Detection and measurement of planetary systems with GAIA

We use detailed numerical simulations and the $\upsilon$ Andromedae, planetary system as a template to evaluate the capability of the ESA Cornerstone Mission GAIA in detecting and measuring multiple planets around solar-type stars in the neighborhood of the Solar System. For the outer two planets of the $\upsilon$ Andromedae, system, GAIA high-precision global astrometric measurements would provide estimates of the full set of orbital elements and masses accurate to better than 1--10%, and would be capable of addressing the coplanarity issue by determining the true geometry of the system with uncertainties of order of a few degrees. Finally, we discuss the generalization to a variety of configurations of potential planetary systems in the solar neighborhood for which GAIA could provide accurate measurements of unique value for the science of extra-solar planets.Comment: 4 pages, 2 pictures, accepted for publication in A&A Letter

The GSC-II-based survey of ancient cool white dwarfs I. The sample of spectroscopically confirmed WDs

The GSC-II white dwarf survey was designed to identify faint and high proper motion objects, which we used to define a new and independent sample of cool white dwarfs. With this survey we aim to derive new constraints on the halo white dwarf space density. Also, these data can provide information on the age of thick disk and halo through the analysis of the luminosity function. On the basis of astrometric and photometric parameters, we selected candidates with mu > 0.28 as/yr and R_F > 16 in an area of 1150 square degrees. Then, we separated white dwarfs from late type dwarfs and subdwarfs by means of the reduced proper motion diagram. Finally, spectroscopic follow-up observations were carried out to confirm the white dwarf nature of the selected candidates. We found 41 white dwarfs of which 24 are new discoveries. Here we present the full sample and for each object provide positions, absolute proper motions, photometry, and spectroscopy.Comment: 14 pages, 7 figures, submitted to A&

Testing Planet Formation Models with Gaia μ\muas Astrometry

In this paper, we first summarize the results of a large-scale double-blind tests campaign carried out for the realistic estimation of the Gaia potential in detecting and measuring planetary systems. Then, we put the identified capabilities in context by highlighting the unique contribution that the Gaia exoplanet discoveries will be able to bring to the science of extrasolar planets during the next decade.Comment: 4 pages, 1 figure. To appear in the proceedings of "IAU Symposium 248 - A Giant Step: from Milli- to Micro-arcsecond Astrometry", held in Shanghai, China, 15-19 Oct. 200

Comparision of the frying performance of olive oil and palm superolein

Deep-fat frying is an important method of food preparation in wich foods are immersed in hot oil. Repeated use of frying oils is a common practice and in the presence of atmospheric oxygen it produces various undesiderable reactions in used oils. Stable frying oils usually required low linolenic acid (LnA < 3%). The aim of this study was to establish the behaviour of palm superolein (PSO) (OA 45%, LA 12.5%, LnA 0.2%) and olive oil (OO) during repeated, discontinous deep frying of French fries. The behaviour of the oils under controlled heating conditions was also studied by maintaining all of the process variables the same as those in deep frying except that there was no food in the oil. The PSO selected to be tested in this study may represent an alternative to OO as a frying medium. Although PSO presented a faster increase in some oxidation indices, such as free acid and total polar compounds, for other indicators, PSO showed better behaviour than OO (less formation of C8:0 and lower peroxide value)

Model atmosphere analysis of the extreme DQ white dwarf GSC2U J131147.2+292348

A new model atmosphere analysis for the peculiar DQ white dwarf discovered by Carollo et al. (2002) is presented. The effective temperature and carbon abundance have been estimated by fitting both the photometric data (UBJ,VRF,IN,JHK) and a low resolution spectrum (3500<lambda<7500 A) with a new model grid for helium-rich white dwarfs with traces of carbon (DQ stars). We estimate Teff ~ 5120 +/- 200 K and log[C/He] ~ -5.8 +/- 0.5, which make GSC2U J131147.2+292348 the coolest DQ star ever observed. This result indicates that the hypothetical transition from C2 to C2H molecules around Teff = 6000 K, which was inferred to explain the absence of DQ stars at lower temperatures, needs to be reconsidered.Comment: 4 pages, 2 figures, accepted for publication in Astronomy and Astrophysics Letter

Testing planet formation models with Gaia μas astrometry

In this paper, we first summarize the results of a large-scale double-blind tests campaign carried out for the realistic estimation of the Gaia potential in detecting and measuring planetary systems. Then, we put the identified capabilities in context by highlighting the unique contribution that the Gaia exoplanet discoveries will be able to bring to the science of extrasolar planets during the next decad