Search Publications
Active Galactic Nucleus Feedback and Gas Mixing in the Core of NGC 4636
O'Sullivan, E.; Vrtilek, J. M.; Kempner, J. C.
Chandra observations of NGC 4636 show disturbances in the galaxy X-ray halo, including armlike high surface brightness features (tentatively identified as active galactic nucleus-driven shocks) and a possible cavity on the west side of the galaxy core. We present Chandra and XMM-Newton spectral maps of NGC 4636 that confirm the presence of the cav…
Atomic and Molecular Gas in Colliding Galaxy Systems. I. The Data
Yun, Min S.; Iono, Daisuke; Ho, Paul T. P.
We present H I and CO (1-0) interferometric observations of 10 comparable-mass interacting systems obtained at the Very Large Array (VLA) and the Owens Valley Radio Observatory (OVRO) millimeter array. The primary intent of this study is to investigate the response of cold gas during the early stages of collision of massive disk galaxies. The samp…
Opening the Treasure Chest: A Newborn Star Cluster Emerges from Its Dust Pillar in Carina
Smith, Nathan; Stassun, Keivan G.; Bally, John
We present detailed observations of the Treasure Chest, a compact nebula at the head of a dust pillar in the southern Carina Nebula. This object is of interest because it is an example of a dense young cluster containing at least one massive star, the formation of which may have been triggered by feedback from the very massive stars in the Carina …
The low X-ray state of LS 5039 / RX J1826.2-1450
Motch, C.; Negueruela, I.; Martocchia, A.
Recent XMM-Newton and Chandra observations of the high mass X-ray binary LS 5039 / RX J1826.2-1450 caught the source in a faint X-ray state. In contrast with previous RXTE observations, we fail to detect any evidence of iron line emission. We also fail to detect X-ray pulsations. The X-ray spectrum can be well fitted by a simple powerlaw, slightly…
The XMM-LSS survey. The XMDS/VVDS 4σ catalogue
Maccagni, D.; Maraschi, L.; Chiappetti, L. +15 more
We present a first catalogue of X-ray sources resulting from the central area of the XMM-LSS (Large Scale Structure survey). We describe the reduction procedures and the database tools we developed and used to derive a well defined catalogue of X-ray sources. The present catalogue is limited to a sub-sample of 286 sources detected at 4 σ in the 1 …
The Role of Magnetic Helicity in Coronal Mass Ejections
MacNeice, P. J.; Antiochos, S. K.; Phillips, A. D.
We investigate the factors responsible for initiating coronal mass ejections (CMEs), specifically, the role of magnetic helicity. Using numerical simulations of the breakout model for CMEs, we show that eruption occurs at a fixed magnitude of free energy in the corona, independent of the value of helicity. Almost identical eruptions are obtained f…
Detection and Diagnostics of a Coronal Shock Wave Driven by a Partial-Halo Coronal Mass Ejection on 2000 June 28
Raymond, J. C.; Ciaravella, A.; Li, J. +2 more
A fast partial-halo coronal mass ejection (CME) was observed on 2000 June 28 by instruments on the SOHO spacecraft. The CME leading edge and filamentary cold core were detected over the northwest limb at 2.32 Rsolar by the SOHO UV Coronagraph Spectrometer (UVCS). The broad profile of the O VI λ1032 line gives evidence of a shock front a…
Red Thick Disks of Nearby Galaxies
Mould, Jeremy
Edge-on systems reveal the properties of disk galaxies as a function of height, z, above the plane. Four local edge-on galaxies that are close enough to have been resolved into stars by the Hubble Space Telescope show thick disks composed of a red stellar population that is old and relatively metal rich. Color gradients, Δ(V-I)/Δz, are zero or sli…
The Lens Redshift and Galaxy Environment for HE 0435-1223
Pevunova, O.; Kochanek, C. S.; Morgan, N. D. +1 more
The redshift of the galaxy lensing HE 0435-1223 is 0.4546+/-0.0002, based on observations obtained with the Low Dispersion Survey Spectrograph 2 on the Magellan Consortium's 6.5 m Clay Telescope. Hubble Space Telescope Advanced Camera for Surveys observations of the system also reveal a spiral-rich group of 10 galaxies within 40" of the elliptical…
Space Telescope Imaging Spectrograph Observations of Young Star Clusters in the Antennae Galaxies (NGC 4038/4039)
Gilmore, Diane; Blair, William P.; Leitherer, C. +6 more
Long-slit spectra of several dozen young star clusters have been obtained at three positions in the Antennae galaxies with the Space Telescope Imaging Spectrograph and its 52''×0.2" slit. Based on Hα emission-line measurements, the average cluster-to-cluster velocity dispersion in seven different cluster aggregates (``knots'') is <10…