Search Publications
The Influence of Metallicity on the Leavitt Law from Geometrical Distances of Milky Way and Magellanic Cloud Cepheids
Breuval, Louise; Gieren, Wolfgang; Pietrzyński, Grzegorz +7 more
The Cepheid period-luminosity (PL) relation is the key tool for measuring astronomical distances and for establishing the extragalactic distance scale. In particular, the local value of the Hubble constant (H0) strongly depends on Cepheid distance measurements. The recent Gaia Data Releases and other parallax measurements from the Hubbl…
Spectral Shapes of the Lyα Emission from Galaxies. I. Blueshifted Emission and Intrinsic Invariance with Redshift
Scarlata, Claudia; Gronke, Max; Hayes, Matthew J. +1 more
We demonstrate the redshift evolution of the spectral profile of H I Lyα emission from star-forming galaxies. In this first study we pay special attention to the contribution of blueshifted emission. At redshift z = 2.9-6.6, we compile spectra of a sample of 229 Lyα-selected galaxies identified with the Multi-Unit Spectroscopic Explorer at the Ver…
A Number of nearby Moving Groups May Be Fragments of Dissolving Open Clusters
Faherty, Jacqueline K.; Gagné, Jonathan; Moranta, Leslie +1 more
We propose that 14 co-moving groups of stars uncovered by Kounkel & Covey may be related to known nearby moving groups and bridge those and nearby open clusters with similar ages and space velocities. This indicates that known nearby moving groups may be spatially much more extended than previously thought, and some of them might be parts of t…
Dwarf Galaxies in the MATLAS Survey: Hubble Space Telescope Observations of the Globular Cluster System in the Ultra-diffuse Galaxy MATLAS-2019
Emsellem, Eric; Müller, Oliver; Agnello, Adriano +11 more
Ultra-diffuse galaxies (UDGs) are very-low-surface-brightness galaxies with large effective radii. Spectroscopic measurements of a few UDGs have revealed a low dark-matter content based on the internal motion of stars or globular clusters (GCs). This is in contrast to the large number of GCs found for these systems, from which it would be expected…
White Dwarf Subsystems in Core-Collapsed Globular Clusters
Rui, Nicholas Z.; Rodriguez, Carl L.; Chatterjee, Sourav +5 more
Numerical and observational evidence suggests that massive white dwarfs dominate the innermost regions of core-collapsed globular clusters by both number and total mass. Using NGC 6397 as a test case, we constrain the features of white dwarf populations in core-collapsed clusters, both at present day and throughout their lifetimes. The dynamics of…
Anisotropy of Solar Wind Turbulence in the Inner Heliosphere at Kinetic Scales: PSP Observations
Chen, Christopher H. K.; He, Jiansen; Bale, Stuart D. +5 more
The anisotropy of solar wind turbulence is a critical issue in understanding the physics of energy transfer between scales and energy conversion between fields and particles in the heliosphere. Using the measurement of Parker Solar Probe (PSP), we present an observation of the anisotropy at kinetic scales in the slow, Alfvénic, solar wind in the i…
The R-Process Alliance: Chemodynamically Tagged Groups of Halo r-process-enhanced Stars Reveal a Shared Chemical-evolution History
Beers, Timothy C.; Holmbeck, Erika M.; Hansen, Terese T. +11 more
We derive dynamical parameters for a large sample of 446 r-process-enhanced (RPE) metal-poor stars in the halo and disk systems of the Milky Way, based on data releases from the R-Process Alliance, supplemented by additional literature samples. This sample represents more than a 10-fold increase in size relative to that previously considered by Ro…
Discovery of Beryllium in White Dwarfs Polluted by Planetesimal Accretion
Weinberger, Alycia J.; Zuckerman, B.; Blouin, Simon +5 more
The element beryllium is detected for the first time in white dwarf stars. This discovery in the spectra of two helium-atmosphere white dwarfs was made possible only because of the remarkable overabundance of Be relative to all other elements, heavier than He, observed in these stars. The measured Be abundances, relative to chondritic, are by far …
The Strength and Structure of the Magnetic Field in the Galactic Outflow of Messier 82
Lopez-Rodriguez, Enrique; Guerra, Jordan A.; Asgari-Targhi, Mahboubeh +1 more
Galactic outflows driven by starbursts can modify the galactic magnetic fields and drive them away from the galactic planes. Here, we quantify how these fields may magnetize the intergalactic medium (IGM). We estimate the strength and structure of the fields in the starburst galaxy M82 using thermal polarized emission observations from the Stratos…
Constraints on the Assembly History of the Milky Way's Smooth, Diffuse Stellar Halo from the Metallicity-dependent, Radially Dominated Velocity Anisotropy Profiles Probed with K Giants and BHB Stars Using LAMOST, SDSS/SEGUE, and Gaia
Bird, Sarah A.; Zhao, Gang; Tian, Hai-Jun +5 more
We analyze the anisotropy profile of the Milky Way's smooth, diffuse stellar halo using the Sloan Digital Sky Survey (SDSS) SEGUE blue horizontal branch stars and the SDSS/SEGUE and LAMOST K giants. These intrinsically luminous stars allow us to probe the halo to approximately 100 kpc from the Galactic center. Line-of-sight velocities, distances, …