Search Publications
Cyclic Changes of the Sun’s Seismic Radius
Rozelot, Jean-Pierre; Kosovichev, Alexander
The questions asking whether the Sun shrinks with the solar activity and what causes this have been a subject of debate. Helioseismology provides a means to measure with high precision the radial displacement of subsurface layers, the so-called “seismic radius,” through the analysis of oscillation frequencies of surface gravity (f) modes. Here, we…
Resolving the X-Ray Obscuration in a Low-flux Observation of the Quasar PDS 456
Turner, T. J.; O'Brien, P. T.; Reeves, J. N. +5 more
Simultaneous XMM-Newton, NuSTAR, and HST observations, performed in 2017 March, of the nearby (z = 0.184) luminous quasar PDS 456 are presented. PDS 456 had a low X-ray flux compared to past observations, where the first of the two new XMM-Newton observations occurred during a pronounced dip in the X-ray light curve. The broadband X-ray spectrum i…
Simultaneous Spectral Energy Distribution and Near-infrared Interferometry Modeling of HD 142666
Monnier, John D.; Kraus, Stefan; Baron, Fabien +10 more
We present comprehensive models of the Herbig Ae star, HD 142666, which aim to simultaneously explain its spectral energy distribution (SED) and near-infrared (NIR) interferometry. Our new submilliarcsecond resolution CHARA (CLASSIC and CLIMB) interferometric observations, supplemented with archival shorter baseline data from VLTI/PIONIER and the …
Intensity-corrected Herschel Observations of Nearby Isolated Low-mass Clouds
Bourke, Tyler L.; Di Francesco, James; Myers, Philip C. +8 more
We present intensity-corrected Herschel maps at 100, 160, 250, 350, and 500 µm for 56 isolated low-mass clouds. We determine the zero-point corrections for Herschel Photodetector Array Camera and Spectrometer (PACS) and Spectral Photometric Imaging Receiver (SPIRE) maps from the Herschel Science Archive (HSA) using Planck data. Since these H…
Helium Reionization Simulations. III. The Helium Lyα Forest
Trac, Hy; La Plante, Paul; Croft, Rupert +1 more
In a previous paper we presented a new suite of hydrodynamic simulations with the aim of accurately capturing the process of helium II reionization. In this paper, we discuss the observational signatures present in the He II Lyα forest. We show that the effective optical depth of the volume-averaged τ eff alone is not sufficient for cap…
Mass Modeling of Frontier Fields Cluster MACS J1149.5+2223 Using Strong and Weak Lensing
Treu, Tommaso; Bradač, Maruša; Schrabback, Tim +8 more
We present a gravitational-lensing model of MACS J1149.5+2223 using ultra-deep Hubble Frontier Fields imaging data and spectroscopic redshifts from HST grism and Very Large Telescope (VLT)/MUSE spectroscopic data. We create total mass maps using 38 multiple images (13 sources) and 608 weak-lensing galaxies, as well as 100 multiple images of 31 sta…
A Slowly Precessing Disk in the Nucleus of M31 as the Feeding Mechanism for a Central Starburst
Ghez, A. M.; Rich, R. M.; Lu, J. R. +3 more
We present a kinematic study of the nuclear stellar disk in M31 at infrared wavelengths using high spatial resolution integral field spectroscopy. The spatial resolution achieved, FWHM = 0.″12 (0.45 pc at the distance of M31), has only previously been equaled in spectroscopic studies by space-based long-slit observations. Using adaptive-optics-cor…
Parallaxes of Cool Objects with WISE: Filling in for Gaia
Theissen, Christopher A.
This paper uses the multi-epoch astrometry from the Wide-field Infrared Survey Explorer (WISE) to demonstrate a method to measure proper motions and trigonometric parallaxes with precisions of ∼4 mas yr-1 and ∼7 mas, respectively, for low-mass stars and brown dwarfs. This method relies on WISE single exposures (Level 1b frames) and a Ma…
Spatially Resolved Broadband Synchrotron Emission from the Nonthermal Limbs of SN1006
Bregman, Joel N.; Acero, Fabio; Ballet, Jean +6 more
We present ∼400 ks NuSTAR observations of the northeast (NE) and southwest (SW) nonthermal limbs of the Galactic SNR SN1006. We discovered three sources with X-ray emission detected at ≳50 keV. Two of them are identified as background active galactic nuclei. We extract the NuSTAR spectra from a few regions along the nonthermal limbs and jointly an…
Searching for Exoplanets around X-Ray Binaries with Accreting White Dwarfs, Neutron Stars, and Black Holes
Di Stefano, Rosanne; Imara, Nia
We recommend that the search for exoplanets around binary stars be extended to include X-ray binaries (XRBs) in which the accretor is a white dwarf, neutron star, or black hole. We present a novel idea for detecting planets bound to such mass transfer binaries, proposing that the X-ray light curves of these binaries be inspected for signatures of …