The Be Star 66 Ophiuchi: 60 Years of Disk Evolution

Abstract

We use a time-dependent hydrodynamic code and a non-LTE Monte Carlo code to model disk dissipation for the Be star 66 Ophiuchi. We compiled 63 years of observations from 1957 to 2020 to encompass the complete history of the growth and subsequent dissipation of the star's disk. Our models are constrained by new and archival photometry, spectroscopy and polarization observations, allowing us to model the disk dissipation event. Using Markov chain Monte Carlo methods, we find 66 Oph is consistent with standard B2Ve stellar properties. We computed a grid of 61568 Be star disk models to constrain the density profile of the disk before dissipation using observations of the H$\alpha$ line profile and SED. We find at the onset of dissipation the disk has a base density of $2.5\times 10^{-11}\mathrm{g}\mathrm{c}{\mathrm{m}}^{-3}$ with a radial power-law index of $n=2.6$. Our models indicate that after 21 years of disk dissipation 66 Oph's outer disk remained present and bright in the radio. We find an isothermal disk with constant viscosity with an $\alpha =0.4$ and an outer disk radius of $\sim$115 stellar radii best reproduces the rate of 66 Oph's disk dissipation. We determined the interstellar polarization in the direction of the star in the V-band is $p=0.63\pm 0.02\%$ with a polarization position angle of ${\theta }_{IS}\approx 85.7\pm 0.7^{\circ }$. Using the Stokes QU diagram, we find the intrinsic polarization position angle of 66 Oph's disk is ${\theta }_{int}\approx 98\pm 3^{\circ }$.

20 pages, 16 figures

References in corpus (32)

• emcee: The MCMC Hammer
• Gaia Data Release 2. Summary of the contents and survey properties
• Validation of the new Hipparcos reduction
• Correcting for the Effects of Interstellar Extinction
• Las Cumbres Observatory Global Telescope Network
• Classical Be Stars: Rapidly Rotating B Stars with Viscous Keplerian Decretion Disks
• NLTE Monte Carlo Radiative Transfer: I. The Thermal Properties of Keplerian Disks around Classical Be Stars
• Viscous Effects on the Interaction between the Coplanar Decretion Disc and the Neutron Star in Be/X-Ray Binaries
• Viscous Transonic Decretion in Disks of Be Stars
• Dynamical Evolution of Viscous Disks around Be Stars. I: photometry
• Mass and angular momentum loss via decretion disks
• Non-LTE Monte Carlo Radiative Transfer: II. Non-Isothermal Solutions for Viscous Keplerian Disks
• Short-term variability and mass loss in Be stars I. BRITE satellite photometry of $\eta$ and $\mu$ Centauri
• The life cycles of Be viscous decretion discs: fundamental disc parameters of 54 SMC Be stars
• Fundamental parameters of Be stars located in the seismology fields of COROT
• The life cycles of Be viscous decretion discs: time-dependent modelling of infrared continuum observations
• Prevalence of SED turndown among classical Be stars: Are all Be stars close binaries?
• The first determination of the viscosity parameter in the circumstellar disk of a Be Star
• Be discs in binary systems I. Coplanar orbits
• Disk Loss and Disk Renewal Phases in Classical Be Stars I: Analysis of Long-Term Spectropolarimetric Data
• Properties of the H-alpha-emitting Circumstellar Regions of Be Stars
• Achernar: Rapid Polarization Variability as Evidence of Photospheric and Circumstellar Activity
• The life cycles of Be viscous decretion discs: The case of ω CMa
• Be discs in binary systems: II. Misaligned orbits
• A Parameter Study of Classical Be Star Disk Models Constrained by Optical Interferometry
• Disk-Loss and Disk-Renewal Phases in Classical Be Stars II. Contrasting with Stable and Variable Disks
• A Multi-observing-technique Study of the Dynamical Evolution of the Viscous Disk around the Be Star $\omega$ CMa
• Viscous decretion discs around rapidly rotating stars
• The Large Scale Behaviour in the Disk of $\delta$ Scorpii from 2000-2018
• Differential interferometric phases at high spectral resolution as a sensitive physical diagnostic of circumstellar disks
• Radio observations of IRAS selected southern hemisphere classical Be stars
• The disk physical conditions of 48 Persei constrained by contemporaneous Hα spectroscopy and interferometry

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• Study of the transient nature of classical Be stars using multi-epoch optical spectroscopy