Search Publications
Brown Dwarf Photospheres are Patchy: A Hubble Space Telescope Near-infrared Spectroscopic Survey Finds Frequent Low-level Variability
Apai, Dániel; Radigan, Jacqueline; Buenzli, Esther +2 more
Condensate clouds strongly impact the spectra of brown dwarfs and exoplanets. Recent discoveries of variable L/T transition dwarfs argued for patchy clouds in at least some ultracool atmospheres. This study aims to measure the frequency and level of spectral variability in brown dwarfs and to search for correlations with spectral type. We used Hub…
Radial Dependence of the Frequency Break between Fluid and Kinetic Scales in the Solar Wind Fluctuations
Bruno, R.; Trenchi, L.
We investigate the radial dependence of the spectral break separating the inertial from the dissipation range in power density spectra of interplanetary magnetic field fluctuations, between 0.42 and 5.3 AU, during radial alignments between MESSENGER and WIND for the inner heliosphere and between WIND and ULYSSES for the outer heliosphere. We found…
Cosmological constraints from the double source plane lens SDSSJ0946+1006
Auger, Matthew W.; Collett, Thomas E.
We present constraints on the equation of state of dark energy, w, and the total matter density, ΩM, derived from the double-source-plane strong lens SDSSJ0946+1006, the first cosmological measurement with a galaxy-scale double-source-plane lens. By modelling the primary lens with an elliptical power-law mass distribution, and including…
Three-Dimensional Evolution of Flux-Rope CMEs and Its Relation to the Local Orientation of the Heliospheric Current Sheet
Kilpua, E. K. J.; Vourlidas, A.; Isavnin, A.
Flux ropes ejected from the Sun may change their geometrical orientation during their evolution, which directly affects their geoeffectiveness. Therefore, it is crucial to understand how solar flux ropes evolve in the heliosphere to improve our space-weather forecasting tools. We present a follow-up study of the concepts described by Isavnin, Vour…
Testing chameleon gravity with the Coma cluster
Bacon, David; Nichol, Robert C.; Lombriser, Lucas +3 more
We propose a novel method to test the gravitational interactions in the outskirts of galaxy clusters. When gravity is modified, this is typically accompanied by the introduction of an additional scalar degree of freedom, which mediates an attractive fifth force. The presence of an extra gravitational coupling, however, is tightly constrained by lo…
Ubiquitous argonium (ArH+) in the diffuse interstellar medium: A molecular tracer of almost purely atomic gas
Menten, K. M.; Falgarone, E.; Godard, B. +14 more
Aims: We describe the assignment of a previously unidentified interstellar absorption line to ArH+ and discuss its relevance in the context of hydride absorption in diffuse gas with a low H2 fraction. The confidence of the assignment to ArH+ is discussed, and the column densities are determined toward several …
The Nature of Extreme Emission Line Galaxies at z = 1-2: Kinematics and Metallicities from Near-infrared Spectroscopy
Bell, Eric F.; Ferguson, Henry C.; Koekemoer, Anton M. +21 more
We present near-infrared spectroscopy of a sample of 22 Extreme Emission Line Galaxies at redshifts 1.3 < z < 2.3, confirming that these are low-mass (M sstarf = 108-109 M ⊙) galaxies undergoing intense starburst episodes (M sstarf/SFR ~ 10-100 Myr). The sample is selected by [O III] or …
Indications for an influence of hot Jupiters on the rotation and activity of their host stars
Poppenhaeger, K.; Wolk, S. J.
Context. The magnetic activity of planet-hosting stars is an important factor for estimating the atmospheric stability of close-in exoplanets and the age of their host stars. It has long been speculated that close-in exoplanets can influence the stellar activity level. However, testing for tidal or magnetic interaction effects in samples of planet…
Cosmological constraints on interacting dark energy with redshift-space distortion after Planck data
Yang, Weiqiang; Xu, Lixin
The interacting dark energy model could propose a effective way to avoid the coincidence problem. In this paper, dark energy is taken as a fluid with a constant equation-of-state parameter wx. In a general gauge, we could obtain two sets of different perturbation equations when the momentum transfer potential is vanished in the rest fra…
Characterizing and predicting the magnetic environment leading to solar eruptions
Amari, Tahar; Canou, Aurélien; Aly, Jean-Jacques
The physical mechanism responsible for coronal mass ejections has been uncertain for many years, in large part because of the difficulty of knowing the three-dimensional magnetic field in the low corona. Two possible models have emerged. In the first, a twisted flux rope moves out of equilibrium or becomes unstable, and the subsequent reconnection…