Search Publications
Magnetic Helicity Signs and Flaring Propensity: Comparing the Force-free Parameter with the Helicity Signs of Hα Filaments and X-Ray Sigmoids
Martens, Petrus C.; Georgoulis, Manolis K.; Aparna, V.
Sigmoids produce strong eruptive events. Earlier studies have shown that the ICME axial magnetic field Bz can be predicted with some credibility by observing the corresponding filament or the polarity inversion line in the region of eruption and deriving the magnetic field direction from that. Sigmoids are coronal structures often associated with …
Discovering Subsolar Metallicity Brown Dwarf Candidates in the Small Magellanic Cloud
Pacifici, Camilla; Manjavacas, Elena; Sabbi, Elena +3 more
We present the discovery of the first rich population of brown dwarf candidates (cBD) at subsolar metallicity, observed by JWST outside the Milky Way (MW) in the young SMC star cluster NGC 602. Located in the Small Magellanic Cloud (SMC) "wing," in a very low-density environment (1.3 cm‑3) and at subsolar metallicity, NGC 602 is very yo…
Decay Timescales of Chromospheric Condensations in Solar Flare Footpoints
Kowalski, Adam F.; Butler, Elizabeth C.
Chromospheric condensations (CCs) are a prominent feature of flare footpoint heating in the solar flare standard model, yet their timescales and velocities are not well understood. Fisher derived several important analytical relationships, which have rarely been examined with modern spectral observations. The Interface Region Imaging Spectrograph …
Multispacecraft Energetic Particle Enhancements Associated with a Single Corotating Interaction Region
Desai, M. I.; Dayeh, M. A.; Elliott, H. A. +3 more
The radial evolution of particles accelerated at corotating interaction regions (CIRs) is not fully understood, particularly the distance range over which this particle acceleration occurs and how the energy spectra are modulated by transport through the inner heliosphere. Here, we present observations of energetic proton enhancements associated w…
Are There Local Dynamos Acting in Sunspot Regions?
Wang, Jingxiu; Jin, Chunlan; Ji, Haisheng +1 more
In solar physics, a long-unanswered question is whether or not there are local dynamos acting in sunspot regions. Here we report an observed pattern of magnetic evolution that makes the sunspots alive with ample complexity and energy. This anomalous pattern manifests as peculiar bipolar magnetic emergences (BMEs), exhibiting the following characte…
Cross-correlation of Luminous Red Galaxies with Machine Learning Selected Active Galactic Nuclei in HSC-SSP: Unobscured AGN Residing in More Massive Halos
Strauss, Michael A.; Greene, Jenny E.; Goulding, Andy D. +7 more
Active galactic nuclei (AGN) are the signposts of black hole growth, and likely play an important role in galaxy evolution. An outstanding question is whether AGN of different spectral types indicate different evolutionary stages in the coevolution of black holes and galaxies. We present the angular correlation function between an AGN sample selec…
Constraining Quasar Feedback from Analysis of the Hydrostatic Equilibrium of the Molecular Gas in Their Host Galaxies
Ho, Luis C.; Bauer, Franz E.; Treister, Ezequiel +4 more
We investigate the kinematics and dynamics of the molecular and ionized gas in the host galaxies of three Palomar-Green quasars at low redshifts, benefiting from the archival millimeter-wave interferometric and optical integral field unit data. We study the kinematics of both cold molecular and hot ionized gas by analyzing the CO and Hα data cubes…
Double-edged Sword: The Influence of Tidal Interaction on Stellar Activity in Binaries
Fang, Min; Wang, Song; Han, Henggeng +4 more
Using the LAMOST DR7 low-resolution spectra, we carried out a systematic study of stellar chromospheric activity in both single and binary stars. We constructed a binary sample and a single-star sample, mainly using the binary belt and the main sequence in the Hertzsprung–Russell diagram, respectively. By comparing the S indices between single and…
BST1047+1156: A (Failing) Ultradiffuse Tidal Dwarf in the Leo I Group
Mihos, J. Christopher; Durrell, Patrick R.; McGaugh, Stacy S. +2 more
We use deep Hubble Space Telescope imaging to study the resolved stellar populations in BST1047+1156, a gas-rich, ultradiffuse dwarf galaxy found in the intragroup environment of the Leo I galaxy group. While our imaging reaches approximately two magnitudes below the tip of the red giant branch at the Leo I distance of 11 Mpc, we find no evidence …
Recurrent Coronal Mass Ejections and Their Geomagnetic Storms Association on 2012 January 19: Solar Surface to Upper Earth's Atmosphere Analyses
Minta, F. N.; Hassanin, A.; Shimeis, Amira +1 more
In this study, we have conducted an analysis of space weather disruptions that occurred on 19 January 2012. Our analysis identified three coronal mass ejections (CMEs), CME1, CME2, and CME3—which were ejected at 09:48:05 universal time (UT), 14:36:05 UT, and 16:12:06 UT, respectively. Nonrecurrent disturbances in space weather, such as geomagnetic…