Search Publications
Bias in the estimation of global luminosity functions
Maccagni, D.; Ilbert, O.; Adami, C. +13 more
We discuss a bias present in the calculation of the global luminosity function (LF) which occurs when analysing faint galaxy samples. This effect exists as a result of the different spectral energy distributions of galaxies, which are in turn quantified by the k corrections. We demonstrate that this bias occurs because not all galaxy types are vis…
The young pulsar PSR B0540-69.3 and its synchrotron nebula in the optical and X-rays
Sollerman, J.; Lundqvist, P.; Shibanov, Yu. A. +1 more
The young PSR B0540-69.3 in the LMC is the only pulsar (except the Crab pulsar) for which a near-UV spectrum has been obtained. However, the absolute flux and spectral index of the HST/FOS spectrum are significantly higher than suggested by previous broad-band time-resolved groundbased UBVRI photometry. To investigate this difference, observations…
Life cycles of spots on Jupiter from Cassini images
Porco, Carolyn C.; Ingersoll, Andrew P.; Ewald, Shawn P. +3 more
Using the sequence of 70-day continuum-band (751 nm) images from the Cassini Imaging Science System (ISS), we record over 500 compact oval spots and study their relation to the large-scale motions. The ∼100 spots whose vorticity could be measured—the large spots in most cases—were all anticyclonic. We exclude cyclonic features (chaotic regions) be…
A Possible Explanation for the Size Difference of Red and Blue Globular Clusters
Jordán, Andrés
Most observations of the projected half-light radii of metal-rich globular clusters in a variety of galaxies have shown them to be ~20% smaller than those of their metal-poor counterparts. We show using multimass isotropic Michie-King models that the combined effects of mass segregation and the dependence of main-sequence lifetimes on metallicity …
Hubble Space Telescope Observations of NGC 6240: A Case Study of an Ultraluminous Infrared Galaxy with Obscured Activity
Gerssen, Joris; van der Marel, Roeland P.; Hernquist, Lars +3 more
We present results from a Hubble Space Telescope (HST) study of the morphology and kinematics of NGC 6240. This merging galaxy with a double nucleus is one of the nearest and best-studied ultraluminous infrared galaxies. HST resolves both nuclei into separate components. The distance between the northern and southern optical/near-infrared componen…
Multiband modelling of the Sun as a variable star from VIRGO/SoHO data
Pagano, I.; Lanza, A. F.; Rodonò, M.
The time series of total solar irradiance (TSI) and optical spectral irradiance at 402, 500 and 862 nm (SSIs) obtained by the VIRGO experiment on board the satellite SoHO are analysed in order to model their variability in the framework of a purely stellar-like approach. The different time scales of variability are estimated by means of the pooled…
Quantitative morphological analysis of the Hubble Deep Field North and Hubble Deep Field South - I. Early- and late-type luminosity-size relations of galaxies out to z~ 1
Aguerri, J. A. L.; Trujillo, I.
Based on drizzled F606W and F814W images, we present quantitative structural parameters in the V-band rest-frame for all galaxies with z < 1 and I814(AB) < 24.5 mag in the Hubble Deep Fields North and South. Our structural parameters are based on a two-component surface brightness distribution using a Sérsic bulge and an exponenti…
Measurement of Cosmic Shear with the Space Telescope Imaging Spectrograph
Refregier, Alexandre; Gardner, Jonathan P.; Rhodes, Jason +3 more
Weak lensing by large-scale structure allows a direct measure of the dark matter distribution. We have used parallel images taken with the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope to measure weak lensing, or cosmic shear. We measure the shapes of 26,036 galaxies in 1292 STIS fields and measure the shear variance at…
Variability of Narrow, Associated Absorption Lines in Moderate- and Low-Redshift Quasars
Charlton, Jane C.; Eracleous, Michael; Ganguly, Rajib +1 more
We present the results of a search for variability in the equivalent widths (EWs) of narrow, associated (|Δv|<=5000 km s-1) absorption lines found in the UV spectra of z<=1.5 quasars. The goal of this search was to use variability as a means of identifying absorption lines arising in gas that is intrinsic to the quasar central eng…
The Hot White Dwarf in the Cataclysmic Variable MV Lyrae
Szkody, Paula; Sion, Edward M.; Hoard, D. W. +4 more
We have obtained the first far-ultraviolet spectrum of the nova-like cataclysmic variable MV Lyrae using the Far Ultraviolet Spectroscopic Explorer (FUSE). We also obtained contemporaneous optical light curves and spectra. All data are from a deep faint accretion state of MV Lyr. We constructed a model for the system using the BINSYN software pack…