Search Publications
Internal Structure of Protocluster Galaxies: Accelerated Structural Evolution in Overdense Environments?
Zirm, Andrew W.; Toft, Sune; Tanaka, Masayuki
We present a high spatial resolution Hubble Space Telescope/NICMOS imaging survey in the field of a known protocluster surrounding the powerful radio galaxy MRC1138-262 at z = 2.16. Previously, we have shown that this field exhibits a substantial surface overdensity of red J-H galaxies. Here we focus on the stellar masses and galaxy effective radi…
X-Ray Emission from the Wolf-Rayet Bubble S 308
Gruendl, R. A.; Smith, R. C.; Chu, Y. -H. +4 more
The Wolf-Rayet (WR) bubble S 308 around the WR star HD 50896 is one of the only two WR bubbles known to possess X-ray emission. We present XMM-Newton observations of three fields of this WR bubble that, in conjunction with an existing observation of its northwest quadrant, map most of the nebula. The X-ray emission from S 308 displays a limb-brigh…
Stellar laboratories: new Ge V and Ge VI oscillator strengths and their validation in the hot white dwarf RE 0503-289
Rauch, T.; Werner, K.; Kruk, J. W. +2 more
Context. State-of-the-art spectral analysis of hot stars by means of non-LTE model-atmosphere techniques has arrived at a high level of sophistication. The analysis of high-resolution and high-S/N spectra, however, is strongly restricted by the lack of reliable atomic data for highly ionized species from intermediate-mass metals to trans-iron elem…
A Possible Ultra Strong and Broad Fe Kα Emission Line in Seyfert 2 Galaxy IRAS 00521-7054
Shu, X. W.; Wang, J. X.; Tan, Y. +1 more
We present XMM-Newton spectra of the Seyfert 2 Galaxy IRAS 00521-7054. A strong feature at ~6 keV (observer's frame) can be formally fitted with a strong (EW = 1.3 ± 0.3 keV in the rest frame) and broad Fe Kα line, extending down to 3 keV. The underlying X-ray continuum could be fitted with an absorbed power law (with Γ = 1.8 ± 0.2 and N H
On the Shapes and Structures of High-redshift Compact Galaxies
Glazebrook, Karl; Chevance, Mélanie; Abraham, Roberto G. +5 more
Recent deep Hubble Space Telescope WFC3 imaging suggests that a majority of compact quiescent massive galaxies at z ~ 2 may contain disks. To investigate this claim, we have compared the ellipticity distribution of 31 carefully selected high-redshift massive quiescent compact galaxies to a set of mass-selected ellipticity and Sérsic index distribu…
AE Aurigae: First Detection of Non-thermal X-Ray Emission from a Bow Shock Produced by a Runaway Star
Miceli, M.; Bonito, R.; Romero, G. E. +6 more
Runaway stars produce shocks when passing through interstellar medium at supersonic velocities. Bow shocks have been detected in the mid-infrared for several high-mass runaway stars and in radio waves for one star. Theoretical models predict the production of high-energy photons by non-thermal radiative processes in a number sufficiently large to …
Episodic bright and dark spots on Uranus
Sromovsky, L. A.; Fry, P. M.; Hueso, R. +14 more
The northern mid-latitudes of Uranus produce greater episodes of bright cloud formation than any other region on the planet. Near 30°N, very bright cloud features were observed in 1999, 2004, and 2005, with lifetimes of the order of months. In October 2011, Gemini and HST observations revealed another unusually bright cloud feature near 23°N, whic…
GK Per (Nova Persei 1901): Hubble Space Telescope Imagery and Spectroscopy of the Ejecta, and First Spectrum of the Jet-like Feature
Livio, Mario; De Marco, Orsola; Shara, Michael M. +3 more
We have imaged the ejecta of GK Persei (Nova Persei 1901 A.D.) with the Hubble Space Telescope (HST), whose 0.1 arcsec resolution reveals hundreds of cometary-like structures with long axes aligned toward GK Per. One or both ends of the structures often show a brightness enhancement relative to the structures' middle sections, but there is no simp…
Near-infrared spectroscopy of gamma-ray burst host galaxies at z %≳ 1.5: insights into host galaxy dynamics and interpretations of afterglow absorption spectra
Chen, Hsiao-Wen
This paper presents near-infrared echellette spectra of faint galaxies in the fields around GRB 050820A at redshift z= 2.613 and GRB 060418 at z= 1.490. The spectroscopic data show that both gamma-ray bursts (GRBs) originate in a dynamic environment of interacting galaxies separated by <15 h-1 kpc in projected distance and |Δv| ≲ 60 …
New X-Ray Detections of WNL Stars
Skinner, Stephen L.; Zhekov, Svetozar A.; Güdel, Manuel +2 more
Previous studies have demonstrated that putatively single nitrogen-type Wolf-Rayet stars (WN stars) without known companions are X-ray sources. However, almost all WN star X-ray detections so far have been of earlier WN2-WN6 spectral subtypes. Later WN7-WN9 subtypes (also known as WNL stars) have proved more difficult to detect, an important excep…