Search Publications
Late-time VLA reobservations rule out ULIRG-like host galaxies for most pre- Swift long-duration gamma-ray bursts
Hjorth, Jens; Perley, Daniel A.; Tanvir, Nial R. +1 more
We present new Jansky Very Large Array observations of five pre-Swift gamma-ray bursts for which an ultraluminous [star formation rate (SFR) >100 M⊙ yr-1] dusty host galaxy had previously been inferred from radio or submillimetre observations taken within a few years after the burst. In four of the five cases, we no longer…
The Solar Flare Complex Network
Safari, Hossein; Gheibi, Akbar; Javaherian, Mohsen
We investigate the characteristics of the solar flare complex network. The limited predictability, nonlinearity, and self-organized criticality of the flares allow us to study systems of flares in the field of the complex systems. Both the occurrence time and the location of flares detected from 2006 January 1 to 2016 July 21 are used to design th…
Metallicity calibrations for dwarf stars and giants in the Geneva photometric system
Netopil, Martin
We use the most homogeneous Geneva seven-colour photometric system to derive new metallicity calibrations for early A- to K-type stars that cover both, dwarf stars and giants. The calibrations are based on several spectroscopic data sets that were merged to a common scale, and we applied them to open cluster data to obtain an additional proof of t…
Shocks in collisionless plasmas
Liu, Y.; Parks, G. K.; Fu, S. Y. +3 more
The Earth's bow shock is the best-known collisionless shock in space. Although much is known about the bow shock, the mechanisms of heating and thermalization processes still remain poorly understood. Collisionless shocks are different from ordinary fluid shocks, because a fraction of the incident solar wind is reflected from the bow shock and the…
Resolving the Circumstellar Environment of the Galactic B[e] Supergiant Star MWC 137 from Large to Small Scales
Liimets, Tiina; Kraus, Michaela; Maravelias, Grigoris +10 more
The Galactic object MWC 137 has been suggested to belong to the group of B[e] supergiants. However, with its large-scale optical bipolar ring nebula and high-velocity jet and knots, it is a rather atypical representative of this class. We performed multiwavelength observations spreading from the optical to the radio regimes. Based on optical imagi…
Evidence for Reduced Specific Star Formation Rates in the Centers of Massive Galaxies at z = 4
Papovich, Casey; Finkelstein, Steven L.; Dickinson, Mark +11 more
We perform the first spatially resolved stellar population study of galaxies in the early universe (z = 3.5-6.5), utilizing the Hubble Space Telescope Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey imaging data set over the GOODS-S field. We select a sample of 418 bright and extended galaxies at z = 3.5-6.5 from a parent sample of …
Testing cosmic acceleration for w(z) parametrizations using fgas measurements in galaxy clusters
Foëx, G.; Motta, V.; Magaña, Juan +1 more
In this paper, we study the cosmic acceleration for five dynamical dark energy models whose equation of state varies with redshift. The cosmological parameters of these models are constrained by performing a Markov chain Monte Carlo (MCMC) analysis using mainly gas mass fraction, fgas, measurements in two samples of galaxy clusters: one…
Search for grain growth toward the center of L1544
Désert, F. -X.; Spaans, M.; Caselli, P. +4 more
In dense and cold molecular clouds dust grains are surrounded by thick icy mantles. It is not clear, however, if dust growth and coagulation take place before the protostar switches on. This is an important issue as the presence of large grains may affect the chemical structure of dense cloud cores, including the dynamically important ionization f…
The footprint of cometary dust analogues - I. Laboratory experiments of low-velocity impacts and comparison with Rosetta data
Blum, J.; Gundlach, B.; Dominik, C. +8 more
Cometary dust provides a unique window on dust growth mechanisms during the onset of planet formation. Measurements by the Rosetta spacecraft show that the dust in the coma of comet 67P/Churyumov-Gerasimenko has a granular structure at size scales from sub-µmup to several hundreds of µm, indicating hierarchical growth took place across…
A halo substructure in Gaia Data Release 1
Myeong, G. C.; Evans, N. W.; Belokurov, V. +2 more
We identify a halo substructure in the Tycho Gaia Astrometric Solution (TGAS) data set, cross-matched with the Radial Velocity Experiment (RAVE-on) data release. After quality cuts, the stars with large radial action (JR > 800 km s-1 kpc) are extracted. A subset of these stars is clustered in longitude and velocity and can…