What causes the large extensions of red-supergiant atmospheres? Comparisons of interferometric observations with 1-D hydrostatic, 3-D convection, and 1-D pulsating model atmospheres

Abstract

We present the atmospheric structure and the fundamental parameters of three red supergiants, increasing the sample of RSGs observed by near-infrared spectro-interferometry. Additionally, we test possible mechanisms that may explain the large observed atmospheric extensions of RSGs. We carried out spectro-interferometric observations of 3 RSGs in the near-infrared K-band with the VLTI/AMBER instrument at medium spectral resolution. To comprehend the extended atmospheres, we compared our observational results to predictions by available hydrostatic PHOENIX, available 3-D convection, and new 1-D self-excited pulsation models of RSGs. Our near-infrared flux spectra are well reproduced by the PHOENIX model atmospheres. The continuum visibility values are consistent with a limb-darkened disk as predicted by the PHOENIX models, allowing us to determine the angular diameter and the fundamental parameters of our sources. Nonetheless, in the case of V602 Car and HD 95686, the PHOENIX model visibilities do not predict the large observed extensions of molecular layers, most remarkably in the CO bands. Likewise, the 3-D convection models and the 1-D pulsation models with typical parameters of RSGs lead to compact atmospheric structures as well, which are similar to the structure of the hydrostatic PHOENIX models. They can also not explain the observed decreases in the visibilities and thus the large atmospheric molecular extensions. The full sample of our RSGs indicates increasing observed atmospheric extensions with increasing luminosity and decreasing surface gravity, and no correlation with effective temperature or variability amplitude, which supports a scenario of radiative acceleration on Doppler-shifted molecular lines.

arXiv commentAccepted for publication in A&A

References in corpus (55)

• Validation of the new Hipparcos reduction
• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• Grids of stellar models with rotation - I. Models from 0.8 to 120 Msun at solar metallicity (Z = 0.014)
• Spectral Irradiance Calibration in the Infrared. XIV: the Absolute Calibration of 2MASS
• The Effective Temperature Scale of Galactic Red Supergiants: Cool, But Not As Cool As We Thought
• The NextGen Model Atmosphere grid: II. Spherically symmetric model atmospheres for giant stars with effective temperatures between 3000 and 6800~K
• Simulations of stellar convection with CO5BOLD
• Interferometric data reduction with AMBER/VLTI.Principle,estimators and illustration
• Thermohaline instability and rotation-induced mixing. III - Grid of stellar models and asymptotic asteroseismic quantities from the pre-main sequence up to the AGB for low- and intermediate-mass stars at various metallicities
• Improved Color-Temperature Relations and Bolometric Corrections for Cool Stars
• Fundamental parameters and infrared excesses of Hipparcos stars
• Probing the mass-loss history of AGB and red supergiant stars from CO rotational line profiles - II. CO line survey of evolved stars: derivation of mass-loss rate formulae
• A close halo of large transparent grains around extreme red giant stars
• Atmospheric dynamics and the mass loss process in red supergiant stars
• Excitation of stellar p-modes by turbulent convection: 1. Theoretical formulation
• Radiative hydrodynamics simulations of red supergiant stars: I. interpretation of interferometric observations
• Imaging the dynamical atmosphere of the red supergiant Betelgeuse in the CO first overtone lines with VLTI/AMBER
• Radiative hydrodynamics simulations of red supergiant stars: II. simulations of convection on Betelgeuse match interferometric observations
• Interferometric observations of the supergiant stars alpha Orionis and alpha Herculis with FLUOR at IOTA
• Radiative hydrodynamics simulations of red supergiant stars. III. Spectro-photocentric variability, photometric variability, and consequences on Gaia measurements
• The magnetic field of Betelgeuse: a local dynamo from giant convection cells?
• Radiative hydrodynamics simulations of red supergiant stars. IV gray versus non-gray opacities
• Synthetic Spectra and Color-Temperature Relations of M Giants
• The Mira variable S Ori: Relationships between the photosphere, molecular layer, dust shell, and SiO maser shell at 4 epochs
• Fundamental properties and atmospheric structure of the red supergiant VY CMa based on VLTI/AMBER spectro-interferometry
• Dynamical Opacity-Sampling Models of Mira Variables. II: Time-Dependent Atmospheric Structure and Observable Properties of 4 M-Type Model Series
• New insights into the dust formation of oxygen-rich AGB stars
• High spectral resolution imaging of the dynamical atmosphere of the red supergiant Antares in the CO first overtone lines with VLTI/AMBER
• Near-IR Spectra of Red Supergiants and Giants. I- Models with Solar and with Mixing-Induced Surface Abundance Ratios
• VLTI/AMBER spectro-interferometric imaging of VX Sgr's inhomogenous outer atmosphere
• Systematic detection of magnetic fields in massive, late-type supergiants
• Dynamical Opacity-Sampling Models of Mira Variables. I: Modelling Description and Analysis of Approximations
• Amorphous alumina in the extended atmosphere of Alpha Orionis
• J, H, K spectro-interferometry of the Mira variable S Orionis
• Cool luminous stars: the hybrid nature of their infrared spectra -- Carbon, oxygen, and their isotopic abundances in 23 K - M giant stars
• The atmospheric structure and fundamental parameters of the red supergiants AH Sco, UY Sct and KW Sgr
• The Keck Aperture Masking Experiment: spectro-interferometry of 3 Mira Variables from 1.1 to 3.8 microns
• Supergiant Temperatures and Linear Radii from Near-Infrared Interferometry
• Detection of Water Vapor in the Photosphere of Arcturus
• Pulsation of M-type Mira variables with moderately different mass: search for observable mass effects
• Inhomogeneities in molecular layers of Mira atmospheres
• Exploring wind-driving dust species in cool luminous giants II. Constraints from photometry of M-type AGB stars
• Study of molecular layers in the atmosphere of the supergiant star mu Cep by interferometry in the K band
• Water Vapor on Betelgeuse as Revealed by TEXES High-Resolution 12 Micron Spectra
• Mid-infrared interferometric monitoring of evolved stars - The dust shell around the Mira variable RR Aql at 13 epochs
• The dynamic atmospheres of Mira stars: comparing the CODEX models to PTI time series of TU And
• Spatially resolved, high-spectral resolution observation of the K giant Aldebaran in the CO first overtone lines with VLTI/AMBER
• Spatially resolving the outer atmosphere of the M giant BK Vir in the CO first overtone lines with VLTI/AMBER
• AMBER observations of the AGB star RS Cap: extended atmosphere and comparison with stellar models
• Water vapor on supergiants. The 12 micron TEXES spectra of mu Cephei
• The Magnetised Bellows of Betelgeuse
• VLTI/AMBER observations of cold giant stars: atmospheric structures and fundamental parameters
• Dust-forming molecules in VY Canis Majoris (and Betelgeuse)
• Long-term spectropolarimetric monitoring of the cool supergiant Betelgeuse
• Effects of moderate abundance changes on the atmospheric structure and colours of Mira variables (Research Note)

Cited by in corpus (45)

• Global 3D radiation-hydrodynamics models of AGB stars. Effects of convection and radial pulsations on atmospheric structures
• Pseudomagnitudes and Differential Surface Brightness: Application to the apparent diameter of stars
• Mass Transfer and Disc Formation in AGB Binary Systems
• A dusty veil shading Betelgeuse during its Great Dimming
• Numerical Simulations of Convective 3-Dimensional Red Supergiant Envelopes
• Evolution and Mass Loss of Cool Ageing Stars: a Daedalean Story
• The Photospheric Temperatures of Betelgeuse during the Great Dimming of 2019/2020: No New Dust Required
• Analytic, dust-independent mass-loss rates for red supergiant winds initiated by turbulent pressure
• Large dust grains in the wind of VY Canis Majoris
• The close circumstellar environment of Betelgeuse. IV. VLTI/PIONIER interferometric monitoring of the photosphere
• Vigorous atmospheric motion in the red supergiant star Antares
• Episodic Gaseous Outflows and Mass Loss from Red Supergiants
• Tomography of cool giant and supergiant star atmospheres II. Signature of convection in the atmosphere of the red supergiant star $\mu$ Cep
• Near-infrared spectro-interferometry of Mira variables and comparisons to 1D dynamic model atmospheres and 3D convection simulations
• Establishing a mass-loss rate relation for red supergiants in the Large Magellanic Cloud
• The VLT-FLAMES Tarantula Survey: XXXI. Radial velocities and multiplicity constraints of red supergiant stars in 30 Doradus
• NOEMA maps the CO $J=2-1$ environment of the red supergiant $\mu$ Cep
• Silicate condensation in Mira variables
• A Massive Star's Dying Breaths: Pulsating Red Supergiants and Their Resulting Type IIP Supernovae
• Properties of self-excited pulsations in 3D simulations of AGB stars and red supergiants
• Is Betelgeuse Really Rotating? Synthetic ALMA Observations of Large-scale Convection in 3D Simulations of Red Supergiants
• The effect of mass loss in models of red supergiants in the Small Magellanic Cloud
• VLTI/AMBER spectro-interferometry of the late-type supergiants V766 Cen (=HR 5171 A), sigma Oph, BM Sco, and HD 206859
• Red Supergiant Candidates for Multimessenger Monitoring of the Next Galactic Supernova
• Long Term Evolution of Surface Features on the Red Supergiant AZ Cyg
• Optical properties of non-stoichiometric amorphous silicates with application to circumstellar dust extinction
• VLTI-PIONIER imaging of the red supergiant V602 Carinae
• The convective surface of the red supergiant Antares. VLTI/PIONIER interferometry in the near infrared
• The extended atmosphere and circumstellar environment of the cool evolved star VX Sagittarii as seen by MATISSE
• Red Supergiants in the JWST Era. I: Near-IR Photometric Diagnostics
• Spatially resolving the thermally inhomogeneous outer atmosphere of the red giant Arcturus in the 2.3 micron CO lines
• Investigating the metallicity dependence of the mass-loss rate relation of red supergiants
• A CO-multilayer outer atmosphere for eight evolved stars revealed with VLTI/AMBER
• Tomography of cool giant and supergiant star atmospheres III. Validation of the method on VLTI/AMBER observations of the Mira star S Ori
• The convective photosphere of the red supergiant CE Tau. I. VLTI/PIONIER H-band interferometric imaging
• The effect of winds on atmospheric layers of red supergiants I. Modelling for interferometric observations
• A Non-Detection of Red Supergiant Convection in Gaia
• The effect of winds on atmospheric layers of red supergiants II. Modelling VLTI/GRAVITY and MATISSE observations of AH Sco, KW Sgr, V602 Car, CK Car and V460 Car
• Investigating episodic mass loss in evolved massive stars: III. Spectroscopy of dusty massive stars in three northern galaxies
• On the nature of VX Sagitarii: Is it a TZO, a RSG or a high-mass AGB star?
• MOLsphere and pulsations of the Galactic Center's red supergiant GCIRS 7 from VLTI/GRAVITY
• The demographics of core-collapse supernovae. The role of binary evolution and CSM interaction
• The extreme scarcity of dust-enshrouded red supergiants: consequences for producing stripped stars via winds
• VLTI-GRAVITY measurements of cool evolved stars: II. Pulsation properties and mass-loss process of the Mira star R Car and the red supergiant VX Sgr
• Pathways for Observing Stellar Surfaces Using 3D Hydrodynamical Simulations of Evolved Stars