Double-Mode Radial Pulsations among RR Lyrae Stars

Double-mode RR Lyr type stars are important for studies of properties of horizontal-branch stars. In particular, two periods coupled with spectral properties give a mass estimate that is independent of evolutionary models. Here, we present 59 new Galactic double-mode RR Lyr stars found in the LINEAR survey data with the fundamental radial mode and the first overtone exited (RRd stars). These stars may be useful for constraining the mass-metallicity relation for field horizontal-branch stars. Also, new RRd stars found in the LMC by EROS-II are verified. We present the updated Petersen diagram and the distribution of the fundamental mode periods. Comments on selected variable stars from LINEAR and LMC EROS-II surveys are also presented, including very rare objects: the third known mode-switching RR Lyr and Cepheid pulsating simultaneously in three radial modes.Comment: large tables included as ancillary file

ASAS Eclipsing Binaries with Observed High Period Change Rates

We present 31 bright eclipsing contact and semi-detached binaries that showed high period change rates in a 5 year interval in observations by the All-Sky Automated Survey (ASAS). The time-scales of these changes range from only 50 up to 400 kyr. The orbital periods of 10 binaries are increasing and of 21 are decreasing, and even a larger excess is seen in contact binaries, where the numbers are 5 and 17, respectively. Period change has previously been noticed for only two of these binaries; our observations confirmed a secular period drift for SV Cen and period oscillations for VY Cet. The spectroscopic quadruple system V1084 Sco shows both period change and brightness modulation. All investigated binaries were selected from a sample of 1711 (1135 contact and 576 semi-detached) that fulfilled all criteria of data quality. We also introduce a "branch" test to check if luminosity changes on part of the binary's photosphere has led to a spurious or poorly characterized period change detection.Comment: 12 pages, 13 figures, submitted to MNRA