CD Tau: a detached eclipsing binary with a solar-mass companion

We present a detailed analysis of the detached eclipsing binary CD Tau. A large variety of observational data, in form of IR photometry, CORAVEL radial velocity observations and high-resolution spectra, are combined with the published light curves to derive accurate absolute dimensions and effective temperature of the components, as well as the metal abundance of the system. We obtain: MA=1.442(16) Mo, RA=1.798(17) Ro, TeffA=6200(50) K, MB=1.368(16) Msun, RB=1.584(20) Run and TeffB=6200(50) K. The metal content of the system is determined to be [Fe/H]=+0.08(15) dex. In addition, the eclipsing binary has a K-type close visual companion at about 10-arcsec separation, which is shown to be physically linked, thus sharing a common origin. The effective temperature of the visual companion (Teff=5250(200) K) is determined from synthetic spectrum fitting, and its luminosity (log L/Lo=-0.27(6)), and therefore its radius (R=0.89(9) Ro), are obtained from comparison with the apparent magnitude of the eclipsing pair. The observed fundamental properties of the eclipsing components are compared with the predictions of evolutionary models, and we obtain good agreement for an age of 2.6 Gyr and a chemical composition of Z=0.026 and Y=0.26. Furthermore, we test the evolutionary models for solar-mass stars and we conclude that the physical properties of the visual companion are very accurately described by the same isochrone that fits the more massive components.Comment: 9 pages, 6 figures, accepted for publication in MNRA

Under-the-cell routing to improve manufacturability

The progressive miniaturization of technology and the unequal scalability of the BEOL and FEOL layers aggravate the routing congestion problem and have a negative impact on manufacturability. Standard cells are designed in a way that they can be treated as black boxes during physical design. However, this abstraction often prevents an efficient use of its internal free resources. This paper proposes an effective approach for using internal routing resources without sacrificing modularity. By using cell generation tools for regular layouts, libraries are enriched with cell instances that have lateral pins and allow under-the-cell connections between adjacent cells, thus reducing pin count, via count and routing congestion. An approach to generate cells with regular layouts and lateral pins is proposed. Additionally, algorithms to maximize the impact of under-the-cell routing are presented. The proposed techniques are integrated in an industrial design flow. Experimental results show a significant reduction of design rule check violations with negligible impact on timing.Peer ReviewedPostprint (author's final draft

Marcinkiewicz-Zygmund inequalities and interpolation by spherical harmonics

We find necessary density conditions for Marcinkiewicz-Zygmund inequalities and interpolation for spaces of spherical harmonics with respect to the L^p norm. Moreover, we prove that there are no complete interpolation families for p\neq 2

Dark matter searches with asteroseismology

High-precision asteroseismic data provides an excellent opportunity to test theories of stellar evolution and new physics, such as the properties of the dark matter (DM) of the Universe. Here we will show that some models of DM lead to changes in the classical scenario of stellar evolution. The accumulation of DM in the core of low-mass stars reduces their central temperatures and inhibits the formation of small convective cores in 1.1-1.3 Ms stars. We review the asteroseismic constraints that have been set to the characteristics of the DM particles, obtained comparing the oscillations of the star Alpha Cen B with modified stellar models. To conclude, we discuss the prospects to use CoRoT and Kepler data on main-sequence stars and red giants to further constrain the nature of DM.Comment: Proceedings of "The Space Photometry Revolution, CoRoT3-KASC7 joint meeting", Toulouse 201