Search Publications
Spectroscopy and Photometry of the Least Massive Type II Globular Clusters: NGC 1261 and NGC 6934
Da Costa, G. S.; Milone, A. P.; Cordoni, G. +10 more
Recent work has revealed two classes of globular clusters (GCs), dubbed Type I and Type II. Type II GCs are characterized by both a blue and a red red giant branch composed of stars with different metallicities, often coupled with distinct abundances in the slow neutron-capture elements (s-elements). Here we continue the chemical tagging of Type I…
Resolving the Dust-to-Metals Ratio and CO-to-H2 Conversion Factor in the Nearby Universe
Sandstrom, Karin M.; Leroy, Adam K.; Schruba, Andreas +8 more
We investigate the relationship between the dust-to-metals ratio (D/M) and the local interstellar medium environment at ∼2 kpc resolution in five nearby galaxies: IC 342, M31, M33, M101, and NGC 628. A modified blackbody model with a broken power-law emissivity is used to model the dust emission from 100 to 500 µm observed by Herschel. We ut…
Grain Growth in Escaping Atmospheres: Implications for the Radius Inflation of Super-Puffs
Ohno, Kazumasa; Tanaka, Yuki A.
Super-puffs-low-mass exoplanets with extremely low bulk density-are attractive targets for exploring their atmospheres and formation processes. Recent studies suggested that the large radii of super-puffs may be caused by atmospheric dust entrained in the escaping atmospheres. In this study, we investigate how the dust grows in escaping atmosphere…
Head-to-Toe Measurement of El Gordo: Improved Analysis of the Galaxy Cluster ACT-CL J0102-4915 with New Wide-field Hubble Space Telescope Imaging Data
Sifón, Cristóbal; Hughes, John P.; Jee, M. James +6 more
We present an improved weak-lensing (WL) study of the high-z (z = 0.87) merging galaxy cluster ACT-CL J0102-4915 ("El Gordo") based on new wide-field Hubble Space Telescope imaging data. The new imaging data cover the ~3.5 × ~3.5 Mpc region centered on the cluster and enable us to detect WL signals beyond the virial radius, which was not possible …
Revisiting Dynamical Friction: The Role of Global Modes and Local Wakes
Babul, Arif; Quinn, Thomas R.; Mayer, Lucio +4 more
The orbital decay of a perturber within a larger system plays a key role in the dynamics of many astrophysical systems-from nuclear star clusters or globular clusters in galaxies, to massive black holes in galactic nuclei, to dwarf galaxy satellites within the dark matter halos of more massive galaxies. For many decades, there have been various at…
R-process-rich Stellar Streams in the Milky Way
Roederer, Ian U.; Frebel, Anna; Ji, Alexander P. +3 more
We present high-resolution Magellan/MIKE spectra of 22 bright (9 < V < 13.5) metal-poor stars (-3.18 < [Fe/H] < -1.37) in three different stellar streams, the Helmi debris stream, the Helmi trail stream, and the ω Centauri progenitor stream. We augment our Helmi debris sample with results for 10 stars by Roederer et al. for a total of …
ALMA Observations of the Sub-kpc Structure of the Host Galaxy of a z = 6.5 Lensed Quasar: A Rotationally Supported Hyper-Starburst System at the Epoch of Reionization
Fan, Xiaohui; Keeton, Charles R.; Walter, Fabian +11 more
We report Atacama Large Millimeter/Submillimeter Array (ALMA) observations of the dust continuum and [C II] emission of the host galaxy of J0439+1634, a gravitationally lensed quasar at z = 6.5. Gravitational lensing boosts the source-plane resolution to ~0"15 (~0.8 kpc). The lensing model derived from the ALMA data is consistent with the fiducial…
TESS Asteroseismology of α Mensae: Benchmark Ages for a G7 Dwarf and Its M Dwarf Companion
Butler, R. Paul; Chaplin, William J.; Stassun, Keivan G. +27 more
Asteroseismology of bright stars has become increasingly important as a method to determine the fundamental properties (in particular ages) of stars. The Kepler Space Telescope initiated a revolution by detecting oscillations in more than 500 main-sequence and subgiant stars. However, most Kepler stars are faint and therefore have limited constrai…
Inspecting the Cepheid Distance Ladder: the Hubble Space Telescope Distance to the SN Ia Host Galaxy NGC 5584
Mérand, Antoine; Breuval, Louise; Gieren, Wolfgang +7 more
The current tension between the direct and the early-universe measurements of the Hubble constant, H0, requires detailed scrutiny of all the data and methods used in the studies on both sides of the debate. The Cepheids in the Type Ia supernova (SN Ia) host galaxy NGC 5584 played a key role in the local measurement of H0. The…
Further Evidence for Tidal Spin-up of Hot Jupiter Host Stars
Winn, Joshua N.; Anderson, Kassandra R.; Tejada Arevalo, Roberto A.
For most hot Jupiters around main-sequence Sun-like stars, tidal torques are expected to transfer angular momentum from the planet's orbit to the star's rotation. The timescale for this process is difficult to calculate, leading to uncertainties in the history of orbital evolution of hot Jupiters. We present evidence for tidal spin-up by taking ad…