Search Publications
A Spectral and Timing Study of MAXI J1535-571, Based on Swift/XRT, XMM-Newton, and NICER Observations Obtained in Fall 2017
Stiele, H.; Kong, A. K. H.
We present a spectral-timing analysis of observations taken in fall 2017 of the newly detected X-ray transient MAXI J1535-571. We included 38 Swift/XRT window timing mode observations, 3 XMM-Newton observations, and 31 Neutron star Interior Composition Explorer observations in our study. We computed the fundamental diagrams commonly used to study …
Probing the Southern Fermi Bubble in Ultraviolet Absorption Using Distant AGNs
Jenkins, Edward B.; Jorgenson, Regina A.; Savage, Blair D. +7 more
The Fermi Bubbles are two giant gamma-ray emitting lobes extending 55° above and below the Galactic center. While the Northern Bubble has been extensively studied in ultraviolet (UV) absorption, little is known about the gas kinematics of the southern Bubble. We use UV absorption-line spectra from the Cosmic Origins Spectrograph (COS) on the Hubbl…
Magnetic Braids in Eruptions of a Spiral Structure in the Solar Atmosphere
Tian, Hui; Chen, Yao; Li, Bo +6 more
We report on high-resolution imaging and spectral observations of eruptions of a spiral structure in the transition region, which were taken with the Interface Region Imaging Spectrograph, and the Atmospheric Imaging Assembly (AIA) and the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO). The eruption coincided w…
Detection of Magnetic Nulls around Reconnection Fronts
Divin, A.; Xu, Y.; Fu, H. S. +2 more
Magnetic nulls, where magnetic-field strength becomes zero, play a crucial role in energy conversion and particle acceleration during magnetic reconnection. Recent simulations have suggested that reconnection fronts (RFs) inside the reconnection jet can host magnetic nulls. However, observational evidence for the RF-associated magnetic nulls remai…
Chemical Compositions of Evolved Stars from Near-infrared IGRINS High-resolution Spectra. I. Abundances in Three Red Horizontal Branch Stars
Kim, Hwihyun; Jaffe, Daniel T.; Mace, Gregory N. +6 more
We have derived elemental abundances of three field red horizontal branch stars using high-resolution (R ≃ 45,000), high signal-to-noise ratio (S/N ≳ 200) H- and K-band spectra obtained with the Immersion Grating Infrared Spectrograph (IGRINS). We have determined the abundances of 21 elements, including α (Mg, Si, Ca, S), odd-Z (Na, Al, P, K), Fe-…
The Properties of Planck Galactic Cold Clumps in the L1495 Dark Cloud
Sanhueza, Patricio; Soam, Archana; Di Francesco, James +19 more
Planck Galactic Cold Clumps (PGCCs) possibly represent the early stages of star formation. To understand better the properties of PGCCs, we studied 16 PGCCs in the L1495 cloud with molecular lines and continuum data from Herschel, JCMT/SCUBA-2, and the PMO 13.7 m telescope. Thirty dense cores were identified in 16 PGCCs from 2D Gaussian fitting. T…
A Multi-instrument and Multi-wavelength High Angular Resolution Study of MWC 614: Quantum Heated Particles Inside the Disk Cavity
Monnier, John D.; Kraus, Stefan; Hinkley, Sasha +13 more
High angular resolution observations of young stellar objects are required to study the inner astronomical units of protoplanetary disks in which the majority of planets form. As they evolve, gaps open up in the inner disk regions and the disks are fully dispersed within ∼10 Myr. MWC 614 is a pretransitional object with a ∼10 au radius gap. We pre…
Incorporating Uncertainties in Atomic Data into the Analysis of Solar and Stellar Observations: A Case Study in Fe XIII
Del Zanna, Giulio; Warren, Harry P.; van Dyk, David A. +6 more
Information about the physical properties of astrophysical objects cannot be measured directly but is inferred by interpreting spectroscopic observations in the context of atomic physics calculations. Ratios of emission lines, for example, can be used to infer the electron density of the emitting plasma. Similarly, the relative intensities of emis…
Discovery of a New Fundamental Plane Dictating Galaxy Cluster Evolution from Gravitational Lensing
Donahue, Megan; Umetsu, Keiichi; Medezinski, Elinor +5 more
In cold dark-matter (CDM) cosmology, objects in the universe have grown under the effect of gravity of dark matter. The intracluster gas in a galaxy cluster was heated when the dark-matter halo formed through gravitational collapse. The potential energy of the gas was converted to thermal energy through this process. However, this process and the …
Sequential Eruptions Triggered by Flux Emergence: Observations and Modeling
Long, D. M.; van Driel-Gesztelyi, L.; Démoulin, P. +5 more
We describe and analyze observations by the Solar Dynamics Observatory of the emergence of a small, bipolar active region within an area of unipolar magnetic flux that was surrounded by a circular, quiescent filament. Within only 8 hours from the start of the emergence, a partial splitting of the filament and two consecutive coronal mass ejections…