Search Publications
Valles Marineris dune sediment provenance and pathways
Wray, James J.; Chojnacki, Matthew; Moersch, Jeffrey E. +1 more
Although low-albedo sand is a prevalent component of the martian surface, sources and pathways of the sands are uncertain. As one of the principal present-day martian sediment sinks, the Valles Marineris (VM) rift system hosts a diversity of dune field populations associated with a variety of landforms that serve as potential sediment sources, inc…
Investigating evidence for different black hole accretion modes since redshift z ∼ 1
Cooper, M. C.; Georgakakis, A.; Salvato, M. +11 more
Chandra data in the COSMOS, AEGIS-XD and 4 Ms Chandra Deep Field South are combined with multiwavelength photometry available in those fields to determine the rest-frame U - V versus V - J colours of X-ray AGN hosts in the redshift intervals 0.1 < z < 0.6 (mean overline{z}=0.40) and 0.6 < z < 1.2 (mean overline{z}=0.85). This combinati…
Accurate Spectroscopic Characterization of Oxirane: A Valuable Route to its Identification in Titan's Atmosphere and the Assignment of Unidentified Infrared Bands
Puzzarini, Cristina; Barone, Vincenzo; Biczysko, Malgorzata +1 more
In an effort to provide an accurate spectroscopic characterization of oxirane, state-of-the-art computational methods and approaches have been employed to determine highly accurate fundamental vibrational frequencies and rotational parameters. Available experimental data were used to assess the reliability of our computations, and an accuracy on a…
Modelling the alumina abundance of oxygen-rich evolved stars in the Large Magellanic Cloud
Zijlstra, A. A.; McDonald, I.; Jones, O. C. +3 more
In order to determine the composition of the dust in the circumstellar envelopes of oxygen-rich asymptotic giant branch (AGB) stars, we have computed a grid of MODUST radiative-transfer models for a range of dust compositions, mass-loss rates, dust-shell inner radii and stellar parameters. We compare the resulting colours with the observed oxygen-…
Discovery of X-ray pulsations from a massive star
Huenemoerder, David P.; Ignace, Richard; Hamann, Wolf-Rainer +4 more
X-ray emission from stars much more massive than the Sun was discovered only 35 years ago. Such stars drive fast stellar winds where shocks can develop, and it is commonly assumed that the X-rays emerge from the shock-heated plasma. Many massive stars additionally pulsate. However, hitherto it was neither theoretically predicted nor observed that …
Force-free Field Modeling of Twist and Braiding-induced Magnetic Energy in an Active-region Corona
Wiegelmann, T.; Thalmann, J. K.; Tiwari, S. K.
The theoretical concept that braided magnetic field lines in the solar corona may dissipate a sufficient amount of energy to account for the brightening observed in the active-region (AR) corona has only recently been substantiated by high-resolution observations. From the analysis of coronal images obtained with the High Resolution Coronal Imager…
Chaotic inflation with right-handed sneutrinos after Planck
Nakayama, Kazunori; Yanagida, Tsutomu T.; Takahashi, Fuminobu
We propose a chaotic inflation model in which the lightest right-handed sneutrino serves as the inflaton and the predicted values of the spectral index and tensor-to-scalar ratio are consistent with the Planck data. Interestingly, the observed magnitude of primordial density perturbations is naturally explained by the inflaton mass of order 10
Planet X revamped after the discovery of the Sedna-like object 2012 VP113?
Iorio, L.
The recent discovery of the Sedna-like dwarf planet 2012 VP113 by Trujillo and Sheppard has revamped the old-fashioned hypothesis that a still unseen trans-Plutonian object of planetary size, variously dubbed over the years as Planet X, Tyche and Telisto, might lurk in the distant peripheries of the Solar system. This time, the presence…
Search for X-ray occultations in active galactic nuclei
Salvati, M.; Risaliti, G.; Pietrini, P. +1 more
Recent time-resolved spectral studies of a few active galactic nuclei (AGNs) in hard X-rays revealed occultations of the X-ray primary source probably by broad-line region (BLR) clouds. An important open question on the structure of the circumnuclear medium of AGN is whether this phenomenon is common, i.e. whether a significant fraction of the X-r…
Roche-lobe Overflow Systems Powered by Black Holes in Young Star Clusters: The Importance of Dynamical Exchanges
Zampieri, Luca; Mapelli, Michela
We have run 600 N-body simulations of intermediate-mass (~3500 M ⊙) young star clusters (SCs; with three different metallicities (Z = 0.01, 0.1, and 1 Z ⊙). The simulations include the dependence of stellar properties and stellar winds on metallicity. Massive stellar black holes (MSBHs) with mass >25 M ⊙ are all…