Search Publications
The Saga of M81: Global View of a Massive Stellar Halo in Formation
Bell, Eric F.; Monachesi, Antonela; Bailin, Jeremy +7 more
Recent work has shown that Milky Way-mass galaxies display an incredible range of stellar halo properties, yet the origin of this diversity is unclear. The nearby galaxy M81—currently interacting with M82 and NGC 3077—sheds unique light on this problem. We present a Subaru Hyper Suprime-Cam survey of the resolved stellar populations around M81, re…
Different Fates of Young Star Clusters after Gas Expulsion
Tang, Shih-Yun; Pang, Xiaoying; Pasquato, Mario +2 more
We identify structures of the young star cluster NGC 2232 in the solar neighborhood (323.0 pc) and a newly discovered star cluster, LP 2439 (289.1 pc). Member candidates are identified using the Gaia DR2 sky position, parallax, and proper-motion data by an unsupervised machine-learning method, STARGO. Member contamination from the Galactic disk is…
The Ionizing Photon Production Efficiency (ξion) of Lensed Dwarf Galaxies at z ∼ 2
Richard, Johan; Siana, Brian; Freeman, William R. +5 more
We measure the ionizing photon production efficiency (ξion) of low-mass galaxies (107.8-109.8 M⊙) at 1.4 < z < 2.7 to better understand the contribution of dwarf galaxies to the ionizing background and reionization. We target galaxies that are magnified by strong-lensing galaxy clusters and use Kec…
Distinguishing between Wet and Dry Atmospheres of TRAPPIST-1 e and f
Rauer, H.; Sánchez-López, A.; López-Puertas, M. +7 more
The nearby TRAPPIST-1 planetary system is an exciting target for characterizing the atmospheres of terrestrial planets. The planets e, f, and g lie in the circumstellar habitable zone and could sustain liquid water on their surfaces. During the extended pre-main-sequence phase of TRAPPIST-1, however, the planets may have experienced extreme water …
Blasts from the Past: Supernova Shock Breakouts among X-Ray Transients in the XMM-Newton Archive
Alp, Dennis; Larsson, Josefin
The first electromagnetic signal from a supernova (SN) is released when the shock crosses the progenitor surface. This shock breakout (SBO) emission provides constraints on progenitor and explosion properties. Observationally, SBOs appear as minute- to hour-long extragalactic X-ray transients. They are challenging to detect and only one SBO has be…
Orbital Parameter Determination for Wide Stellar Binary Systems in the Age of Gaia
Vanderburg, Andrew; Dupuy, Trent J.; Kraus, Adam L. +4 more
The orbits of binary stars and planets, particularly eccentricities and inclinations, encode the angular momentum within these systems. Within stellar multiple systems, the magnitude and (mis)alignment of angular momentum vectors among stars, disks, and planets probes the complex dynamical processes guiding their formation and evolution. The accur…
Abundances in the Milky Way across Five Nucleosynthetic Channels from 4 Million LAMOST Stars
Lewis, Geraint F.; Buder, Sven; Bland-Hawthorn, Joss +10 more
Large stellar surveys are revealing the chemodynamical structure of the Galaxy across a vast spatial extent. However, the many millions of low-resolution spectra observed to date are yet to be fully exploited. We employ The Cannon, a data-driven approach for estimating chemical abundances, to obtain detailed abundances from low-resolution (R = 180…
Coronal Magnetic Field Topology from Total Solar Eclipse Observations
Druckmüller, Miloslav; Boe, Benjamin; Habbal, Shadia
Measuring the global magnetic field of the solar corona remains exceptionally challenging. The fine-scale density structures observed in white-light images taken during total solar eclipses are currently the best proxies for inferring the magnetic field direction in the corona from the solar limb out to several solar radii (R⊙). We pres…
The Strength of the 2175 Å Feature in the Attenuation Curves of Galaxies at 0.1 < z ≲ 3
Calzetti, D.; Battisti, A. J.; Cunha, E. da +1 more
We update the spectral modeling code MAGPHYS to include a 2175 Å absorption feature in its UV to near-IR dust attenuation prescription. This allows us to determine the strength of this feature and the shape of the dust attenuation curve in ∼5000 star-forming galaxies at $0.1\lt z\lesssim 3$ in the COSMOS field. We find that a 2175 Å absorption fea…
Astrophysical Distance Scale: The AGB J-band Method. I. Calibration and a First Application
Madore, Barry F.; Freedman, Wendy L.
A near-infrared, color-selected subset of carbon-rich asymptotic giant branch (C-AGB) stars is found to have tightly constrained luminosities in the near-infrared J band. Based on JK photometry of some 3300 C-AGB stars in the bar of the Large Magellanic Cloud (LMC) we find that these stars have a constant absolute magnitude of $\langle {M}_{J}\ran…