Search Publications
Hubble Space Telescope survey of the Perseus cluster - II. Photometric scaling relations in different environments
de Rijcke, S.; Held, E. V.; Conselice, C. J. +2 more
We investigate the global photometric scaling relations traced by early-type galaxies in different environments, ranging from dwarf spheroidals, over dwarf elliptical galaxies (dEs), up to giant ellipticals (-8mag >~ MV >~ -24 mag). These results are based, in part, on our new Hubble Space Telescope (HST)/Advanced Camera for Surve…
Unabsorbed Seyfert 2 galaxies: the case of `naked' AGN
Bianchi, S.; Gastaldello, F.; Barcons, X. +6 more
Hawkins reported on a class of `naked' active galactic nuclei (AGN) characterized by strong amplitude optical brightness variability and the complete absence of broad emission lines in the optical spectrum. The variability suggests that the nucleus is seen directly, however the absence of broad lines contradicts the simple formulation of Unified M…
Strong z ~ 0.5 OVI absorption towards PKS 0405-123: implications for ionization and metallicity of the Cosmic Web
Prochaska, J. Xavier; Chen, Hsiao-Wen; Lehner, Nicolas +2 more
We present observations of the intervening OVI absorption-line system at zabs = 0.495096 towards the quasi-stellar object (QSO) PKS 0405-123 (zem = 0.5726) obtained with the Far Ultraviolet Spectroscopic Explorer and Space Telescope Imaging Spectrograph on board the Hubble Space Telescope. In addition to strong OVI, with , an…
Asteroseismic analysis of the roAp star α Circini: 84d of high-precision photometry from the WIRE satellite
Handler, G.; Kurtz, D. W.; Bruntt, H. +8 more
We present a detailed study of the pulsation of αCircini, the brightest of the rapidly oscillating Ap stars. We have obtained 84d of high-precision photometry from four runs with the star tracker on the WIRE satellite. Simultaneously, we collected ground-based Johnson B observations on 16 nights at the South African Astronomical Observatory. In ad…
Search for corannulene (C20H10) in the Red Rectangle
Gerin, M.; Giesen, T. F.; Joblin, C. +10 more
Polycyclic Aromatic Hydrocarbons (PAHs) are widely accepted as the carriers of the Aromatic Infrared Bands (AIBs), but an unambiguous identification of any specific interstellar PAH is still missing. For polar PAHs, pure rotational transitions can be used as spectral fingerprints for identification. Combining dedicated experiments, detailed simula…
Discovery of a 30-d period in the supergiant fast X-ray transient SAX J1818.6-1703
Hill, A. B.; Bird, A. J.; McBride, V. A. +4 more
SAX J1818.6-1703 has been characterized as a supergiant fast X-ray transient system on the basis of several INTEGRAL/IBIS detections since the original BeppoSAX Wide Field Camera detection. Using IBIS/ISGRI, Swift/BAT and archival observations, we show that, in fact, SAX J1818.6-1703 exhibits emission on a period of 30 +/- 0.1 d, with a high degre…
Exploring the formation of spheroidal galaxies out to z ~ 1.5 in GOODS
Lisker, Thorsten; Kaviraj, Sugata; Pasquali, Anna +1 more
The formation of massive spheroidal galaxies is studied on a visually classified sample extracted from the Advanced Camera for Surveys/Hubble Space Telescope (ACS/HST) images of the Great Observatories Origins Deep Survey north and south fields, covering a total area of 360 arcmin2. The sample size (910 galaxies brighter than iF775…
Constraining the energy budget of GRB080721
Howarth, I. D.; Rol, E.; Fynbo, J. P. U. +17 more
We follow the bright, highly energetic afterglow of Swift-discovered GRB080721 at z = 2.591 out to 36 d or 3 × 106s since the trigger in the optical and X-ray bands. We do not detect a break in the late-time light curve inferring a limit on the opening angle of and setting tight constraints on the total energy budget of the burst of E
The properties of the stellar populations in ULIRGs - I. Sample, data and spectral synthesis modelling
Tadhunter, C. N.; González Delgado, R. M.; Rodríguez Zaurín, J.
We present deep long-slit optical spectra for a sample of 36 ultraluminous infrared galaxies (ULIRGs), taken with the William Herschel Telescope on La Palma with the aim of investigating the star formation histories and testing evolutionary scenarios for such objects. Here we present the sample, the analysis techniques and a general overview of th…
Hierarchical star formation: stars and stellar clusters in the Gould Belt
Alfaro, E. J.; Cabrera-Caño, J.; Elias, F.
We perform a study of the spatial and kinematical distribution of young open clusters in the solar neighbourhood, discerning between bound clusters and transient stellar condensations within our sample. Then, we discriminate between Gould Belt (GB) and local Galactic disc (LGD) members, using our previous estimate of the structural parameters of b…