Search Publications
The Geometry of Cold, Metal-enriched Gas around Galaxies at z ∼ 1.2
van Dokkum, Pieter; York, Donald G.; Chisholm, John +10 more
We present the first results from a Hubble Space Telescope Wide Field Camera 3/Infrared program, which obtained direct imaging and grism observations of galaxies near quasar sightlines with a high frequency of uncorrelated foreground Mg II absorption. These highly efficient observations targeted 54 Mg II absorbers along the line of sight to nine q…
Evidence for Radial Expansion at the Core of the Orion Complex with Gaia EDR3
Meingast, Stefan; Alves, João; Zucker, Catherine +6 more
We present a phase-space study of two stellar groups located at the core of the Orion Complex: Briceño-1 and Orion Belt Population-near (OBP-near). We identify the groups with the unsupervised clustering algorithm, Shared Nearest Neighbor (SNN), which previously identified 12 new stellar substructures in the Orion Complex. For each of the two grou…
Velocity Dispersion of the GD-1 Stellar Stream
Naidu, Rohan P.; Bonaca, Ana; Gialluca, Megan T.
Tidally dissolved globular clusters form thin stellar streams that preserve a historical record of their past evolution. We report a radial velocity dispersion of 2.1 ± 0.3 km s-1 in the GD-1 stellar stream using a sample of 43 spectroscopically confirmed members. The GD-1 velocity dispersion is constant over the surveyed ≈15° span of t…
Abundance Patterns of α and Neutron-capture Elements in the Helmi Stream
Chiappini, Cristina; Limberg, Guilherme; Rossi, Silvia +6 more
We identified eight additional stars as members of the Helmi stream (HStr) in the combined GALAH+ DR3 and Gaia EDR3 catalog. By consistently reevaluating claimed members from the literature, we consolidate a sample of 22 HStr stars with parameters determined from high-resolution spectroscopy and spanning a considerably wider (by ∼0.5 dex) metallic…
Alfvénic Perturbations in a Sunspot Chromosphere Linked to Fractionated Plasma in the Corona
Stangalini, Marco; Brooks, David H.; Baker, Deborah +7 more
In this study, we investigate the spatial distribution of highly varying plasma composition around one of the largest sunspots of solar cycle 24. Observations of the photosphere, chromosphere, and corona are brought together with magnetic field modeling of the sunspot in order to probe the conditions that regulate the degree of plasma fractionatio…
An Energy Inventory of Tidal Disruption Events
Ramirez-Ruiz, Enrico; Mockler, Brenna
Tidal disruption events (TDEs) offer a unique opportunity to study a single supermassive black hole (SMBH) under feeding conditions that change over timescales of days to months. However, the primary mechanism for generating luminosity during the flares remains debated. Despite the increasing number of observed TDEs, it is unclear whether most of …
Improved Constraints on the Initial-to-final Mass Relation of White Dwarfs Using Wide Binaries
Chanamé, Julio; Barrientos, Manuel
We present observational constraints for the initial-to-final mass relation (IFMR) derived from 11 white dwarfs (WDs) in wide binaries (WBs) that contain a turnoff/subgiant primary. Because the components of WBs are coeval to a good approximation, the age of the WD progenitor can be determined from the study of its wide companion. However, previou…
Nonequilibrium Flux Rope Formation by Confined Flares Preceding a Solar Coronal Mass Ejection
Masuda, Satoshi; Liu, Chang; Liu, Rui +3 more
We present evidence that a magnetic flux rope was formed before a coronal mass ejection (CME) and its associated long-duration flare during a pair of preceding confined eruptions and associated impulsive flares in a compound event in NOAA Active Region 12371. Extreme-ultraviolet images and the extrapolated nonlinear force-free field show that the …
Exploring the Solar Wind from Its Source on the Corona into the Inner Heliosphere during the First Solar Orbiter-Parker Solar Probe Quadrature
Telloni, Daniele; Zank, Gary P.; Susino, Roberto +68 more
This Letter addresses the first Solar Orbiter (SO)-Parker Solar Probe (PSP) quadrature, occurring on 2021 January 18 to investigate the evolution of solar wind from the extended corona to the inner heliosphere. Assuming ballistic propagation, the same plasma volume observed remotely in the corona at altitudes between 3.5 and 6.3 solar radii above …
The Metal-poor Metallicity Distribution of the Ancient Milky Way
Frebel, Anna; Mardini, Mohammad K.; Chiti, Anirudh +1 more
We present a low-metallicity map of the Milky Way consisting of ∼110,000 metal-poor giants with -3.5 < [Fe/H] < -0.75, based on public photometry from the second data release of the SkyMapper survey. These stars extend out to ∼7 kpc from the solar neighborhood and cover the main Galactic stellar populations, including the thick disk and the …