Search Publications
Disintegration of Magnetic Flux in Decaying Sunspots as Observed with the Hinode SOT
Kubo, M.; Lites, B. W.; Ichimoto, K. +8 more
Continuous observations of sunspot penumbrae with the Solar Optical Telescope aboard Hinode clearly show that the outer boundary of the penumbra fluctuates around its averaged position. The penumbral outer boundary moves inward when granules appear in the outer penumbra. We discover that such granules appear one after another while moving magnetic…
Understanding the Relations between QSOs and Their Host Galaxies from Combined HST Imaging and VLT Spectroscopy
Magain, P.; Courbin, F.; Hutsemékers, D. +2 more
The host galaxies of six nearby QSOs are studied on the basis of high-resolution HST optical images and spatially resolved VLT slit spectra. The gas ionization and velocity are mapped as a function of the distance to the central QSO. In the majority of the cases, the QSO significantly contributes to the gas ionization in its whole host galaxy, and…
Interstellar Krypton Abundances: The Detection of Kiloparsec-scale Differences in Galactic Nucleosynthetic History
Sofia, Ulysses J.; Meyer, David M.; Cartledge, Stefan I. B. +2 more
We present an analysis of Kr I λ1236 line measurements from 50 sight lines in the Hubble Space Telescope Space Telescope Imaging Spectrograph and Goddard High Resolution Spectrograph data archives that have sufficiently high resolution and signal-to-noise ratio to permit reliable krypton-to-hydrogen abundance ratio determinations. The distribution…
XMM-Newton Observations of Broad Absorption Line Quasars with Polar Outflows
Zhou, Hongyan; Wang, Huiyuan; Jiang, Peng +3 more
We have selected a sample of broad absorption line (BAL) quasars which show significant radio variations, indicating the presence of polar BAL outflows. We obtained snapshot XMM observations of four polar BAL QSOs, to check whether strong X-ray absorption, one of the most prominent characteristics of most BAL QSOs, also exists in polar outflows. T…
Hydrodynamical Simulations of the Barred Spiral Galaxy NGC 6782
Lin, Lien-Hsuan; Yuan, Chi; Buta, R.
NGC 6782 is an early-type barred spiral galaxy exhibiting a rich and complex morphology with multiple ring patterns. To provide a physical understanding of its structure and kinematical properties, two-dimensional hydrodynamical simulations have been carried out. Numerical calculations reveal that the striking features in NGC 6782 can be reproduce…
Young Stellar Objects in the Large Magellanic Cloud: N63 and N180 H II Regions
Gruendl, R. A.; Chu, Y. -H.; Caulet, Adeline
We used Spitzer infrared observations to find the young stars of two H II regions in the Large Magellanic Cloud, N63 and N180. The young stellar object (YSO) candidates were identified in each nebula by means of color-color, color-magnitude diagrams, and the shapes of their spectral energy distributions (SEDs). The most luminous YSOs are found nea…
IRAC Excess in Distant Star-Forming Galaxies: Tentative Evidence for the 3.3 µm Polycyclic Aromatic Hydrocarbon Feature?
Magnelli, B.; Elbaz, D.; Morrison, G. +3 more
We present evidence for the existence of an IRAC excess in the spectral energy distribution (SED) of five galaxies at 0.6 < z < 0.9 and one galaxy at z = 1.7. These six galaxies, located in the Great Observatories Origins Deep Survey field (GOODS-N), are star-forming since they present strong 6.2, 7.7, and, 11.3 µm polycyclic aromatic …
Interferometric Studies of the Extreme Binary epsilon Aurigae: Pre-Eclipse Observations
Stencel, Robert E.; Creech-Eakman, Michelle; Hart, Alexa +3 more
We report new and archival K-band interferometric uniform disk diameters obtained with the Palomar Testbed Interferometer for the eclipsing binary star epsilon Aurigae, in advance of the start of its eclipse in 2009. The observations were intended to test whether low-amplitude variations in the system are connected with the F supergiant star (prim…
Expansion Velocities and Core Masses of Bright Planetary Nebulae in the Virgo Cluster
Freeman, Kenneth C.; Gerhard, Ortwin; Ciardullo, Robin +5 more
The line-of-sight velocities and [O III] 5007 Å expansion velocities are measured for 11 planetary nebulae (PNs) in the Virgo Cluster core, at 15 Mpc distance, with the FLAMES spectrograph on the ESO VLT. These PNs are located about halfway between the two giant elliptical galaxies M87 and M86. From the [O III] 5007 Å line profile widths, the aver…
A Lyman Break Galaxy Candidate at z ~ 9
Teplitz, Harry I.; Siana, Brian; Malkan, Matthew A. +3 more
We report the discovery of a z ~ 9 Lyman break galaxy candidate, selected from the NICMOS Parallel Imaging Survey as a J-dropout with J110 - H160 = 1.7. Spitzer/IRAC photometry reveals that the galaxy has a blue H160 - 3.6 µm color and a spectral break between 3.6 and 4.5 µm. We interpret this break as …