Astrometric and Photometric Measurements of Binary Stars with Adaptive Optics: Observations from 2002

The adaptive optics system at the 3.6 m AEOS telescope was used to measure the astrometry and differential magnitude in I-band of 56 binary stars in 2002. The astrometric measurements will be of use for future orbital determination, and the photometric measurements will be of use in estimating the spectral types of the component stars. Two candidate companions were detected, but neither is likely to be gravitationally bound. Nine systems had not been observed in over 40 years. Eight of these are shown to share common proper motion, while HD 182352 is shown to be a background star. One of the two components of the HD 114378 (Alpha Com) is shown to be a variable star of unknown type. In addition, 86 stars were unresolved and the full-width half maxima of the images are presented.Comment: 9 pages, 1 figure, 3 Table

Optimal emission-extraction policy in a world of scarcity and irreversibility

This paper extends the classical exhaustible-resource/stock-pollution model with the irreversibility of pollution decay. Within this framework, we answer the question how the potential irreversibility of pollution affects the extraction path. We investigate the conditions under which the economy will optimally adopt a reversible policy, and when it is optimal to enter the irreversible region. In the case of irreversibility it may be optimal to leave a positive amount of resource in the ground forever. As far the optimal extraction/emission policy is concerned, several types of solutions may arise, including solutions where the economy stays at the threshold for a while. Given that different programs may satisfy the first order conditions for optimality, we further investigate when each of these is optimal. The analysis is illustrated by means of a numerical example. To sum up, for any pollution level, we can identify a critical resource stock such that there exist multiple optima i.e. a reversible and an irreversible policy that yield exactly the same present value. For any resource stock below this critical value, the optimal policy is reversible whereas with large enough resource, irreversible policies outperform reversible programs. Finally, the comparison between irreversible policies reveals that it is never optimal for the economy to stay at the threshold for a while before entering the irreversible region