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arXiv · 2109.11026

Outbursts and stellar properties of the classical Be star HD 6226

Noel D. Richardson·Olivier Thizy·Jon E. Bjorkman·Alex Carciofi·Amanda C. Rubio·Joshua D. Thomas·Karen S. Bjorkman·Jonathan Labadie-Bartz·Matheus Genaro·John P. Wisniewski·Luqian Wang·Douglas R. Gies·S. Drew Chojnowski·Andrea Daly·Thompson Edwards·Carlie Fowler·Allison D. Gullingsrud·Nolan Habel·David J. James·Emily Kehoe·Heidi Kuchta·Alexis Lane·Anatoly Miroshnichenko·Ashish Mishra·Herbert Pablo·Maurice Peploski·Joshua Pepper·Joseph E. Rodriguez·Robert J. Siverd·Keivan G. Stassun·Daniel J. Stevens·Jesica L. Trucks·James Windsor·Mackenna Wood·Étienne Bertrand·Jean-Jacques Broussat·Erik Bryssinck·Christian Buil·Stéphane Charbonnel·Arnold de Bruin·Joe Daglen·Valerie Desnoux·James Dull·Olivier Garde·Keith Graham·Kevin Gurney·Alun Halsey·Patrik Fosanelli·Joan Guarro Fló·Franck Houpert·Foster James·Christian Kreider·Robin Leadbeater·Tim Lester·Dong Li·Alain Maetz·Albert Stiewing·Peter Somogyi·Jean-Noël Terry·Stéphane Ubaud·Ulrich Waldschlaeger
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Abstract

The bright and understudied classical Be star HD 6226 has exhibited multiple outbursts in the last several years during which the star grew a viscous decretion disk. We analyze 659 optical spectra of the system collected from 2017-2020, along with a UV spectrum from the Hubble Space Telescope and high cadence photometry from both TESS and the KELT survey. We find that the star has a spectral type of B2.5IIIe, with a rotation rate of 74% of critical. The star is nearly pole-on with an inclination of $13.4$ degree. We confirm the spectroscopic pulsational properties previously reported, and report on three photometric oscillations from KELT photometry. The outbursting behavior is studied with equivalent width measurements of H$\alpha$ and H$\beta$, and the variations in both of these can be quantitatively explained with two frequencies through a Fourier analysis. One of the frequencies for the emission outbursts is equal to the difference between two photometric oscillations, linking these pulsation modes to the mass ejection mechanism for some outbursts. During the TESS observation time period of 2019 October 7 to 2019 November 2, the star was building a disk. With a large dataset of H$\alpha$ and H$\beta$ spectroscopy, we are able to determine the timescales of dissipation in both of these lines, similar to past work on Be stars that has been done with optical photometry. HD 6226 is an ideal target with which to study the Be disk-evolution given its apparent periodic nature, allowing for targeted observations with other facilities in the future.

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Noel D. Richardson, Olivier Thizy, Jon E. Bjorkman, Alex Carciofi, Amanda C. Rubio, Joshua D. Thomas, Karen S. Bjorkman, Jonathan Labadie-Bartz, Matheus Genaro, John P. Wisniewski, Luqian Wang, Douglas R. Gies, S. Drew Chojnowski, Andrea Daly, Thompson Edwards, Carlie Fowler, Allison D. Gullingsrud, Nolan Habel, David J. James, Emily Kehoe, Heidi Kuchta, Alexis Lane, Anatoly Miroshnichenko, Ashish Mishra, Herbert Pablo, Maurice Peploski, Joshua Pepper, Joseph E. Rodriguez, Robert J. Siverd, Keivan G. Stassun, Daniel J. Stevens, Jesica L. Trucks, James Windsor, Mackenna Wood, Étienne Bertrand, Jean-Jacques Broussat, Erik Bryssinck, Christian Buil, Stéphane Charbonnel, Arnold de Bruin, Joe Daglen, Valerie Desnoux, James Dull, Olivier Garde, Keith Graham, Kevin Gurney, Alun Halsey, Patrik Fosanelli, Joan Guarro Fló, Franck Houpert, Foster James, Christian Kreider, Robin Leadbeater, Tim Lester, Dong Li, Alain Maetz, Albert Stiewing, Peter Somogyi, Jean-Noël Terry, Stéphane Ubaud, Ulrich Waldschlaeger. 2021-09-22. Outbursts and stellar properties of the classical Be star HD 6226. https://doi.org/10.1093/mnras/stab2759

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