Investigating the Circumstellar Disk of the Be Shell Star 48 Librae

Abstract

A global disk oscillation implemented in the viscous decretion disk (VDD) model has been used to reproduce most of the observed properties of the well known Be star $\zeta$ Tau. 48 Librae shares several similarities with $\zeta$ Tau -- they are both early-type Be stars, they display shell characteristics in their spectra, and they exhibit cyclic $V/R$ variations -- but has some marked differences as well, such as a much denser and more extended disk, a much longer $V/R$ cycle, and the absence of the so-called triple-peak features. We aim to reproduce the photometric, polarimetric, and spectroscopic observables of 48 Librae with a self-consistent model, and to test the global oscillation scenario for this target. Our calculations are carried out with the three-dimensional NLTE radiative transfer code HDUST. We employ a rotationally deformed, gravity-darkened central star, surrounded by a disk whose unperturbed state is given by the VDD model. A two-dimensional global oscillation code is then used to calculate the disk perturbation, and superimpose it on the unperturbed disk. A very good, self-consistent fit to the time-averaged properties of the disk is obtained with the VDD. The calculated perturbation has a period $P=12$ yr, which agrees with the observed period, and the behaviour of the $V/R$ cycle is well reproduced by the perturbed model. The perturbed model improves the fit to the photometric data and reproduces some features of the observed spectroscopic data. Some suggestions to improve the synthesized spectroscopy in a future work are given.

References in corpus (24)

• The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
• Validation of the new Hipparcos reduction
• Binary interaction dominates the evolution of massive stars
• The Infrared Astronomical Mission AKARI
• The AKARI/IRC Mid-Infrared All-Sky Survey
• VOSA: Virtual Observatory SED Analyzer. An application to the Collinder 69 open cluster
• Classical Be Stars: Rapidly Rotating B Stars with Viscous Keplerian Decretion Disks
• A CHARA Array Survey of Circumstellar Disks around Nearby Be-type Stars
• NLTE Monte Carlo Radiative Transfer: I. The Thermal Properties of Keplerian Disks around Classical Be Stars
• A Statistical Study of Threshold Rotation Rates for the Formation of Disks around Be Stars
• The Thermal Structure of the Circumstellar Disk Surrounding the Classical Be Star gamma Cassiopeia
• First direct detection of a Keplerian rotating disk around the Be star $\alpha$ Arae using the VLTI/AMBER instrument
• Non-LTE Monte Carlo Radiative Transfer: II. Non-Isothermal Solutions for Viscous Keplerian Disks
• Gas Distribution, Kinematics, and Excitation Structure in the Disks around the Classical Be Stars Beta Canis Minoris and Zeta Tauri
• On the Determination of the Rotational Oblateness of Achernar
• Dynamical Evolution of Viscous Disks around Be Stars. II : polarimetry
• The pseudo-photosphere model for the continuum emission of gaseous discs
• Probing the properties of Be star discs with spectroastrometry and NLTE radiative transfer modelling: beta CMi
• Gravity Darkening in Binary Stars
• Disk-Loss and Disk-Renewal Phases in Classical Be Stars II. Contrasting with Stable and Variable Disks
• The Variability of Halpha Equivalent Widths in Be Stars
• 2.5D global-disk oscillation models of the Be shell star ζ Tauri I. Spectroscopic and polarimetric analysis
• New activity in the large circumstellar disk of the Be-shell star 48 Lib
• On the Intrinsic Continuum Linear Polarization of Classical Be Stars: The Effects of Metallicity and One-Armed Density Perturbations

Cited by in corpus (6)

• Prevalence of SED turndown among classical Be stars: Are all Be stars close binaries?
• Revealing the structure of the outer disks of Be stars
• Stellar parameters and H$\alpha$ line profile variability of Be stars in the BeSOS survey
• Surveying the Bright Stars by Optical Interferometry III: A Magnitude-Limited Multiplicity Survey of Classical Be-Stars
• The Large Scale Behaviour in the Disk of $\delta$ Scorpii from 2000-2018
• A peculiar interacting Be star binary in the Small Magellanic Cloud