Context.
The derivation of accurate and precise masses and radii is possible for eclipsing binary stars, allowing for insights into their evolution. When residing in star clusters, they provide ...measurements of even greater precision, along with additional information on their properties. Asteroseismic investigations of solar-like oscillations offers similar possibilities for single stars.
Aims.
We wish to improve the previously established properties of the Hyades eclipsing binary HD 27130 and re-assess the asteroseismic properties of the giant star
ϵ
Tau. The physical properties of these members of the Hyades can be used to constrain the helium content and age of the cluster.
Methods.
New multi-colour light curves were combined with multi-epoch radial velocities to yield masses and radii of HD 27130. Measurements of
T
eff
were derived from spectroscopy and photometry, and verified using the
Gaia
parallax. We estimated the cluster age from re-evaluated asteroseismic properties of
ϵ
Tau while using HD 27130 to constrain the helium content.
Results.
The masses, radii, and
T
eff
of HD 27130 were found to be
M
= 1.0245 ± 0.0024
M
⊙
,
R
= 0.9226 ± 0.015
R
⊙
,
T
eff
= 5650 ± 50 K for the primary, and
M
= 0.7426 ± 0.0016
M
⊙
,
R
= 0.7388 ± 0.026
R
⊙
,
T
eff
= 4300 ± 100 K for the secondary component. Our re-evaluation of
ϵ
Tau suggests that the previous literature estimates are trustworthy and that the
HIPPARCOS
parallax is more reliable than the
Gaia
DR2 parallax.
Conclusions.
The helium content of HD 27130 and, thus, of the Hyades is found to be
Y
= 0.27 but with a significant model dependency. Correlations with the adopted metallicity result in a robust helium enrichment law, with Δ
Y
/Δ
Z
close to 1.2 We estimate the age of the Hyades to be 0.9 ± 0.1 (stat) ±0.1 (sys) Gyr, which is in slight tension with recent age estimates based on the cluster white dwarfs. The precision of the age estimate can be much improved via asteroseismic investigations of the other Hyades giants and by future improvements to the
Gaia
parallax for bright stars.
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We present photometric observations of four transits in the WASP-17 planetary system, obtained using telescope defocusing techniques and with scatters reaching 0.5mmag per point. Our revised orbital ...period is 4.0 ± 0.6s longer than previous measurements, a difference of 6.6σ, and does not support the published detections of orbital eccentricity in this system. We model the light curves using the jktebop code and calculate the physical properties of the system by recourse to five sets of theoretical stellar model predictions. The resulting planetary radius, Rb = 1.932 ± 0.052 ± 0.010RJup (statistical and systematic errors, respectively), provides confirmation that WASP-17b is the largest planet currently known. All 14 planets with radii measured to be greater than 1.6RJup are found around comparatively hot (Teff > 5900K) and massive (MA > 1.15M) stars. Chromospheric activity indicators are available for eight of these stars, and all imply a low activity level. The planets have small or zero orbital eccentricities, so tidal effects struggle to explain their large radii. The observed dearth of large planets around small stars may be natural but could also be due to observational biases against deep transits, if these are mistakenly labelled as false positives and so not followed up. PUBLICATION ABSTRACT
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BFBNIB, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
Concentrations of maternal glucose and lipid during pregnancy affect both fetal growth and the risk of pregnancy complications. The aim of this study was to investigate the effect of two different ...exercise interventions on maternal blood HbA1c and lipid concentrations. Healthy pregnant women (n=219) were enrolled in the study at gestational age ≤15+0 weeks and randomized 2:2:1 to supervised exercise sessions three times per week, to a motivational group having seven counselling sessions on physical activity, or to standard care. Venous blood samples were drawn at 6+4 to 15+0 weeks, at 28+0-6 weeks, at 34+0-6 weeks and at delivery. HbA1c, total cholesterol, LDL-C and triglyceride concentrations were measured by standard biochemical methods and compared within and between groups using constrained linear mixed models. No differences in HbA1c or lipid concentrations between the groups were detected (Figure 1). Overall, HbA1c decreased from ≤15+0 to 28+0-6 weeks (p<0.001) and increased from ≤15+0 to 34+0-6 weeks (p=0.032). Overall, total cholesterol, LDL-C and triglyceride concentrations increased throughout pregnancy (all p<0.001 for ≤15+0 weeks vs. 28+0-6 weeks, 34+0-6 weeks and delivery). Exercise interventions did not affect maternal HbA1c or lipid concentrations during pregnancy. The overall pattern of changes during pregnancy resembled findings from previous studies.
Disclosure
I.K.B.Jensen: None. B.Stallknecht: None. T.D.Clausen: None. E.Løkkegaard: None. C.B.Roland: None. S.P.Knudsen: None. A.D.Jessen: None. S.A.Alomairah: None. O.H.Mortensen: None. L.J.Friis-hansen: None. J.M.Bendix: None. S.Molsted: None.
We report the discovery of Kepler-77b (alias KOI-127.01), a Saturn-mass transiting planet in a 3.6-day orbit around a metal-rich solar-like star. We combined the publicly available Kepler photometry ...(quarters 1−13) with high-resolution spectroscopy from the Sandiford at McDonald and FIES at NOT spectrographs. We derived the system parameters via a simultaneous joint fit to the photometric and radial velocity measurements. Our analysis is based on the Bayesian approach and is carried out by sampling the parameter posterior distributions using a Markov chain Monte Carlo simulation. Kepler-77b is a moderately inflated planet with a mass of Mp = 0.430 ± 0.032 MJup, a radius of Rp = 0.960 ± 0.016 RJup, and a bulk density of ρp = 0.603 ± 0.055 g cm-3. It orbits a slowly rotating (Prot = 36 ± 6 days) G5 V star with M⋆ = 0.95 ± 0.04 M⊙, R⋆ = 0.99 ± 0.02 R⊙, Teff = 5520 ± 60 K, M/H = 0.20 ± 0.05 dex, that has an age of 7.5 ± 2.0 Gyr. The lack of detectable planetary occultation with a depth higher than ~10 ppm implies a planet geometric and Bond albedo of Ag ≤ 0.087 ± 0.008 and AB ≤ 0.058 ± 0.006, respectively, placing Kepler-77b among the gas-giant planets with the lowest albedo known so far. We found neither additional planetary transit signals nor transit-timing variations at a level of ~0.5 min, in accordance with the trend that close-in gas giant planets seem to belong to single-planet systems. The 106 transitsobserved in short-cadence mode by Kepler for nearly 1.2 years show no detectable signatures of the planet’s passage in front of starspots. We explored the implications of the absence of detectable spot-crossing events for the inclination of the stellar spin-axis, the sky-projected spin-orbit obliquity, and the latitude of magnetically active regions.
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Under the hypothesis that brown adipose tissue (BAT) is a metformin target tissue we investigated metformin uptake in vivo and studied the in vitro effects of metformin on cultured human brown ...adipocytes. Human brown adipose tissue was obtained from elective neck surgery and OCT expression levels in human and murine...
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Aims. We present 11 high-precision photometric transitobservations of the transiting super-Earth planet GJ 1214 b. Combining these data with observations from other authors, we investigate the ...ephemeris for possible signs of transit timing variations (TTVs) using a Bayesian approach. Methods. The observations were obtained using telescope-defocusing techniques, and achieve a high precision with random errors in the photometry as low as 1 mmag per point. To investigate the possibility of TTVs in the light curve, we calculate the overall probability of a TTV signal using Bayesian methods. Results. The observations are used to determine the photometric parameters and the physical properties of the GJ 1214 system. Our results are in good agreement with published values. Individual times of mid-transit are measured with uncertainties as low as 10 s, allowing us to reduce the uncertainty in the orbital period by a factor of two. Conclusions. A Bayesian analysis reveals that it is highly improbable that the observed transit times is explained by TTV caused by a planet in the nominal habitable zone, when compared with the simpler alternative of a linear ephemeris.
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We present new photometric observations of WASP-15 and WASP-16, two transiting extrasolar planetary systems with measured orbital obliquities but without photometric follow-up since their discovery ...papers. Our new data for WASP-15 comprise observations of one transit simultaneously in four optical passbands using GROND on the MPG/European Southern Observatory (ESO) 2.2 m telescope, plus coverage of half a transit from DFOSC on the Danish 1.54 m telescope, both at ESO La Silla. For WASP-16 we present observations of four complete transits, all from the Danish telescope. We use these new data to refine the measured physical properties and orbital ephemerides of the two systems. Whilst our results are close to the originally determined values for WASP-15, we find that the star and planet in the WASP-16 system are both larger and less massive than previously thought.
Maternal blood lipid and glucose concentrations during pregnancy affect fetal growth and the risk of pregnancy and delivery complications.
We aimed to investigate the effects of physical activity ...(PA) during pregnancy on maternal blood lipid and hemoglobin A1c (HbA1c) concentrations. We hypothesized that higher PA was associated with improved lipid profile and glycemic control.
In a secondary analysis of a randomized controlled trial, we included 216 pregnant women before week 15 + 0 and tested the effects of two different PA interventions throughout pregnancy compared to standard care on maternal blood lipid and HbA1c concentrations. Additionally, we investigated the effect of PA per se measured by an activity tracker. Total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglyceride, and HbA1c concentrations were measured at week ≤15 + 0, 28+0-6, 34+0-6, and at delivery (week 32 + 1 to 42 + 0). Effects of the interventions and PA per se were tested using linear mixed effects models and linear regression analyses, respectively.
No effects of the PA interventions were detected on maternal lipids or HbA1c during pregnancy. In PA per se analyses, more minutes per week of moderate-to-vigorous intensity PA were associated with less increase in TC (−1.3E-04, P = .020) and LDL-C (−8.5E-05, P = .035) as pregnancy progresses. More active kilocalories were associated with less increase in TC (−5.5E-05, P < .001), HDL-C (−9.5E-06, P = .024), and LDL-C (−3.2E-05, P = .005).
Whilst there were no effects of offering PA interventions, higher PA was associated with reduced increases in TC, HDL-C, and LDL-C as pregnancy progressed.
Context.
Models of stellar structure and evolution can be constrained using accurate measurements of the parameters of eclipsing binary members of open clusters. Multiple binary stars provide the ...means to tighten the constraints and, in turn, to improve the precision and accuracy of the age estimate of the host cluster. In the previous two papers of this series, we have demonstrated the use of measurements of multiple eclipsing binaries in the old open cluster NGC 6791 to set tighter constraints on the properties of stellar models than was previously possible, thereby improving both the accuracy and precision of the cluster age.
Aims.
We identify and measure the properties of a non-eclipsing cluster member, V56, in NGC 6791 and demonstrate how this provides additional model constraints that support and strengthen our previous findings.
Methods.
We analyse multi-epoch spectra of V56 from FLAMES in conjunction with the existing photometry and measurements of eclipsing binaries in NGC6971.
Results.
The parameters of the V56 components are found to be
M
p
= 1.103 ± 0.008
M
⊙
and
M
s
= 0.974 ± 0.007
M
⊙
,
R
p
= 1.764 ± 0.099
R
⊙
and
R
s
= 1.045 ± 0.057
R
⊙
,
T
eff,p
= 5447 ± 125 K and
T
eff,s
= 5552 ± 125 K, and surface Fe/H = +0.29 ± 0.06 assuming that they have the same abundance.
Conclusions.
The derived properties strengthen our previous best estimate of the cluster age of 8.3 ± 0.3 Gyr and the mass of stars on the lower red giant branch (RGB), which is
M
RGB
= 1.15 ± 0.02
M
⊙
for NGC 6791. These numbers therefore continue to serve as verification points for other methods of age and mass measures, such as asteroseismology.
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