Search Publications
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 …
Reconstruction of Cluster Masses Using Particle Based Lensing. I. Application to Weak Lensing
Goldberg, David M.; Deb, Sanghamitra; Ramdass, Vede J.
We present Particle Based Lensing (PBL), a new technique for gravitational lensing mass reconstructions of galaxy clusters. Traditionally, most methods have employed either a finite inversion or gridding to turn observational lensed galaxy ellipticities into an estimate of the surface mass density of a galaxy cluster. We approach the problem from …
New XMM-Newton Analysis of Three Bright X-Ray Sources in M31 Globular Clusters, Including a New Black Hole Candidate
Stiele, H.; Pietsch, W.; Haberl, F. +6 more
We present a detailed analysis of three globular cluster X-ray sources in the XMM-Newton extended survey of M31. The X-ray counterpart to the M31 globular cluster Bo 45 (XBo 45) was observed with XMM-Newton on 2006 December 26. Its combined pn+MOS 0.3-10 keV light curve was seen to vary by ~10%, and its 0.3-7.0 keV emission spectrum was well descr…
A Comparison of Weak-Lensing Measurements from Ground- and Space-Based Facilities
Ellis, Richard S.; Massey, Richard; Rhodes, Jason +2 more
We assess the relative merits of weak-lensing surveys, using overlapping imaging data from the ground-based Subaru telescope and the Hubble Space Telescope (HST). Our tests complement similar studies undertaken with simulated data. From observations of 230,000 matched objects in the 2 deg2 COSMOS field, we identify the limit at which fa…
The Host Galaxy and the Extended Emission-Line Region of the Radio Galaxy 3C 79
Fu, Hai; Stockton, Alan
We present extensive ground-based spectroscopy and HST imaging of 3C 79, an FR II radio galaxy associated with a luminous extended emission-line region (EELR). Surface brightness modeling of an emission-line-free HST R-band image reveals that the host galaxy is a massive elliptical with a compact companion 0.8'' away and 4 mag fainter. …