Search Publications
Modification of the Hall physics in magnetic reconnection due to cold ions at the Earth's magnetopause
André, M.; Vaivads, A.; Toledo-Redondo, S. +1 more
Magnetic reconnection is a process permitting mass and energy exchange across plasma boundaries and converting magnetic energy into particle kinetic energy. Strong electric fields and currents due to the Hall effect are set up in narrow regions where ions are demagnetized but electrons remain magnetized. It has been recently shown that cold (few e…
The Lyman alpha reference sample. IV. Morphology at low and high redshift
Schaerer, D.; Östlin, G.; Hayes, M. +21 more
Context. The transport of Lyα photons in galaxies is a complex process and the conditions under which Lyα photons manage to escape from certain galaxies is still under investigation. The Lyman alpha reference sample (LARS) is a sample of 14 local star-forming galaxies, designed to study Lyα in detail and relate it to rest-frame UV and optical emis…
The hidden quasar nucleus of a WISE-selected, hyperluminous, dust-obscured galaxy at z ~ 2.3
Maiolino, R.; Fiore, F.; Bianchi, S. +8 more
We present the first X-ray spectrum of a hot dust-obscured galaxy (DOG), namely W1835+4355 at z ~ 2.3. Hot DOGs represent a very rare population of hyperluminous (≥1047 erg s-1), dust-enshrouded objects at z ≥ 2 recently discovered in the WISE All Sky Survey. The 40 ks XMM-Newton spectrum reveals a continuum as flat (Γ ~ 0.8)…
ALMA observations of anisotropic dust mass loss in the inner circumstellar environment of the red supergiant VY Canis Majoris
Kervella, P.; Decin, L.; Richards, A. M. S. +8 more
The processes leading to dust formation and the subsequent role it plays in driving mass loss in cool evolved stars is an area of intense study. Here we present high resolution ALMA Science Verification data of the continuum emission around the highly evolved oxygen-rich red supergiant VY CMa. These data enable us to study the dust in its inner ci…
No Evidence of Mass Segregation in the Low-mass Galactic Globular Cluster NGC 6101
Dalessandro, E.; Massari, D.; Beccari, G. +3 more
We used a combination of Hubble Space Telescope and ground-based data to probe the dynamical state of the low-mass Galactic globular cluster NGC 6101. We have rederived the structural parameters of the cluster by using star counts and we find that it is about three times more extended than thought before. By using three different indicators, namel…
Observational Evidence of Electron-driven Evaporation in Two Solar Flares
Li, D.; Zhang, Q. M.; Ning, Z. J.
We have explored the relationship between hard X-ray (HXR) emissions and Doppler velocities caused by the chromospheric evaporation in two X1.6 class solar flares on 2014 September 10 and October 22, respectively. Both events display double ribbons and the Interface Region Imaging Spectrograph slit is fixed on one of their ribbons from the flare o…
A radar survey of M- and X-class asteroids. III. Insights into their composition, hydration state, & structure
Nolan, Michael C.; Springmann, Alessondra; Howell, Ellen S. +13 more
Using the S-band radar at Arecibo Observatory, we observed thirteen X/M-class asteroids; nine were previously undetected and four were re-observed, bringing the total number of Tholen X/M-class asteroids observed with radar to 29. Of these 29M-class asteroids, 13 are also W-class, defined as M-class objects that also display a 3-µm absorptio…
Characterizing motion types of G-band bright points in the quiet Sun
Feng, Song; Wang, Feng; Deng, Hui +4 more
We study the motion of G-band bright points (GBPs) in the quiet Sun to obtain the characteristics of different motion types. A high resolution image sequence taken with the Hinode/Solar Optical Telescope (SOT) is used, and GBPs are automatically tracked by segmenting 3D evolutional structures in a space-time cube. After putting the GBPs that do no…
The two-colour EMCCD instrument for the Danish 1.54 m telescope and SONG
Christensen-Dalsgaard, J.; Andersen, M. F.; Grundahl, F. +13 more
We report on the implemented design of a two-colour instrument based on electron-multiplying CCD (EMCCD) detectors. This instrument is currently installed at the Danish 1.54 m telescope at ESO's La Silla Observatory in Chile, and will be available at the SONG (Stellar Observations Network Group) 1m telescope node at Tenerife and at other SONG node…
Stellar Mass Functions of Galaxies At 4 < z < 7 from an IRAC-selected Sample in Cosmos/Ultravista: Limits on the Abundance of Very Massive Galaxies
van Dokkum, Pieter G.; Muzzin, Adam; Labbé, Ivo +7 more
We build a Spitzer IRAC-complete catalog of objects complementing the Ks-band selected UltraVISTA catalog with objects detected in IRAC only. To identify massive (log ({{M}*}/{{M}⊙ })\gt 11) galaxies at 4\lt z\lt 7, we consider the systematic effects on photometric redshift measurements from the introduction of an …