Search Publications
Can a Long Nanoflare Storm Explain the Observed Emission Measure Distributions in Active Region Cores?
Winebarger, Amy R.; Warren, Harry P.; Mulu-Moore, Fana M.
All theories that attempt to explain the heating of the high-temperature plasma observed in the solar corona are based on short bursts of energy. The intensities and velocities measured in the cores of quiescent active regions, however, can be steady over many hours of observation. One heating scenario that has been proposed to reconcile such obse…
Deep Multiwaveband Observations of the Jets of 0208-512 and 1202-262
Perlman, Eric S.; Georganopoulos, Markos; Gelbord, Jonathan +8 more
We present deep Hubble Space Telescope, Chandra, Very Large Array, and Australia Telescope Compact Array images of the jets of PKS 0208-512 and PKS 1202-262, which were found in a Chandra survey of a flux-limited sample of flat-spectrum radio quasars with jets. We discuss in detail their X-ray morphologies and spectra. We find optical emission fro…
Carbon-chain Species in Warm-up Models
Herbst, Eric; Hassel, George E.; Harada, Nanase
In previous warm-up chemical models of the low-mass star-forming region L1527, we investigated the evolution of carbon-chain unsaturated hydrocarbon species when the envelope temperature is slightly elevated to T ≈ 30 K. These models demonstrated that enhanced abundances of such species can be explained by gas-phase ion-molecule chemistry followin…
Gravitational Lens Candidates in the E-CDFS
Barden, M.; Häußler, B.; Jahnke, K. +4 more
We report 10 lens candidates in the Extended Chandra Deep Field South from the GEMS survey. Nine of the systems are new detections and only one of the candidates is a known lens system. For the most promising five systems including the known lens system, we present results from preliminary lens mass modeling, which tests if the candidates are plau…
Submillimeter Sources behind the Massive Lensing Clusters A370 and A2390
Chen, Chian-Chou; Williams, Jonathan P.; Wang, Wei-Hao +2 more
We report 850 µm Submillimeter Array (SMA) observations of four gravitationally lensed submillimeter galaxies (SMGs), A370-2, A2390-1, A2390-3, and A2390-4, which were originally discovered with the Submillimeter Common-User Bolometer Array (SCUBA). Our SMA detection of A370-2 with a submillimeter flux of 7.95 ± 0.60 mJy unambiguously identi…
Hubble Space Telescope Spectral Observations Near the He II Lyα Break: Implications for He II Reionization
Anderson, Scott F.; Schneider, Donald P.; York, Donald G. +4 more
Quasars that allow the study of intergalactic medium (IGM) He II are very rare, since they must be at high redshift along sightlines free of substantial hydrogen absorption, but recent work has dramatically expanded the number of such quasars known. We analyze two dozen higher-redshift (z = 3.1-3.9) low-resolution He II quasar spectra from the Hub…
Is There a Black Hole in NGC 4382?
Gebhardt, Karl; Kormendy, John; Lauer, Tod R. +5 more
We present Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph observations of the galaxy NGC 4382 (M85) and axisymmetric models of the galaxy to determine mass-to-light ratio (Upsilon V ) and central black hole mass (M BH). We find Upsilon V = 3.74 ± 0.1 M sun/L sun and M …
A Magnetohydrodynamic Model of the 2006 December 13 Eruptive Flare
Fan, Y.
We present a three-dimensional magnetohydrodynamic simulation that qualitatively models the coronal magnetic field evolution associated with the eruptive flare that occurred on 2006 December 13 in the emerging δ-sunspot region NOAA 10930 observed by the Hinode satellite. The simulation is set up to drive the emergence of an east-west-oriented magn…
Identification of Three New Protoplanetary Nebulae Exhibiting the Unidentified Feature at 21 µm
Hora, Joseph L.; Fazio, Giovanni; Trigilio, Corrado +3 more
Among its great findings, the Infrared Astronomical Satellite mission showed the existence of an unidentified mid-IR feature around 21 µm. Since its discovery, this feature has been detected in all C-rich protoplanetary nebulae (PPNe) of intermediate spectral type (F-G) and—weakly—in a few PNe and asymptotic giant branch (AGB) stars, but the…
Initiation and Early Development of the 2008 April 26 Coronal Mass Ejection
Pick, M.; Auchère, F.; Démoulin, P. +3 more
We present a detailed study of a coronal mass ejection (CME) with high temporal cadence observations in radio and extreme-ultraviolet (EUV). The radio observations combine imaging of the low corona with radio spectra in the outer corona and interplanetary space. The EUV observations combine the three points of view of the STEREO and SOHO spacecraf…