The EBLM project. II. A very hot, low-mass M dwarf in an eccentric and long period eclipsing binary system from SuperWASP

In this paper, we derive the fundamental properties of 1SWASPJ011351.29+314909.7 (J0113+31), a metal-poor (-0.40 +/- 0.04 dex), eclipsing binary in an eccentric orbit (~0.3) with an orbital period of ~14.277 d. Eclipsing M dwarfs orbiting solar-type stars (EBLMs), like J0113+31, have been identified from WASP light curves and follow-up spectroscopy in the course of the transiting planet search. We present the first binary of the EBLM sample to be fully analysed, and thus, define here the methodology. The primary component with a mass of 0.945 +/- 0.045 Msun has a large radius (1.378 +/- 0.058 Rsun) indicating that the system is quite old, ~9.5 Gyr. The M-dwarf secondary mass of 0.186 +/- 0.010 Msun and radius of 0.209 +/- 0.011 Rsun are fully consistent with stellar evolutionary models. However, from the near-infrared secondary eclipse light curve, the M dwarf is found to have an effective temperature of 3922 +/- 42 K, which is ~600 K hotter than predicted by theoretical models. We discuss different scenarios to explain this temperature discrepancy. The case of J0113+31 for which we can measure mass, radius, temperature and metallicity, highlights the importance of deriving mass, radius and temperature as a function of metallicity for M dwarfs to better understand the lowest mass stars. The EBLM Project will define the relationship between mass, radius, temperature and metallicity for M dwarfs providing important empirical constraints at the bottom of the main sequence.Comment: 13 pages, 7 figures. Accepted for publication in A&

Single transit candidates from K2 : detection and period estimation

Photometric surveys such as Kepler have the precision to identify exoplanet and eclipsing binary candidates from only a single transit. K2, with its 75 d campaign duration, is ideally suited to detect significant numbers of single-eclipsing objects. Here we develop a Bayesian transit-fitting tool (‘Namaste: An Mcmc Analysis of Single Transit Exoplanets’) to extract orbital information from single transit events. We achieve favourable results testing this technique on known Kepler planets, and apply the technique to seven candidates identified from a targeted search of K2 campaigns 1, 2 and 3. We find EPIC203311200 to host an excellent exoplanet candidate with a period, assuming zero eccentricity, of 540+410 −230 d and a radius of 0.51 ± 0.05RJup. We also find six further transit candidates for which more follow-up is required to determine a planetary origin. Such a technique could be used in the future with TESS, PLATO and ground-based photometric surveys such as NGTS, potentially allowing the detection of planets in reach of confirmation by Gaia

The EBLM project : III. A Saturn-size low-mass star at the hydrogen-burning limit

This work was partially supported by a grant from the Simons Foundation (PI Queloz, grant number 327127).We report the discovery of an eclipsing binary system with mass-ratio q ∼ 0.07. After identifying a periodic photometric signal received by WASP, we obtained CORALIE spectroscopic radial velocities and follow-up light curves with the Euler and TRAPPIST telescopes. From a joint fit of these data we determine that EBLM J0555-57 consists of a sun-like primary star that is eclipsed by a low-mass companion, on a weakly eccentric 7.8-day orbit. Using a mass estimate for the primary star derived from stellar models, we determine a companion mass of 85 ± 4 MJup (0.081 M⊙) and a radius of 0.84+ 0.14 -0.04RJup (0.084 R⊙) that is comparable to that of Saturn. EBLM J0555-57Ab has a surface gravity log g2 =5.50+ 0.03 -0.13 and is one of the densest non-stellar-remnant objects currently known. These measurements are consistent with models of low-mass stars.PostprintPeer reviewe

The EBLM Project : IV. Spectroscopic orbits of over 100 eclipsing M dwarfs masquerading as transiting hot-Jupiters

We present 2271 radial velocity measurements taken on 118 single-line binary stars, taken over eight years with the CORALIE spectrograph. The binaries consist of F/G/K primaries and M dwarf secondaries. They were initially discovered photometricallyby the WASP planet survey, as their shallow eclipses mimic a hot Jupiter transit. The observations we present permit a precise characterisation of the binary orbital elements and mass function. With modelling of the primary star, this mass function is converted to a mass of the secondary star. In the future, this spectroscopic work will be combined with precise photometric eclipses to draw anempirical mass/radius relation for the bottom of the mass sequence. This has applications in both stellar astrophysics and the growing number of exoplanet surveys around M dwarfs. In particular, we have discovered 34 systems with a secondary mass below 0.2M⊙ and so we will ultimately double the number of known very low-mass stars with well-characterised masses and radii.The quality of our data combined with the amplitude of the Doppler variations mean that we are able to detect eccentricities as small as 0.001 and orbital periods to sub-second precision. Our sample can revisit some earlier work on the tidal evolution of close binaries, extending it to low mass ratios. We find some exceptional binary systems that are eccentric at orbital periods below three days, while our longest circular orbit has a period of 10.4 days. Amongst our systems, we note one remarkable architecture in J1146-42 that boasts three stars within one astronomical unit. By collating the EBLM binaries with published WASP planets and brown dwarfs, we derive a mass spectrum with twice the resolutionof previous work. We compare the WASP/EBLM sample of tightly bound orbits with work in the literature on more distant companionsup to 10 AU. We note that the brown dwarf desert appears wider, as it carves into the planetary domain for our short-period orbits.This would mean that a significantly reduced abundance of planets begins at ∼3MJup, well before the deuterium-burning limit. This may shed light on the formation and migration history of massive gas giants.PostprintPeer reviewe

Systematic versus on-demand early palliative care: results from a multicentre, randomised clinical trial

Background Early palliative care (EPC) in oncology has been shown to have a positive impact on clinical outcome, quality-of-care outcomes, and costs. However, the optimal way for activating EPC has yet to be defined. Methods This prospective, multicentre, randomised study was conducted on 207 outpatients with metastatic or locally advanced inoperable pancreatic cancer. Patients were randomised to receive ‘standard cancer care plus on-demand EPC’ (n = 100) or ‘standard cancer care plus systematic EPC’ (n = 107). Primary outcome was change in quality of life (QoL) evaluated through the Functional Assessment of Cancer Therapy – Hepatobiliary questionnaire between baseline (T0) and after 12 weeks (T1), in particular the integration of physical, functional, and Hepatic Cancer Subscale (HCS) combined in the Trial Outcome Index (TOI). Patient mood, survival, relatives' satisfaction with care, and indicators of aggressiveness of care were also evaluated. Findings The mean changes in TOI score and HCS score between T0 and T1 were −4.47 and −0.63, with a difference between groups of 3.83 (95% confidence interval [CI] 0.10–7.57) (p = 0.041), and −2.23 and 0.28 (difference between groups of 2.51, 95% CI 0.40–4.61, p = 0.013), in favour of interventional group. QoL scores at T1 of TOI scale and HCS were 84.4 versus 78.1 (p = 0.022) and 52.0 versus 48.2 (p = 0.008), respectively, for interventional and standard arm. Until February 2016, 143 (76.9%) of the 186 evaluable patients had died. There was no difference in overall survival between treatment arms. Interpretations Systematic EPC in advanced pancreatic cancer patients significantly improved QoL with respect to on-demand EPC

Pattern of care and effectiveness of treatment for glioblastoma patients in the real world: Results from a prospective population-based registry. Could survival differ in a high-volume center?

BACKGROUND: As yet, no population-based prospective studies have been conducted to investigate the incidence and clinical outcome of glioblastoma (GBM) or the diffusion and impact of the current standard therapeutic approach in newly diagnosed patients younger than aged 70 years. METHODS: Data on all new cases of primary brain tumors observed from January 1, 2009, to December 31, 2010, in adults residing within the Emilia-Romagna region were recorded in a prospective registry in the Project of Emilia Romagna on Neuro-Oncology (PERNO). Based on the data from this registry, a prospective evaluation was made of the treatment efficacy and outcome in GBM patients. RESULTS: Two hundred sixty-seven GBM patients (median age, 64 y; range, 29-84 y) were enrolled. The median overall survival (OS) was 10.7 months (95% CI, 9.2-12.4). The 139 patients 64aged 70 years who were given standard temozolomide treatment concomitant with and adjuvant to radiotherapy had a median OS of 16.4 months (95% CI, 14.0-18.5). With multivariate analysis, OS correlated significantly with KPS (HR = 0.458; 95% CI, 0.248-0.847; P = .0127), MGMT methylation status (HR = 0.612; 95% CI, 0.388-0.966; P = .0350), and treatment received in a high versus low-volume center (HR = 0.56; 95% CI, 0.328-0.986; P = .0446). CONCLUSIONS: The median OS following standard temozolomide treatment concurrent with and adjuvant to radiotherapy given to (72.8% of) patients aged 6470 years is consistent with findings reported from randomized phase III trials. The volume and expertise of the treatment center should be further investigated as a prognostic factor

The EBLM Project VI. The mass and radius of five low-mass stars in F+M binaries discovered by the WASP survey

peer reviewedSome M-dwarfs around F-/G-type stars have been measured to be hotter and larger than predicted by stellar evolution models. Inconsistencies between observations and models need addressing with more mass, radius and luminosity measurements of low-mass stars to test and refine evolutionary models. Our aim is to measure the masses, radii and ages of the stars in five low-mass eclipsing binary systems discovered by the WASP survey. We use WASP photometry to establish eclipse-time ephemerides and to obtain initial estimates for the transit depth and width. Radial velocity measurements were simultaneously fitted with follow-up photometry to find the best-fitting orbital solution. This solution was combined with measurements of atmospheric parameters to interpolate evolutionary models and estimate the mass of the primary star, and the mass and radius of the M-dwarf companion. We assess how the best fitting orbital solution changes if an alternative limb- darkening law is used and quantify the systematic effects of unresolved companions. We also gauge how the best-fitting evolutionary model changes if different values are used for the mixing length parameter and helium enhancement. We report the mass and radius of five M-dwarfs and find little evidence of inflation with respect to evolutionary models. The primary stars in two systems are near the ``blue hook'' stage of their post sequence evolution, resulting in two possible solutions for mass and age. We find that choices in helium enhancement and mixing- length parameter can introduce an additional 3-5\,\% uncertainty in measured M-dwarf mass. Unresolved companions can introduce an additional 3-8\% uncertainty in the radius of an M-dwarf, while the choice of limb- darkening law can introduce up to an additional 2\% uncertainty

Search for eccentric black hole coalescences during the third observing run of LIGO and Virgo

Despite the growing number of confident binary black hole coalescences observed through gravitational waves so far, the astrophysical origin of these binaries remains uncertain. Orbital eccentricity is one of the clearest tracers of binary formation channels. Identifying binary eccentricity, however, remains challenging due to the limited availability of gravitational waveforms that include effects of eccentricity. Here, we present observational results for a waveform-independent search sensitive to eccentric black hole coalescences, covering the third observing run (O3) of the LIGO and Virgo detectors. We identified no new high-significance candidates beyond those that were already identified with searches focusing on quasi-circular binaries. We determine the sensitivity of our search to high-mass (total mass M>70 M⊙) binaries covering eccentricities up to 0.3 at 15 Hz orbital frequency, and use this to compare model predictions to search results. Assuming all detections are indeed quasi-circular, for our fiducial population model, we place an upper limit for the merger rate density of high-mass binaries with eccentricities 0<e≤0.3 at 0.33 Gpc−3 yr−1 at 90\% confidence level