Search Publications
A shock front at the radio relic of Abell 2744
Kneib, J. -P.; Eckert, D.; Vazza, F. +5 more
Radio relics are Mpc-scale diffuse radio sources at the peripheries of galaxy clusters which are thought to trace outgoing merger shocks. We present XMM-Newton and Suzaku observations of the galaxy cluster Abell 2744 (z = 0.306), which reveal the presence of a shock front 1.5 Mpc east of the cluster core. The surface-brightness jump coincides with…
The Correlation between Metallicity and Debris Disk Mass
Rieke, George H.; Gáspár, András; Ballering, Nicholas
We find that the initial dust masses in planetary debris disks are correlated with the metallicities of their central stars. We compiled a large sample of systems, including Spitzer, the Herschel DUNES and DEBRIS surveys, and WISE debris disk candidates. We also merged 33 metallicity catalogs to provide homogeneous [Fe/H] and {σ }[{Fe/{…
Understanding star formation in molecular clouds. III. Probability distribution functions of molecular lines in Cygnus X
Hill, T.; Schneider, N.; Ossenkopf, V. +11 more
The probability distribution function of column density (N-PDF) serves as a powerful tool to characterise the various physical processes that influence the structure of molecular clouds. Studies that use extinction maps or H2 column-density maps (N) that are derived from dust show that star-forming clouds can best be characterised by lo…
Whistler emission in the separatrix regions of asymmetric magnetic reconnection
André, M.; Vaivads, A.; Khotyaintsev, Yu. V. +1 more
At Earth's dayside magnetopause asymmetric magnetic reconnection occurs between the cold dense magnetosheath plasma and the hot tenuous magnetospheric plasma, which differs significantly from symmetric reconnection. During magnetic reconnection the separatrix regions are potentially unstable to a variety of instabilities. In this paper observation…
Rest-frame Optical Emission Lines in z ∼ 3.5 Lyman-break-selected Galaxies: The Ubiquity of Unusually High [OIII]/Hβ Ratios at 2 Gyr
Oesch, P. A.; van Dokkum, P.; Illingworth, G. D. +6 more
We present K-band spectra of rest-frame optical emission lines for 24 star-forming galaxies at z ∼ 3.2-3.7 using MOSFIRE on the Keck I telescope. Strong rest-frame optical [O III] and Hβ emission lines were detected in 18 Lyman break galaxies (LBGs). The median flux ratio of [O III]λ5007 to Hβ is {5.1}-0.5+0.5. This is a fact…
VISION - Vienna survey in Orion. I. VISTA Orion A Survey
Kainulainen, Jouni; Meingast, Stefan; Alves, João +17 more
Context. Orion A hosts the nearest massive star factory, thus offering a unique opportunity to resolve the processes connected with the formation of both low- and high-mass stars. Here we present the most detailed and sensitive near-infrared (NIR) observations of the entire molecular cloud to date.
Aims: With the unique combination of high im…
The Ionized Gas in Nearby Galaxies as Traced by the [N II] 122 and 205 µm Transitions
Boquien, M.; Rigopoulou, D.; Armus, L. +20 more
The [N II] 122 and 205 µm transitions are powerful tracers of the ionized gas in the interstellar medium. By combining data from 21 galaxies selected from the Herschel KINGFISH and Beyond the Peak surveys, we have compiled 141 spatially resolved regions with a typical size of ∼1 kpc, with observations of both [N II] far-infrared lines. We me…
Hα features with hot onsets. I. Ellerman bombs
Rutten, R. J.
Ellerman bombs are transient brightenings of the wings of the Balmer lines that uniquely mark reconnection in the solar photosphere. They are also bright in strong Ca II and ultraviolet lines and in ultraviolet continua, but they are not visible in the optical continuum and the Na I D and Mg I b lines. These discordant visibilities invalidate all …
Refining the Dynamical Clock for Star Clusters
Dalessandro, E.; Vesperini, E.; Ferraro, F. R. +3 more
We used a sample of 25 Galactic globular clusters to empirically measure the parameter A + recently introduced by Alessandrini et al., and defined as the area enclosed between the cumulative radial distribution of blue straggler stars (BSSs) and that of a reference population. Based on N-body simulations, this parameter is expected to e…
Orbital and physical characteristics of meter-scale impactors from airburst observations
Brown, P.; Clark, D.; Wiegert, P. +1 more
We have analyzed the orbits and ablation characteristics in the atmosphere of 59 Earth-impacting fireballs, produced by meteoroids 1 m in diameter or larger, described here as meter-scale. Using heights at peak luminosity as a proxy for strength, we determine that there is roughly an order of magnitude spread in strengths of the population of mete…