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.
The Sloan Digital Sky Survey IV extended Baryonic Oscillation Spectroscopic Survey (SDSS-IV/eBOSS) will observe 195 000 emission-line galaxies (ELGs) to measure the baryonic acoustic oscillation ...(BAO) standard ruler at redshift 0.9. To test different ELG selection algorithms, 9000 spectra were observed with the SDSS spectrograph as a pilot survey based on data from several imaging surveys. First, using visual inspection and redshift quality flags, we show that the automated spectroscopic redshifts assigned by the pipeline meet the quality requirements for a reliable BAO measurement. We also show the correlations between sky emission, signal-to-noise ratio in the emission lines, and redshift error. Then we provide a detailed description of each target selection algorithm we tested and compare them with the requirements of the eBOSS experiment. As a result, we provide reliable redshift distributions for the different target selection schemes we tested. Finally, we determine an target selection algorithms that is best suited to be applied on DECam photometry because they fulfill the eBOSS survey efficiency requirements.
Context. The F8 star HD 181906 (effective temperature ${\sim}6300$ K) was observed for 156 days by the CoRoT satellite during the first long run in the direction of the galactic centre. Analysis of ...the data reveals a spectrum of solar-like acoustic oscillations. However, the faintness of the target (mv = 7.65) means the signal-to-noise (S/N) in the acoustic modes is quite low, and this low S/N leads to complications in the analysis. Aims. We extract global variables of the star, as well as key parameters of the p modes observed in the power spectrum of the lightcurve. Methods. The power spectrum of the lightcurve, a wavelet transform and spot fitting were used to obtain the average rotation rate of the star and its inclination angle. Then, the autocorrelation of the power spectrum and the power spectrum of the power spectrum were used to properly determine the large separation. Finally, estimations of the mode parameters were done by maximizing the likelihood of a global fit, where several modes were fit simultaneously. Results. We have been able to infer the mean surface rotation rate of the star (~4 μHz) with indications of the presence of surface differential rotation, the large separation of the p modes (~87 μHz), hence also the “ridges” corresponding to overtones of the acoustic modes.
Context. The star HD 52265 is a G0V metal-rich exoplanet-host star observed in the seismology field of the CoRoT space telescope from November 2008 to March 2009. The satellite collected 117 days of ...high-precision photometric data on this star, showing that it presents solar-like oscillations. HD 52265 was also observed in spectroscopy with the Narval spectrograph at the same epoch. Aims. We characterise HD 52265 using both spectroscopic and seismic data. Methods. The fundamental stellar parameters of HD 52265 were derived with the semi-automatic software VWA, and the projected rotational velocity was estimated by fitting synthetic profiles to isolated lines in the observed spectrum. The parameters of the observed p modes were determined with a maximum-likelihood estimation. We performed a global fit of the oscillation spectrum, over about ten radial orders, for degrees l = 0 to 2. We also derived the properties of the granulation, and analysed a signature of the rotation induced by the photospheric magnetic activity. Results. Precise determinations of fundamental parameters have been obtained: Teff = 6100 ± 60 K, log g = 4.35 ± 0.09, M/H = 0.19 ± 0.05, as well as \hbox{$\vsini=3.6^{+0.3}_{-1.0}\kms$}vsini=3.6-1.0+0.3 km s-1. We have measured a mean rotation period Prot = 12.3 ± 0.15 days, and find a signature of differential rotation. The frequencies of 31 modes are reported in the range 1500–2550 μHz. The large separation exhibits a clear modulation around the mean value \hbox{$\Dnu=98.3\,\pm\,0.1~\muHz$}Δν=98.3 ± 0.1 μHz. Mode widths vary with frequency along an S-shape with a clear local maximum around 1800 μHz. We deduce lifetimes ranging between 0.5 and 3 days for these modes. Finally, we find a maximal bolometric amplitude of about 3.96 ± 0.24 ppm for radial modes.
Photometric observations made by the NASA Kepler Mission have led to a dramatic increase in the number of main-sequence and subgiant stars with detected solar-like oscillations. We present an ...ensemble asteroseismic analysis of 76 solar-type stars. Using frequencies determined from the Kepler time-series photometry, we have measured three asteroseismic parameters that characterize the oscillations: the large frequency separation ( Delta *D Delta *n), the small frequency separation between modes of l = 0 and l = 2 ( Delta *d Delta *n02), and the dimensionless offset (). These measurements allow us to construct asteroseismic diagrams, namely the so-called Christensen-Dalsgaard diagram of Delta *d Delta *n02 versus Delta *D Delta *n, and the recently re-introduced diagram. We compare the Kepler results with previously observed solar-type stars and with theoretical models. The positions of stars in these diagrams places constraints on their masses and ages. Additionally, we confirm the observational relationship between and T eff that allows for the unambiguous determination of radial order and should help resolve the problem of mode identification in F stars.
Context. The CoRoT short runs give us the opportunity to observe a large variety of late-type stars through their solar-like oscillations. We report observations of the star HD 175726 that lasted for ...27 days during the first short run of the mission. The time series reveals a high-activity signal and the power spectrum presents an excess due to solar-like oscillations with a low signal-to-noise ratio. Aims. Our aim is to identify the most efficient tools to extract as much information as possible from the power density spectrum. Methods. The most productive method appears to be the autocorrelation of the time series, calculated as the spectrum of the filtered spectrum. This method is efficient, very rapid computationally, and will be useful for the analysis of other targets, observed with CoRoT or with forthcoming missions such as Kepler and Plato. Results. The mean large separation has been measured to be $97.2\pm0.5$ μHz, slightly below the expected value determined from solar scaling laws. We also show strong evidence for variation of the large separation with frequency. The bolometric mode amplitude is only $1.7\pm0.25$ ppm for radial modes, which is 1.7 times less than expected. Due to the low signal-to-noise ratio, mode identification is not possible for the available data set of HD 175726.
Aims. We investigate the asteroseismology of two solar-like targets as observed with the CoRoT satellite, with particular attention paid to the mode fitting. HD 181420 and HD 49933 are typical CoRoT ...solar-like targets (156 and 60-day runs). The low signal-to-noise ratio (SNR) of about $3{-}10$ prevents us from unambiguously identifying the individual oscillation modes. In particular, convergence problems appear at the edges of the oscillation spectrum. Methods. We apply a Bayesian approach to the analysis of these data. We compare the global fitting of the power spectra obtained by the classical maximum likelihood (MLE) and the maximum a posteriori (MAP) estimators. Results. We examine the impact of the choice of the priors upon the fitted parameters. We also propose to reduce the number of free parameters in the fitting, by replacing the individual estimate of mode height associated with each overtone by a continuous function of frequency (Gaussian profile). Conclusions. The MAP appears as a powerful tool to constrain the global fits, but it must be used carefully and only with reliable priors. The mode width of the stars increases with the frequency over all the oscillation spectrum.
We present the first detections by the NASA K2 mission of oscillations in solar-type stars, using short-cadence data collected during K2 Campaign 1 (C1). We understand the asteroseismic detection ...thresholds for C1-like levels of photometric performance, and we can detect oscillations in subgiants having dominant oscillation frequencies around 1000 μHz. Changes to the operation of the fine-guidance sensors are expected to give significant improvements in the high-frequency performance from C3 onwards. A reduction in the excess high-frequency noise by a factor of 2.5 in amplitude would bring main-sequence stars with dominant oscillation frequencies as high as ≃2500 μHz into play as potential asteroseismic targets for K2.
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