Search Publications
Missions
Journals
Publication Years
Spectral Analysis of the September 2017 Solar Energetic Particle Events
de Nolfo, G. A.; Christian, E. R.; Ryan, J. M. +2 more
An interval of exceptional solar activity was registered in early September 2017, late in the decay phase of solar cycle 24, involving the complex Active Region 12673 as it rotated across the western hemisphere with respect to Earth. A large number of eruptions occurred between 4 and 10 September, including four associated with X-class flares. The…
Comparison of Gaia DR2 Parallaxes of Stars with VLBI Astrometry
Reid, Mark J.; Zhang, Bo; Xu, Shuangjing +2 more
We compare the parallaxes of stars from VLBI astrometry in the literature to those in the Gaia DR2 catalog. Our full sample contains young stellar objects, evolved AGB stars, pulsars, and other radio stars. Excluding AGB stars, which show significant discrepancies between Gaia and VLBI parallaxes, and stars in binary systems, we obtain an average,…
On the Use of Field RR Lyrae as Galactic Probes. I. The Oosterhoff Dichotomy Based on Fundamental Variables
Valenti, E.; Marinoni, S.; Thévenin, F. +21 more
We collected a large data set of field RR Lyrae stars (RRLs) by using catalogs already available in the literature and Gaia DR2. We estimated the iron abundances for a subsample of 2382 fundamental RRLs (ΔS method: Ca II K, Hβ, Hγ, and Hδ lines) for which there are publicly available medium-resolution SDSS-SEGUE spectra. We also included similar e…
Stellar ages, masses, and radii from asteroseismic modeling are robust to systematic errors in spectroscopy
Hekker, S.; Basu, S.; Stokholm, A. +2 more
Context. The search for twins of the Sun and Earth relies on accurate characterization of stellar and the exoplanetary parameters age, mass, and radius. In the modern era of asteroseismology, parameters of solar-like stars are derived by fitting theoretical models to observational data, which include measurements of their oscillation frequencies, …
The missing light of the Hubble Ultra Deep Field
Borlaff, Alejandro; Eliche-Moral, M. Carmen; Beckman, John E. +11 more
Context. The Hubble Ultra Deep field (HUDF) is the deepest region ever observed with the Hubble Space Telescope. With the main objective of unveiling the nature of galaxies up to z ∼ 7 - 8, the observing and reduction strategy have focused on the properties of small and unresolved objects, rather than the outskirts of the largest objects, which ar…
Photodynamical analysis of the triply eclipsing hierarchical triple system EPIC 249432662
Vanderburg, A.; Haas, M.; Rappaport, S. +16 more
Using Campaign 15 data from the K2 mission, we have discovered a triply eclipsing triple star system: EPIC 249432662. The inner eclipsing binary system has a period of 8.23 d, with shallow ∼3 per cent eclipses. During the entire 80-d campaign, there is also a single eclipse event of a third body in the system that reaches a depth of nearly 50 per …
GROWTH on S190426c: Real-time Search for a Counterpart to the Probable Neutron Star-Black Hole Merger using an Automated Difference Imaging Pipeline for DECam
Duev, Dmitry A.; Andreoni, Igor; De, Kishalay +17 more
The discovery of a transient kilonova following the gravitational-wave (GW) event GW170817 highlighted the critical need for coordinated rapid and wide-field observations, inference, and follow-up across the electromagnetic spectrum. In the southern hemisphere, the Dark Energy Camera (DECam) on the Blanco 4 m telescope is well suited to this task,…
Radio frequency timing analysis of the compact jet in the black hole X-ray binary Cygnus X-1
Maccarone, T. J.; Gandhi, P.; Casella, P. +5 more
We present simultaneous multiband radio and X-ray observations of the black hole X-ray binary Cygnus X-1, taken with the Karl G. Jansky Very Large Array and the Nuclear Spectroscopic Telescope Array. With these data, we detect clear flux variability consistent with emission from a variable compact jet. To probe how the variability signal propagate…
Primordial gravitational waves and the H0-tension problem
Benetti, Micol; Graef, Leila L.; Alcaniz, Jailson S.
We analyze the H0-tension problem in the context of models of the early universe that predict a blue tilted spectrum of primordial gravitational waves (GWs), which is a positive value of the tensor tilt nT. By considering the GW's contribution, NeffGW, to the effective number of relativistic degrees of f…
Determining the recurrence time-scale of long-lasting YSO outbursts
Naylor, Tim; Morrell, Sam; Contreras Peña, Carlos
We have determined the rate of large accretion events in Class I and II young stellar objects (YSOs) by comparing the all-sky digitized photographic plate surveys provided by SuperCOSMOS with the latest data release from Gaia (DR2). The long mean baseline of 55 yr along with a large sample of Class II YSOs (≃15 000) allows us to study approximatel…