Search Publications
Magnetic Field near Venus: Comparison between Solar Cycle 24 and Previous Cycles
Xu, Qi; Zhang, Tielong; Xu, Xiaojun +3 more
Solar Cycle 24 has been proven to be the weakest cycle in solar activity in the last century. So far, most of the evidence has been presented near Earth at 1 au. In this study, we statistically studied the magnetic field of the solar wind near Venus and the induced magnetosphere of Venus using Pioneer Venus Orbiter (PVO) and Venus Express (VEX) ob…
“Red” but Not “Dead”: Actively Star-forming Brightest Cluster Galaxies at Low Redshifts
Yan, Haojing; Runge, James
Brightest cluster galaxies (BCGs) are believed to have assembled most of their stars early in time and therefore should be passively evolving at low redshifts and appear “red-and-dead.” However, there have been reports that a minority of low-redshift BCGs still have ongoing star formation rates (SFRs) of a few to even ∼ 100 {M}⊙ {{yr}}…
Angular Momentum Evolution of Stellar Disks at High Redshifts
Shimasaku, Kazuhiro; Kawamata, Ryota; Okamura, Taku
The stellar disk size of a galaxy depends on the ratio of the disk stellar mass to the halo mass, m ⋆ ≡ M ⋆/M dh, and the fraction of the dark halo angular momentum transferred to the stellar disk, j ⋆ ≡ J ⋆/J dh. Since m ⋆ and j ⋆ are determined by many star f…
X-Ray Reverberation Mapping and Dramatic Variability of Seyfert 1 Galaxy 1H 1934-063
Frederick, Sara; Kara, Erin; Fabian, Andrew +2 more
A fraction of active galactic nuclei (AGN) exhibit dramatic variability, which is observed on timescales down to minutes in the X-ray band. We introduce the case study of 1H 1934-063 (z = 0.0102), a Narrow-line Seyfert 1 among the brightest and most variable AGN ever observed with XMM-Newton. This work includes spectral and temporal analyses of a …
SU Lyn: Diagnosing the Boundary Layer with UV and Hard X-Ray Data
Nelson, T.; Mukai, K.; Sokoloski, J. L. +2 more
Symbiotic stars in which the symbiotic phenomenon is powered solely by accretion, often at an average rate that is higher than in cataclysmic variable stars, provide an important opportunity to diagnose boundary layers around disk-accreting white dwarfs. Here, we investigate SU Lyncis (SU Lyn), a recently discovered example of a purely accretion-p…
They Might Be Giants: An Efficient Color-based Selection of Red Giant Stars
Conroy, Charlie; Dotter, Aaron; Johnson, Benjamin D. +4 more
We present a color-based method for identifying red giants based on the Pan-STARRS grz and WISE W1 and W2 photometry. We utilize a subsample of bright stars with precise parallaxes from Gaia’s second data release (DR2) to verify that the color-based selection reliably separates dwarfs from giants. The selection is conservative in the sense that co…
Angular Sizes and Effective Temperatures of O-type Stars from Optical Interferometry with the CHARA Array
Gies, Douglas R.; Schaefer, Gail H.; Hillier, D. John +3 more
We present interferometric observations of six O-type stars that were made with the Precision Astronomical Visible Observations beam combiner at the Center for High Angular Resolution Astronomy (CHARA) Array. The observations include multiple brackets for three targets, λ Ori A, ζ Oph, and 10 Lac, but there are only preliminary, single observation…
Synthesis of Molecular Oxygen via Irradiation of Ice Grains in the Protosolar Nebula
Wurz, P.; Lunine, J. I.; Danger, G. +4 more
Molecular oxygen has been detected in the coma of comet 67P/Churyumov-Gerasimenko with a mean abundance of 3.80 ± 0.85% by the ROSINA mass spectrometer on board the Rosetta spacecraft. To account for the presence of this species in comet 67P/Churyumov-Gerasimenko, it has been shown that the radiolysis of ice grain precursors of comets is a viable …
Hα Emitting Galaxies at z ∼ 0.6 in the Deep And Wide Narrow-band Survey
Mobasher, Bahram; Zheng, Zhen-Ya; Veilleux, Sylvain +14 more
We present new measurements of the Hα luminosity function (LF) and star formation rate (SFR) volume density for galaxies at z ∼ 0.62 in the COSMOS field. Our results are part of the Deep And Wide Narrow-band Survey (DAWN), a unique infrared imaging program with large areal coverage (∼1.1 deg2 over five fields) and sensitivity (9.9× {10}…
Properties of Decaying Plasma Turbulence at Subproton Scales
Servidio, Sergio; Lapenta, Giovanni; Primavera, Leonardo +2 more
We study the properties of plasma turbulence at subproton scales using kinetic electromagnetic three-dimensional simulations with nonidentical initial conditions. Particle-in-cell modeling of the Taylor-Green vortex has been performed, starting from three different magnetic field configurations. All simulations expose very similar energy evolution…