Search Publications
The energy transfer process in planetary flybys
Anderson, John D.; Campbell, James K.; Nieto, Michael Martin
We illustrate the energy transfer during planetary flybys as a function of time using a number of flight mission examples. The energy transfer process is rather more complicated than a monotonic increase (or decrease) of energy with time. It exhibits temporary maxima and minima with time which then partially moderate before the asymptotic conditio…
Anisotropy in the Hubble constant as observed in the HST extragalactic distance scale key project results
McClure, M. L.; Dyer, C. C.
Based on general relativity, it can be argued that deviations from a uniform Hubble flow should be thought of as variations in the Universe's expansion velocity field, rather than being thought of as peculiar velocities with respect to a uniformly expanding space. The aim of this paper is to use the observed motions of galaxies to map out variatio…
ConvPhot: A profile-matching algorithm for precision photometry
Santini, P.; Fontana, A.; Grazian, A. +1 more
We describe in this paper a new, public software for accurate "PSF-matched" multiband photometry for images of different resolution and depth, that we have named ConvPhot, of which we analyse performances and limitations. It is designed to work when a high resolution image is available to identify and extract the objects, and colours or variations…
On the effect of emission lines on UBVR photometry
Skopal, A.
We investigate the effect on the U, B, V, RC and RJ magnitudes of the removal of emission lines from a spectrum. We determined Δ m corrections from the ratio of fluxes with and without emission lines, transmitted from the object through a photometric filter. An exact and simplified approach for operative use was applied. The …
A fully 3-dimensional thermal model of a comet nucleus
Rosenberg, Eric D.; Prialnik, Dina
A 3-D numerical model of comet nuclei is presented. An implicit numerical scheme was developed for the thermal evolution of a spherical nucleus composed of a mixture of ice and dust. The model was tested against analytical solutions, simplified numerical solutions, and 1-D thermal evolution codes. The 3-D code was applied to comet 67P/Churyumov-Ge…
Is V899 Herculis an unsolved quadruple system containing double close binary stars?
Qian, S. -B.; Liao, W. -P.; He, J. -J. +2 more
Orbital period variation of the W UMa-type eclipsing binary, V899 Herculis, discovered by the Hipparcos satellite was investigated based on all available photoelectric and CCD times of light minimum. It is discovered that the orbital period of the binary shows a cyclic change with an amplitude of 0.0117 days. The cyclic period change can be explai…
Gamma-ray constraints on the infrared background excess
Salvaterra, R.; Ferrara, A.; Mapelli, M.
Motivated by the idea that the recently detected near-infrared (1.2-4 µm) excess over the contribution of known galaxies is due to redshifted light from the first cosmic stars [MNRAS 339 (2003) 973], we have used the effect caused by photon-photon absorption on gamma-ray spectra of blazars to put constraints on extragalactic background light…
On the nature of nearby GRB/SN host galaxies
Sollerman, J.; Östlin, G.; Fynbo, J. P. U. +3 more
We present and discuss optical diagnostics of the low redshift ( z < 0.2) galaxies that are known to have hosted supernovae associated with γ-ray bursts (GRBs). The three galaxies are all actively star forming sub-luminous ( L < L⋆) galaxies with relatively low metallicities ( Z ≲ Z⊙). We find no evidence for substantia…
An ISO-LWS two-colour diagram of Herbig Ae/Be stars
Elia, Davide; Strafella, Francesco; Campeggio, Loretta +2 more
In this paper, we present and discuss an infrared two-colour diagram built with the 60, 100, and 170 µm photometry of the whole sample of Herbig Ae/Be stars observed by the spectrometers on board of ISO satellite. An overview of this diagram reveals a certain degree of homogeneity in the behaviour of these stars and their IR-emitting environ…
Some implications of the introduction of scattered starlight in the spectrum of reddened stars
Zagury, Frédéric
This paper presents new investigations on coherent scattering in the forward direction (orders of magnitude; conservation of energy; dependence of scattered light on geometry and wavelength), and on how scattered light contamination in the spectrum of reddened stars is possibly related to as yet unexplained observations (the diminution of the 2200…