Context. We wish to determine accurate ages for open clusters and use this, in conjunction with colour–magnitude diagrams, to constrain models of stellar structure and evolution. Aims. The detached ...eclipsing binary V20 in the old, metal-rich (${\rm Fe/H}$ = +0.40) open cluster NGC 6791 is studied in order to determine highly accurate masses and radii of its components. This allows the cluster age to be established with high precision, using isochrones in the mass-radius diagram. Methods. We employ high-resolution UVES spectroscopy of V20 to determine the spectroscopic orbit and time-series $V, I$ photometry to obtain the photometric elements. Results. The masses and radii of the V20 components are found to be $1.074\pm0.008~M_{\odot}$ and $1.399\pm0.016~R_{\odot}$ (primary) and $0.827\pm0.004~M_{\odot}$ and $0.768\pm0.006~R_{\odot}$ (secondary). The primary is located almost exactly at the hottest point along the cluster isochrone, and the secondary is a ~7 times fainter main-sequence star. We determine an apparent cluster distance-modulus of $(m-M)_V\,=\,13.46\pm0.10$ (average of primary and secondary). The cluster age is obtained from comparisons with theoretical isochrones in the mass-radius diagram. Using the isochrones from Victoria-Regina with ${\rm Fe/H}$ = +0.37 we find $7.7\pm0.5$ Gyr, whereas the Yonsei-Yale (Y2) isochrones lead to $8.2\pm0.5$ Gyr, and BaSTI isochrones to $9.0\pm0.5$ Gyr. In a mass-radius diagram, the 7.7 Gyr VRSS and 9.0 Gyr BaSTI isochrones overlap nearly perfectly despite the age-difference. This model dependence, which is significantly larger than the precision determined from mass, radius, and abundance uncertainties, prevents a definitive age-determination of the cluster. Conclusions. Using detached eclipsing binaries for determination of cluster ages, the dominant error is due to differences among stellar models and no longer to observational errors in cluster reddening and distance. By observing a suitable number of detached eclipsing binaries in several open clusters it should be possible to calibrate the age-scale and provide firm constraints which stellar models must reproduce.
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.
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.
We present the first high-precision photometry of the transiting extrasolar planetary system WASP-7, obtained using telescope defocussing techniques and reaching a scatter of 0.68 mmag per point. We ...find that the transit depth is greater and that the host star is more evolved than previously thought. The planet has a significantly larger radius (1.330 ± 0.093 RJup versus $\er{0.915}{0.046}{0.040}$ 0.91 5 -0.040 + 0.046 RJup) and much lower density (0.41 ± 0.10 ρJup versus $\er{1.26}{0.25}{0.21}$ 1.2 6 -0.21 + 0.25 ρJup) and surface gravity (13.4 ± 2.6 m s-2 versus $\er{26.4}{4.4}{4.0}$ 26. 4 -4.0 + 4.4 m s-2) than previous measurements showed. Based on the revised properties it is no longer an outlier in planetary mass-radius and period-gravity diagrams. We also obtain a more precise transit ephemeris for the WASP-7 system.
Aims. With the aim of characterizing the flux and color variations of the multiple components of the gravitationally lensed quasar UM673 as a function of time, we have performed multiepoch and ...multiband photometric observations with the Danish telescope at the La Silla Observatory. Methods. The observations were carried out in the VRi spectral bands during four seasons (2008–2011). We reduced the data using the point spread function photometric technique as well as aperture photometry. Results. Our results show for the brightest lensed component some significant decrease in flux between the first two seasons (+ 0.09/+ 0.11/+ 0.05 mag) and a subsequent increase during the following ones (− 0.11/− 0.11/− 0.10 mag) in the V/R/i spectral bands, respectively. Comparing our results with previous studies, we find smaller color variations between these seasons as compared with previous ones. We also separate the contribution of the lensing galaxy from that of the fainter and close lensed component.
We present new ground-based, multi-colour, broad-band photometric measurements of the physical parameters, transmission and emission spectra of the transiting extrasolar planet WASP-19b. The ...measurements are based on observations of eight transits and four occultations through a Gunn i filter using the 1.54-m Danish Telescope, 14 transits through an R
c
filter at the Perth Exoplanet Survey Telescope (PEST) observatory and one transit observed simultaneously through four optical (Sloan g
′, r
′, i
′, z
′) and three near-infrared (J, H, K) filters, using the Gamma Ray Burst Optical and Near-Infrared Detector (GROND) instrument on the MPG/ESO 2.2-m telescope. The GROND optical light curves have a point-to-point scatter around the best-fitting model between 0.52 and 0.65 mmag rms. We use these new data to measure refined physical parameters for the system. We find the planet to be more bloated (R
b = 1.410 ± 0.017R
Jup; M
b = 1.139 ± 0.030M
Jup) and the system to be twice as old as initially thought. We also used published and archived data sets to study the transit timings, which do not depart from a linear ephemeris. We detected an anomaly in the GROND transit light curve which is compatible with a spot on the photosphere of the parent star. The starspot position, size, spot contrast and temperature were established. Using our new and published measurements, we assembled the planet's transmission spectrum over the 370-2350 nm wavelength range and its emission spectrum over the 750-8000 nm range. By comparing these data to theoretical models we investigated the theoretically predicted variation of the apparent radius of WASP-19b as a function of wavelength and studied the composition and thermal structure of its atmosphere. We conclude that: (i) there is no evidence for strong optical absorbers at low pressure, supporting the common idea that the planet's atmosphere lacks a dayside inversion; (ii) the temperature of the planet is not homogenized, because the high warming of its dayside causes the planet to be more efficient in re-radiating than redistributing energy to the night side; (iii) the planet seems to be outside of any current classification scheme.
Aims. We present V and R photometry of the gravitationally lensed quasars WFI 2033-4723 and HE 0047-1756. The data were taken by the MiNDSTEp collaboration with the 1.54 m Danish telescope at the ESO ...La Silla observatory from 2008 to 2012. Methods. Differential photometry has been carried out using the image subtraction method as implemented in the HOTPAnTS package, additionally using GALFIT for quasar photometry. Results. The quasar WFI 2033-4723 showed brightness variations of order 0.5 mag in V and R during the campaign. The two lensed components of quasar HE 0047-1756 varied by 0.2–0.3 mag within five years. We provide, for the first time, an estimate of the time delay of component B with respect to A of Δt = (7.6 ± 1.8) days for this object. We also find evidence for a secular evolution of the magnitude difference between components A and B in both filters, which we explain as due to a long-duration microlensing event. Finally we find that both quasars WFI 2033-4723 and HE 0047-1756 become bluer when brighter, which is consistent with previous studies.
Cor pulmonale is a common complication to Chronic Obstructive Pulmonary Disease (COPD), and may result in increased pressure in the inferior caval vein and stasis of the liver. The chronic pulmonary ...hypertension may lead to stasis in the veins from the small intestine and thereby compromise absorption of nutrients.
To investigate whether patients with pulmonary hypertension have reduced absorption capacity compared to COPD patients without cor pulmonale.
Absorption of d-xylose (25 g) and zinc (132 mg), administered as a single dose, was tested in 14 COPD patients, seven with and seven without cor pulmonale. The presence of cor pulmonale was determined by echocardiography. The concentration of d-xylose and zinc were measured in peripheral blood one, two and three hours after ingestion and used as markers of absorption. Furthermore, urine was collected for five hours to determine the amount of excreted d-xylose.
No significant difference in absorption of d-xylose (p = 0.28) or zinc (p = 0.51) was found between the two groups. However, a trend towards a delay in d-xylose absorption, as assessed by time-to-peak concentration, was observed in patients with cor pulmonale (p = 0.08). There was no significant difference in the amount of excreted d-xylose in the urine between the groups (p = 0.52). No correlation was found between the tricuspid regurgitation gradient and the absorption of both test-markers (rs = 0.34 and rs = -0.25). Likewise, no correlations were found between the inferior caval pressure during the in- and expiration phases and the absorption of d-xylose (rs = -0.09 rs = 0.23) or zinc (rs = -0.39, rs = -0.39).
We found no indications that small intestinal absorption is affected in a clinically relevant degree in patients with cor pulmonale.
Aims. We present the analysis of 26 nights of V and I time-series observations from 2011 and 2012 of the globular cluster M 30 (NGC 7099). We used our data to search for variable stars in this ...cluster and refine the periods of known variables; we then used our variable star light curves to derive values for the cluster’s parameters. Methods. We used difference image analysis to reduce our data to obtain high-precision light curves of variable stars. We then estimated the cluster parameters by performing a Fourier decomposition of the light curves of RR Lyrae stars for which a good period estimate was possible. We also derived an estimate for the age of the cluster by fitting theoretical isochrones to our colour-magnitude diagram (CMD). Results. Out of 13 stars previously catalogued as variables, we find that only 4 are bona fide variables. We detect two new RR Lyrae variables, and confirm two additional RR Lyrae candidates from the literature. We also detect four other new variables, including an eclipsing blue straggler system, and an SX Phoenicis star. This amounts to a total number of confirmed variable stars in M 30 of 12. We perform Fourier decomposition of the light curves of the RR Lyrae stars to derive cluster parameters using empirical relations. We find a cluster metallicity Fe/HZW = −2.01 ± 0.04, or Fe/HUVES = −2.11 ± 0.06, and a distance of 8.32 ± 0.20 kpc (using RR0 variables), 8.10 kpc (using one RR1 variable), and 8.35 ± 0.42 kpc (using our SX Phoenicis star detection in M 30). Fitting isochrones to the CMD, we estimate an age of 13.0 ± 1.0 Gyr for M 30.
PDF
