A study of the stars in the instability strip of Hyades cluster has been performed taking into account the new estimate of the stellar parallaxes. For taking advantage of the improved accuracy of the distances and hence absolute magnitudes it is necessary to separate the photometric effects of close companions, which appear quite common in Hyades. The δ Scuti stars, differently from nonpulsatin...

I review statistical parallax absolute magnitude determinations which employ data from the Hipparcos satellite for RR Lyrae and Cepheid variables, and for several other stellar classes. Five groups have studied the RR Lyrae stars, and the results are reassuringly consistent: MV (RR) = 0.77 ± 0.13 mag at [Fe/H] = –1.6 dex. Extensive Monte Carlo simulations showed that systematic errors are small...

The Galactic kinematics of Mira variables have been studied using infrared photometry, radial velocities, and Hipparcos parallaxes and proper motions. For Miras in the period range 145 to 200 days (probably corresponding to [Fe/H] in the range –0.8 to –1.3) the major axes of the stellar orbits are concentrated in the first quadrant of Galactic longitude. This is interpreted as a continuation of...

The release of the Hipparcos catalogue (Perryman et al. 1997) provides an opportunity to check results from asteroseismology. This has already been done for the double-mode δ Scuti star SX Phe: Høg & Petersen (1997) found excellent agreement with the parallax derived from model calculations by Petersen & Christensen-Dalsgaard (1996). Here we show that Hipparcos parallaxes for two other stars ar...

Most stars previously identified as Maunder minimum stars are old stars evolved off of the main sequence. Analysis of activity measurements from the California and Carnegie Planet Search program stars and Hipparcos parallaxes implies that the canonical age-chromospheric activity relation breaks down for stars older than ∼ 6 Gyr when activity is calculated from Mount Wilson S values. Stars only ...

New ages are computed for the stars from the Edvardsson et al. (1993) data set. The revised values are systematically larger toward older ages (t>4 Gyr), while they are slightly lower for t<4 Gyr. The systematic difference to older age becomes ∼2 Gyr smaller, when the LutzKelker correction is applied. The Lutz-Kelker corrected values are slightly older than the ages computed from the Hipparcos ...

We study the kinematics of a sample classical Cepheids younger than 120 Myr. For these stars, estimates distances taken from Skowron et al., which are based on period–luminosity relation, and line-of-sight velocities proper motions Gaia catalog available. There also distance derived trigonometric parallaxes contained in ERD3 catalog. A method, relies comparison first-order derivative Galactic r...

Over the past decade, BeSSeL Survey and VERA project have measured trigonometric parallaxes to approximately 250 massive, young stars using VLBI techniques. These sources trace spiral arms over nearly half of Milky Way. What is now needed are accurate distances such which well Galactic center. Here we analyze potential for addressing this need by combining line-of-sight velocities proper motion...

Abstract As part of the BeSSeL Survey, we have used Very Long Baseline Array to measure 16 trigonometric parallaxes and proper motions molecular masers associated with 14 high-mass star-forming regions in Scutum arm first quadrant Milky Way. This increases number maser sources accurate distances this 42. The can now be traced over a length ≈8 kpc spanning ≈100° Galactic azimuth. We find that la...