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A Bayesian Analysis of Physical Parameters for 783 Kepler Close Binaries: Extreme-mass-ratio Systems and a New Mass Ratio versus Period Lower Limit
Kobulnicky, Henry A.; Cook, Evan M.; Molnar, Lawrence A. +1 more
Contact binary star systems represent the long-lived penultimate phase of binary evolution. Population statistics of their physical parameters inform an understanding of binary evolutionary pathways and end products. We use light curves and new optical spectroscopy to conduct a pilot study of ten (near) contact systems in the long-period (P > 0…
Metallicities and ages for star clusters and their surrounding fields in the Large Magellanic Cloud
Smolec, R.; Piatti, A. E.; Lewis, M. O. +15 more
Aims: We study 147 star clusters in the Large Magellanic Cloud (LMC) in order to determine their mean metallicities and ages, as well as the mean metallicities of 80 surrounding fields. We construct an age-metallicity relation (AMR) for the clusters in the LMC.
Methods: For this purpose, we used Strömgren photometry obtained with the SOI…
Discovery, Timing, and Multiwavelength Observations of the Black Widow Millisecond Pulsar PSR J1555-2908
Ransom, Scott M.; Michelson, P. F.; Halpern, Jules P. +21 more
We report the discovery of PSR J1555-2908, a 1.79 ms radio and gamma-ray pulsar in a 5.6 hr binary system with a minimum companion mass of 0.052 M ⊙. This fast and energetic ( $\dot{E}=3\times {10}^{35}$ erg s-1) millisecond pulsar was first detected as a gamma-ray point source in Fermi Large Area Telescope (LAT) sky survey o…
Inhomogeneity within Local Interstellar Clouds
Redfield, Seth; Linsky, Jeffrey L.; Ryder, Diana +1 more
Analysis of interstellar absorption lines observed in high-resolution Hubble Space Telescope spectra of nearby stars provides temperatures, turbulent velocities, and kinetic properties of warm interstellar clouds. A new analysis of 97 interstellar-velocity components reveals a wide range of temperatures and turbulent velocities within the Local In…
Extending empirical constraints on the SZ-mass scaling relation to higher redshifts via HST weak lensing measurements of nine clusters from the SPT-SZ survey at z ≳ 1
Schrabback, Tim; Hoekstra, Henk; Sharon, Keren +17 more
We present a Hubble Space Telescope (HST) weak gravitational lensing study of nine distant and massive galaxy clusters with redshifts 1.0 ≲ z ≲ 1.7 (zmedian = 1.4) and Sunyaev Zel'dovich (SZ) detection significance ξ > 6.0 from the South Pole Telescope Sunyaev Zel'dovich (SPT-SZ) survey. We measured weak lensing galaxy shapes in HST/…
Age Spreads and Systematics in λ Orionis with Gaia DR2 and the SPOTS Tracks
Pinsonneault, Marc H.; Hillenbrand, Lynne A.; Cao, Lyra +1 more
In this paper we investigate the robustness of age measurements, age spreads, and stellar models in young pre-main-sequence stars. For this effort, we study a young cluster, λ Orionis, within the Orion star-forming complex. We use Gaia data to derive a sample of 357 targets with spectroscopic temperatures from spectral types or from the automated …
A "Hyperburst" in the MAXI J0556-332 Neutron Star: Evidence for a New Type of Thermonuclear Explosion
Homan, Jeroen; Wijnands, Rudy; Degenaar, Nathalie +5 more
The study of transiently accreting neutron stars provides a powerful means to elucidate the properties of neutron star crusts. We present extensive numerical simulations of the evolution of the neutron star in the transient low-mass X-ray binary MAXI J0556-332. We model nearly 20 observations obtained during the quiescence phases after four differ…
NuSTAR Observations of Intrinsically X-Ray Weak Quasar Candidates: An Obscuration-only Scenario
Stern, D.; Alexander, D. M.; Bauer, F. E. +6 more
We utilize recent NuSTAR observations (co-added depth ≈55-120 ks) of PG 1001+054, PG 1254+047, and PHL 1811 to constrain their hard X-ray (≳5 keV) weakness and spectral shapes and thus to investigate the nature of their extreme X-ray weakness. These quasars showed very weak soft X-ray emission, and they were proposed to be intrinsically X-ray weak…
Weighing the Galactic disk using phase-space spirals. III. Probing distant regions of the disk using the Gaia EDR3 proper motion sample
Monari, G.; Widmark, A.; Laporte, C. F. P.
We have applied our method to weigh the Galactic disk using phase-space spirals to the proper motion sample of Gaia's early third release (EDR3). For stars in distant regions of the Galactic disk, the latitudinal proper motion has a close projection with vertical velocity, such that the phase-space spiral in the plane of vertical position and vert…
Rivers and Lakes in Western Arabia Terra: The Fluvial Catchment of the ExoMars 2022 Rover Landing Site
Fawdon, Peter; Davis, Joel; Bridges, John +3 more
Oxia Planum, the landing site for the ExoMars rover mission, is a shallow basin on the southern margin of Chryse Planitia that hosts remnants of fan-shaped sedimentary deposits associated with the ancient channel system Coogoon Vallis. This indicates runoff from a catchment in Arabia Terra has transported sediment into the landing site. To explore…