Search Publications
Variability of the coronal line region in NGC 4151
Ferland, Gary J.; Steenbrugge, Katrien C.; Landt, Hermine +1 more
We present the first extensive study of the coronal line variability in an active galaxy. Our data set for the nearby source NGC 4151 consists of six epochs of quasi-simultaneous optical and near-infrared spectroscopy spanning a period of about 8 yr and five epochs of X-ray spectroscopy overlapping in time with it. None of the coronal lines showed…
The Born-again Planetary Nebula A78: An X-Ray Twin of A30
Gruendl, R. A.; Hamann, W. -R.; Chu, Y. -H. +8 more
We present the XMM-Newton discovery of X-ray emission from the planetary nebula (PN) A78, the second born-again PN detected in X-rays apart from A30. These two PNe share similar spectral and morphological characteristics: they harbor diffuse soft X-ray emission associated with the interaction between the H-poor ejecta and the current fast stellar …
A radio and X-ray study of the merging cluster A2319
Rudnick, Lawrence; Jeltema, Tesla E.; Storm, Emma
A2319 is a massive, merging galaxy cluster with a previously detected radio halo that roughly follows the X-ray emitting gas. We present the results from recent observations of A2319 at ∼20 cm with the Karl G. Jansky Very Large Array and a re-analysis of the X-ray observations from XMM-Newton, to investigate the interactions between the thermal an…
Newly Determined Explosion Center of Tycho's Supernova and the Implications for Proposed Ex-companion Stars of the Progenitor
Schaefer, Bradley E.; Xue, Zhichao
“Star G,” near the center of the supernova remnant of Tycho’s SN 1572, has been claimed to be the ex-companion star of the exploding white dwarf, thus pointing to the progenitor being like a recurrent nova. This claim has been controversial, but there have been no confident proofs or disproofs. Previously, no one has seriously addressed the questi…
Object-based Dune Analysis: Automated dune mapping and pattern characterization for Ganges Chasma and Gale crater, Mars
Fenton, Lori K.; Michaels, Timothy I.; Vaz, David A. +2 more
A method that enables the automated mapping and characterization of dune fields on Mars is described. Using CTX image mosaics, the introduced Object-based Dune Analysis (OBDA) technique produces an objective and reproducible mapping of dune morphologies over extensive areas. The data set thus obtained integrates a large variety of data, allowing a…
The 1999aa-like Type Ia Supernova iPTF14bdn in the Ultraviolet and Optical
Suntzeff, Nicholas B.; Wang, Xiaofeng; Zhang, Jujia +5 more
We present ultraviolet (UV) and optical photometry and spectra of the 1999aa-like supernova (SN) iPTF14bdn. The UV data were observed using the Swift Ultraviolet/Optical Telescope and constitute the first UV spectral series of a 1999aa-like SN. From the photometry, we measure Δm15(B) = 0.84 ± 0.05 mag and blue UV colors at epochs earlie…
Plasma regions, charged dust and field-aligned currents near Enceladus
Gurnett, D. A.; Dougherty, M. K.; Kurth, W. S. +7 more
We use data from several instruments on board Cassini to determine the characteristics of the plasma and dust regions around Saturn's moon Enceladus. For this we utilize the Langmuir probe and the electric antenna connected to the wideband receiver of the radio and plasma wave science (RPWS) instrument package as well as the magnetometer (MAG). We…
A Herschel/HIFI Legacy Survey of HF and H2O in the Galaxy: Probing Diffuse Molecular Cloud Chemistry
Gerin, M.; Neufeld, D. A.; Sonnentrucker, P. +5 more
We combine Herschel observations for a total of 12 sources to construct the most uniform survey of HF and H2O in our Galactic disk. Both molecules are detected in absorption along all sight lines. The high spectral resolution of the Heterodyne Instrument for the Far-infrared (HIFI) allows us to compare the HF and H2O distribu…
Redshifted Fe Kα line from the unusual γ-ray source PMN J1603-4904
Stawarz, Ł.; Dauser, T.; Wilms, J. +13 more
Context. Multiwavelength observations have revealed the highly unusual properties of the γ-ray source PMN J1603-4904, which are difficult to reconcile with any other well-established γ-ray source class. The object is either a very atypical blazar or a compact jet source seen at a larger angle to the line of sight.
Aims: To determine the physi…
The Relation between Dynamical Mass-to-light Ratio and Color for Massive Quiescent Galaxies out to z ~ 2 and Comparison with Stellar Population Synthesis Models
van Dokkum, Pieter G.; Franx, Marijn; Bezanson, Rachel +2 more
We explore the relation between the dynamical mass-to-light ratio (M/L) and rest-frame color of massive quiescent galaxies out to z ~ 2. We use a galaxy sample with measured stellar velocity dispersions in combination with Hubble Space Telescope and ground-based multi-band photometry. Our sample spans a large range in log M dyn/L g…