Short Term Variability of Evolved Massive Stars with TESS II: A New Class of Cool, Pulsating Supergiants

Abstract

Massive stars briefly pass through the yellow supergiant (YSG) phase as they evolve redward across the HR diagram and expand into red supergiants (RSGs). Higher-mass stars pass through the YSG phase again as they evolve blueward after experiencing significant RSG mass loss. These post-RSG objects offer us a tantalizing glimpse into which stars end their lives as RSGs, and why. One telltale sign of a post-RSG object may be an instability to pulsations, depending on the star's interior structure. Here we report the discovery of five YSGs with pulsation periods faster than 1 day, found in a sample of 76 cool supergiants observed by \tess at two-minute cadence. These pulsating YSGs are concentrated in a HR diagram region not previously associated with pulsations; we conclude that this is a genuine new class of pulsating star, Fast Yellow Pulsating Supergiants (FYPS). For each FYPS, we extract frequencies via iterative prewhitening and conduct a time-frequency analysis. One FYPS has an extracted frequency that is split into a triplet, and the amplitude of that peak is modulated on the same timescale as the frequency spacing of the triplet; neither rotation nor binary effects are likely culprits. We discuss the evolutionary status of FYPS and conclude that they are candidate post-RSGs. All stars in our sample also show the same stochastic low-frequency variability (SLFV) found in hot OB stars and attributed to internal gravity waves. Finally, we find four $\alpha$ Cygni variables in our sample, of which three are newly discovered.

arXiv comment29 pages, 13 figures, 8 tables. Accepted for publication in ApJ. Comments welcome

References in corpus (75)

• Astropy: A Community Python Package for Astronomy
• The NumPy array: a structure for efficient numerical computation
• The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
• The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package
• Modules for Experiments in Stellar Astrophysics (MESA)
• The Transiting Exoplanet Survey Satellite
• Modules for Experiments in Stellar Astrophysics (MESA): Giant Planets, Oscillations, Rotation, and Massive Stars
• Modules for Experiments in Stellar Astrophysics (MESA): Binaries, Pulsations, and Explosions
• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• The SIMBAD astronomical database
• Binary interaction dominates the evolution of massive stars
• Modules for Experiments in Stellar Astrophysics (MESA): Convective Boundaries, Element Diffusion, and Massive Star Explosions
• Modules for Experiments in Stellar Astrophysics (MESA): Pulsating Variable Stars, Rotation, Convective Boundaries, and Energy Conservation
• Mass-loss predictions for O and B stars as a function of metallicity
• Grids of stellar models with rotation - I. Models from 0.8 to 120 Msun at solar metallicity (Z = 0.014)
• The VizieR database of Astronomical Catalogues
• Mind your Ps and Qs: the Interrelation between Period (P) and Mass-ratio (Q) Distributions of Binary Stars
• Core-Collapse Supernovae from 9 to 120 Solar Masses Based on Neutrino-powered Explosions
• astroquery: An Astronomical Web-Querying Package in Python
• The death of massive stars - I. Observational constraints on the progenitors of type II-P supernovae
• The TESS Input Catalog and Candidate Target List
• The VLT-FLAMES Tarantula Survey VIII. Multiplicity properties of the O-type star population
• The Effective Temperature Scale of Galactic Red Supergiants: Cool, But Not As Cool As We Thought
• Stellar evolution with rotation VII: Low metallicity models and the blue to red supergiant ratio in the SMC
• The Effects of Stellar Rotation. II. A Comprehensive Set of Starburst99 Models
• An empirical formula for the mass-loss rates of dust-enshrouded red supergiants and oxygen-rich Asymptotic Giant Branch stars
• Assessing statistical significance of periodogram peaks
• The connection between stellar granulation and oscillation as seen by the Kepler mission
• Grids of stellar models with rotation II. WR populations and supernovae/GRB progenitors at Z = 0.014
• High Resolution Study of Presupernova Compactness
• The evolution of runaway stellar collision products
• The mass-loss rates of red supergiants and the de Jager prescription
• Spitzer SAGE Infrared Photometry of Massive Stars in the Large Magellanic Cloud
• The Effective Temperatures and Physical Properties of Magellanic Cloud Red Supergiants: The Effects of Metallicity
• A Class of Eccentric Binaries with Dynamic Tidal Distortions Discovered with Kepler
• Variability in red supergiant stars: pulsations, long secondary periods and convection noise
• On the Effect of Rotation on Populations of Classical Cepheids II. Pulsation Analysis for Metallicities 0.014, 0.006, and 0.002
• Low-frequency gravity waves in blue supergiants revealed by high-precision space photometry
• Kepler observations of variability in B-type stars
• Circumstellar dust as a solution to the red supergiant supernova progenitor problem
• A comparison of evolutionary tracks for single Galactic massive stars
• On Variations Of Pre-Supernova Model Properties
• Yellow and Red Supergiants in the Large Magellanic Cloud
• The Reddening of Red Supergiants: When Smoke Gets In Your Eyes
• On Absorption by Circumstellar Dust, With the Progenitor of SN2012aw as a Case Study
• Variability in the CoRoT photometry of three hot O-type stars. HD 46223, HD 46150 and HD 46966
• Photometric detection of internal gravity waves in upper main-sequence stars. II. Combined TESS photometry and high-resolution spectroscopy
• The `Red Supergiant Problem': the upper luminosity boundary of type-II supernova progenitors
• On the photometric detection of Internal Gravity Waves in upper main-sequence stars I. Methodology and application to CoRoT targets
• Diverse Variability of O and B Stars Revealed from 2-minute Cadence Light Curves in Sectors 1 and 2 of the TESS Mission: Selection of an Asteroseismic Sample
• Crossing the `Yellow Void' -- Spatially Resolved Spectroscopy of the Post- Red Supergiant IRC+10420 and Its Circumstellar Ejecta
• Evolution of blue supergiants and αCygni variables; Puzzling CNO surface abundances
• Yellow Supergiants in the Small Magellanic Cloud (SMC): Putting Current Evolutionary Theory to the Test
• Detection of a large sample of Gamma Dor stars from Kepler space photometry and high-resolution ground-based spectroscopy
• The SDSS-2MASS-WISE Ten Dimensional Stellar Color Locus
• Missing Red Supergiants and Carbon Burning
• Searching for Cool Dust in the Mid-to-Far Infrared: the Mass Loss Histories of The Hypergiants $\mu$ Cep, VY CMa, IRC+10420, and $\rho$ Cas
• Large dust grains in the wind of VY Canis Majoris
• Rotational modulation in TESS B stars
• The puzzle of the CNO abundances of α Cygni variables resolved by the Ledoux criterion?
• Low-frequency variability in massive stars: Core generation or surface phenomenon?
• On The Red Supergiant Problem
• Kepler's first view of O-star variability: K2 data of five O stars in Campaign 0 as a proof-of-concept for O-star asteroseismology
• The Physical Properties of the Red Supergiant WOH G64: The Largest Star Known?
• PX Andromedae: Superhumps and variable eclipse depth
• The Luminosity Function of Red Supergiants in M31
• Radial pulsation as a function of hydrogen abundance
• The inner dust shell of Betelgeuse detected by polarimetric aperture-masking interferometry
• Short Term Variability of Evolved Massive Stars with TESS
• Metallicity dependence of turbulent pressure and macroturbulence in stellar envelopes
• A Comparison of Rotating and Binary Stellar Evolution Models: Effects on Massive Star Populations
• Red Supergiants, Yellow Hypergiants, and Post-RSG Evolution
• MUSE library of stellar spectra
• The Evolution of Massive Stars: Bridging the Gap in the Local Group
• Detection of intrinsic variability in the eclipsing massive main sequence O+B binary HD 165246

Cited by in corpus (17)

• Probing the interior physics of stars through asteroseismology
• Numerical Simulations of Convective 3-Dimensional Red Supergiant Envelopes
• On the Origin of Stochastic, Low-Frequency Photometric Variability in Massive Stars
• Rejuvenated accretors have less bound envelopes: Impact of Roche lobe overflow on subsequent common envelope events
• Stochastic Low Frequency Variability in 3-Dimensional Radiation Hydrodynamical Models of Massive Star Envelopes
• The photometric variability of massive stars due to gravity waves excited by core convection
• The impact of realistic red supergiant mass-loss on stellar evolution
• Contamination in TESS light curves: The case of the Fast Yellow Pulsating Supergiants
• The role of stellar expansion on the formation of gravitational wave sources
• Photometric detection of internal gravity waves in upper main-sequence stars. III. Comparison of amplitude spectrum fitting and Gaussian process regression using celerite2
• Yellow Supergiants and Post-Red Supergiant Evolution in the Large Magellanic Cloud
• Search for magnetic accretion in SW Sextantis systems
• The Red and Yellow Hypergiants
• Variability of Galactic blue supergiants observed with TESS
• Catalog of Integrated-Light Star Cluster Light Curves in TESS
• The Properties of Fast Yellow Pulsating Supergiants: FYPS Point the Way to Missing Red Supergiants
• Fast optical variability in Supergiant X-ray binaries