Search Publications
HST/COS Observations of Quasar Outflows in the 500-1050 Å Rest Frame. III. Four Similar Outflows in 2MASS J1051+1247 with Enough Energy to Be Major Contributors to AGN Feedback
Xu, Xinfeng; Kriss, Gerard A.; Arav, Nahum +2 more
We detect four very energetic outflows in the Hubble Space Telescope/Cosmic Origins Spectrograph spectra of quasar 2MASS J1051+1247 with a combined kinetic luminosity (\dot{E}_{K}) of 1046 erg s-1. Remarkable similarities are seen in these outflows: velocity centroids between 4900 and 5700 km s-1, distances from th…
The Streamer Blowout Origin of a Flux Rope and Energetic Particle Event Observed by Parker Solar Probe at 0.5 au
Luhmann, J. G.; Lario, D.; Arge, C. N. +18 more
The distribution of spacecraft in the inner heliosphere during 2019 March enabled comprehensive observations of an interplanetary coronal mass ejection (ICME) that encountered Parker Solar Probe (PSP) at 0.547 au from the Sun. This ICME originated as a slow (∼311 km s-1) streamer blowout (SBO) on the Sun as measured by the white-light c…
Detection of the Red Supergiant Wind from the Progenitor of Cassiopeia A
Chevalier, Roger A.; Raymond, John C.; Milisavljevic, Dan +4 more
Cassiopeia A (Cas A) is one of the best studied young Galactic supernova remnants. While it provides a rare opportunity to study in detail the remnant of a supernova (SN) type IIb, questions remain regarding the nature of its progenitor, its mass-loss history, and its pre-SN evolution. Here we present an optical investigation of the circumstellar …
HST/COS Observations of Quasar Outflows in the 500-1050 Å Rest Frame. V. Richness of Physical Diagnostics and Ionization Potential-dependent Velocity Shift in PKS J0352-0711
Xu, Xinfeng; Kriss, Gerard A.; Arav, Nahum +2 more
We analyze absorption troughs from two outflows within PKS J0352-0711 (S1 at -1950 km s-1 and S2 at -3150 km s-1) from spectra taken with Hubble Space Telescope/Cosmic Origins Spectrograph, which cover the diagnostic-rich 585-900 Å rest-frame wavelength range. In S2, for the first time we clearly detect absorption troughs fro…
Cyclotron line energy in Hercules X-1: stable after the decay
Harrison, F.; Ducci, L.; Wilms, J. +6 more
We summarize the results of a dedicated effort made between 2012 and 2019 to follow the evolution of the cyclotron line in Her X-1 through repeated NuSTAR observations. The previously observed nearly 20-year-long decay of the cyclotron line energy has ended in 2012: from then on, the pulse-phase-averaged flux-corrected cyclotron line energy has re…
The pulsation properties of λ bootis stars I. the southern TESS sample
Paunzen, E.; Huber, D.; Bedding, T. R. +2 more
We analyse TESS light curves for 70 southern λ Boo stars to identify binaries and to determine which of them pulsate as δ Scuti stars. We find two heartbeat stars and two eclipsing binaries among the sample. We calculate that 81 per cent of λ Boo stars pulsate as δ Sct variables, which is about twice that of normal stars over the same parameter sp…
The infrared view of dust and molecules around V4334 Sgr (Sakurai's object): a 20-yr retrospective
Gehrz, R. D.; Joyce, R. R.; Eyres, S. P. S. +16 more
We present an analysis of the evolution of circumstellar dust and molecules in the environment of the very late thermal pulse object V4334 Sgr (Sakurai's object) over an ∼20-yr period, drawing on ground-, airborne-, and space-based infrared photometry and spectroscopy. The dust emission, which started in 1997, resembles a blackbody that cooled fro…
Astraea: Predicting Long Rotation Periods with 27 Day Light Curves
Angus, Ruth; Grunblatt, Sam; Agüeros, Marcel A. +5 more
The rotation periods of planet-hosting stars can be used for modeling and mitigating the impact of magnetic activity in radial velocity measurements and can help constrain the high-energy flux environment and space weather of planetary systems. Millions of stars and thousands of planet hosts are observed with the Transiting Exoplanet Survey Satell…
CCD VI time-series of the extremely metal-poor globular cluster M92: revisiting its variable star population
Arellano Ferro, A.; Deras, D.; Yepez, M. A.
We present an analysis of VI CCD time-series photometry of the Oo II type globular cluster M92. The variable star population of the cluster is studied with the aim of revising their classifications, identifications, frequency spectra, and to select indicators of the parental cluster metallicity and distance. The Fourier decomposition of RR Lyrae l…
The Warm Gas in the MW: A Kinematical Model
Bregman, Joel N.; Qu, Zhijie; Lindley, Ryan +2 more
We develop a kinematical model for the Milky Way Si IV-bearing gas to determine its density distribution and kinematics. This model is constrained by a column density line-shape sample extracted from the Hubble Space Telescope/Cosmic Origins Spectrograph archival data, which contains 186 active galactic nucleus sight lines. We find that the Si IV …