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A truncation model for the Be star alpha col

Grant number: 18/13285-7
Support Opportunities:Scholarships abroad - Research Internship - Master's degree
Start date: October 22, 2018
End date: March 21, 2019
Field of knowledge:Physical Sciences and Mathematics - Astronomy - Stellar Astrophysics
Principal Investigator:Alex Cavaliéri Carciofi
Grantee:Amanda Caveagna Rubio
Supervisor: Carol Evelyn Jones
Host Institution: Instituto de Astronomia, Geofísica e Ciências Atmosféricas (IAG). Universidade de São Paulo (USP). São Paulo , SP, Brazil
Institution abroad: Western University , Canada  
Associated to the scholarship:17/08001-7 - Searching for invisible binary companions of Be stars, BP.MS

Abstract

Be stars are fast rotating B type stars that, through the elusive Be phenomenon, eject mass into orbit, forming an equatorial viscous Keplerian disk. When a Be star is in a sufficiently close binary system, the presence of the companion can disrupt the Be disk. This includes the formation of two-armed structures, density waves, and, in its strongest form, disk truncation. While the companion itself can be elusive, the truncation can be detected in the stellar spectral energy distribution (SED) of the Be star, as it causes a steeping in the spectral slope at centimetre wavelengths (SED turndown). Such a characteristic has been detected for 8 out of 8 studied Be stars, one of which is alpha Col, whose disk truncation was discovered during the student's MsC work. The goal of this project is to model the disk truncation of alpha Col using a 3D SPH code in order to define its structure and the orbital parameters of the system. It is worth noting that this will be the first time that the SED of a Be star is modelled using SPH hydrodynamic simulations. As such, this study will represent a major step forward in our understanding of the physics behind the truncation and will further cement studies of the radio SED as an indirect mean of detecting companions around Be stars, improving the current statistics for binarity among them. This work will contribute to a major issue regarding Be research, which is the importance of binarity in Be stars in how B stars acquire their fast rotation. (AU)

News published in Agência FAPESP Newsletter about the scholarship:
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Scientific publications
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
RICHARDSON, NOEL D.; THIZY, OLIVIER; BJORKMAN, JON E.; CARCIOFI, ALEX; RUBIO, AMANDA C.; THOMAS, JOSHUA D.; BJORKMAN, KAREN S.; LABADIE-BARTZ, JONATHAN; GENARO, MATHEUS; WISNIEWSKI, JOHN P.; et al. utbursts and stellar properties of the classical Be star HD 622. Monthly Notices of the Royal Astronomical Society, v. 508, n. 2, p. 2002-2018, . (18/05326-5, 09/54006-4, 18/13285-7, 18/04055-8, 17/08001-7)
MARR, K. C.; JONES, C. E.; CARCIOFI, A. C.; RUBIO, A. C.; MOTA, B. C.; GHOREYSHI, M. R.; HATFIELD, D. W.; RIMULO, L. R.. The Be Star 66 Ophiuchi: 60 Years of Disk Evolution. ASTROPHYSICAL JOURNAL, v. 912, n. 1, p. 15-pg., . (18/04055-8, 17/08001-7, 18/13285-7, 09/54006-4)