Short-term variability and mass loss in Be stars

Borre, Camilla C.; Pigulski, A.; Rivinius, Thomas; Wang, Luqian; Martayan, C.; Handler, G.; Panoglou, D.; Carciofi, A. C.; Kuschnig, R.; Mehner, A.; Moffat, A. F. J.; Pablo, H.; Ruciński, S. M.; Wade, G. A.; Weiß, W. W.; Zwintz, K.

doi:10.1051/0004-6361/201834161

Cited by 19 publications

(17 citation statements)

References 82 publications

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“…The modes would be expected to lie in the frequency range between 0.3 and 3 d −1 (Aerts et al 2010). BRITE-Constellation observations are known to be in particular sensitive to frequencies in this range (e.g., Baade et al 2018b;Ramiaramanantsoa et al 2018) because of the observing strategy of the satellites (Weiss et al 2014).…”

Section: Discussionmentioning

confidence: 99%

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Revisiting the pulsational characteristics of the exoplanet host starβPictoris

Zwintz

Reese

Neiner

et al. 2019

A&A

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Context. Exoplanet properties crucially depend on the parameters of their host stars: more accurate stellar parameters yield more accurate exoplanet characteristics. When the exoplanet host star shows pulsations, asteroseismology can be used for an improved description of the stellar parameters. Aims. We aim to revisit the pulsational properties of β Pic and identify its pulsation modes from normalized amplitudes in five different passbands. We also investigate the potential presence of a magnetic field. Methods. We conducted a frequency analysis using three seasons of BRITE-Constellation observations in the two BRITE filters, the about 620-day-long bRing light curve, and the nearly 8-year-long SMEI photometric time series. We calculated normalized amplitudes using all passbands and including previously published values obtained from ASTEP observations. We investigated the magnetic properties of β Pic using spectropolarimetric observations conducted with the HARPSpol instrument. Using 2D rotating models, we fit the normalized amplitudes and frequencies through Monte Carlo Markov chains. Results. We identify 15 pulsation frequencies in the range from 34 to 55 d−1, where two, F13 at 53.6917 d−1 and F11 at 50.4921 d−1, display clear amplitude variability. We use the normalized amplitudes in up to five passbands to identify the modes as three ℓ = 1, six ℓ = 2, and six ℓ = 3 modes. β Pic is shown to be non-magnetic with an upper limit of the possible undetected dipolar field of 300 Gauss. Conclusions. Multiple fits to the frequencies and normalized amplitudes are obtained, including one with a near equator-on inclination for β Pic, which corresponds to our expectations based on the orbital inclination of β Pic b and the orientation of the circumstellar disk. This solution leads to a rotation rate of 27% of the Keplerian breakup velocity, a radius of 1.497 ± 0.025 R⊙, and a mass of 1.797 ± 0.035 M⊙. The ∼2% errors in radius and mass do not account for uncertainties in the models and a potentially erroneous mode-identification.

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Section: Discussionmentioning

confidence: 99%

“…Although BRITE-Constellation observations are sensitive in the low-frequency domain, as was illustrated by Baade et al (2018b) or Ramiaramanantsoa et al (2018), for instance, there is no evidence for the presence of g-modes.…”

Section: Combined Brite Red-filter Datamentioning

confidence: 99%

Revisiting the pulsational characteristics of the exoplanet host starβPictoris

Zwintz

Reese

Neiner

et al. 2019

A&A

Self Cite

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“…The former primaries often appear as hot, subluminous sdO stars that are challenging to detect even in UV spectra (Wang et al [82]) and contribute little flux in the BRITE passbands. However, first photometric Doppler shifts derived from BRITE and SMEI data spanning 25 years have set an upper limit of ∼1 M on the mass of a putative companion of ν Pup (Baade et al [83]).…”

Section: Be Starsmentioning

confidence: 99%

Space Photometry with Brite-Constellation

et al. 2021

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BRITE-Constellation is devoted to high-precision optical photometric monitoring of bright stars, distributed all over the Milky Way, in red and/or blue passbands. Photometry from space avoids the turbulent and absorbing terrestrial atmosphere and allows for very long and continuous observing runs with high time resolution and thus provides the data necessary for understanding various processes inside stars (e.g., asteroseismology) and in their immediate environment. While the first astronomical observations from space focused on the spectral regions not accessible from the ground it soon became obvious around 1970 that avoiding the turbulent terrestrial atmosphere significantly improved the accuracy of photometry and satellites explicitly dedicated to high-quality photometry were launched. A perfect example is BRITE-Constellation, which is the result of a very successful cooperation between Austria, Canada and Poland. Research highlights for targets distributed nearly over the entire HRD are presented, but focus primarily on massive and hot stars.

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“…The most relevant study for this work is Haubois et al (2012) who used the hydrodynamic simulations to show the capability of the VDD model for reproducing the light curves of Be stars. In addition, HDUST was used in several studies where the model predictions were constrained by observations such as visible and infrared photometry (e.g., Carciofi et al 2012;Baade et al 2018a;Rímulo et al 2018;Ghoreyshi et al 2018), radio photometry (e.g., Klement et al 2017Klement et al , 2019, polarimetry (e.g., Carciofi et al 2007Carciofi et al , 2009Faes et al 2016), spec-troscopy (e.g., Carciofi et al 2010;Suffak et al 2020), and spectro-interferometry (e.g., Carciofi et al 2009;Klement et al 2015;Faes et al 2016;de Almeida et al 2020).…”

Section: Hdust Codementioning

confidence: 99%

“…The Viscous Decretion Disk (VDD) model has been successful in reproducing the observed variations of these disks (e.g., Carciofi et al 2009Carciofi et al , 2010Carciofi et al , 2012Klement et al 2015Klement et al , 2017Klement et al , 2019Faes et al 2016;Baade et al 2018a;Rímulo et al 2018;Ghoreyshi et al 2018;de Almeida et al 2020;Suffak et al 2020). In the VDD model, the material ejected by the star carries AM which is redistributed within the disk facilitated by viscosity.…”

Section: Introductionmentioning

confidence: 99%

A Multi-technique Study of the Dynamical Evolution of the Viscous Disk around the Be Star CMa

Ghoreyshi

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The observed emission lines of Be stars originate from a circumstellar Keplerian disk that are generally well explained by the Viscous Decretion Disk model. In an earlier work we performed the modeling of the full light curve of the bright Be star ω CMa (Ghoreyshi et al. 2018) with the 1-D time-dependent hydrodynamics code SINGLEBE and the Monte Carlo radiative-transfer code HDUST. We used the V-band light curve that probes the inner disk through four disk formation and dissipation cycles. This new study compares predictions of the same set of model parameters with time-resolved photometry from the near UV through the mid-infrared, comprehensive series of optical spectra, and optical broad-band polarimetry, that overall represent a larger volume of the disk. Qualitatively, the models reproduce the trends in the observed data due to the growth and decay of the disk. However, quantitative differences exist, e.g., an overprediction of the flux increasing with wavelength, too slow decreases in Balmer emission-line strength that are too slow during disk dissipation, and the discrepancy between the range of polarimetric data and the model. We find that a larger value of the viscosity parameter alone, or a truncated disk by a companion star, reduces these discrepancies by increasing the dissipation rate in the outer regions of the disk.

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Short-term variability and mass loss in Be stars

Cited by 19 publications

References 82 publications

Revisiting the pulsational characteristics of the exoplanet host starβPictoris

Revisiting the pulsational characteristics of the exoplanet host starβPictoris

Space Photometry with Brite-Constellation

A Multi-technique Study of the Dynamical Evolution of the Viscous Disk around the Be Star CMa

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