Search Publications
Spectral Properties of Regions and Structures in the Interstellar Boundary Explorer (IBEX) Sky Maps
Reisenfeld, D. B.; McComas, D. J.; Schwadron, N. A. +5 more
We study the spectral properties of different regions and structures in the energetic neutral atom (ENA) maps at energies from ~0.5 keV to ~6 keV from the Interstellar Boundary Explorer (IBEX) mission. We find that (1) an ankle-shaped break (spectrum hardens) between ~1 keV and ~2 keV characterizes the polar spectra and the right flank, while a kn…
PDR Model Mapping of Physical Conditions via Spitzer/IRS Spectroscopy of H2: Theoretical Success toward NGC 2023-South
Wolfire, M. G.; Sheffer, Y.; Hollenbach, D. J. +2 more
We use the Infrared Spectrograph on Spitzer to observe the southern part of the reflection nebula NGC 2023, including the Southern Ridge, which is a photodissociation region (PDR) par excellence excited by HD 37903. Five pure-rotational H2 emission lines are detected and mapped over and around the Southern Ridge in order to compare with…
EUV Spectral Line Formation and the Temperature Structure of Active Region Fan Loops: Observations with Hinode/EIS and SDO/AIA
Warren, Harry P.; Young, Peter R.; Brooks, David H.
With the aim of studying active region fan loops using observations from the Hinode EUV Imaging Spectrometer (EIS) and Solar Dynamics Observatory Atmospheric Imaging Assembly (AIA), we investigate a number of inconsistencies in modeling the absolute intensities of Fe VIII and Si VII lines, and address why spectroheliograms formed from these lines …
Galactic-scale Absorption Outflow in the Low-luminosity Quasar IRAS F04250-5718: Hubble Space Telescope/Cosmic Origins Spectrograph Observations
Kriss, Gerard A.; Kaastra, Jelle; Behar, Ehud +17 more
We present absorption line analysis of the outflow in the quasar IRAS F04250-5718. Far-ultraviolet data from the Cosmic Origins Spectrograph on board the Hubble Space Telescope reveal intrinsic narrow absorption lines from high ionization ions (e.g., C IV, N V, and O VI) as well as low ionization ions (e.g., C II and Si III). We identify three kin…
SWAP-SECCHI Observations of a Mass-loading Type Solar Eruption
Berghmans, David; Mierla, Marilena; Zhukov, Andrei N. +2 more
We present a three-dimensional reconstruction of an eruption that occurred on 2010 April 3 using observations from SWAP on board PROBA2 and SECCHI on board STEREO. The event unfolded in two parts: an initial flow of cooler material confined to a height low in the corona, followed by a flux rope eruption higher in the corona. We conclude that mass …
XMM-Newton/Sloan Digital Sky Survey: Star Formation Efficiency in Galaxy Clusters and Constraints on the Matter-density Parameter
Reiprich, Thomas H.; Schneider, Peter; Zhang, Yu-Ying +1 more
It is believed that the global baryon content of clusters of galaxies is representative of the matter distribution of the universe, and can, therefore, be used to reliably determine the matter-density parameter Ωm. This assumption is challenged by the growing evidence from optical and X-ray observations that the total baryon mass fracti…
X-Ray and Ultraviolet Emission from the Recurrent Nova RS Ophiuchi in Quiescence: Signatures of Accretion and Shocked Gas
Nelson, T.; Mukai, K.; Sokoloski, J. L. +2 more
RS Ophiuchi is a recurrent nova system that experiences outbursts every ~20 years, implying accretion at a high rate onto a massive white dwarf. However, previous X-ray observations of the system in quiescence have detected only faint emission that is difficult to reconcile with the high accretion rate (>2 × 10-8 M sun yr<…
Hubble Space Telescope Observations of Field Ultracool Dwarfs at High Galactic Latitude
Ryan, R. E.; Yan, L.; Fan, X. +8 more
We present a sample of 17 newly discovered ultracool dwarf candidates later than ~M8, drawn from 231.90 arcmin2 of Hubble Space Telescope Wide Field Camera 3 infrared imaging. By comparing the observed number counts for 17.5 <= J 125 <= 25.5 AB mag to an exponential disk model, we estimate a vertical scale height of z <…
The Old Environment of the Faint Calcium-rich Supernova SN 2005cz
Leonard, Douglas C.; Neill, James D.; James, Phil A. +5 more
The supernova SN 2005cz has recently attracted some attention due to the fact that it was spectroscopically similar to type Ib supernovae (SNe Ib), a class that is presumed to result from the core collapse of massive stars, yet it occurred in an elliptical galaxy, where one expects very few massive stars to exist. Two explanations for this remarka…
Pre-flare Activity and Magnetic Reconnection during the Evolutionary Stages of Energy Release in a Solar Eruptive Flare
Joshi, Bhuwan; Veronig, Astrid M.; Tiwari, Sanjiv Kumar +3 more
In this paper, we present a multi-wavelength analysis of an eruptive white-light M3.2 flare that occurred in active region NOAA 10486 on 2003 November 1. The excellent set of high-resolution observations made by RHESSI and the TRACE provides clear evidence of significant pre-flare activities for ~9 minutes in the form of an initiation phase observ…