Search for Southern Galactic Be Star Candidates

Sabogal, B. E.; García-Varela, A.; Mennickent, R. E.

doi:10.1086/675972

Cited by 5 publications

(9 citation statements)

References 35 publications

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“…Type-2 stars show a brightness discontinuity or jump of the order of a few tenths of magnitudes that occurs on timescales of about few hundreds of days. This behaviour had never been observed in Galactic Be stars, as was also confirmed by Sabogal et al (2014). Type-3 stars show periodic or quasiperiodic magnitude variations.…”

Section: Introductionsupporting

confidence: 63%

“…In their study, Sabogal et al (2014) used kurtosis and skewness. Kurtosis is a measure of both peakedness and tail weight.…”

Section: Set Of Featuresmentioning

confidence: 99%

“…Despite the diversity of the shape of their light curves, these stars are collectively classified as BeSC. Other light curve examples can be found in Mennickent et al (2002) and Sabogal et al (2014).…”

Section: Introductionmentioning

confidence: 98%

“…Following the ideas of Sabogal et al (2014), who used descriptive statistics of the magnitude density to search for BeSC, in this work we propose and evaluate a new set of features to classify variable stars and particularly BeSC. Since light curves sometimes contain atypical measurements, our descriptive statistics needs to be robust to the presence of such measurements.…”

Section: Introductionmentioning

confidence: 99%

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Machine learning techniques to select Be star candidates

Pérez-Ortiz

García-Varela

Quiróz

et al. 2017

A&A

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Context. Optical and infrared variability surveys produce a large number of high quality light curves. Statistical pattern recognition methods have provided competitive solutions for variable star classification at a relatively low computational cost. In order to perform supervised classification, a set of features is proposed and used to train an automatic classification system. Quantities related to the magnitude density of the light curves and their Fourier coefficients have been chosen as features in previous studies. However, some of these features are not robust to the presence of outliers and the calculation of Fourier coefficients is computationally expensive for large data sets. Aims. We propose and evaluate the performance of a new robust set of features using supervised classifiers in order to look for new Be star candidates in the OGLE-IV Gaia south ecliptic pole field. Methods. We calculated the proposed set of features on six types of variable stars and also on a set of Be star candidates reported in the literature. We evaluated the performance of these features using classification trees and random forests along with the K-nearest neighbours, support vector machines, and gradient boosted trees methods. We tuned the classifiers with a 10-fold cross-validation and grid search. We then validated the performance of the best classifier on a set of OGLE-IV light curves and applied this to find new Be star candidates. Results. The random forest classifier outperformed the others. By using the random forest classifier and colours criteria we found 50 Be star candidates in the direction of the Gaia south ecliptic pole field, four of which have infrared colours that are consistent with Herbig Ae/Be stars. Conclusions. Supervised methods are very useful in order to obtain preliminary samples of variable stars extracted from large databases. As usual, the stars classified as Be stars candidates must be checked for the colours and spectroscopic characteristics expected for them.

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Section: Introductionsupporting

confidence: 63%

“…In their study, Sabogal et al (2014) used kurtosis and skewness. Kurtosis is a measure of both peakedness and tail weight.…”

Section: Set Of Featuresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Machine learning techniques to select Be star candidates

Pérez-Ortiz

García-Varela

Quiróz

et al. 2017

A&A

Self Cite

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“…We also developed a search for BeSC within the ASAS catalog of variable stars ( [8]). These Galactic stars are located mainly in the Galactic disk at different distances.…”

Section: Techniques Used In Searches For Bescmentioning

confidence: 99%

Searching for Be star candidates within large databases

Sabogal

García-Varela

2017

EPJ Web Conf.

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A Multi-technique Study of the Dynamical Evolution of the Viscous Disk around the Be Star CMa

Ghoreyshi

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The observed emission lines of Be stars originate from a circumstellar Keplerian disk that are generally well explained by the Viscous Decretion Disk model. In an earlier work we performed the modeling of the full light curve of the bright Be star ω CMa (Ghoreyshi et al. 2018) with the 1-D time-dependent hydrodynamics code SINGLEBE and the Monte Carlo radiative-transfer code HDUST. We used the V-band light curve that probes the inner disk through four disk formation and dissipation cycles. This new study compares predictions of the same set of model parameters with time-resolved photometry from the near UV through the mid-infrared, comprehensive series of optical spectra, and optical broad-band polarimetry, that overall represent a larger volume of the disk. Qualitatively, the models reproduce the trends in the observed data due to the growth and decay of the disk. However, quantitative differences exist, e.g., an overprediction of the flux increasing with wavelength, too slow decreases in Balmer emission-line strength that are too slow during disk dissipation, and the discrepancy between the range of polarimetric data and the model. We find that a larger value of the viscosity parameter alone, or a truncated disk by a companion star, reduces these discrepancies by increasing the dissipation rate in the outer regions of the disk.

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Search for Southern Galactic Be Star Candidates

Cited by 5 publications

References 35 publications

Machine learning techniques to select Be star candidates

Machine learning techniques to select Be star candidates

Searching for Be star candidates within large databases

A Multi-technique Study of the Dynamical Evolution of the Viscous Disk around the Be Star CMa

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