Radial-velocity measurements and sine-curve fits to the orbital velocity variations are presented for the seventh set of ten close binary systems: V410 Aur, V523 Cas, QW Gem, V921 Her, V2357 Oph, V1130 Tau, HN UMa, HX UMa, HD 93917, NSV 223. All systems, but three (V523 Cas, HD 93917, NSV 223), were discovered photometrically by the Hipparcos mission. All systems are double-lined (SB2) binaries and all, but the detached, very close system V1130 Tau, are contact binaries. The broadeningfunction permitted improvement of the orbital elements for V523 Cas, which was the only system observed before for radial velocity variations. Spectroscopic/visual companions were detected for V410 Aur and HX UMa. Several of the studied systems are prime candidates for combined light and radial-velocity synthesis solutions.

Radial-velocity measurements and sine-curve fits to the orbital velocity variations are presented for the sixth set of ten close binary systems: SV Cam, EE Cet, KR Com, V410 Cyg, GM Dra, V972 Her, ET Leo, FS Leo, V2388 Oph, II UMa. All systems except FS Leo are double-lined spectroscopic binaries. The type of FS Leo is unknown while SV Cam is a close, detached binary; all remaining systems are contact binaries. Eight binaries (all except SV Cam and V401 Cyg) are the recent photometric discoveries of the Hipparcos satellite project. Five systems, EE Cet, KR Com, V401 Cyg, V2388 Oph, II UMa, are members of visual/spectroscopic triple systems. We were able to observe EE Cet separate from its companion, but in the remaining four triple systems we could separate the spectral components only through the use of the broadening-function approach. Several of the studied systems are prime candidates for combined light and radial-velocity synthesis solutions.RS CVn-type system.Our double-lined (SB2) spectroscopic orbit is very well defined, with small errors of the orbital parameters. We note that determinations of the radial velocity semi-amplitude of the primary component, K 1 , agree well in the four existing solutions. Starting with Hiltner (1953) (as reanalyzed by Rainger et al. (1991)), Rainger et al. (1991), Pojmanski (1998) and the current, the results have been (in km s −1 ) : 121.7 ± 1.9, 122.3 ± 1.5, 118.5 ± 2.0, and 121.86 ± 0.76. The results of Pojmanski (1998) differ the most, but are still within the errors of the solutions. The center of mass velocity, V 0 , seems to show a secular progression, although the data of Pojmanski (1998) deviate from the trend. In the same order as before: −16.2 ± 1.4, −11.2 ± 1.2, −13.7 ± 1.5 and −9.13 ± 0.78 km s −1 . Noting that the observations were made in 1947, 1988, 1993 and 1997, the trend may be related to the motion about the third body with the period of about 65 -75 years and the semi-amplitude of about 2 km s −1 (Rainger et al. 1991).The results of Pojmanski (1998), although the first to reveal the motion of the secondary component, show deviations described above and, even more importantly, differ rather substantially from our results in the value of K 2 : 211.5 ± 5.5 versus our 190.17 ± 1.73 km s −1 . Possibly, the discrepancies are due to the rather complex reduction scheme of the previous study which involved successive removal of the two spectral signatures from individual spectra. This was entirely unnecessary in our case because the broadening functions that we analyzed were very well defined and radial velocities of both components could be measured with great ease. Figure 4 shows one of the broadening functions for SV Cam, in comparison with other systems analyzed in this paper. On the basis of the widths of the individual signatures in the broadening functions, and taking into consideration the instrumental broadening, we estimate the apparent rotation velocity of the components, V 1 sin i = 122 ± 10 km s −1 and V 2 sin i = 85 ± 8 km s −1 . Patkos & Hempelman...

Micron size extrasolar dust particles have been convincingly detected by satellites. Larger extrasolar meteoroids (5-35 microns) have most likely been detected by ground based radar at Arecibo and New Zealand. We present estimates of the minimum detectable particle sizes and collecting areas for both radar systems. We show that particles larger than ∼ 10µm can propagate for tens of parsecs through the interstellar medium, opening up the possibility that ground based radar systems can detect AGB stars, young stellar objects such as T Tauri stars, and debris disks around Vega-like stars. We provide analytical and numerical estimates of the ejection velocity in the case of a debris disk interacting with a Jupiter mass planet. We provide rough estimates of the flux of large micrometeoroids from all three classes of sources. Current radar systems are unlikely to detect significant numbers of meteors from debris disks such as Beta Pictoris. However, we suggest improvements to radar systems that should allow for the detection of multiple examples of all three classes. Subject headings:1.