have strong local maxima ("blobs") in the scrape-off layer. The motion of this 2-D structure motion has also been measured using an ultra-fast framing camera with 12 frames taken at 250,000 frames/sec. Numerical simulations produce turbulent structures with roughly similar spatial and temporal scales and transport levels as that observed in the experiment; however, some differences are also noted, perhaps requiring diagnostic improvement and/or additional physics in the numerical model.
We present high precision radial velocities (RVs) of double-lined spectroscopic binary stars HD78418, HD123999, HD160922, HD200077 and HD210027. They were obtained based on the high resolution echelle spectra collected with the Keck I/Hires, Shane/CAT/Hamspec and TNG/Sarge telescopes/spectrographs over the years 2003-2008 as a part of TATOOINE search for circumbinary planets. The RVs were computed using our novel iodine cell technique for double-line binary stars which relies on tomographically disentangled spectra of the components of the binaries. The precision of the RVs is of the order of 1-10 m s −1 and to properly model such measurements one needs to account for the light time effect within the binary's orbit, the relativistic effects and the RV variations due to the tidal distortions of the components of the binaries. With such proper modeling, our RVs combined with the archival visibility measurements from the Palomar Testbed Interferometer allow us to derive very precise spectroscopic/astrometric orbital and physical parameters of the binaries. In particular, we derive the masses, the absolute K and H band magnitudes and the parallaxes. The masses together with the absolute magnitudes in the K and H bands enable us to estimate the ages of the binaries.These RVs allow us to obtain some of the most accurate mass determinations of binary stars. The fractional accuracy in m sin i only and hence based on the RVs alone ranges from 0.02% to 0.42%. When combined with the PTI astrometry, the fractional accuracy in the masses ranges in the three best cases from 0.06% to 0.5%. Among them, the masses of HD210027 components rival in precision the mass determination of the components of the relativistic double pulsar system PSR J0737-3039. In the near future, for double-lined eclipsing binary stars we expect to derive masses with a fractional accuracy of the order of up to ∼0.001% with our technique. This level of precision is an order of magnitude higher than of the most accurate mass determination for a body outside the Solar System -the double neutron star system PSR B1913+16.
We have used the Palomar Testbed Interferometer to perform very high precision differential astrometry on the 0.25 arcsecond separation binary star HD 171779. In 70 minutes of observation we achieve a measurement uncertainty of ≈ 9 micro-arcseconds in one axis, consistent with theoretical expectations. Nightto-night repeatability over four nights is at the level of 16 micro-arcseconds. This method of very-narrow-angle astrometry may be extremely useful for searching for planets with masses as small as 0.5 M Jup around a previously neglected class of stars -so-called "speckle binaries." It will also provide measurements of stellar parameters such as masses and distances, useful for constraining stellar models at the 10 −3 level.
We present preliminary results of the first and on-going radial velocity survey for circumbinary planets. With a novel radial velocity technique employing an iodine absorption cell, we achieve an unprecedented radial velocity (RV) precision of up to 2 m s −1 for double-lined binary stars. The high-resolution spectra collected with the Keck I/Hires, TNG/Sarg, and Shane/CAT/Hamspec telescopes/spectrographs over the years 2003-2008 allow us to derive RVs and compute planet detection limits for 10 double-lined binary stars. For this initial sample of targets, we can rule out planets on dynamically stable orbits with masses as small as ∼0.3 to 3 M Jup for the orbital periods of up to ∼5.3 years. Even though the presented sample of stars is too small to make any strong conclusions, it is clear that the search for circumbinary planets is now technique-wise possible and eventually will provide new constraints for the planet formation theories.
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