We present new absolute trigonometric parallaxes and relative proper motions for nine Galactic Cepheid variable stars: l Car, ζ Gem, β Dor, W Sgr, X Sgr, Y Sgr, FF Aql, T Vul, and RT Aur. We obtain these results with astrometric data from Fine Guidance Sensor 1r, a white-light interferometer on Hubble Space Telescope. We find absolute parallaxes in milliseconds of arc: l Car, 2.01± 0.20 ; ζ Gem...

Out of ∼ 500 Lithium-rich ROSAT counterparts, which were presumed to be low-mass pre-main sequence stars, 21 stars have been observed by HIPPARCOS. We study their parallaxes, proper motions, and photometric data. For 7 out of 10 Taurus and Lupus stars in our sample, proper motions and parallaxes are not inconsistent with membership to these associations, while most of the stars in Chamaeleon an...

By using HIPPARCOS data (magnitudes, parallaxes, proper motions), (1) we determine new values of the apparent luminosity of the central stars of 19 planetary nebulae, (2) we discuss their distance and position on the T/L diagram. By comparison with the distances determined by individual or statistical methods, we see that most of these “ground” distances look overestimated when we trust the HIP...

It is well known that the frequency functions of a set of quantities and of their measures are different;' if the error of measurement is comparable in magnitude to the quantity determined, they may be decidedly dissimilar. In the case of good photographic parallaxes the reported probable errors average about eight one-thousandths of a second of arc, making a dispersion of twelve. Moreover, as ...

The Baade-Wesselink method using VJK photometry was shown by Laney and Stobie (1995) to yield apparently precise results, free of obvious systematics with phase, surface gravity and microturbulence. Here we extend the empirical calibration of the p-factor [1] to a maximal sample of galactic classical Cepheids. HADS or 'dwarf Cepheids' have been shown to follow the same PL relation (at least for...