Colours and magnitudes of the central star of NGC 650 and its two companions have been obtained from HST images. The spectral types of the companions, which have been deduced from the colours, suggest a probable distance to the companions of between 5 and 6 kpc. Using the spectral and photometric characteristics of the central star, which are very similar to the very well studied PN PG 1159, we...

We present an analysis of 11 yr of precision radial velocity measurements of 76 nearby solar-type stars from the Lick radial velocity survey. For each star, we report on variability, periodicity, and long-term velocity trends. Our sample of stars contains eight known companions with mass less than 8 (M p sin i) Jupiter masses six of which were discovered at Lick. For the remaining stars, we pla...

We say that two elliptic curves E1, E2 over a number field K are n-Selmer companions for a positive integer n if for every quadratic character χ of K, there is an isomorphism Seln(E χ 1 /K) ∼= Seln(E 2 /K) between the nSelmer groups of the quadratic twists E 1 , E χ 2 . We give sufficient conditions for two elliptic curves to be n-Selmer companions, and give a number of examples of non-isogenou...

Sun-like stars have stellar, brown dwarf and planetary companions. To help constrain their formation and migration scenarios, we analyse the close companions (orbital period < 5 years) of nearby Sun-like stars. By using the same sample to extract the relative numbers of stellar, brown dwarf and planetary companions, we verify the existence of a very dry brown dwarf desert and describe it quanti...

Early research on imaginary companions viewed the phenomenon negatively. Imaginary companions were often associated with psychopathology and an inability to distinguish between fantasy and reality. The prevailing view on imaginary companions has shifted in recent years with many studies focusing on the positive attributes exhibited by children with imaginary friends. Methodological issues which...

Affect sensitivity is an important requirement for artificial companions to be capable of engaging in social interaction with human users. This paper provides a general overview of some of the issues arising from the design of an affect recognition framework for artificial companions. Limitations and challenges are discussed with respect to other capabilities of companions and real world scenar...

We analyze a 19 night photometric search for transiting extrasolar planets in the open cluster NGC 1245. An automated transit search algorithm with quantitative selection criteria finds six transit candidates; none are bona fide planetary transits.We characterize the survey detection probability viaMonte Carlo injection and recovery of realistic limb-darkened transits. We use this to derive upp...