Astronomy & Astrophysics

All Tables

Table 1: Examples of sources at different distances. - For LMC/SMC and M 31 we have chosen two series of sources with comparable apparent luminosities ( $M_V\sim 18.5$ and $\sim$ 20.5). - The size of a SNIa envelope is estimated assuming $10~000~{\rm km~s^{-1}}$ expansion rate during 20 days (Filippenko 1997). - The angular and luminosity distances of the Einstein cross multi-image quasar are estimated with the cosmological parameters of Bennett et al. (2003). The upper size of the continuum source is constrained by microlensing studies. The absolute magnitude given here is only indicative, as it does not take into account the magnification due to gravitational lensing.
Table 2: Examples of screen positions, corresponding Fresnel sizes, and fringing time scales at $\lambda=500~{\rm nm}$ . The typical relative velocity of the nearby stars is taken from the dispersions published by Cox (Allen) (2000).
Table 3: Conditions and characteristics of the different scintillation regimes for point-like and extended sources of apparent angular size $\theta _{\rm S}$ . $R_{\rm scint}$ is the characteristic length scale of the illumination pattern, and $t_{\rm scint}$ is the characteristic time scale of the intensity variations for a screen moving at transverse speed $V_{\rm T}$ with respect to the line of sight. The modulation index $m_{\rm scint}$ is the root mean square amplitude of the intensity scintillation. $m_{\rm scint}$ depends only on the $\theta _{\rm diff}$ to $\theta _{\rm S}$ ratio for the diffractive mode. For the other scintillation modes, $m_{\rm scint}$ is given for stochastic fluctuations of the optical path length due to Kolmogorov turbulence in the scattering medium.
Table 4: Configurations leading to strong diffractive scintillation. Numbers are given for $\lambda=500~{\rm nm}$ . Interstellar absorption is not taken into account for the magnitude estimates.