Search Publications
Evolution of tidal disruption candidates discovered by XMM-Newton
Read, A. M.; Esquej, P.; Freyberg, M. J. +8 more
Context: It has been demonstrated that active galactic nuclei are powered by gas accretion onto supermassive black holes located at their centres. The paradigm that the nuclei of inactive galaxies are also occupied by black holes was predicted long ago by theory. In the past decade, this conjecture was confirmed by the discovery of giant-amplitude…
The fraction of second generation stars in globular clusters from the analysis of the horizontal branch
D'Antona, F.; Caloi, V.
The majority of globular clusters show chemical inhomogeneities in the composition of their stars, apparently due to a second stellar generation in which the forming gas is enriched by hot-CNO cycled material processed in stars belonging to a first stellar generation. Clearly this evidence prompts questions on the modalities of formation of globul…
Three-dimensional MHD Simulation of the 2003 October 28 Coronal Mass Ejection: Comparison with LASCO Coronagraph Observations
Vourlidas, Angelos; Lugaz, Noé; Roussev, Ilia I. +6 more
We numerically model the coronal mass ejection (CME) event of 2003 October 28 that erupted from AR 10486 and propagated to Earth in less than 20 hr, causing severe geomagnetic storms. The magnetohydrodynamic (MHD) model is formulated by first arriving at a steady state corona and solar wind employing synoptic magnetograms. We initiate two CMEs fro…
Evidence for Merger Remnants in Early-Type Host Galaxies of Low-Redshift QSOs
Schweizer, François; Lacy, Mark; Stockton, Alan +4 more
We present results from a pilot HST ACS deep imaging study in broadband V of five low-redshift QSO host galaxies classified in the literature as ellipticals. The aim of our study is to determine whether these early-type hosts formed at high redshift and have since evolved passively, or whether they have undergone relatively recent mergers that may…
Flows in active region loops observed by Hinode EIS
Del Zanna, G.
We aim to investigate the overall characteristics of coronal active region loops and their evolution. The Hinode database was searched for observations of active regions as they crossed the Sun centre. NOAA 10926 was selected. The morphology of this young active region did not significantly change over the course of a few days. Persistent redshift…
Flare Irradiance Spectral Model (FISM): Flare component algorithms and results
Chamberlin, Phillip C.; Woods, Thomas N.; Eparvier, Francis G.
The Flare Irradiance Spectral Model (FISM) is an empirical model developed for space weather applications that estimates the solar irradiance at wavelengths from 0.1 to 190 nm at 1 nm resolution with a time cadence of 60 s. This is a high enough temporal resolution to model variations due to solar flares, where few accurate measurements at these w…
Detection of hot gas in the filament connecting the clusters of galaxies Abell 222 and Abell 223
Finoguenov, A.; Böhringer, H.; Simionescu, A. +4 more
Context: About half of the baryons in the local Universe are invisible and - according to simulations - their dominant fraction resides in filaments connecting clusters of galaxies in the form of low density gas with temperatures in the range of 105 < T < 107 K. This warm-hot intergalactic medium has never been detected…
Quantitative Spectroscopy of 24 A Supergiants in the Sculptor Galaxy NGC 300: Flux-weighted Gravity-Luminosity Relationship, Metallicity, and Metallicity Gradient
Bresolin, Fabio; Kudritzki, Rolf-Peter; Urbaneja, Miguel A. +3 more
A quantitative spectral analysis of 24 A supergiants in the Sculptor Group spiral galaxy NGC 300 at a distance of 1.9 Mpc is presented. A new method is introduced to analyze low-resolution (~5 Å) spectra, which yields metallicities accurate to 0.2 dex including the uncertainties arising from the errors in Teff (5%) and log g (0.2 dex). …
Black Holes in Pseudobulges and Spheroidals: A Change in the Black Hole-Bulge Scaling Relations at Low Mass
Ho, Luis C.; Barth, Aaron J.; Greene, Jenny E.
We investigate the relationship between black hole mass and host galaxy properties for active galaxies with the lowest black hole masses currently known in galaxy nuclei. HST imaging confirms that the host galaxies have correspondingly low luminosity; they are ~1 mag below L*. In terms of morphology, ~60% of the members of the sample are disk domi…
Mapping of molecular gas inflow towards the Seyfert nucleus of NGC4051 using Gemini NIFS
Storchi-Bergmann, Thaisa; Riffel, Rogemar A.; Winge, Cláudia +3 more
We present 2D stellar and gaseous kinematics of the inner ~130×180 pc2 of the Narrow-Line Seyfert 1 galaxy NGC4051 at a sampling of 4.5pc, from near-infrared K-band spectroscopic observations obtained with the Gemini's Near-infrared Integral Field Spectrograph (NIFS) operating with the ALTAIR adaptive optics module. We have used the CO …