Search Publications
The Timescales of Star Cluster Emergence: The Case of NGC 4449
Smith, Linda J.; Calzetti, Daniela; Johnson, Kelsey E. +7 more
We survey the young star cluster population in the dwarf galaxy NGC 4449 with the goal of investigating how stellar feedback may depend on the clusters' properties. Using ultraviolet (UV)–optical–near-infrared photometry obtained with the Hubble Space Telescope, we have recovered 99 compact sources exhibiting emission in the Paβ hydrogen recombina…
Hemispheric Distribution of Halo Coronal Mass Ejection Source Locations
Mei, Ying; Wang, Feng; Deng, Hui +2 more
The hemispheric asymmetry of solar activity is one of the essential physical consequences of the interior dynamo process. However, the hemispheric distribution of halo coronal mass ejection (HCME) source locations has not been investigated in detail. Based on the HCME catalog identified from the Large Angle and Spectrometric Coronagraph Experiment…
Surface Flux Transport Modeling Using Physics-informed Neural Networks
Cheung, Mark C. M.; Athalathil, Jithu J.; Vaidya, Bhargav +2 more
Studying the magnetic field properties on the solar surface is crucial for understanding the solar and heliospheric activities, which in turn shape space weather in the solar system. Surface flux transport (SFT) modeling helps us to simulate and analyze the transport and evolution of magnetic flux on the solar surface, providing valuable insights …
Deep Chandra Observations of A2495: A Possible Sloshing-regulated Feedback Cycle in a Triple-offset Galaxy Cluster
Gastaldello, F.; Gaspari, M.; O'Sullivan, E. +6 more
We present the analysis of new, deep Chandra observations (130 ks) of the galaxy cluster A2495. This object is known for the presence of a triple offset between the peaks of the intracluster medium (ICM), the brightest cluster galaxy (BCG), and the warm gas glowing in Hα line. The new Chandra data confirm that the X-ray emission peak is located at…
Connecting Solar Wind Velocity Spikes Measured by Solar Orbiter and Coronal Brightenings Observed by SDO
Sorriso-Valvo, Luca; Verscharen, Daniel; D'Amicis, Raffaella +28 more
The Parker Solar Probe's discovery that magnetic switchbacks and velocity spikes in the young solar wind are abundant has prompted intensive research into their origin(s) and formation mechanism(s) in the solar atmosphere. Recent studies, based on in situ measurements and numerical simulations, argue that velocity spikes are produced through inter…
An HST Study of the Substellar Population of NGC 2024
Da Rio, Nicola; Gennaro, Mario; Sabbi, Elena +6 more
We performed an HST/WFC3-IR imaging survey of the young stellar cluster NGC 2024 in three filters probing the 1.4 µm H2O absorption feature, characteristic of the population of low-mass and substellar-mass objects down to a few Jupiter masses. We detect 812 point sources, 550 of them in all three filters with signal-to-noise ratio…
Solar Wind Density and Core Temperature Derived from the PSP Quasi-thermal Noise Measurements
Liu, Mingzhe; Liu, Kaijun; Pierrard, Viviane +6 more
Quasi-thermal noise (QTN) spectroscopy is a valuable method to deduce important parameters in space plasma, such as plasma density and temperature, especially when direct particle measurements are not available. The present study develops a new fitting method to fit the QTN spectra observed by the Parker Solar Probe (PSP) with a comprehensive theo…
Nitrogen Abundance Distribution in the Inner Milky Way
Gong, Yan; Menten, Karl M.; Anderson, L. D. +9 more
We combine a new Galactic plane survey of hydrogen radio recombination lines (RRLs) with far-infrared surveys of ionized nitrogen, N+, to determine nitrogen abundance across Galactic radius. RRLs were observed with the NASA Deep Space Network Station 43 70 m antenna and the Green Bank Telescope in 108 lines of sight spanning ‑135°< l…
Binary Yellow Supergiants in the Magellanic Clouds. I. Photometric Candidate Identification
Drout, Maria R.; O'Grady, Anna J. G.; Gaensler, B. M. +3 more
Recent works have constrained the binary fraction of evolved populations of massive stars in local galaxies such as red supergiants and Wolf–Rayet stars, but the binary fraction of yellow supergiants (YSGs) in the Hertzsprung gap remains unconstrained. Binary evolution theory predicts that the Hertzsprung gap is home to multiple populations of bin…
Modeling Cassini UVIS Interplanetary Hydrogen Lyα Observations from 1999 to 2017
Pryor, Wayne R.; Esposito, Larry W.; Gladstone, G. Randall +3 more
The Cassini Orbiter Ultraviolet Imaging Spectrograph (UVIS) obtained interplanetary hydrogen Lyα observations from 1999 to 2017, with mid-2004 to 2017 observations obtained from Saturn orbit. During its Saturn orbital phase, the spacecraft moved from mostly downwind and sidewind in the heliosphere to upwind. We analyze the full set of observations…