ABSTRACT The precision of photometric and spectroscopic observations has been systematically improved in the last decade, mostly thanks to space-borne photometric missions and ground-based ...spectrographs dedicated to finding exoplanets. The field of eclipsing binary stars strongly benefited from this development. Eclipsing binaries serve as critical tools for determining fundamental stellar properties (masses, radii, temperatures, and luminosities), yet the models are not capable of reproducing observed data well, either because of the missing physics or because of insufficient precision. This led to a predicament where radiative and dynamical effects, insofar buried in noise, started showing up routinely in the data, but were not accounted for in the models. PHOEBE (PHysics Of Eclipsing BinariEs; http://phoebe-project.org) is an open source modeling code for computing theoretical light and radial velocity curves that addresses both problems by incorporating missing physics and by increasing the computational fidelity. In particular, we discuss triangulation as a superior surface discretization algorithm, meshing of rotating single stars, light travel time effects, advanced phase computation, volume conservation in eccentric orbits, and improved computation of local intensity across the stellar surfaces that includes the photon-weighted mode, the enhanced limb darkening treatment, the better reflection treatment, and Doppler boosting. Here we present the concepts on which PHOEBE is built and proofs of concept that demonstrate the increased model fidelity.
To investigate the asymptotic giant branch (AGB) population in the Galactic halo, we search for pulsating AGB stars at a heliocentric distance
D
> 50 kpc. Our research is based on the Catalina ...Southern Survey (CSS) catalogue of variables, comprising 1286 long-period variables (LPVs) with
δ
< −20°. We first focus on the 77 stars in the cap |
b
| > 30° for which spectral M-type or C-type classification can be derived from Hamburg-ESO objective prism spectra. Most of these are oxygen-rich (M-type) and very few are carbon rich. The periods are in the range 100–500 days, and CSS amplitudes are up to 3 mag. In this small sample, no halo AGB star is fainter than
K
s
0
= 12.5. This may be due to the scarcity of AGBs in the outer halo, or insufficient instrumental depth. Leaving aside spectral information, we then searched for even fainter pulsators (
K
s
> 12.5) in the entire CSS catalogue.
G
a
i
a
astrometry makes it possible to identify some contaminants. Our final result is the identification of ten candidate distant LPVs. If these ten stars obey the fundamental mode
K
-band period–luminosity relation used for Miras and small-amplitude Miras, their distances are between 50 and 120 kpc from the Sun. In a diagram showing distance versus
Gaia
tangential velocity, these ten stars have positions consistent with that of other objects in the halo, such as globular clusters and dwarf galaxies. We detect some underluminous AGBs that deserve further study. Finally, the halo LPVs ressemble the slow redder variable of globular clusters when colour and periods are compared.
Abstract The North America and Caribbean (NAC) Region faces a high burden of diabetes. In 2013, the number of children (aged 0–14 years) with type 1 diabetes was 108,600, with 16.7 new cases ...diagnosed per 100,000 children. Furthermore, there were 36,755,500 individuals with diabetes (mostly type 2 diabetes) in adults (20–79 years), and an additional 44,277,700 individuals had impaired glucose tolerance. The age-adjusted prevalence of diabetes in adults was 9.6%; the second highest among the seven Regions of the International Diabetes Federation. This estimate is expected to grow to 9.9% by 2035. There was some heterogeneity in the estimates within the Region with the age-adjusted prevalence for the USA estimated at 9.2%, 7.9% for Canada, 12.6% for Mexico, and 9.6% for the Caribbean islands. Mortality due to diabetes in the NAC Region is not limited to older age groups, with 37.6% of deaths occurring in people under the age of 60. The economic impact was also enormous, with healthcare expenditure due to diabetes estimated at 263.2 billion USD for 2013 – the highest of all IDF Regions. Diabetes threatens the public health and economies of countries in the NAC Region, and efforts in prevention and management must be intensified in order to surmount this growing problem.
KIC 8560861 (HD 183648) is a marginally eccentric (e = 0.05) eclipsing binary with an orbital period of Porb = 31.973 d, exhibiting mmag amplitude pulsations on time-scales of a few days. We present ...the results of the complex analysis of high- and medium-resolution spectroscopic data and Kepler Q0 - Q16 long cadence photometry. The iterative combination of spectral disentangling, atmospheric analysis, radial velocity and eclipse timing variation studies, separation of pulsational features of the light curve, and binary light curve analysis led to the accurate determination of the fundamental stellar parameters. We found that the binary is composed of two main-sequence stars with an age of 0.9 plus or minus 0.2 Gyr, having masses, radii and temperatures of M1 = 1.93 plus or minus 0.12 M..., R1 = 3.30 plus or minus 0.07 R..., Teff1 = 7650 plus or minus 100 K for the primary, and M2 = 1.06 plus or minus 0.08 M..., R2 = 1.11 plus or minus 0.03 R..., Teff2 = 6450 plus or minus 100 K for the secondary. After substracting the binary model, we found three independent frequencies, two of which are separated by twice the orbital frequency. We also found an enigmatic half orbital period sinusoidal variation that we attribute to an anomalous ellipsoidal effect. Both of these observations indicate that tidal effects are strongly influencing the luminosity variations of HD 183648. The analysis of the eclipse timing variations revealed both a parabolic trend, and apsidal motion with a period of Pobsapse=10400 plus or minus 3000 y, which is ten times faster than what is theoretically expected. These findings might indicate the presence of a distant, unseen companion. (ProQuest: ... denotes formulae/symbols omitted.)
Encoded within the morphological structure of galaxies are clues related to their formation and evolutionary history. Recent advances pertaining to the statistics of galaxy morphology include ...sophisticated measures of concentration (C), asymmetry (A) and clumpiness (S). In this study, these three parameters (CAS) have been applied to a suite of simulated galaxies and compared with observational results inferred from a sample of nearby galaxies. The simulations span a range of late-type systems, with masses between ∼1010 and ∼1012 M⊙, and employ star formation density thresholds between 0.1 and 100 cm−3. We have found that the simulated galaxies possess comparable concentrations to their observed counterparts. However, the results of the CAS analysis revealed that the simulated galaxies are generally more asymmetric, and that the range of clumpiness values extends beyond the range of those observed. Strong correlations were obtained between the three CAS parameters and colour (B − V), consistent with observed galaxies. Furthermore, the simulated galaxies possess strong links between their CAS parameters and Hubble type, mostly in-line with their observed counterparts.
We present Kepler photometry and ground-based spectroscopy of KIC 4544587, a short-period eccentric eclipsing binary system with self-excited pressure and gravity modes, tidally excited modes, ...tidally influenced p modes and rapid apsidal motion of 182 yr per cycle. The primary and secondary components of KIC 4544587 reside within the δ Scuti and γ Dor instability region of the Hertzsprung-Russell diagram, respectively. By applying the binary modelling software phoebe to prewhitened Kepler photometric data and radial velocity data obtained using the William Herschel Telescope and 4-m Mayall telescope at Kitt Peak Northern Observatory (KPNO), the fundamental parameters of this important system have been determined, including the stellar masses, 1.98 ±0.07 and 1.60 ± 0.06 M, and radii, 1.76 ± 0.03 and 1.42 ± 0.02 R⊙, for the primary and secondary components, respectively. Frequency analysis of the residual data revealed 31 modes, 14 in the gravity mode region and 17 in the pressure mode region. Of the 14 gravity modes, 8 are orbital harmonics: a signature of tidal resonance. While the measured amplitude of these modes may be partially attributed to residual signal from binary model subtraction, we demonstrate through consideration of the folded light curve that these frequencies do in fact correspond to tidally excited pulsations. Furthermore, we present an echelle diagram of the pressure mode frequency region (modulo the orbital frequency) and demonstrate that the tides are also influencing the p modes. A first look at asteroseismology hints that the secondary component is responsible for the p modes, which is contrary to our expectation that the hotter star should pulsate in higher radial overtone, higher frequency p modes.
The inflammatory effect of cardiopulmonary bypass on leukocyte extravasation in vivo Evans, B.J., MRCS; Haskard, D.O., DM; Finch, J.R., MRCS ...
Journal of thoracic and cardiovascular surgery/The Journal of thoracic and cardiovascular surgery/The journal of thoracic and cardiovascular surgery,
05/2008, Letnik:
135, Številka:
5
Journal Article
Recenzirano
Odprti dostop
Objective Extravascular trafficking of leukocytes into organs is thought to play a major role in the pathophysiologic mechanisms of the inflammatory response to cardiopulmonary bypass, yet leukocyte ...extravasation is difficult to study clinically. Here we have tested the hypothesis that leukocyte emigration into skin blisters can provide a way to monitor the inflammatory effect of cardiopulmonary bypass that allows testing of anti-inflammatory interventions (exemplified by aprotinin). Methods Patients undergoing primary elective coronary artery bypass grafting (n = 14) were randomized into 2 equal groups to receive saline infusion during cardiopulmonary bypass (control group) or high-dose aprotinin. Experimental skin blisters (in duplicate) were induced on the forearm by means of topical application of the vesicant cantharidin, and blister fluid was sampled at 5 hours postoperatively. Inflammatory leukocyte subsets in blister fluid were analyzed by means of flow cytometry by using expression of CD11b and CD62L as a phenotypic marker of activation. Results In the control group of patients, cardiopulmonary bypass surgery triggered a 381% increase in leukocyte extravasation into the skin compared with reference blisters carried out before surgical intervention, with neutrophil ( P = .014), monocyte ( P = .014), and eosinophil ( P = .009) levels all statistically significantly increased. In the aprotinin group there was no statistically significant increase during cardiopulmonary bypass surgery in any inflammatory leukocyte subset. The activation phenotype of extravascular leukocytes was not significantly altered between surgical groups. Conclusions This study introduces the cantharidin blister technique as a powerful new research tool for analyzing the inflammatory effect of cardiopulmonary bypass in vivo. It has provided detailed molecular insight into the extravascular leukocyte population during cardiopulmonary bypass. Although aprotinin blocked cardiopulmonary bypass–dependent extravasation of leukocytes, there was no change in their CD11b/CD62L activation status. The cantharidin skin test thus represents a novel research tool for evaluating future anti-inflammatory interventions in cardiothoracic surgery.
Context. Theoretical scaling relations for solar-like oscillators and red giants are widely used to estimate fundamental stellar parameters. The accuracy and precision of these relations have often ...been questioned in the literature, with studies often utilising binarity for model-independent validation. However, it has not been tested if the photometric effects of binarity introduce a systematic effect on the extraction of the seismic properties of the pulsating component(s). Aims. In this paper, we present an estimation of the impact of a contaminating photometric signal with a distinct background profile on the global asteroseismic parameter νmax through the analysis of synthetic red-giant binary light curves. Methods. We generated the pulsational and granulation parameters for single red giants with different masses, radii and effective temperatures from theoretical scaling relations and use them to simulate single red-giant light curves with the characteristics of Kepler long-cadence photometric data. These are subsequently blended together according to their light ratio to generate binary red-giant light curves of various configurations. We then performed a differential analysis to characterise the systematic effects of binarity on the extraction of νmax. Results. We quantify our methodological uncertainties through the analysis of single red-giant light curves, both in the presence and absence of granulation. This is used as a reference for our subsequent differential binary analysis, where we find that the νmax extraction for red-giant power spectra featuring overlapping power excesses is unreliable if unconstrained priors are used. Outside of this scenario, we obtain results that are nearly identical to single-star case. Conclusions. We conclude that (i) the photometric effects of binarity on the extraction of νmax are largely negligible as long as the power excesses of the individual components do not overlap, and that (ii) there is minimal advantage to using more than two super-Lorentzian components to model the granulation signal of a binary red-giant.
Context.
Binary systems constitute a valuable astrophysics tool for testing our understanding of stellar structure and evolution. Systems containing at least one oscillating component are interesting ...in this regard because asteroseismology offers independent parameters for the oscillating component that aid in the analysis. Systems of particular interest include those with known inclinations. With ∼0.8 million binary candidates, the two-body orbit catalog (TBO) of
Gaia
Data Release 3 (DR3) substantially increases the number of known binaries and the quality of the astrometric data available for them.
Aims.
To enlarge the sample of these astrophysically valuable benchmark objects, we searched for new binary system candidates identified in the
Gaia
DR3 TBO, for which one component has a detection of solar-like oscillations reported in the literature.
Methods.
We cross-matched the TBO, the full non-single star (NSS) and eclipsing binary catalogs from
Gaia
DR3 with catalogs of confirmed solar-like oscillators in the main-sequence and red-giant phase from the NASA
Kepler
mission and stars in the Southern Continuous Viewing Zone of NASA TESS. The wealth of seismic information is used to characterize the oscillating primary. To test the completeness and robustness of the values reported in the TBO catalog, we performed a similar analysis on stars of the Ninth Catalog of Spectroscopic Binary Orbits (SB9).
Results.
The analysis of the SB9 reveals an overall completeness factor for the
Gaia
TBO catalog of up to ∼30% providing reliable orbital parameters for ≥90% of the systems below
P
orb, SB9
≲ 250 d. We obtained new 954 unique binary system candidates from
Gaia
DR3, which host solar-like oscillators, of which we found 45 stars in binary candidates to be on the main sequence and 909 in the red giant phase. Additionally, we report 918 oscillators in potentially long-periodic systems. We present the seismic properties of the full sample and test whether the reported orbital periods are physically possible. For 146 giants, the evolutionary state has been determined from their mixed-mode period spacing, showing a clear trend to long periodic and less eccentric systems in the advanced phases of stellar evolution. Two new eclipsing binary systems, hosting a red-giant primary were found. For another 146 systems hosting oscillating stars, the values for the orbital inclination were found in the TBO. Of 181 TBO candidate systems observed multiple times with APOGEE, 149 (82%) are confirmed as binaries from radial-velocity (RV) measurement.
Conclusions.
We conclude that the grand majority of the orbital elements reported in the TBO catalog are physically reasonable and realistic. This finding increases the number included in the sample of known solar-like oscillators in binary systems by an order of magnitude. The large fraction of confirmed binaries from APOGEE RV measurements indicates that the TBO catalog is robust. We suggest that due to instrumental noise, the seismically inferred masses and radii of stars observed with the TESS satellite and with an excess of oscillation power of
ν
max
≲ 30 μHz could be significantly overestimated. The differences in the distributions of the orbital period and eccentricity are due to the accumulative effect of the equilibrium tide acting in these evolved binary systems.
Context. Binary systems constitute a valuable astrophysics tool for testing our understanding of stellar structure and evolution. Systems containing at least one oscillating component are interesting ...in this regard because asteroseismology offers independent parameters for the oscillating component that aid in the analysis. Systems of particular interest include those with known inclinations. With ∼0.8 million binary candidates, the two-body orbit catalog (TBO) of Gaia Data Release 3 (DR3) substantially increases the number of known binaries and the quality of the astrometric data available for them. Aims. To enlarge the sample of these astrophysically valuable benchmark objects, we searched for new binary system candidates identified in the Gaia DR3 TBO, for which one component has a detection of solar-like oscillations reported in the literature. Methods. We cross-matched the TBO, the full non-single star (NSS) and eclipsing binary catalogs from Gaia DR3 with catalogs of confirmed solar-like oscillators in the main-sequence and red-giant phase from the NASA Kepler mission and stars in the Southern Continuous Viewing Zone of NASA TESS. The wealth of seismic information is used to characterize the oscillating primary. To test the completeness and robustness of the values reported in the TBO catalog, we performed a similar analysis on stars of the Ninth Catalog of Spectroscopic Binary Orbits (SB9). Results. The analysis of the SB9 reveals an overall completeness factor for the Gaia TBO catalog of up to ∼30% providing reliable orbital parameters for ≥90% of the systems below Porb, SB9 ≲ 250 d. We obtained new 954 unique binary system candidates from Gaia DR3, which host solar-like oscillators, of which we found 45 stars in binary candidates to be on the main sequence and 909 in the red giant phase. Additionally, we report 918 oscillators in potentially long-periodic systems. We present the seismic properties of the full sample and test whether the reported orbital periods are physically possible. For 146 giants, the evolutionary state has been determined from their mixed-mode period spacing, showing a clear trend to long periodic and less eccentric systems in the advanced phases of stellar evolution. Two new eclipsing binary systems, hosting a red-giant primary were found. For another 146 systems hosting oscillating stars, the values for the orbital inclination were found in the TBO. Of 181 TBO candidate systems observed multiple times with APOGEE, 149 (82%) are confirmed as binaries from radial-velocity (RV) measurement. Conclusions. We conclude that the grand majority of the orbital elements reported in the TBO catalog are physically reasonable and realistic. This finding increases the number included in the sample of known solar-like oscillators in binary systems by an order of magnitude. The large fraction of confirmed binaries from APOGEE RV measurements indicates that the TBO catalog is robust. We suggest that due to instrumental noise, the seismically inferred masses and radii of stars observed with the TESS satellite and with an excess of oscillation power of νmax ≲ 30 μHz could be significantly overestimated. The differences in the distributions of the orbital period and eccentricity are due to the accumulative effect of the equilibrium tide acting in these evolved binary systems.
PDF
