Search Publications
Determination of Differential Emission Measure from Solar Extreme Ultraviolet Images
Veronig, Astrid M.; Gan, Weiqun; Cheung, Mark C. M. +5 more
The Atmospheric Imaging Assembly (AIA) on board the Solar Dynamic Observatory (SDO) has been providing high-cadence, high-resolution, full-disk UV-visible/extreme ultraviolet (EUV) images since 2010, with the best time coverage among all the solar missions. A number of codes have been developed to extract plasma differential emission measures (DEM…
The R-Process Alliance: First Release from the Northern Search for r-process-enhanced Metal-poor Stars in the Galactic Halo
Grebel, Eva K.; Steinmetz, Matthias; Beers, Timothy C. +26 more
This paper presents the detailed abundances and r-process classifications of 126 newly identified metal-poor stars as part of an ongoing collaboration, the R-Process Alliance. The stars were identified as metal-poor candidates from the RAdial Velocity Experiment (RAVE) and were followed up at high spectral resolution (R ∼ 31,500) with the 3.5 m te…
The evolution of surface magnetic fields in young solar-type stars II: the early main sequence (250-650 Myr)
Donati, J. -F.; Petit, P.; Vidotto, A. A. +6 more
There is a large change in surface rotation rates of sun-like stars on the pre-main sequence and early main sequence. Since these stars have dynamo-driven magnetic fields, this implies a strong evolution of their magnetic properties over this time period. The spin-down of these stars is controlled by interactions between stellar and magnetic field…
The Kepler Light Curves of AGN: A Detailed Analysis
Howell, Steve B.; Gelino, Dawn M.; Boyd, Patricia T. +3 more
We present a comprehensive analysis of 21 light curves of Type 1 active galactic nuclei (AGN) from the Kepler spacecraft. First, we describe the necessity and development of a customized pipeline for treating Kepler data of stochastically variable sources like AGN. We then present the light curves, power spectral density functions (PSDs), and flux…
Dynamical Constraints on the HR 8799 Planets with GPI
Duchêne, Gaspard; Esposito, Thomas M.; Oppenheimer, Rebecca +52 more
The HR 8799 system uniquely harbors four young super-Jupiters whose orbits can provide insights into the system’s dynamical history and constrain the masses of the planets themselves. Using the Gemini Planet Imager, we obtained down to one milliarcsecond precision on the astrometry of these planets. We assessed four-planet orbit models with differ…
The 55 Cancri system reassessed
Moutou, C.; Ehrenreich, D.; Lovis, C. +9 more
Orbiting a bright, nearby star the 55 Cnc system offers a rare opportunity to study a multiplanet system that has a wide range of planetary masses and orbital distances. Using two decades of photometry and spectroscopy data, we have measured the rotation of the host star and its solar-like magnetic cycle. Accounting for this cycle in our velocimet…
Evidence for a variable Ultrafast Outflow in the newly discovered Ultraluminous Pulsar NGC 300 ULX-1
Fabian, A. C.; Pinto, C.; Bachetti, M. +5 more
Ultraluminous pulsars are a definite proof that persistent super-Eddington accretion occurs in nature. They support the scenario according to which most Ultraluminous X-ray Sources (ULXs) are super-Eddington accretors of stellar mass rather than sub-Eddington intermediate mass black holes. An important prediction of theories of supercritical accre…
Retrieval of planetary and stellar properties in transmission spectroscopy with AURA
Madhusudhan, Nikku; Apai, Dániel; Rackham, Benjamin V. +1 more
Transmission spectroscopy provides a powerful probe of the atmospheric properties of transiting exoplanets. To date, studies of exoplanets in transit have focused on inferring their atmospheric properties such as chemical compositions, cloud/haze properties, and temperature structures. However, surface inhomogeneities in the host stars of exoplane…
Age as a major factor in the onset of multiple populations in stellar clusters
Martocchia, S.; Dalessandro, E.; Salaris, M. +16 more
It is now well established that globular clusters (GCs) exhibit star-to-star light-element abundance variations (known as multiple populations, MPs). Such chemical anomalies have been found in (nearly) all the ancient GCs (more than 10 Gyr old) of our Galaxy and its close companions, but so far no model for the origin of MPs is able to reproduce a…
Cluster mass calibration at high redshift: HST weak lensing analysis of 13 distant galaxy clusters from the South Pole Telescope Sunyaev-Zel'dovich Survey
Simon, P.; Schrabback, T.; Foley, R. J. +26 more
We present an HST/Advanced Camera for Surveys (ACS) weak gravitational lensing analysis of 13 massive high-redshift (zmedian = 0.88) galaxy clusters discovered in the South Pole Telescope (SPT) Sunyaev-Zel'dovich Survey. This study is part of a larger campaign that aims to robustly calibrate mass-observable scaling relations over a wide…