Search Publications
Hubble Space Telescope Proper Motions along the Sagittarius Stream. I. Observations and Results for Stars in Four Fields
Anderson, Jay; Law, David R.; van der Marel, Roeland P. +5 more
We present a multi-epoch Hubble Space Telescope (HST) study of stellar proper motions (PMs) for four fields spanning 200° along the Sagittarius (Sgr) stream: one trailing arm field, one field near the Sgr dwarf spheroidal tidal radius, and two leading arm fields. We determine absolute PMs of dozens of individual stars per field, using established …
The Seyfert 2 galaxy NGC 2110: hard X-ray emission observed by NuSTAR and variability of the iron Kα line
Harrison, F.; Stern, D.; Bauer, F. E. +16 more
We present NuSTAR observations of the bright Seyfert 2 galaxy NGC 2110 obtained in 2012, when the source was at the highest flux level ever observed, and in 2013, when the source was at a more typical flux level. We include archival observations from other X-ray satellites, namely XMM-Newton, Suzaku, BeppoSAX, Chandra and Swift. Simultaneous NuSTA…
The Gemini NICI Planet-Finding Campaign: asymmetries in the HD 141569 disc
Kuchner, Marc J.; Wahhaj, Zahed; Biller, Beth A. +8 more
We report here the highest resolution near-IR imaging to date of the HD 141569A disc taken as part of the NICI (near infrared coronagraphic imager) Science Campaign. We recover four main features in the NICI images of the HD 141569 disc discovered in previous Hubble Space Telescope (HST) imaging: (1) an inner ring/spiral feature. Once deprojected,…
On Flare Predictability Based on Sunspot Group Evolution
Erdélyi, R.; Korsós, M. B.; Ludmány, A. +1 more
The forecast method introduced by Korsós et al. is generalized from the horizontal magnetic gradient (GM), defined between two opposite polarity spots, to all spots within an appropriately defined region close to the magnetic neutral line of an active region. This novel approach is not limited to searching for the largest GM …
Suzaku Observations of γ-Ray Bright Radio Galaxies: Origin of the X-Ray Emission and Broadband Modeling
Fukazawa, Yasushi; Itoh, Ryosuke; Stawarz, Łukasz +3 more
We performed a systematic X-ray study of eight nearby γ-ray bright radio galaxies with Suzaku in order to understand the origins of their X-ray emissions. The Suzaku spectra for five of those have been presented previously, while the remaining three (M87, PKS 0625-354, and 3C 78) are presented here for the first time. Based on the Fe-K line streng…
Measuring Infrared Surface Brightness Fluctuation Distances with HST WFC3: Calibration and Advice
Blakeslee, John P.; Jensen, Joseph B.; Cantiello, Michele +5 more
We present new calibrations of the near-infrared (near-IR) surface brightness fluctuation (SBF) distance method for the F110W ({J}110) and F160W ({H}160) bandpasses of the Wide Field Camera 3 Infrared Channel (WFC3/IR) on the Hubble Space Telescope. The calibrations are based on data for 16 early-type galaxies in the Virgo an…
Explosive volcanic activity on Venus: The roles of volatile contribution, degassing, and external environment
Wilson, C. F.; Glaze, L. S.; Airey, M. W. +3 more
We investigate the conditions that will promote explosive volcanic activity on Venus. Conduit processes were simulated using a steady-state, isothermal, homogeneous flow model in tandem with a degassing model. The response of exit pressure, exit velocity, and degree of volatile exsolution was explored over a range of volatile concentrations (H
Predictions for Ultra-deep Radio Counts of Star-forming Galaxies
Cai, Zhen-Yi; Lapi, Andrea; Negrello, Mattia +6 more
We have worked outty predictions for the radio counts of star-forming galaxies down to nJy levels, along with redshift distributions down to the detection limits of the phase 1 Square Kilometer Array MID telescope (SKA1-MID) and of its precursors. Such predictions were obtained by coupling epoch-dependent star formation rate (SFR) functions with r…
Parallel Evolution of Quasi-separatrix Layers and Active Region Upflows
Pick, M.; Mandrini, C. H.; van Driel-Gesztelyi, L. +6 more
Persistent plasma upflows were observed with Hinode’s EUV Imaging Spectrometer (EIS) at the edges of active region (AR) 10978 as it crossed the solar disk. We analyze the evolution of the photospheric magnetic and velocity fields of the AR, model its coronal magnetic field, and compute the location of magnetic null-points and quasi-sepratrix layer…
The Ch-class Asteroids: Connecting a Visible Taxonomic Class to a 3 µm Band Shape
Emery, Joshua P.; Rivkin, Andrew S.; Thomas, Cristina A. +1 more
Asteroids belonging to the Ch spectral taxonomic class are defined by the presence of an absorption near 0.7 µm, which is interpreted as due to Fe-bearing phyllosilicates. Phyllosilicates also cause strong absorptions in the 3 µm region, as do other hydrated and hydroxylated minerals and H2O ice. Over the past decade, spectr…