THE VLT-FLAMES TARANTULA SURVEY: THE FASTEST ROTATING O-TYPE STAR AND SHORTEST PERIOD LMC PULSAR-REMNANTS OF A SUPERNOVA DISRUPTED BINARY?

We present a spectroscopic analysis of an extremely rapidly rotating late O-type star, VFTS102, observed during a spectroscopic survey of 30 Doradus. VFTS102 has a projected rotational velocity larger than 500 km s(-1) and probably as large as 600 km s-1; as such it would appear to be the most rapidly rotating massive star currently identified. Its radial velocity differs by 40 kms(-1) from the mean for 30 Doradus, suggesting that it is a runaway. VFTS102 lies 12 pc from the X-ray pulsar PSR J0537-6910 in the tail of its X-ray diffuse emission. We suggest that these objects originated from a binary system with the rotational and radial velocities of VFTS102 resulting from mass transfer from the progenitor of PSR J0537-691 and the supernova explosion, respectively.

New identifications for blue objects towards the Galactic center: post-AGE stars, Be/disk stars and others

As part of a programme to investigate spatial variations in the Galactic chemical composition, we have been searching for normal B-type stars and A-type supergiants near the Galactic center. During this search we have found eleven peculiar stars, and in some cases performed detailed abundance analyses of them which suggest that they may be at a post-AGB evolutionary stage.

A metal deficient early B-type star near the edge of the galactic disk

High resolution spectra of an early B-type star associated with the H II region detected by de Geus et al. (1993) are analysed using LTE model atmosphere techniques to derive stellar atmospheric parameters and a chemical composition. A distance to the star of 8.2 kpc is estimated, placing it near the edge of the galactic disk and closer than the kinematic distance of 20 kpc to the H II region, calculated by de Geus et al. A differential line by line abundance analysis with respect to the spectroscopic standard tau Sco indicates a significant metal depletion, with elements down on average by -0.5 dex.

A STRUCTURE-FROM-MOTION SCHEME THAT LOOKS FOR PARALLELS, AND ITS IMPLICATIONS FOR APPARENT REVERSALS IN ROTATING TRAPEZIA

Apparent reversals in rotating trapezia have been regarded as evidence that human vision favours methods which are heuristic or form dependent. However, the argument is based on the assumption that general algorithmic methods would avoid the illusion, and that has never been clear. A general algorithm for interpreting moving parallels has been developed to address the issue. It handles a considerable range of stimuli successfully, but finds multiple interpretations in situations which correspond closely to those where apparent reversals occur. This strengthens the hypothesis that apparent reversals may occur when general algorithmic methods fail and heuristics are invoked as a stopgap.