Search Publications
The Nature of the Double Nuclei in the Barred S0 Galaxy IC 676
Zhou, Xu; Ma, Jun; Zhou, Zhimin +1 more
The lenticular galaxy IC 676 is a barred galaxy with double nuclei and active star formation in the central region. In this work we present the long-slit spectroscopy and archival multiwavelength images to investigate the nature and origin of the double nuclei in IC 676. Through photometric 1D brightness profiles and 2D image decomposition, we sho…
Solar-cycle-related Changes in the Helium Ionization Zones of the Sun
Basu, Sarbani; Watson, Courtney B.
Helioseismic data for solar cycles 23 and 24 have shown unequivocally that solar dynamics changes with solar activity. Changes in solar structure have been more difficult to detect. Basu & Mandel had claimed that the then-available data revealed changes in the He II ionization zone of the Sun. The amount of change, however, indicated the need …
Understanding the Structure of Rapid Intensity Fluctuations in the Chromosphere with IRIS
De Pontieu, B.; Schmit, D.; Winebarger, A. +2 more
Several recent data sets have taken advantage of the unique capabilities of orbital and suborbital spacecraft to image the chromosphere and transition region at a very high cadence. We find that both the chromosphere and transition region exhibit spatially coherent transient features at frequencies above 80 mHz. We have analyzed narrowband imaging…
In Search of an Interface between Warm and Hot Gas within the Local Bubble
Jenkins, Edward B.; Gry, Cécile
We have examined UV spectra recorded by the Space Telescope Imaging Spectrograph on the Hubble Space Telescope for three stars, HD32309, 41 Ari, and η Tel, that are located well inside the boundary of the Local Hot Bubble in our search for absorption features of Si IV, C IV, and N V that could reveal the presence of an interface between the local …
SOFIA/FORCAST Observations of R Aqr: Monitoring the Dust Emission
Gorti, Uma; Wagner, R. Mark; Sankrit, Ravi +2 more
We present mid-infrared spectra of the symbiotic Mira, R Aqr obtained with the Faint Object infraRed CAmera instrument on the Stratospheric Observatory for Infrared Astronomy in 2016 and 2017. These data, supplemented with Infrared Space Observatory observations from 20 yr earlier, allow us to study the variation of the silicate dust emission over…
On Making Magnetic-flux-rope Ω Loops for Solar Bipolar Magnetic Regions of All Sizes by Convection Cells
Tiwari, Sanjiv K.; Panesar, Navdeep K.; Moore, Ronald L. +1 more
We propose that the flux-rope Ω loop that emerges to become any bipolar magnetic region (BMR) is made by a convection cell of the Ω-loop's size from initially horizontal magnetic field ingested through the cell's bottom. This idea is based on (1) observed characteristics of BMRs of all spans (∼1000 to ∼200,000 km), (2) a well-known simulation of t…
Decadal Variability Survey in MACSJ1149
Strolger, Louis-Gregory; Sarajedini, Vicki L.; Della Costa, John, III
We present a long temporal baseline variability survey in the Frontier Field MACSJ1149. In this study, we identify active galactic nuclei (AGNs) and other transient sources via their variability using over a decade of Hubble Space Telescope (HST) images for thousands of galaxies in the cluster region and detect significant variability in galaxies …
The Initiation of a Solar Streamer Blowout Coronal Mass Ejection Arising from the Streamer Flank
Chen, Yao; Zheng, Ruisheng; Wang, Bing
Streamer blowout (SBO) coronal mass ejections (CMEs) represent a particular class of CMEs that are characterized by a gradual swelling of the overlying streamer and a slow CME containing a flux-rope structure. SBO CMEs arising from the streamer flank fall into a special category of SBO CMEs involving three lower arches under the higher streamer ar…
A NICER View of Spectral and Profile Evolution for Three X-Ray-emitting Millisecond Pulsars
Enoto, Teruaki; Bogdanov, Slavko; Ray, Paul S. +17 more
We present two years of Neutron star Interior Composition Explorer (NICER) X-ray observations of three energetic rotation-powered millisecond pulsars (MSPs): PSRs B1937+21, B1821-24, and J0218+4232. We fit Gaussians and Lorentzians to the pulse profiles for different energy sub-bands of the soft X-ray regime to measure the energy dependence of pul…
The Relaxation of Reconnected Open Magnetic Field Lines in the Earth's Magnetosphere
Xu, Qi; Xu, Xiaojun; Wang, Jing +3 more
Magnetic reconnection is a fundamental and important physical process that can release magnetic energy and change magnetic topology. A statistic study of reconnected magnetic field lines has been carried out by Cluster spacecraft 1 during 58 current sheet crossing events. We calculated the values of $| {B}_{n}/B| $ at different distances from reco…