Close double degenerate binaries are one of the favoured progenitor channels for type Ia supernovae, but it is unclear how many suitable systems there are in the Galaxy. We report results of a large ...radial velocity survey for double degenerate (DD) binaries using the UVES spectrograph at the ESO VLT (ESO SN Ia Progenitor surveY – SPY). Exposures taken at different epochs are checked for radial velocity shifts indicating close binary systems. We observed 689 targets classified as DA white dwarfs (displaying hydrogen-rich atmospheres), of which 46 were found to possess a cool companion. We measured radial velocities (RV) of the remaining 643 DA white dwarfs. We managed to secure observations at two or more epochs for 625 targets, supplemented by eleven objects meeting our selection criteria from literature. The data reduction and analysis methods applied to the survey data are described in detail. The sample contains 39 double degenerate binaries, only four of which were previously known. Twenty are double-lined systems, in which features from both components are visible, the other 19 are single-lined binaries. We provide absolute RVs transformed to the heliocentric system suitable for kinematic studies. Our sample is large enough to sub-divide by mass: 16 out of 44 low mass targets (≤0.45 M⊙) are detected as DDs, while just 23 of the remaining 567 targets with multiple spectra and mass > 0.45 M⊙ are double. The detected fraction amongst the low mass objects (36.4 ± 7.3%) is significantly higher than for the higher-mass, carbon-oxygen core dominated part of the sample (3.9 ± 0.8%), but it is much lower than expected from the detection efficiency for companion masses of 0.05 M⊙ or higher and a 100% binary fraction. This suggests either companion stars of with a mass below 0.05 M⊙ or some of the low mass white dwarfs are single.
The primary symptoms of restless legs syndrome (RLS) are sleep onset insomnia and difficulty to maintain sleep. Previous studies have shown that regular physical activity can reduce the risk of ...developing RLS. However, the relationship between physical activity and sleep quality parameters in individuals suffering from RLS has not yet been investigated by applying accelerometry. Thus, the present study investigates the impact of physical activity (measuring both intensity levels and duration of physical activity) during the day (7-12 h, 12-18 h, 18-23 h) on sleep quality in patients suffering from idiopathic RLS by applying a real-time approach.
In a sample of 47 participants suffering from idiopathic RLS, physical activity and sleep quality were measured over one week using accelerometers. For data analysis, physical activity levels and step counts during three periods of the day (morning, afternoon, evening) were correlated with sleep quality parameters of the subsequent night.
This observational study revealed that in most instances physical activity was not correlated with sleep parameters (two exceptions exist: steps taken in the morning were negatively correlated with periodic leg movements during sleep, and physical activity in the evening was negatively correlated with total sleep time). The physical activity levels of the participants in this study, however, were unexpectedly high compared to population-level data and variance in physical activity was low. The average activity was 13,817 (SD = 4086) steps and 347 (SD = 117) minutes of moderate physical activity per day in females, and 10,636 (SD = 3748) steps and 269 (SD = 69) minutes of moderate physical activity in males, respectively. Participants did not engage in any vigorous physical activity.
Further interventional studies are needed to investigate the daily effects of different intensities of physical activity on RLS symptoms.
Physical activity reduces many major mortality risk factors including arterial hypertension, diabetes mellitus type 2, dyslipidemia, coronary heart disease, stroke, and cancer. All-cause mortality is ...decreased by about 30% to 35% in physically active as compared to inactive subjects. The purpose of this paper was to synthesize the literature on life expectancy in relation to physical activity. A systematic PubMed search on life expectancy in physically active and inactive individuals was performed. In addition, articles comparing life expectancy of athletes compared to that of nonathletes were reviewed. Results of 13 studies describing eight different cohorts suggest that regular physical activity is associated with an increase of life expectancy by 0.4 to 6.9 years. Eleven studies included confounding risk factors for mortality and revealed an increase in life expectancy by 0.4 to 4.2 years with regular physical activity. Eleven case control studies on life expectancy in former athletes revealed consistently greater life expectancy in aerobic endurance athletes but inconsistent results for other athletes. None of these studies considered confounding risk factors for mortality. In conclusion, while regular physical activity increases life expectancy, it remains unclear if high-intensity sports activities further increase life expectancy.
Aims. We derive the physical properties of a filament discovered in the dark cometary-shaped cloud L1251. Methods. Mapping observations in the NH3(1, 1) and (2, 2) inversion lines, encompassing 300 ...positions toward L1251, were performed with the Effelsberg 100-m telescope at a spatial resolution of 40′′ and a spectral resolution of 0.045 km s-1. Results. The filament L1251A consists of three condensations (α, β, and γ) of elongated morphology, which are combined in a long and narrow structure covering a 38′ × 3′ angular range (∼3.3 pc × 0.3 pc). Comparing the kinematics with the more extended envelope (∼61′ × 33′) emitting in 13CO, we find that: (1) the angular velocity of the envelope around the horizontal axis E → W is ΩEWCO ≈−2 × 10-14 rad s-1 (the line-of-sight velocity is more negative to the north); (2) approximately one half of the filament (combined α and β condensations) exhibits counter-rotation with ΩEWαβ ≈2 × 10-14 rad s-1; (3) one third of the filament (the γ condensation) co-rotates with ΩEWγ ≈−2 × 10-14 rad s-1; (4) the central part of the filament between these two kinematically distinct regions does not show any rotation around this axis; (5) the whole filament revolves slowly around the vertical axis S → N with ΩSNtot ≈7 × 10-15 rad s-1. The opposite chirality (dextral and sinistral) of the αβ and γ condensations indicates magnetic field helicities of two types, negative and positive, which were most probably caused by dynamo mechanisms. We estimated the magnetic Reynolds number Rm ≳ 600 and the Rossby number ℛ < 1, which means that dynamo action is important.
We report the discovery of a 16th magnitude star, HE 0437-5439, with a heliocentric radial velocity of +723 c 3 km s super(-1). A quantitative spectral analysis of high-resolution optical spectra ...obtained with the VLT and UVES shows that HE 0437-5439 is a main-sequence B-type star with T sub(eff) = 20,350 K, log g = 3.77, a solar (within a factor of a few) helium abundance and metal content, and rotating at v sin i = 54 km s super(-1). Using appropriate evolutionary tracks, we derive a mass of 8 M sub(z) and a corresponding distance of 61 kpc. Its Galactic rest-frame velocity is at least 563 km s super(-1), almost twice the local Galactic escape velocity, indicating that the star is unbound to the Galaxy. Numerical kinematical experiments are carried out to constrain its place of birth. It has been suggested that such hypervelocity stars can be formed by the tidal disruption of a binary through interaction with the supermassive black hole at the Galactic center (GC). HE 0437-5439 needs about 100 Myr to travel from the GC to its present position, much longer than its main-sequence lifetime of 25 Myr. This can only be reconciled if HE 0437-5439 is a blue straggler star. In this case, the predicted proper motion is so small that it can only be measured by future space missions. Since the star is much closer to the Large Magellanic Cloud (LMC; 18 kpc) than to the GC, it can reach its position from the center of the LMC. The proper motion predicted in this case is about 2 mas yr super(-1) (relative to the LMC), large enough to be measurable with conventional techniques
Context. We present a detailed spectroscopic analysis of the stars with helium-dominated spectra in the ESO Supernova Ia Progenitor Survey (SPY). Aims. Atmospheric parameters, masses, and abundances ...of trace hydrogen are determined and discussed in the context of spectral evolution of white dwarfs. Methods. The spectra are compared with theoretical model atmospheres using a \chi arrow up fitting technique, leading to determinations of effective temperature, surface gravity, and hydrogen abundance. Results. Our final sample contains 71 objects, of which 6 are new detections and 14 are reclassified from DB to DBA because of the presence of H lines. One is a cool DO with weak He II lines, 2 are composite DB+dM. 55% of the DB sample show hydrogen and are thus DBA, a significantly higher fraction than found before. Conclusions. The large incidence of DBA, and the derived total hydrogen masses are compatible with the scenario that DBs "reappear" around 30 000 K from the DB gap by mixing and diluting a thin hydrogen layer of the order of 10 super(-15) M_{\odot}. This hydrogen mass is then during the evolution continuously increased by interstellar accretion. There are indications that the accretion rate increases smoothly with age or decreasing temperature, a trend which continuous even below the current low temperature limit (Dufour 2006). A remaining mystery is the low accretion rate of H compared to that of Ca observed in the DBZA, but a stellar wind extending down to the lowest temperatures with decreasing strength might be part of the solution.
We present the results of analysis of "snapshot" spectra of 253 metal-poor halo stars-3.8 , Fe/H , -1.5 obtained in the HERES survey. The snapshot spectra have been obtained with VLT/UVES and have ...typically S/N 6 54 per pixel (ranging from 17 to 308), R 6 20 000, l = 3760-4980 AA. This sample represents the major part of the complete HERES sample of 373 stars; however, the CH strong content of the sample is not dealt with here. The spectra are analysed using an automated line profile analysis method based on the Spectroscopy Made Easy (SME) codes of Valenti & Piskunov. Elemental abundances of moderate precision (absolute rms errors of order 0.25 dex, relative rms errors of order 0.15 dex) have been obtained for 22 elements, C, Mg, Al, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, Sr, Y, Zr, Ba, La, Ce, Nd, Sm, and Eu, where detectable. Of these elements, 14 are usually detectable at the 3s confidence level for our typical spectra. The remainder can be detected in the least metal-poor stars of the sample, spectra with higher than average S/N, or when the abundance is enhanced. Among the sample of 253 stars, disregarding four previously known comparison stars, we find 8 r-II stars and 35 r-I stars. The r-II stars, including the two previously known examples CS 22892-052 and CS 31082-001, are centred on a metallicity of Fe/H = -2.81, with a very small scatter, on the order of 0.16 dex. The r-I stars are found across practically the entire metallicity range of our sample. We also find three stars with strong enhancements of Eu which are s-process rich. A significant number of new very metal-poor stars are confirmed: 49 stars with Fe/H < -3 and 181 stars with -3 < Fe/H < -2. We find one star with Fe/H < -3.5. We find the scatter in the abundance ratios of Mg, Ca, Sc, Ti, Cr, Fe, Co, and Ni, with respect to Fe and Mg, to be similar to the estimated relative errors and thus the cosmic scatter to be small, perhaps even non-existent. The elements C, Sr, Y, Ba and Eu, and perhaps Zr, show scatter at Fe/H QQQ ? -2.5 significantly larger than can be explained from the errors in the analysis, implying scatter which is cosmic in origin. Significant scatter is observed in abundance ratios between light and heavy neutron-capture elements at low metallicity and low levels of r-process enrichment.
We present the quantitative methods used for selecting candidate metal-poor stars in the Hamburg/ESO objective-prism survey (HES). The selection is based on the strength of the Ca II K line, B-V ...colors (both measured directly from the digital HES spectra), as well as J-K colors from the 2 Micron All Sky Survey. The KP index for Ca II K can be measured from the HES spectra with an accuracy of 1.0 Aa, and a calibration of the HES B-V colors, using CCD photometry, yields a 1-\sigma uncertainty of 0.07 mag for stars in the color range 0.3 < B-V < 1.4. These accuracies make it possible to reliably reject stars with Fe/H >-2.0 without sacrificing completeness at the lowest metallicities. A test of the selection using 1121 stars of the HK survey of Beers, Preston, and Shectman present on HES plates suggests that the completeness at Fe/H <-3.5 is close to 100% and that, at the same time, the contamination of the candidate sample with false positives is low: 50% of all stars with Fe/H >-2.5 and 97% of all stars with Fe/H >-2.0 are rejected. The selection was applied to 379 HES fields, covering a nominal area of 8853 deg super(2) of the southern high Galactic latitude sky. The candidate sample consists of 20 271 stars in the magnitude range 10 lesssim B lesssim 18. A comparison of the magnitude distribution with that of the HK survey shows that the magnitude limit of the HES sample is about 2 mag fainter. Taking the overlap of the sky areas covered by both surveys into account, it follows that the survey volume for metal-poor stars has been increased by the HES by about a factor of 10 with respect to the HK survey. We have already identified several very rare objects with the HES, including, e.g., the three most heavy-element deficient stars currently known.
We present an accurate analysis of the H2 absorption lines from the z
abs ∼ 2.4018 damped Lyα system towards HE 0027−1836 observed with the Very Large Telescope Ultraviolet and Visual Echelle ...Spectrograph (VLT/UVES) as a part of the European Southern Observatory Large Programme 'The UVES large programme for testing fundamental physics' to constrain the variation of proton-to-electron mass ratio, μ ≡ m
p
/m
e
. We perform cross-correlation analysis between 19 individual exposures taken over three years and the combined spectrum to check the wavelength calibration stability. We notice the presence of a possible wavelength-dependent velocity drift especially in the data taken in 2012. We use available asteroids spectra taken with UVES close to our observations to confirm and quantify this effect. We consider single- and two-component Voigt profiles to model the observed H2 absorption profiles. We use both linear regression analysis and Voigt profile fitting where Δμ/μ is explicitly considered as an additional fitting parameter. The two-component model is marginally favoured by the statistical indicators and we get Δμ/μ = −2.5 ± 8.1stat ± 6.2sys ppm. When we apply the correction to the wavelength-dependent velocity drift, we find Δμ/μ = −7.6 ± 8.1stat ± 6.3sys ppm. It will be important to check the extent to which the velocity drift we notice in this study is present in UVES data used for previous Δμ/μ measurements.
We assess the cosmological variability of the fine-structure constant α from the analysis of an ensemble of $\ion{Fe}{ii}$ $\lambda1608$, $\lambda2344$, $\lambda2374$, $\lambda2383$, $\lambda2587$, ...and $\lambda2600$ absorption lines at the redshift $z=1.15$ toward the QSO HE 0515–4414 by means of the standard many-multiplet (MM) technique and its revision based on linear regression (RMM). This is the first time the MM technique is applied to exceptional high-resolution and high signal-to-noise QSO spectra recorded with the UV-Visual Echelle Spectrograph (UVES) at the ESO Very Large Telescope (VLT). Our analysis results in $\langle\Delta\alpha/\alpha\rangle_\mathrm{MM}=(0.1\pm1.7) \times10^{-6}$ and $\langle\Delta\alpha/\alpha\rangle_\mathrm{RMM}=(-0.4 \pm1.9\pm2.7_\mathrm{sys})\times10^{-6}$, which are the most stringent bounds hitherto infered from an individual QSO absorption system. Our results support the null hypothesis $\langle\Delta\alpha/\alpha\rangle=0$ at a significance level of 91 percent, whereas the support for the result $\langle\Delta\alpha/\alpha\rangle=-5.7\times10^{-6}$ presented in former MM studies is 12 percent.
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