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Star Formation Histories of the LEGUS Dwarf Galaxies. II. Spatially Resolved Star Formation History of the Magellanic Irregular NGC 4449
Cignoni, M.; Tosi, M.; Sabbi, E. +16 more
We present a detailed study of the Magellanic irregular galaxy NGC 4449 based on both archival and new photometric data from the Legacy Extragalactic UV Survey, obtained with the Hubble Space Telescope Advanced Camera for Surveys and Wide Field Camera 3. Thanks to its proximity (D = 3.82 ± 0.27 Mpc), we reach stars 3 mag fainter than the tip of th…
Onset of Photospheric Impacts and Helioseismic Waves in X9.3 Solar Flare of 2017 September 6
Kosovichev, Alexander G.; Sharykin, Ivan N.
The X9.3 flare of 2017 September 6, was the most powerful flare of Solar Cycle 24. It generated strong white-light emission and multiple helioseismic waves (sunquakes). By using data from the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory as well as hard X-ray (HXR) data from the KONUS instrument on board the WIND s…
Filament Eruption with a Deflection of Nearly 90 Degrees
Yang, Jiayan; Chen, Hechao; Dai, Jun +2 more
Using the data from the Solar Dynamics Observatory, the Ahead of Solar Terrestrial Relations Observatory, the Global Oscillation Network Group (GONG), and the Large Angle and Spectrometric Coronagraphs, the nearly 90° deflected eruption of a filament and the following coronal mass ejection (CME) occurring on the northern edge of AR 11123 on 2010 N…
The Recoiling Black Hole Candidate 3C 186: Spatially Resolved Quasar Feedback and Further Evidence of a Blueshifted Broad-line Region
Chiaberge, Marco; Capetti, Alessandro; Norman, Colin +1 more
We present the results of integral field spectroscopy of the gravitational wave (GW) recoiling black hole candidate 3C 186. The goal of the observation is to study the kinematics of the [O III]5007 narrow emission-line region (NLR) of the quasar, and investigate the origin of the velocity offsets originally measured for different UV lines. The res…
Wolf 1130: A Nearby Triple System Containing a Cool, Ultramassive White Dwarf
Skiff, Brian A.; Kirkpatrick, J. Davy; Kim, Hwihyun +9 more
Following the discovery of the T8 subdwarf WISE J200520.38+542433.9 (Wolf 1130C), which has a proper motion in common with a binary (Wolf 1130AB) consisting of an M subdwarf and a white dwarf, we set out to learn more about the old binary in the system. We find that the A and B components of Wolf 1130 are tidally locked, which is revealed by the c…
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-…