Search Publications
HST STIS Observations of the Mixing Layer in the Cat’s Eye Nebula
Toalá, Jesús A.; Guerrero, Martín A.; Chu, You-Hua +2 more
Planetary nebulae (PNe) are expected to have a ∼105 K interface layer between the ≥slant 106 K inner hot bubble and the ∼104 K optical nebular shell. The PN structure and evolution, and the X-ray emission, depend critically on the efficiency of the mixing of material at this interface layer. However, neither its lo…
Multiple Outflows in the Giant Eruption of a Massive Star
Humphreys, Roberta M.; Jones, Terry J.; Gordon, Michael S. +1 more
The supernova impostor PSN J09132750+7627410 in NGC 2748 reached a maximum luminosity of ≈-14 mag. It was quickly realized that it was not a true supernova, but another example of a nonterminal giant eruption. PSN J09132750+7627410 is distinguished by multiple P Cygni absorption minima in the Balmer emission lines that correspond to outflow veloci…
Investigating the Circumstellar Disk of the Be Shell Star 48 Librae
Okazaki, A. T.; Carciofi, A. C.; Bednarski, D. +6 more
A global disk oscillation implemented in the viscous decretion disk (VDD) model has been used to reproduce most of the observed properties of the well known Be star ζ Tau. 48 Librae shares several similarities with ζ Tau—they are both early-type Be stars, display shell characteristics in their spectra, and exhibit cyclic V/R variations—but has som…
Challenging Some Contemporary Views of Coronal Mass Ejections. I. The Case for Blast Waves
Pizzo, V. J.; Howard, T. A.
Since the closure of the “solar flare myth” debate in the mid-1990s, a specific narrative of the nature of coronal mass ejections (CMEs) has been widely accepted by the solar physics community. This narrative describes structured magnetic flux ropes at the CME core that drive the surrounding field plasma away from the Sun. This narrative replaced …
The [Ne III] Jet of DG Tau and its Ionization Scenarios
Herczeg, Gregory J.; Liu, Chun-Fan; Shang, Hsien +1 more
Forbidden neon emission from jets of low-mass young stars can be used to probe the underlying high-energy processes in these systems. We analyze spectra of the jet of DG Tau obtained with the Very Large Telescope/X-Shooter spectrograph in 2010. [Ne III] λ 3869 is clearly detected in the innermost 3″ microjet and the outer knot located at ∼ 6\build…
Variations of the ISM Compactness Across the Main Sequence of Star Forming Galaxies: Observations and Simulations
Zezas, A.; Groves, B.; Ashby, M. L. N. +7 more
The majority of star-forming galaxies follow a simple empirical correlation in the star formation rate (SFR) versus stellar mass (M*) plane, of the form {{SFR}}\propto {M}*α , usually referred to as the star formation main sequence (MS). The physics that sets the properties of the MS is currently a subject of debat…
NuSTAR Observations of Magnetar 1E 1048.1-5937
Yang, C.; Guillot, S.; Kaspi, V. M. +5 more
We report on simultaneous Nuclear Spectroscopic Telescope Array (NuSTAR) and XMM-Newton observations of the magnetar 1E 1048.1-5937, along with Rossi X-ray Timing Explorer (RXTE) data for the same source. The NuSTAR data provide a clear detection of this magnetar’s persistent emission up to 20 keV. We detect a previously unreported small secondary…
Testing Relativistic Reflection and Resolving Outflows in PG 1211+143 with XMM-Newton and NuSTAR
Vaughan, S.; Reeves, J. N.; Pounds, K. +1 more
We analyze the broad-band X-ray spectrum (0.3-50 keV) of the luminous Seyfert 1/quasar PG 1211+143—the archetypal source for high-velocity X-ray outflows—using near-simultaneous XMM-Newton and NuSTAR observations. We compare pure relativistic reflection models with a model including the strong imprint of photoionized emission and absorption from a…
Constraining White Dwarf Structure and Neutrino Physics in 47 Tucanae
Kalirai, J. S.; Heyl, J.; Tremblay, P. E. +2 more
We present a robust statistical analysis of the white dwarf cooling sequence in 47 Tucanae. We combine Hubble Space Telescope UV and optical data in the core of the cluster, Modules for Experiments in Stellar Evolution (MESA) white dwarf cooling models, white dwarf atmosphere models, artificial star tests, and a Markov Chain Monte Carlo sampling m…
Multi-wavelength Observations of a Subarcsecond Penumbral Transient Brightening Event
Su, J. T.; Cao, W. D.; Deng, Y. Y. +3 more
We report a subarcsecond penumbral transient brightening event with the high-spatial resolution observations from the 1.6 m New Solar Telescope (NST), Interface Region Imaging Spectrograph (IRIS), and the Solar Dynamics Observatory. The transient brightening, whose thermal energy is in the range of nanoflares, has signatures in the chromosphere, t…