Search Publications
Progenitors of supernova Ibc: a single Wolf-Rayet star as the possible progenitor of the SN Ib iPTF13bvn
Groh, Jose H.; Ekström, Sylvia; Georgy, Cyril
Core-collapse supernova (SN) explosions mark the end of the tumultuous life of massive stars. Determining the nature of their progenitors is a crucial step towards understanding the properties of SNe. Until recently, no progenitor has been directly detected for SN of type Ibc, which are believed to come from massive stars that lose their hydrogen …
The Densest Galaxy
Forbes, Duncan A.; Romanowsky, Aaron J.; Brodie, Jean P. +8 more
We report the discovery of a remarkable ultra-compact dwarf galaxy around the massive Virgo elliptical galaxy NGC 4649 (M60), which we call M60-UCD1. With a dynamical mass of 2.0 × 108 M ⊙ but a half-light radius of only ~24 pc, M60-UCD1 is more massive than any ultra-compact dwarfs of comparable size, and is arguably the den…
The Spitzer Mid-infrared Active Galactic Nucleus Survey. I. Optical and Near-infrared Spectroscopy of Obscured Candidates and Normal Active Galactic Nuclei Selected in the Mid-infrared
Seymour, N.; Gates, E. L.; Sajina, A. +8 more
We present the results of a program of optical and near-infrared spectroscopic follow-up of candidate active galactic nuclei (AGNs) selected in the mid-infrared. This survey selects both normal and obscured AGNs closely matched in luminosity across a wide range, from Seyfert galaxies with bolometric luminosities L bol ~ 1010 …
Axion hot dark matter bounds after Planck
Mirizzi, Alessandro; Archidiacono, Maria; Hannestad, Steen +2 more
We use cosmological observations in the post-Planck era to derive limits on thermally produced cosmological axions. In the early universe such axions contribute to the radiation density and later to the hot dark matter fraction. We find an upper limit ma < 0.67 eV at 95% C.L. after marginalising over the unknown neutrino masses, usin…
The first SEPServer event catalogue ~68-MeV solar proton events observed at 1 AU in 1996-2010
Kouloumvakos, Athanasios; Heber, Bernd; Sanahuja, Blai +33 more
SEPServer is a three-year collaborative project funded by the seventh framework programme (FP7-SPACE) of the European Union. The objective of the project is to provide access to state-of-the-art observations and analysis tools for the scientific community on solar energetic particle (SEP) events and related electromagnetic (EM) emissions. The proj…
Kinetic Plasma Turbulence in the Fast Solar Wind Measured by Cluster
Li, B.; Li, X.; Roberts, O. W.
The k-filtering technique and wave polarization analysis are applied to Cluster magnetic field data to study plasma turbulence at the scale of the ion gyroradius in the fast solar wind. Waves are found propagating in directions nearly perpendicular to the background magnetic field at such scales. The frequencies of these waves in the solar wind fr…
Investigating Two Successive Flux Rope Eruptions in a Solar Active Region
Liu, Y.; Cheng, X.; Ding, M. D. +4 more
We investigate two successive flux rope (FR1 and FR2) eruptions resulting in two coronal mass ejections (CMEs) on 2012 January 23. Both flux ropes (FRs) appeared as an EUV channel structure in the images of high temperature passbands of the Atmospheric Imaging Assembly prior to the CME eruption. Through fitting their height evolution with a functi…
Variation in dust properties in a dense filament of the Taurus molecular complex (L1506)
Abergel, A.; Juvela, M.; Ristorcelli, I. +6 more
Aims: We observed the L1506 filament, which is located in the Taurus molecular complex, with the Herschel PACS and SPIRE instruments. Our aim is to prove the variation in grain properties along the entire length of the filament. In particular, we want to determine above which gas density this variation arises and what changes in the grain opt…
Massive stars at low metallicity. Evolution and surface abundances of O dwarfs in the SMC
Bouret, J. -C.; Martins, F.; Hillier, D. J. +4 more
Aims: We aim to study the properties of massive stars at low metallicity, with an emphasis on their evolution, rotation, and surface abundances. We focus on O-type dwarfs in the Small Magellanic Cloud. These stars are expected to have weak winds that do not remove significant amounts of their initial angular momentum.
Methods: We analyze…
Resolving the Cosmic Far-infrared Background at 450 and 850 µm with SCUBA-2
Chen, Chian-Chou; Lee, Nicholas; Williams, Jonathan P. +5 more
We use the SCUBA-2 submillimeter camera mounted on the James Clerk Maxwell Telescope to obtain extremely deep number counts at 450 and 850 µm. We combine data on two cluster lensing fields, A1689 and A370, and three blank fields, CDF-N, CDF-S, and COSMOS, to measure the counts over a wide flux range at each wavelength. We use statistical fit…