinds of flat-peak novae are border objects be…
Extreme Red-wing Enhancements of UV Lines during the 2022 March 30 X1.3 Solar Flare
Polito, Vanessa; Xu, Yan; Jing, Ju +3 more
Here, we present the study of a compact emission source during an X1.3 flare on 2022 March 30. Within a ~41 s period (17:34:48 UT to 17:35:29 UT), Interface Region Imaging Spectrograph observations show spectral lines of Mg II, C II, and Si IV with extremely broadened, asymmetric red wings. This source of interest (SOI) is compact, ~1.″6, and is l…
Kinetic Features of Alpha Particles in a Pestchek-like Magnetic Reconnection Event in the Solar Wind Observed by Solar Orbiter
Verscharen, Daniel; He, Jiansen; Fedorov, Andrey +10 more
The acceleration and heating of solar wind particles by magnetic reconnection are important mechanisms in space physics. Although alpha particles (4He2+) are the second most abundant population of solar wind ions, their kinetic behavior in solar wind magnetic reconnection is not well understood. Using the high-energy (1500-30…
Spatial Evolution of 20 MeV Solar Energetic Proton Events
Kahler, S. W.; Reames, D. V.; Ling, A. G.
The longitudinal extents of solar energetic (E > 10 MeV) particle (SEP) events in the heliosphere are a characteristic important for understanding SEP acceleration and transport as well as their space weather effects. SEP detectors on the STEREO A and B spacecraft launched in 2008, combined with those on Earth-orbiting spacecraft, have enabled …
Absorption-line Observations of {{H}}_{3}(+) and CO in Sight Lines Toward the Vela and W28 Supernova Remnants
Indriolo, Nick
Supernova remnants act as particle accelerators, providing the cosmic-ray protons that permeate the interstellar medium and initiate the ion-molecule reactions that drive interstellar chemistry. Enhanced fluxes of cosmic-ray protons in close proximity to supernova remnants have been inferred from observations tracing particle interactions with nea…