Contamination in TESS light curves: The case of the Fast Yellow Pulsating Supergiants

Abstract

Given its large plate scale of 21" / pixel, analyses of data from the TESS space telescope must be wary of source confusion from blended light curves, which creates the potential to attribute observed photometric variability to the wrong astrophysical source. We explore the impact of light curve contamination on the detection of fast yellow pulsating supergiant (FYPS) stars as a case study to demonstrate the importance of confirming the source of detected signals in the TESS pixel data. While some of the FYPS signals have already been attributed to contamination from nearby eclipsing binaries, others are suggested to be intrinsic to the supergiant stars. In this work, we carry out a detailed analysis of the TESS pixel data to fit the source locations of the dominant signals reported for 17 FYPS stars with the Python package TESS_localize. We are able to reproduce the detections of these signals for 14 of these sources, obtaining consistent source locations for four. Three of these originate from contaminants, while the signal reported for BZ Tuc is likely a spurious frequency introduced to the light curve of this 127-day Cepheid by the data processing pipeline. Other signals are not significant enough to be localized with our methods, or have long periods that are difficult to analyze given other TESS systematics. Since no localizable signals hold up as intrinsic pulsation frequencies of the supergiant targets, we argue that unambiguous detection of pulsational variability should be obtained before FYPS are considered a new class of pulsator.

16 pages, 8 figures, 1 table, accepted for publication in the Astronomical Journal

References in corpus (14)

• Array Programming with NumPy
• The Gaia mission
• Modules for Experiments in Stellar Astrophysics (MESA)
• Modules for Experiments in Stellar Astrophysics (MESA): Pulsating Variable Stars, Rotation, Convective Boundaries, and Energy Conservation
• astroquery: An Astronomical Web-Querying Package in Python
• Modules for Experiments in Stellar Astrophysics (MESA): Time-Dependent Convection, Energy Conservation, Automatic Differentiation, and Infrastructure
• Toward Complete Statistics of Massive Binary Stars: Penultimate Results from the Cygnus OB2 Radial Velocity Survey
• The evolution of rotating very massive stars with LMC composition
• Internal mixing of rotating stars inferred from dipole gravity modes
• OGLE-IV: Fourth Phase of the Optical Gravitational Lensing Experiment
• New predictions for radiation-driven, steady-state mass-loss and wind-momentum from hot, massive stars II. A grid of O-type stars in the Galaxy and the Magellanic Clouds
• Rotation Distributions around the Kraft Break with TESS and Kepler: The Influences of Age, Metallicity, and Binarity
• Short Term Variability of Evolved Massive Stars with TESS II: A New Class of Cool, Pulsating Supergiants
• The OGLE Collection of Variable Stars. Eclipsing Binaries in the Magellanic System

Cited by in corpus (3)

• Yellow Supergiants and Post-Red Supergiant Evolution in the Large Magellanic Cloud
• Photometric White Dwarf Rotation
• Pulsation in TESS Objects of Interest