Searching for Anomalies in the ZTF Catalog of Periodic Variable Stars

Abstract

Periodic variables illuminate the physical processes of stars throughout their lifetime. Wide-field surveys continue to increase our discovery rates of periodic variable stars. Automated approaches are essential to identify interesting periodic variable stars for multi-wavelength and spectroscopic follow-up. Here, we present a novel unsupervised machine learning approach to hunt for anomalous periodic variables using phase-folded light curves presented in the Zwicky Transient Facility Catalogue of Periodic Variable Stars by \citet{Chen_2020}. We use a convolutional variational autoencoder to learn a low dimensional latent representation, and we search for anomalies within this latent dimension via an isolation forest. We identify anomalies with irregular variability. Most of the top anomalies are likely highly variable Red Giants or Asymptotic Giant Branch stars concentrated in the Milky Way galactic disk; a fraction of the identified anomalies are more consistent with Young Stellar Objects. Detailed spectroscopic follow-up observations are encouraged to reveal the nature of these anomalies.

26 pages, 17 figures. The full version of Table 4 and Table 5 are available upon request

References in corpus (55)

• Array Programming with NumPy
• Modules for Experiments in Stellar Astrophysics (MESA)
• The Zwicky Transient Facility: System Overview, Performance, and First Results
• Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3
• The All-Sky Automated Survey for Supernovae (ASAS-SN) Light Curve Server v1.0
• astroquery: An Astronomical Web-Querying Package in Python
• The Catalina Surveys Periodic Variable Star Catalog
• The Optical to Mid-Infrared Extinction Law Based on the APOGEE, Gaia DR2, Pan-STARRS1, SDSS, APASS, 2MASS and WISE Surveys
• The Zwicky Transient Facility Catalog of Periodic Variable Stars
• Unexpectedly large mass loss during the thermal pulse cycle of the red giant R Sculptoris!
• Physical Properties and Catalogue of EW-type Eclipsing Binaries Observed by LAMOST
• A blinded determination of $H_0$ from low-redshift Type Ia supernovae, calibrated by Cepheid variables
• The weirdest SDSS galaxies: results from an outlier detection algorithm
• Anisotropic Cosmological Constant and the CMB Quadrupole Anomaly
• A recurrent neural network for classification of unevenly sampled variable stars
• Mass loss on the red giant branch: the value and metallicity dependence of Reimers' η in globular clusters
• First full evolutionary computation of the He-flash induced mixing in Population II stars
• Dust-driven Winds and Mass Loss of C-rich AGB Stars with subsolar Metallicities
• Evolution of Thermally Pulsing Asymptotic Giant Branch Stars IV. Constraining Mass-Loss & Lifetimes of Low Mass, Low Metallicity AGB Stars
• Variable stars across the observational HR diagram
• The Mass-Loss Return from Evolved Stars to the Large Magellanic Cloud IV: Construction and Validation of a Grid of Models for Oxygen-Rich AGB Stars, Red Supergiants, and Extreme AGB Stars
• On Carbon Burning in Super Asymptotic Giant Branch Stars
• The onset of X-ray emission in young stellar objects: a Chandra observation of the Serpens star-forming region
• The trigger of the AGB superwind: the importance of carbon
• Anomaly detection in the Zwicky Transient Facility DR3
• Defining the instability strip of pulsating post-AGB binary stars from ASAS and NSVS photometry
• O and Na abundance patterns in open clusters of the Galactic disk
• A Deep Learning Approach for Active Anomaly Detection of Extragalactic Transients
• Searching for changing-state AGNs in massive datasets -- I: applying deep learning and anomaly detection techniques to find AGNs with anomalous variability behaviours
• Testing the role of environmental effects on the initial mass function of low-mass stars
• The period-luminosity and period-radius relations of Type II and anomalous Cepheids
• Orbital Evolution of Algol Binaries with a Circumbinary Disk
• RR Lyrae variables in Messier 53: Near-infrared Period--Luminosity relations and the calibration using Gaia Early Data Release 3
• Anomaly detection in Hyper Suprime-Cam galaxy images with generative adversarial networks
• Multicolor Variability of Young Stars in the Lagoon Nebula: Driving Causes and Intrinsic Timescales
• A bottom-heavy initial mass function for the likely-accreted blue-halo stars of the Milky Way
• New Near-Infrared $JH{K}_s$ light-curve templates for RR Lyrae variables
• Dust mass-loss rates from AGB stars in the Fornax and Sagittarius dwarf Spheroidal galaxies
• On the separation between RR Lyrae and Type II Cepheids and their importance for distance determination: the case of $\omega$ Cen
• Studies of RR Lyrae Variables in Binary Systems. I.: Evidence of a Trimodal Companion Mass Distribution
• Stellar Evolution in Real Time: Models Consistent with Direct Observation of Thermal Pulse in T Ursae Minoris
• Mira Variable Stars From LAMOST DR4 Data: Emission Features, Temperature Types, and Candidate Selection
• Neural network-based anomaly detection for high-resolution X-ray spectroscopy
• Classification of Periodic Variable Stars with Novel Cyclic-Permutation Invariant Neural Networks
• Variability of young stellar objects in the star-forming region Pelican Nebula
• Multiwavelength Observations of NaSt1 (WR 122): Equatorial Mass Loss and X-rays from an Interacting Wolf-Rayet Binary
• Delayed Detonation Thermonuclear Supernovae With An Extended Dark Matter Component
• Limits to Transits of the Neptune-mass planet orbiting Gl 581
• On the nature of the anomalous event in 2021 in the dwarf nova SS Cygni and its multi-wavelength transition
• HD66051, an eclipsing binary hosting a highly peculiar, HgMn-related star
• New magnetic chemically peculiar stars and candidates in the ATLAS First Catalog of Variable Stars
• The Dusty Evolved Star Kit (DESK): A Python package for fitting the Spectral Energy Distribution of Evolved Stars
• Anomalous Cepheids discovered in a sample of Galactic short period Type II Cepheids
• Multiperiodic semiregular variable stars in the ASAS data base: A pilot study
• SCONE: Supernova Classification with a Convolutional Neural Network

Cited by in corpus (5)

• Machine Learning for Observational Cosmology
• Supernova search with active learning in ZTF DR3
• Cyclotron emitting magnetic white dwarfs in post common envelope binaries discovered with the Zwicky Transient Facility
• Dark Matter-admixed Rotating White Dwarfs as Peculiar Compact Objects
• Automated all-sky detection of γ Doradus / δ Scuti hybrids in TESS data from positive unlabelled (PU) learning