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We present the most comprehensive analysis to date of the Upper Centaurus Lupus eclipsing binary MML 53 (with P-EB = 2.097892 d), and for the first time, confirm the bound-nature of the third star (in a P-3 similar to 9 yr orbit) by constraining its mass dynamically. Our analysis is based on new and archival spectra and time-series photometry, spanning 80% of one orbit of the outer component. From the spectroscopic analysis, we determined the temperature of the primary star to be 4880 +/- 100 K. The study of the close binary incorporated treatment of spots and dilution by the tertiary in the light curves, allowing for the robust measurement of the masses of the eclipsing components within 1% (M-1 = 1.0400 +/- 0.0067 M-circle dot and M-2 = 0.8907 +/- 0.0058 M-circle dot), their radii within 4.5% (R-1 = 1.283 +/- 0.043 R-circle dot and R-2 = 1.107 +/- 0.049 R-circle dot), and the temperature of the secondary star (T-eff,T-2 = 4379 +/- 100 K). From the analysis of the eclipse timings, and the change in systemic velocity of the eclipsing binary and the radial velocities of the third star, we measured the mass of the outer companion to be 0.7 M-circle dot (with a 20% uncertainty). The age we derived from the evolution of the temperature ratio between the eclipsing components is fully consistent with previous, independent estimates of the age of Upper Centaurus Lupus (16 +/- 2 Myr). At this age, the tightening of the MML 53 eclipsing binary has already occurred, thus supporting close-binary formation mechanisms that act early in the stars' evolution. The eclipsing components of MML 53 roughly follow the same theoretical isochrone, but appear to be inflated in radius (by 20% for the primary and 10% for the secondary) with respect to recent evolutionary models. However, our radius measurement of the 1.04 M-circle dot primary star of MML 53 is in full agreement with the independent measurement of the secondary of NP Per which has the same mass and a similar age. The eclipsin

Aims. We present a double-lined orbit solution for MML 53, the recently discovered low-mass pre-main sequence eclipsing binary. Methods. Using high-resolution spectra from the SMARTS 1.5 m echelle spectrograph, we measure precise radial velocities and derive the orbital parameters of the system. Results. The 2.1 d orbit of the eclipsing pair is circular, and we find the minimum masses of the eclipsing components to be M(1) sin(3) i = 0.97 M(circle dot) and M(2) sin(3) i = 0.84 M(circle dot), with formal uncertainties of 2.0% and an additional systematic uncertainty of approximate to 2.5% most likely caused by large star spots on the primary star. MML 53 has been previously identified as a member of the Upper Centaurus Lupus (UCL) star forming region (age similar to 15 Myr). The systemic radial velocity from our orbit solution, v(gamma) = + 1.4 +/- 0.3 +/- 0.8 km s(-1) (statistical and systematic), is also consistent with kinematic membership in this association. In addition, we detect a change in v(gamma) between 2006 and 2009 providing further evidence for the presence of a the third body in a wide (several year) orbit.

We present observations of the Rossiter-McLaughlin effect for the transiting exoplanets WASP-1b, WASP-24b, WASP-38b and HAT-P-8b, and deduce the orientations of the planetary orbits with respect to the host stars' rotation axes. The planets WASP-24b, WASP-38b and HAT-P-8b appear to move in prograde orbits and be well aligned, having sky-projected spin-orbit angles consistent with zero: lambda = -4 degrees.7 +/- 4 degrees.0, 15 degrees(+43)(-33) and -9 degrees.7(-7.7)(+9.0), respectively. The host stars have T(eff) < 6250K and conform with the trend of cooler stars having low obliquities. WASP-38b is a massive planet on a moderately long period, eccentric orbit so may be expected to have a misaligned orbit given the high obliquities measured in similar systems. However, we find no evidence for a large spin-orbit angle. By contrast, WASP-1b joins the growing number of misaligned systems and has an almost polar orbit, lambda = -79 degrees.0(-4.3)(+4.5). It is neither very massive, eccentric nor orbiting a hot host star, and therefore does not share the properties of many other misaligned systems.