Search Publications
Numerical Simulations and Observations of Mg II in the Solar Chromosphere
De Pontieu, Bart; Carlsson, Mats; Hansteen, Viggo H. +3 more
The Mg II h and k lines are among the best diagnostic tools of the upper solar chromosphere. This region of the atmosphere is of particular interest, as it is the lowest region of the Sun's atmosphere where the magnetic field is dominant in the energetics and dynamics, defining its structure. While highly successful in the photosphere and lower to…
Star Formation and AGN Activity 500 Myr after the Big Bang: Insights from JWST
D'Silva, Jordan C. J.; Driver, Simon P.; Lagos, Claudia D. P. +3 more
We consider the effect of including an active galactic nuclei (AGN) component when fitting spectral energy distributions of 109 spectroscopically confirmed z ≈ 3.5-12.5 galaxies with JWST. Remarkably, we find that the resulting cosmic star formation history is ≈0.4 dex lower at z ≳ 9.5 when an AGN component is included in the fitting. This allevia…
Extending the Dynamic Range of Galaxy Outflow Scaling Relations: Massive Compact Galaxies with Extreme Outflows
Moustakas, John; Coil, Alison L.; Rudnick, Gregory H. +11 more
We investigate galactic winds in the HizEA galaxies, a collection of 46 late-stage galaxy mergers at z = 0.4-0.8, with stellar masses of $\mathrm{log}({M}_{* }/{M}_{\odot })=10.4\mbox{--}11.5$ , star formation rates (SFRs) of 20-500 M ⊙ yr-1, and ultra-compact (a few 100 pc) central star-forming regions. We measure their gas …
The Chemical Enrichment of the Milky Way Disk Evaluated Using Conditional Abundances
Ness, Melissa K.; Ratcliffe, Bridget L.
Chemical abundances of Milky Way disk stars are empirical tracers of its enrichment history. However, they capture joint-information that is valuable to disentangle. In this work, we quantify how individual abundances evolve across the present-day Galactic radius, at fixed supernovae contribution ([Fe/H], [Mg/Fe]). We use 18,135 Apache Point Obser…
The Metallicity Variations Along the Chromosome Maps: The Globular Cluster 47 Tucanae
Milone, A. P.; Cordoni, G.; Marino, A. F. +11 more
The "chromosome maps" (ChMs) of globular clusters (GCs) have revealed that these ancient structures are inhomogeneous in metallicity in various ways and in different natures. Type II GCs generally display larger variations, sometimes coupled with slow neutron-capture (s) element enrichments on the ChMs redder sequences, which have been interpreted…
JWST Observations of the Enigmatic Y-Dwarf WISE 1828+2650. I. Limits to a Binary Companion
Johnstone, Doug; Leisenring, Jarron; Rieke, George +20 more
The Y-dwarf WISE 1828+2650 is one of the coldest known brown dwarfs with an effective temperature of ~300 K. Located at a distance of just 10 pc, previous model-based estimates suggest WISE1828+2650 has a mass of ~5-10 M J, making it a valuable laboratory for understanding the formation, evolution, and physical characteristics of gas gi…
Stellar Populations in the Central 0.5 pc of Our Galaxy. III. The Dynamical Substructures
Lu, Jessica R.; Ghez, A. M.; Morris, M. R. +12 more
We measure the 3D kinematic structures of the young stars within the central 0.5 pc of our Galactic Center using the 10 m telescopes of the W. M. Keck Observatory over a time span of 25 yr. Using high-precision measurements of positions on the sky and proper motions and radial velocities from new observations and the literature, we constrain the o…
Spirals and Clumps in V960 Mon: Signs of Planet Formation via Gravitational Instability around an FU Ori Star?
Takami, Michihiro; Kóspál, Ágnes; Garufi, Antonio +11 more
The formation of giant planets has traditionally been divided into two pathways: core accretion and gravitational instability. However, in recent years, gravitational instability has become less favored, primarily due to the scarcity of observations of fragmented protoplanetary disks around young stars and the low occurrence rate of massive planet…
Evolution of Magnetic Field Fluctuations and Their Spectral Properties within the Heliosphere: Statistical Approach
Verscharen, Daniel; Bale, Stuart D.; Horbury, Timothy S. +4 more
We present the first comprehensive statistical study of the evolution of compressive and noncompressive magnetic field fluctuations in the inner heliosphere. Based on Parker Solar Probe (PSP) and Solar Orbiter data at various distances from the Sun, we show the general trends and compare them with Wind observations near 1 au. The paper analyzes so…
A Blueprint for the Milky Way's Stellar Populations. IV. A String of Pearls-the Galactic Starburst Sequence
Beers, Timothy C.; Lee, Young Sun; Masseron, Thomas +1 more
We continue our series of papers on phase-space distributions of stars in the Milky Way based on photometrically derived metallicities and Gaia astrometry, with a focus on the halo-disk interface in the local volume. To exploit various photometric databases, we develop a method of empirically calibrating synthetic stellar spectra based on a compar…