Search Publications
Tracing the Chromospheric and Coronal Magnetic Field with AIA, IRIS, IBIS, and ROSA Data
Aschwanden, Markus J.; Reardon, Kevin; Jess, Dave B.
The aim of this study is to explore the suitability of chromospheric images for magnetic modeling of active regions. We use high-resolution images (≈ 0\buildrel{\prime\prime}\over{.} 2{--}0\buildrel{\prime\prime}\over{.} 3), from the Interferometric Bidimensional Spectrometer in the Ca II 8542 Å line, the Rapid Oscillations in the Solar Atmosphere…
A Study of the Relation between Star Formation and Molecular Clumps on Subparsec Scales in 30 Doradus
Panagia, N.; Indebetouw, R.; Sabbi, E. +4 more
We present 12CO and 13CO molecular gas data observed by ALMA, massive early-stage young stellar objects (YSOs) identified by applying color-magnitude cuts to Spitzer and Herschel photometry, and low-mass late-stage YSOs identified via {{H}}α excess. Using dendrograms, we derive properties for the molecular cloud structures. T…
The Rotation of the Solar Photospheric Magnetic Field
Xu, J. C.; Gao, P. X.
The rotational characteristics of the solar photospheric magnetic field at four flux ranges are investigated together with the total flux of active regions (MFar) and quiet regions (MFqr). The first four ranges (MF1-4) are (1.5-2.9) × 1018, (2.9-32.0) × 1018, (3.20-4.27) × 1019, and…
A Deep X-Ray View of the Bare AGN Ark 120. I. Revealing the Soft X-Ray Line Emission
Turner, T. J.; Porquet, D.; Reeves, J. N. +3 more
The Seyfert 1 galaxy Ark 120 is a prototype example of the so-called class of bare nucleus active galactic nuclei (AGNs), whereby there is no known evidence for the presence of ionized gas along the direct line of sight. Here deep (>400 ks exposure), high-resolution X-ray spectroscopy of Ark 120 is presented from XMM-Newton observations that we…
A Deep X-Ray View of the Bare AGN Ark 120. II. Evidence for Fe K Emission Transients
Porquet, D.; Matt, G.; Reeves, J. N. +3 more
We report on the results from a large observational campaign on the bare Seyfert galaxy Ark 120, jointly carried out in 2014 with XMM-Newton, Chandra, and NuSTAR. The fortunate line of sight to this source, devoid of any significant absorbing material, provides an incomparably clean view to the nuclear regions of an active galaxy. Here we focus on…
Modeling the Initiation of the 2006 December 13 Coronal Mass Ejection in AR 10930: The Structure and Dynamics of the Erupting Flux Rope
Fan, Yuhong
We carry out a 3D magnetohydrodynamic simulation to model the initiation of the coronal mass ejection (CME) on 2006 December 13 in the emerging δ-sunspot active region NOAA 10930. The setup of the simulation is similar to a previous simulation by Fan, but with a significantly widened simulation domain to accommodate the wide CME. The simulation sh…
Transition Region Abundance Measurements During Impulsive Heating Events
Warren, Harry P.; Doschek, George A.; Brooks, David H. +1 more
It is well established that elemental abundances vary in the solar atmosphere and that this variation is organized by first ionization potential (FIP). Previous studies have shown that in the solar corona, low-FIP elements such as Fe, Si, Mg, and Ca, are generally enriched relative to high-FIP elements such as C, N, O, Ar, and Ne. In this paper we…
Evidence for Reflected Light from the Most Eccentric Exoplanet Known
Butler, R. Paul; Mahadevan, Suvrath; Henry, Gregory W. +16 more
Planets in highly eccentric orbits form a class of objects not seen within our solar system. The most extreme case known among these objects is the planet orbiting HD 20782, with an orbital period of 597 days and an eccentricity of 0.96. Here we present new data and analysis for this system as part of the Transit Ephemeris Refinement and Monitorin…
IC 3639—a New Bona Fide Compton-Thick AGN Unveiled by NuSTAR
Harrison, F. A.; Stern, D.; Zhang, W. W. +19 more
We analyze high-quality NuSTAR observations of the local (z = 0.011) Seyfert 2 active galactic nucleus (AGN) IC 3639, in conjunction with archival Suzaku and Chandra data. This provides the first broadband X-ray spectral analysis of the source, spanning nearly two decades in energy (0.5-30 keV). Previous X-ray observations of the source below 10 k…
Constraints on the Binary Companion to the SN Ic 1994I Progenitor
Van Dyk, Schuyler D.; de Mink, Selma E.; Zapartas, Emmanouil
Core-collapse supernovae (SNe), which mark the deaths of massive stars, are among the most powerful explosions in the universe and are responsible, e.g., for a predominant synthesis of chemical elements in their host galaxies. The majority of massive stars are thought to be born in close binary systems. To date, putative binary companions to the p…