Helium in the eroding atmosphere of an exoplanet.

Helium is the second-most abundant element in the Universe after hydrogen and is one of the main constituents of gas-giant planets in our Solar System. Early theoretical models predicted helium to be among the most readily detectable species in the atmospheres of exoplanets, especially in extended and escaping atmospheres 1 . Searches for helium, however, have hitherto been unsuccessful 2 . Here we report observations of helium on an exoplanet, at a confidence level of 4.5 standard deviations. We measured the near-infrared transmission spectrum of the warm gas giant 3 WASP-107b and identified the narrow absorption feature of excited metastable helium at 10,833 angstroms. The amplitude of the feature, in transit depth, is 0.049 ± 0.011 per cent in a bandpass of 98 angstroms, which is more than five times greater than what could be caused by nominal stellar chromospheric activity. This large absorption signal suggests that WASP-107b has an extended atmosphere that is eroding at a total rate of 1010 to 3 × 1011 grams per second (0.1-4 per cent of its total mass per billion years), and may have a comet-like tail of gas shaped by radiation pressure.

Pregnancy failure in patients with obstetric antiphospholipid syndrome with conventional treatment: the influence of a triple positive antibody profile.

Conventional treatment of obstetric antiphospholipid syndrome fails in approximately 20-30% of pregnant women without any clearly identified risk factor. It is important to identify risk factors that are associated with these treatment failures. This study aimed to assess the impact of risk factors on pregnancy outcomes in women with obstetric antiphospholipid syndrome treated with conventional treatment. We carefully retrospectively selected 106 pregnancies in women with obstetric antiphospholipid syndrome treated with heparin + aspirin. Pregnancy outcomes were evaluated according to the following associated risk factors: triple positivity profile, double positivity profile, single positivity profile, history of thrombosis, autoimmune disease, more than four pregnancy losses, and high titers of anticardiolipin antibodies and/or anti-ßeta-2-glycoprotein-I (aß2GPI) antibodies. To establish the association between pregnancy outcomes and risk factors, a single binary logistic regressions analysis was performed. Risk factors associated with pregnancy loss with conventional treatment were: the presence of triple positivity (OR = 5.0, CI = 1.4-16.9, p = 0.01), high titers of aß2GPI (OR = 4.4, CI = 1.2-16.1, p = 0.023) and a history of more than four pregnancy losses (OR = 3.5, CI = 1.2-10.0, p = 0.018). The presence of triple positivity was an independent risk factor associated with gestational complications (OR = 4.1, CI = 1.2-13.9, p = 0.02). Our findings reinforce the idea that triple positivity is a categorical risk factor for poor response to conventional treatment.

Paternal factor V Leiden and recurrent pregnancy loss: a new concept behind fetal genetics?

BACKGROUND: In up to 50% of couples affected by recurrent pregnancy loss, no identifiable cause is established. Fetal and maternal factors may be equally important in the establishment and maintenance of the placental/maternal arteriovenous anastomoses. Therefore,the inheritance of thrombophilia-related genes may be an important factor in the pathophysiology of recurrent pregnancy loss. Most of the research on recurrent pregnancy loss and thrombophilia has focused on maternal factors, but little is known about the paternal contribution. OBJECTIVES: On that basis, we studied the association between inherited paternal thrombophilias and recurrent pregnancy loss in a narrowly selective group of 42 Argentine males from couples that presented without any known risk factors for recurrent pregnancy loss. PATIENTS AND METHODS: The genotypic distributions of factor (F) V Leiden and prothrombin G20210A among cases were compared with those from a reference group composed of 200 Argentine men. RESULTS: We found a significant difference in the distribution of FV Leiden between both groups (16.7% vs. 3.0%), but no difference was found in the distribution of prothrombin G20210A (2.4% vs.2.0%). Those couples with paternal FV Leiden carriage would be six times more likely to experience recurrent pregnancy loss despite no other apparent cause (OR = 6.47; 95% CI, 2.06­20.39). CONCLUSION: We found evidence of an association between the paternal carriage of FV Leiden and the predisposition to recurrent pregnancy loss, thereby supporting the hypothesis that genetic contributions from both parents are essential factors in the development of this obstetric disorder.

An orbital period of 0.94 days for the hot-Jupiter planet WASP-18b.

The 'hot Jupiters' that abound in lists of known extrasolar planets are thought to have formed far from their host stars, but migrate inwards through interactions with the proto-planetary disk from which they were born, or by an alternative mechanism such as planet-planet scattering. The hot Jupiters closest to their parent stars, at orbital distances of only approximately 0.02 astronomical units, have strong tidal interactions, and systems such as OGLE-TR-56 have been suggested as tests of tidal dissipation theory. Here we report the discovery of planet WASP-18b with an orbital period of 0.94 days and a mass of ten Jupiter masses (10 M(Jup)), resulting in a tidal interaction an order of magnitude stronger than that of planet OGLE-TR-56b. Under the assumption that the tidal-dissipation parameter Q of the host star is of the order of 10(6), as measured for Solar System bodies and binary stars and as often applied to extrasolar planets, WASP-18b will be spiralling inwards on a timescale less than a thousandth that of the lifetime of its host star. Therefore either WASP-18 is in a rare, exceptionally short-lived state, or the tidal dissipation in this system (and possibly other hot-Jupiter systems) must be much weaker than in the Solar System.

The Spectroscopic Orbit of the Planetary Companion Transiting HD 209458.

We report a spectroscopic orbit with period P=3.52433+/-0.00027 days for the planetary companion that transits the solar-type star HD 209458. For the metallicity, mass, and radius of the star, we derive [Fe/H&sqbr0;=0.00+/-0.02, M*=1.1+/-0.1 M middle dot in circle, and R*=1.2+/-0.1 R middle dot in circle. This is based on a new analysis of the iron lines in our HIRES template spectrum and also on the absolute magnitude, effective temperature, and color of the star, and it uses isochrones from four different sets of stellar evolution models. Using these values for the stellar parameters, we reanalyze the transit data and derive an orbital inclination of i=86&fdg;1+/-1&fdg;6. For the planet, we derive a mass of Mp=0.69+/-0.05 MJup, a radius of Rp=1.40+/-0.17 RJup, and a density of rho=0.31+/-0.07 g cm-3.