K2 Variable Catalogue II: Machine Learning Classification of Variable Stars and Eclipsing Binaries in K2 Fields 0-4

Abstract

We are entering an era of unprecedented quantities of data from current and planned survey telescopes. To maximise the potential of such surveys, automated data analysis techniques are required. Here we implement a new methodology for variable star classification, through the combination of Kohonen Self Organising Maps (SOM, an unsupervised machine learning algorithm) and the more common Random Forest (RF) supervised machine learning technique. We apply this method to data from the K2 mission fields 0-4, finding 154 ab-type RR Lyraes (10 newly discovered), 377 Delta Scuti pulsators, 133 Gamma Doradus pulsators, 183 detached eclipsing binaries, 290 semi-detached or contact eclipsing binaries and 9399 other periodic (mostly spot-modulated) sources, once class significance cuts are taken into account. We present lightcurve features for all K2 stellar targets, including their three strongest detected frequencies, which can be used to study stellar rotation periods where the observed variability arises from spot modulation. The resulting catalogue of variable stars, classes, and associated data features are made available online. We publish our SOM code in Python as part of the open source PyMVPA package, which in combination with already available RF modules can be easily used to recreate the method.

Accepted for publication in MNRAS, 16 pages, 13 figures. Updated with proof corrections. Full catalogue tables available at https://www2.warwick.ac.uk/fac/sci/physics/research/astro/people/armstrong/ or at the CDS

References in corpus (33)

• The K2 Mission: Characterization and Early results
• Kepler Presearch Data Conditioning II - A Bayesian Approach to Systematic Error Correction
• Kepler Presearch Data Conditioning I - Architecture and Algorithms for Error Correction in Kepler Light Curves
• Rotation Periods of 34,030 Kepler Main-Sequence Stars: The Full Autocorrelation Sample
• A Technique for Extracting Highly Precise Photometry for the Two-Wheeled Kepler Mission
• Kepler Eclipsing Binary Stars. I. Catalog and Principal Characterization of 1879 Eclipsing Binaries in the First Data Release
• Measuring the rotation period distribution of field M-dwarfs with Kepler
• Kepler Eclipsing Binary Stars. II. 2165 Eclipsing Binaries in the Second Data Release
• The Kepler characterization of the variability among A- and F-type stars. I. General overview
• On Machine-Learned Classification of Variable Stars with Sparse and Noisy Time-Series Data
• Hybrid gamma Doradus - delta Scuti pulsators: New insights into the physics of the oscillations from Kepler observations
• A Class of Eccentric Binaries with Dynamic Tidal Distortions Discovered with Kepler
• Kepler Eclipsing Binary Stars. III. Classification of Kepler Eclipsing Binary Light Curves with Locally Linear Embedding
• Metal Abundances, Radial Velocities and other Physical Characteristics for the RR Lyrae Stars in the Kepler Field
• Precise time-series photometry for the Kepler-2.0 mission
• Using Machine Learning for Discovery in Synoptic Survey Imaging
• Global stellar variability study in the field-of-view of the Kepler satellite
• SOMz: photometric redshift PDFs with self organizing maps and random atlas
• Construction of a Calibrated Probabilistic Classification Catalog: Application to 50k Variable Sources in the All-Sky Automated Survey
• K2P${}^2$ $-$ A photometry pipeline for the K2 mission
• K2 Variable Catalogue: Variable Stars and Eclipsing Binaries in K2 Campaigns 1 and 0
• Results of a Search for gamma Dor and delta Sct Stars with the Kepler Spacecraft
• Finding outlier light-curves in catalogs of periodic variable stars
• Detection of a large sample of Gamma Dor stars from Kepler space photometry and high-resolution ground-based spectroscopy
• Active Learning to Overcome Sample Selection Bias: Application to Photometric Variable Star Classification
• The automated classification of astronomical lightcurves using Kohonen self-organising maps
• Automated classification of variable stars for ASAS 1-2 data
• Supervised detection of anomalous light-curves in massive astronomical catalogs
• Automated Classification of Periodic Variable Stars detected by the Wide-field Infrared Survey Explorer
• Automated classification of variable stars in the asteroseismology program of the Kepler space mission
• Automated Probabilistic Classification of Transients and Variables
• Pushing the limits, episode 2: K2 observations of extragalactic RR Lyrae stars in the dwarf galaxy Leo IV
• The K2-TESS Stellar Properties Catalog

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• Surveying the reach and maturity of machine learning and artificial intelligence in astronomy
• An update to the EVEREST K2 pipeline: Short cadence, saturated stars, and Kepler-like photometry down to Kp = 15
• Stellar rotation periods from K2 Campaigns 0-18 -- Evidence for rotation period bimodality and simultaneous variability decrease
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• That's How We Roll: The NASA K2 Mission Science Products and Their Performance Metrics
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• The ZTF Source Classification Project: I. Methods and Infrastructure
• Classifying Kepler light curves for 12,000 A and F stars using supervised feature-based machine learning
• TESS Data for Asteroseismology (T'DA) Stellar Variability Classification Pipeline: Set-Up and Application to the Kepler Q9 Data
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• A Study of Pulsation properties of 57 Non-Blazhko effect ab-type RR Lyrae stars with homogeneous metallicities from the LAMOST-Kepler/K2 survey
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• YOUNG Star detrending for Transiting Exoplanet Recovery (YOUNGSTER) II: Using Self-Organising Maps to explore young star variability in Sectors 1-13 of TESS data
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• K2 Photometry of RR Lyrae Stars
• Heartbeat Stars Recognition Based on Recurrent Neural Networks: Method and Validation
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• A 'Quick Look' at All-Sky Galactic Archeology with TESS: 158,000 Oscillating Red Giants from the MIT Quick-Look Pipeline
• The Visual Survey Group: A Decade of Hunting Exoplanets and Unusual Stellar Events with Space-Based Telescopes
• Advanced Astroinformatics for Variable Star Classification
• Identifying Periodic Variable Stars and Eclipsing Binary Systems with Long-Term Las Cumbres Observatory Photometric Monitoring of ZTF J0139+5245
• Light curve fingerprints: an automated approach to the extraction of X-ray variability patterns with feature aggregation -- an example application to GRS 1915+105