Search Publications
Carbon Abundance of Globular Cluster M22 (NGC 6656) and the Surface Carbon Depletion Rates of the Milky Way Globular Clusters
Lee, Jae-Woo
It is well known that metal-poor red giant branch (RGB) stars show variations in some elemental abundances, including carbon, due to the internal mixing accompanied by their own in situ CN cycle in the hydrogen burning shell. With our new photometric carbon abundance measurements of RGB stars in M22 and other globular clusters (GCs) in our previou…
High-resolution Observations of Plume Footpoints in a Solar Coronal Hole
Cao, Wenda; Yurchyshyn, Vasyl; Madjarska, Maria S. +7 more
Plumes are bright structures in coronal holes extending from the solar surface into the corona and are considered as a possible source of the solar wind. Plumes are thought to be rooted in strong unipolar photospheric flux patches (network/plage region). The magnetic activities at the base of plumes may play a crucial role in producing outflows an…
White Dwarf Photospheric Abundances in Cataclysmic Variables. III. Five Dwarf Novae with an Evolved Secondary Donor Star
Sion, Edward M.; Godon, Patrick
In the last two decades infrared spectroscopy has brought mounting evidence, in the form of weak CO features together with enhanced 13C, of the presence of CNO-processed material in the atmosphere of the donor star of some nonmagnetic cataclysmic variables. Some of these donors also exhibit a temperature too high for their binary orbita…
A New Tool for Understanding the Solar Wind-Venus Interaction: Three-dimensional Multifluid MHD Model
Zhang, Tielong; Yao, Zhonghua; Dang, Tong +5 more
In this paper, we present a new tool to investigate the interaction of the solar wind with Venus with the approach of a global multifluid magnetohydrodynamics (MHD) model. The continuity, momentum, and energy equations for H+, O+, ${{\rm{O}}}_{2}^{+}$ , and ${\mathrm{CO}}_{2}^{+}$ are solved self-consistently together with Fa…
Sequential Remote Brightenings and Co-spatial Fast Downflows during Two Successive Flares
Cheng, X.; Ding, M. D.; Li, C. +2 more
Remote brightenings often appear at the outskirts of the active regions of solar eruptive events. Nevertheless, their origin remains to be ascertained. In this study, we report imaging and spectroscopic observations of sequential remote brightenings with a combination of observations from the Hα Imaging Spectrograph on board the Chinese Hα Solar E…
The Transition Region of Solar Flare Loops
Antiochos, Spiro K.; Young, Peter R.; Gontikakis, Costis
The transition region between the Sun's corona and chromosphere is important to the mass and energy transfer from the lower atmosphere to the corona; consequently, this region has been studied intensely with ultraviolet and extreme ultraviolet (EUV) observations. A major result of these studies is that the amount of plasma at low temperatures, <…
Investigating the Superorbital Modulations in 4U 1909 + 07, IGR J16418-4532, and IGR J16479-4514 with Swift XRT, BAT, and NuSTAR Observations
Pottschmidt, Katja; Corbet, Robin H. D.; Coley, Joel B. +2 more
A puzzling variety of superorbital modulations has been discovered in several supergiant high mass X-ray binaries (sgHMXBs). To investigate the mechanisms driving these superorbital modulations, we have analyzed long-term Neil Gehrels Swift Observatory (Swift) Burst Alert Telescope (BAT) observations of three sgHMXBs: 4U 1909 + 07, IGR J16418-4532…
Imaging of HH80-81 Jet in the Near-infrared Shock Tracers H2 and [Fe II]
Vig, S.; Tej, A.; Mohan, Sreelekshmi +1 more
The HH80-81 system is one of the most powerful jets driven by a massive protostar. We present new near-infrared (NIR) line imaging observations of the HH80-81 jet in the H2 (2.122 µm) and [Fe II] (1.644 µm) lines. These lines trace not only the jet close to the exciting source but also the knots located farther away. We have…
Asteroseismology of the Pulsating Extremely Low-mass White Dwarf SDSS J111215.82 + 111745.0: A Model with p-mode Pulsations Consistent with the Observations
Su, Jie; Li, Yan
SDSS J111215.82+111745.0 is the second pulsating extremely low-mass white dwarf discovered. Two short-period pulsations, 107.56 and 134.275 s, were detected on this star, which would be the first observed pressure mode (p-mode) pulsations observed on a white dwarf. While the two potential p-modes have yet to be confirmed, they make SDSS J111215.82…
Coronal Abundances in an Active Region: Evolution and Underlying Chromospheric and Transition Region Properties
Testa, Paola; Martínez-Sykora, Juan; De Pontieu, Bart
The element abundances in the solar corona and solar wind are often different from those of the solar photosphere, typically with a relative enrichment of elements with low first ionization potential (FIP effect). Here, we study the spatial distribution and temporal evolution of the coronal chemical composition in an active region (AR) over about …