Search Publications
Runaway Young Stars near the Orion Nebula
Kounkel, Marina; McBride, Aidan
The star-forming region of the Orion Nebula (ONC) is ideal to study the stellar dynamics of young stars in a clustered environment. Using Gaia DR2 we search for pre-main sequence stars with unusually high proper motions that may be representative of a dynamical ejection from unstable young triple systems or other close three-body encounters. We id…
Revealing the Milky Way’s Hidden Circumgalactic Medium with the Cosmic Origins Spectrograph Quasar Database for Galactic Absorption Lines
Peek, J. E. G.; Zheng, Y.; Putman, M. E. +1 more
Every quasar (quasi-stellar object; QSO) spectrum contains absorption-line signatures from the interstellar medium, disk-halo interface, and circumgalactic medium (CGM) of the Milky Way (MW). We analyze Hubble Space Telescope/Cosmic Origins Spectrograph (COS) spectra of 132 QSOs to study the significance and origin of Si IV absorption at | {v}
Characteristics of a Gradual Filament Eruption and Subsequent CME Propagation in Relation to a Strong Geomagnetic Storm
Wang, Rui; Liu, Ying D.; Hu, Huidong +3 more
An unexpected strong geomagnetic storm occurred on 2018 August 26, which was caused by a slow coronal mass ejection (CME) from a gradual eruption of a large quiet-region filament. We investigate the eruption and propagation characteristics of this CME in relation to the strong geomagnetic storm with remote sensing and in situ observations. Coronal…
Jellyfish: Ram Pressure Stripping As a Diagnostic Tool in Studies of Cluster Collisions
Ebeling, Harald; Kalita, Boris S.
Prompted by the discovery of A1758N_JFG1, a spectacular case of ram pressure stripping (RPS) in the galaxy cluster A1758N, we investigate the properties of other galaxies suspected to undergo RPS in this equal-mass, post-collision merger. Exploiting constraints derived from Hubble Space Telescope images and Keck longslit spectroscopy, our finding …
Deep Chandra Survey of the Small Magellanic Cloud. III. Formation Efficiency of High-mass X-Ray Binaries
Williams, Benjamin F.; Zezas, Andreas; Drake, Jeremy J. +12 more
We have compiled the most complete census of high-mass X-ray binaries (HMXBs) in the Small Magellanic Cloud with the aim to investigate the formation efficiency of young accreting binaries in its low-metallicity environment. In total, we use 123 X-ray sources with detections in our Chandra X-ray Visionary Program (XVP), supplemented by 14 addition…
Filling in the Quasar Redshift Gap at z ∼ 5.5. II. A Complete Survey of Luminous Quasars in the Post-reionization Universe
Fan, Xiaohui; Jiang, Linhua; McGreer, Ian D. +10 more
We present the final results from our survey of luminous z ∼ 5.5 quasars. This is the first systematic quasar survey focusing on quasars at z ∼ 5.5, during the post-reionization epoch. It has been challenging to select quasars at 5.3 < z < 5.7 using conventional color selections, due to their similar optical colors to those of late-type star…
Spectroscopy and Differential Emission Measure Diagnostics of a Coronal Dimming Associated with a Fast Halo CME
Veronig, Astrid M.; Temmer, Manuela; Dissauer, Karin +2 more
We study the coronal dimming caused by the fast halo CME (deprojected speed v = 1250 km s-1) associated with the C3.7 two-ribbon flare on 2012 September 27, using Hinode/EIS spectroscopy and Solar Dynamics Observatory (SDO)/AIA Differential Emission Measure (DEM) analysis. The event reveals bipolar core dimmings encompassed by hook-shap…
Revealing the Complicated Story of the Cetus Stream with StarGO
Chang, Jiang; Smith, M. C.; Liu, Chao +5 more
We use a novel cluster identification tool, STARGO, to explore the metal-poor ([Fe/H] < -1.5) outer stellar halo (d > 15 kpc) of the Milky Way using data from Gaia, LAMOST, and SDSS. Our method is built using an unsupervised learning algorithm, a self-organizing map, which trains a 2D neural network to learn the topological structures of a d…
Simultaneous X-Ray and Infrared Observations of Sagittarius A*'s Variability
Ponti, G.; Fazio, G. G.; Morris, M. R. +11 more
Emission from Sagitarius A* is highly variable at both X-ray and infrared (IR) wavelengths. Observations over the last ∼20 yr have revealed X-ray flares that rise above a quiescent thermal background about once per day, while faint X-ray flares from Sgr A* are undetectable below the constant thermal emission. In contrast, the IR emission of Sgr A*…
Analysis of Small-scale Magnetic Flux Ropes Covering the Whole Ulysses Mission
Hu, Qiang; Chen, Yu; le Roux, Jakobus A.
Small-scale magnetic flux ropes in the solar wind have been studied for decades via both simulation and observation. Statistical analysis utilizing various in situ spacecraft measurements is the main observational approach, which helps investigate the generation and evolution of these small-scale structures. In this study, we extend the automated …