Search Publications
On the α/Fe Bimodality of the M31 Disks
Kobayashi, Chiaki; Gerhard, Ortwin; Arnaboldi, Magda +1 more
An outstanding question is whether the α/Fe bimodality exists in disk galaxies other than in the Milky Way. Here we present a bimodality using our state-of-the-art galactic chemical evolution models that can explain various observations in the Andromeda galaxy (M31) disks, namely, elemental abundances both of planetary nebulae and of red giant bra…
The Eruption of a Magnetic Flux Rope Observed by Solar Orbiter and Parker Solar Probe
Long, David M.; Davies, Emma E.; Berghmans, David +11 more
Magnetic flux ropes are a key component of coronal mass ejections, forming the core of these eruptive phenomena. However, determining whether a flux rope is present prior to eruption onset and, if so, the rope's handedness and the number of turns that any helical field lines make is difficult without magnetic field modeling or in situ detection of…
Inferences from Surface Brightness Fluctuations of Zwicky 3146 via the Sunyaev-Zel'dovich Effect and X-Ray Observations
Mroczkowski, Tony; Kraft, Ralph; Devlin, Mark +16 more
The galaxy cluster Zwicky 3146 is a sloshing cool-core cluster at z = 0.291 that in Sunyaev-Zel'dovich (SZ) imaging does not appear to exhibit significant pressure substructure in the intracluster medium. We perform a surface brightness fluctuation analysis via Fourier amplitude spectra on SZ (MUSTANG-2) and X-ray (XMM-Newton) images of this clust…
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…