82 research outputs found
Gaia Eclipsing Binary and Multiple Systems. A study of detectability and classification of eclipsing binaries with Gaia
In the new era of large-scale astronomical surveys, automated methods of
analysis and classification of bulk data are a fundamental tool for fast and
efficient production of deliverables. This becomes ever more imminent as we
enter the Gaia era. We investigate the potential detectability of eclipsing
binaries with Gaia using a data set of all Kepler eclipsing binaries sampled
with Gaia cadence and folded with the Kepler period. The performance of fitting
methods is evaluated with comparison to real Kepler data parameters and a
classification scheme is proposed for the potentially detectable sources based
on the geometry of the light curve fits. The polynomial chain (polyfit) and
two-Gaussian models are used for light curve fitting of the data set.
Classification is performed with a combination of the t-SNE (t-distrubuted
Stochastic Neighbor Embedding) and DBSCAN (Density-Based Spatial Clustering of
Applications with Noise) algorithms. We find that approximately 68% of Kepler
Eclipsing Binary sources are potentially detectable by Gaia when folded with
the Kepler period and propose a classification scheme of the detectable sources
based on the morphological type indicative of the light curve, with subclasses
that reflect the properties of the fitted model (presence and visibility of
eclipses, their width, depth, etc.).Comment: 9 pages, 18 figures, accepted for publication in Astronomy &
Astrophysic
Gaia eclipsing binary and multiple systems. Two-Gaussian models applied to OGLE-III eclipsing binary light curves in the Large Magellanic Cloud
The advent of large scale multi-epoch surveys raises the need for automated
light curve (LC) processing. This is particularly true for eclipsing binaries
(EBs), which form one of the most populated types of variable objects. The Gaia
mission, launched at the end of 2013, is expected to detect of the order of few
million EBs over a 5-year mission.
We present an automated procedure to characterize EBs based on the geometric
morphology of their LCs with two aims: first to study an ensemble of EBs on a
statistical ground without the need to model the binary system, and second to
enable the automated identification of EBs that display atypical LCs. We model
the folded LC geometry of EBs using up to two Gaussian functions for the
eclipses and a cosine function for any ellipsoidal-like variability that may be
present between the eclipses. The procedure is applied to the OGLE-III data set
of EBs in the Large Magellanic Cloud (LMC) as a proof of concept. The bayesian
information criterion is used to select the best model among models containing
various combinations of those components, as well as to estimate the
significance of the components.
Based on the two-Gaussian models, EBs with atypical LC geometries are
successfully identified in two diagrams, using the Abbe values of the original
and residual folded LCs, and the reduced . Cleaning the data set from
the atypical cases and further filtering out LCs that contain non-significant
eclipse candidates, the ensemble of EBs can be studied on a statistical ground
using the two-Gaussian model parameters. For illustration purposes, we present
the distribution of projected eccentricities as a function of orbital period
for the OGLE-III set of EBs in the LMC, as well as the distribution of their
primary versus secondary eclipse widths.Comment: 20 pages, 29 figures. Submitted to A&
Updated radial velocities and new constraints on the nature of the unseen source in NGC1850 BH1
A black hole candidate orbiting a luminous star in the Large Magellanic Cloud
young cluster NGC 1850 (Myr) has recently been reported based on
radial velocity and light curve modelling. Subsequently, an alternative
explanation has been suggested for the system: a bloated post-mass transfer
secondary star (M, M) with a more massive, yet luminous companion (the primary). Upon
reanalysis of the MUSE spectra, we found that the radial velocity variations
originally reported were underestimated (km/s vs
km/s) because of the weighting scheme adopted in
the full-spectrum fitting analysis. The increased radial velocity
semi-amplitude translates into a system mass function larger than previously
deduced (=2.83 vs =1.42). By exploiting the spectral disentangling
technique, we place an upper limit of 10\% of a luminous primary source to the
observed optical light in NGC1850 BH1, assuming that the primary and secondary
are the only components contributing to the system. Furthermore, by analysing
archival near-infrared data, we find clues to the presence of an accretion disk
in the system. These constraints support a low-mass post-mass transfer star but
do not provide a definitive answer whether the unseen component in NGC1850 BH1
is indeed a black hole. These results predict a scenario where, if a primary
luminous source of mass M , is present in the system (given
the inclination and secondary mass constraints), it must be hidden in a
optically thick disk to be undetected in the MUSE spectra.Comment: 10 pages, 8 Figures and 2 Tables. Accepted for publication by MNRA
Gaia Data Release 3. The first Gaia catalogue of eclipsing binary candidates
We present the first Gaia catalogue of eclipsing binary candidates released
in Gaia DR3, describe its content, provide tips for its usage, estimate its
quality, and show illustrative samples. The catalogue contains 2,184,477
sources with G magnitudes up to 20 mag. Candidate selection is based on the
results of variable object classification performed within the Gaia Data
Processing and Analysis Consortium, further filtered using eclipsing
binary-tailored criteria based on the G light curves. To find the orbital
period, a large ensemble of trial periods is first acquired using three
distinct period search methods applied to the cleaned G light curve. The G
light curve is then modelled with up-to two Gaussians and a cosine for each
trial period. The best combination of orbital period and geometric model is
finally selected using Bayesian model comparison based on the BIC. A global
ranking metric is provided to rank the quality of the chosen model between
sources. The catalogue is restricted to orbital periods larger than 0.2 days.
About 530,000 of the candidates are classified as eclipsing binaries in the
literature as well, out of ~600,000 available crossmatches, and 93% of them
have published periods compatible with the Gaia periods. Catalogue completeness
is estimated to be between 25% and 50%, depending on the sky region, relative
to the OGLE4 catalogues of eclipsing binaries towards the Galactic Bulge and
the Magellanic Clouds. The analysis of an illustrative sample of ~400,000
candidates with significant parallaxes shows properties in the observational HR
diagram as expected for eclipsing binaries. The subsequent analysis of a
sub-sample of detached bright candidates provides further hints for the
exploitation of the catalogue. The orbital periods, light curve model
parameters, and global rankings are all published in the catalogue with their
related uncertainties where applicable.Comment: Submitted to A&A. Main text: 23 pages, 35 figures. Four appendices
(17 pages) with 38 figure
Kepler Eclipsing Binary Stars. VII. The Catalog of Eclipsing Binaries Found in the Entire Kepler Data Set
The primary Kepler Mission provided nearly continuous monitoring of similar to 200,000 objects with unprecedented photometric precision. We present the final catalog of eclipsing binary systems within the 105 deg(2) Kepler field of view. This release incorporates the full extent of the data from the primary mission (Q0-Q17 Data Release). As a result, new systems have been added, additional false positives have been removed, ephemerides and principal parameters have been recomputed, classifications have been revised to rely on analytical models, and eclipse timing variations have been computed for each system. We identify several classes of systems including those that exhibit tertiary eclipse events, systems that show clear evidence of additional bodies, heartbeat systems, systems with changing eclipse depths, and systems exhibiting only one eclipse event over the duration of the mission. We have updated the period and galactic latitude distribution diagrams and included a catalog completeness evaluation. The total number of identified eclipsing and ellipsoidal binary systems in the Kepler field of view has increased to 2878, 1.3% of all observed Kepler targets. An online version of this catalog with downloadable content and visualization tools is maintained at http://keplerEBs.villanova.edu
Kepler eclipsing binary stars. VII. the catalogue of eclipsing binaries found in the entire Kepler data set
The primary Kepler Mission provided nearly continuous monitoring of ~200,000 objects with unprecedented photometric precision. We present the final catalog of eclipsing binary systems within the 105 deg2 Kepler field of view. This release incorporates the full extent of the data from the primary mission (Q0-Q17 Data Release). As a result, new systems have been added, additional false positives have been removed, ephemerides and principal parameters have been recomputed, classifications have been revised to rely on analytical models, and eclipse timing variations have been computed for each system. We identify several classes of systems including those that exhibit tertiary eclipse events, systems that show clear evidence of additional bodies, heartbeat systems, systems with changing eclipse depths, and systems exhibiting only one eclipse event over the duration of the mission. We have updated the period and galactic latitude distribution diagrams and included a catalog completeness evaluation. The total number of identified eclipsing and ellipsoidal binary systems in the Kepler field of view has increased to 2878, 1.3% of all observed Kepler targets
Updated radial velocities and new constraints on the nature of the unseen source in NGC1850 BH1
A black hole candidate orbiting a luminous star in the Large Magellanic Cloud young cluster NGC 1850 (∼100 Myr) has recently been reported based on radial velocity and light-curve modelling. Subsequently, an alternative explanation has been suggested for the system: a bloated post-mass transfer secondary star (Minitial ∼ 4–5 M⊙ and Mcurrent ∼ 1–2 M⊙) with a more massive, yet luminous companion (the primary). Upon reanalysis of the MUSE spectra, we found that the radial velocity variations originally reported were underestimated (K2, revised = 176 ± 3 km s−1 versus K2, original = 140 ± 3 km s−1) because of the weighting scheme adopted in the full-spectrum fitting analysis. The increased radial velocity semi-amplitude translates into a system mass function larger than previously deduced (frevised = 2.83 M⊙versus foriginal = 1.42 M⊙). By exploiting the spectral disentangling technique, we place an upper limit of 10 per cent of a luminous primary source to the observed optical light in NGC1850 BH1, assuming that the primary and secondary are the only components contributing to the system. Furthermore, by analysing archival near-infrared data, we find clues to the presence of an accretion disc in the system. These constraints support a low-mass post-mass transfer star but do not provide a definitive answer whether the unseen component in NGC1850 BH1 is indeed a black hole. These results predict a scenario where, if a primary luminous source of mass M ≥ 4.7 M⊙ is present in the system (given the inclination and secondary mass constraints), it must be hidden in a optically thick disc to be undetected in the MUSE spectra
<i>Gaia</i> Data Release 1. Summary of the astrometric, photometric, and survey properties
Context. At about 1000 days after the launch of Gaia we present the first Gaia data release, Gaia DR1, consisting of astrometry and photometry for over 1 billion sources brighter than magnitude 20.7.
Aims. A summary of Gaia DR1 is presented along with illustrations of the scientific quality of the data, followed by a discussion of the limitations due to the preliminary nature of this release.
Methods. The raw data collected by Gaia during the first 14 months of the mission have been processed by the Gaia Data Processing and Analysis Consortium (DPAC) and turned into an astrometric and photometric catalogue.
Results. Gaia DR1 consists of three components: a primary astrometric data set which contains the positions, parallaxes, and mean proper motions for about 2 million of the brightest stars in common with the HIPPARCOS and Tycho-2 catalogues – a realisation of the Tycho-Gaia Astrometric Solution (TGAS) – and a secondary astrometric data set containing the positions for an additional 1.1 billion sources. The second component is the photometric data set, consisting of mean G-band magnitudes for all sources. The G-band light curves and the characteristics of ∼3000 Cepheid and RR-Lyrae stars, observed at high cadence around the south ecliptic pole, form the third component. For the primary astrometric data set the typical uncertainty is about 0.3 mas for the positions and parallaxes, and about 1 mas yr−1 for the proper motions. A systematic component of ∼0.3 mas should be added to the parallax uncertainties. For the subset of ∼94 000 HIPPARCOS stars in the primary data set, the proper motions are much more precise at about 0.06 mas yr−1. For the secondary astrometric data set, the typical uncertainty of the positions is ∼10 mas. The median uncertainties on the mean G-band magnitudes range from the mmag level to ∼0.03 mag over the magnitude range 5 to 20.7.
Conclusions. Gaia DR1 is an important milestone ahead of the next Gaia data release, which will feature five-parameter astrometry for all sources. Extensive validation shows that Gaia DR1 represents a major advance in the mapping of the heavens and the availability of basic stellar data that underpin observational astrophysics. Nevertheless, the very preliminary nature of this first Gaia data release does lead to a number of important limitations to the data quality which should be carefully considered before drawing conclusions from the data
KEPLER ECLIPSING BINARY STARS. VII. the CATALOG of ECLIPSING BINARIES FOUND in the ENTIRE KEPLER DATA SET
The primary Kepler Mission provided nearly continuous monitoring of ∼200,000 objects with unprecedented photometric precision. We present the final catalog of eclipsing binary systems within the 105 deg2 Kepler field of view. This release incorporates the full extent of the data from the primary mission (Q0-Q17 Data Release). As a result, new systems have been added, additional false positives have been removed, ephemerides and principal parameters have been recomputed, classifications have been revised to rely on analytical models, and eclipse timing variations have been computed for each system. We identify several classes of systems including those that exhibit tertiary eclipse events, systems that show clear evidence of additional bodies, heartbeat systems, systems with changing eclipse depths, and systems exhibiting only one eclipse event over the duration of the mission. We have updated the period and galactic latitude distribution diagrams and included a catalog completeness evaluation. The total number of identified eclipsing and ellipsoidal binary systems in the Kepler field of view has increased to 2878, 1.3% of all observed Kepler targets. An online version of this catalog with downloadable content and visualization tools is maintained at http://keplerEBs.villanova.edu
Kepler Eclipsing Binary Stars. Vii. The Catalog Of Eclipsing Binaries Found In The Entire Kepler Data Set
The Kepler mission has provided unprecedented, nearly continuous photometric data of ~200,000 objects in the ~105 deg2 field of view (FOV) from the beginning of science operations in May of 2009 until the loss of the second reaction wheel in May of 2013. The Kepler Eclipsing Binary Catalog contains information including but not limited to ephemerides, stellar parameters, and analytical approximation fits for every known eclipsing binary system in the Kepler FOV. Using target pixel level data collected from Kepler in conjunction with the Kepler Eclipsing Binary Catalog, we identify false positives among eclipsing binaries, i.e., targets that are not eclipsing binaries themselves, but are instead contaminated by eclipsing binary sources nearby on the sky and show eclipsing binary signatures in their light curves. We present methods for identifying these false positives and for extracting new light curves for the true source of the observed binary signal. For each source, we extract three separate light curves for each quarter of available data by optimizing the signal-to-noise ratio, the relative percent eclipse depth, and the flux eclipse depth. We present 289 new eclipsing binaries in the Kepler FOV that were not targets for observation, and these have been added to the catalog
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