Search Publications
Determination of Sodium Abundance Ratio from Low-resolution Stellar Spectra and Its Applications
Koo, Jae-Rim; Beers, Timothy C.; Lee, Young Sun +2 more
We present a method to determine sodium abundance ratios ([Na/Fe]) using the Na I D doublet lines in low-resolution (R ~ 2000) stellar spectra. As stellar Na I D lines are blended with those produced by the interstellar medium, we developed a technique for removing the interstellar Na I D lines using the relationship between extinction, which is p…
Contribution of Spicules to Solar Coronal Emission
Klimchuk, James A.; Sarkar, Aveek; Sow Mondal, Shanwlee
Recent high-resolution imaging and spectroscopic observations have generated renewed interest in spicules' role in explaining the hot corona. Some studies suggest that some spicules, often classified as type II, may provide significant mass and energy to the corona. Here we use numerical simulations to investigate whether such spicules can produce…
Kinematical Analysis of Substructure in the Southern Periphery of the Large Magellanic Cloud
Monachesi, Antonela; Choi, Yumi; Majewski, Steven R. +10 more
We report the first 3D kinematical measurements of 88 stars in the direction of several recently discovered substructures in the southern periphery of the Large Magellanic Cloud (LMC) using a combination of Gaia proper motions and radial velocities from the APOGEE-2 survey. More specifically, we explore stars in assorted APOGEE-2 pointings in a re…
Radiative Magnetohydrodynamic Simulation of the Confined Eruption of a Magnetic Flux Rope: Magnetic Structure and Plasma Thermodynamics
Ding, Mingde; Chen, Feng; Wang, Can +1 more
It is widely believed that magnetic flux ropes are the key structure of solar eruptions; however, their observable counterparts are not clear yet. We study a flare associated with flux rope eruption in a comprehensive radiative magnetohydrodynamic simulation of flare-productive active regions, especially focusing on the thermodynamic properties of…
Could the Magnetic Star HD 135348 Possess a Rigidly Rotating Magnetosphere?
Gagliano, Robert; Jayaraman, Rahul; Ricker, George R. +5 more
We report the detection and characterization of a new magnetospheric star, HD 135348, based on photometric and spectropolarimetric observations. The TESS light curve of this star exhibited variations consistent with stars known to possess rigidly rotating magnetospheres (RRMs), so we obtained spectropolarimetric observations using the Robert Stobi…
Luminosity Function and Event Rate Density of XMM-Newton-selected Supernova Shock Breakout Candidates
Liu, Zhu; Yuan, Weimin; Sun, Hui +6 more
A dozen X-ray supernova shock breakout (SN SBO) candidates were reported recently based on XMM-Newton archival data, which increased the X-ray-selected SN SBO sample by an order of magnitude. Assuming that they are genuine SN SBOs, we study the luminosity function (LF) by improving on the method used in our previous work. The light curves and the …
Light from the Darkness: Detecting Ultra-diffuse Galaxies in the Perseus Cluster through Over-densities of Globular Clusters with a Log-Gaussian Cox Process
van Dokkum, Pieter; Romanowsky, Aaron J.; Abraham, Roberto +6 more
We introduce a new method for detecting ultra-diffuse galaxies by searching for over-densities in intergalactic globular cluster populations. Our approach is based on an application of the log-Gaussian Cox process, which is a commonly used model in the spatial statistics literature but rarely used in astronomy. This method is applied to the globul…
The Solar Wind Parker Spiral Angle Distributions and Variations at 1 au
Xu, Qi; Xu, Xiaojun; Wang, Jing +8 more
Using the data from the Advanced Composition Explorer (ACE) and Wind spacecraft, we statistically studied the Parker spiral angle (PSA) of the solar wind magnetic field from 1998 to 2019 at 1 au. The PSA occurrences over both a Carrington rotation (CR) and a year can be well fitted by a Gaussian distribution. However, large-scale magnetic structur…
Searching Extra-tidal Features around the Globular Cluster Whiting 1
Tian, Haijun; Tian, Hao; Carballo-Bello, Julio A. +14 more
Whiting 1 is a faint and young globular cluster in the halo of the Milky Way, and was suggested to have originated in the Sagittarius spherical dwarf galaxy (Sgr dSph). In this paper, we use the deep DESI Legacy Imaging Surveys to explore tentative spatial connection between Whiting 1 and the Sgr dSph. We redetermine the fundamental parameters of …
The Astrometric Animation of Water Masers toward the Mira Variable BX Cam
Kim, Dong-Jin; Sun, Yan; Orosz, Gabor +20 more
We report very long baseline interferometry (VLBI) monitoring observations of the 22 GHz water (H2O) masers around the Mira variable BX Cam, which were carried out as a part of the EAVN Synthesis of Stellar Maser Animations project. Data of 37 epochs in total were obtained from 2018 May to 2021 June with a time interval of 3-4 weeks, sp…