Occultations from an Active Accretion Disk in a 72-day Detached Post-Algol System Detected by K2

Zhou, G. ORCID: https://orcid.org/0000-0002-4891-3517 and Rappaport, S. and Nelson, L. and Huang, C. X. ORCID: https://orcid.org/0000-0003-0918-7484 and Senhadji, A. and Rodriguez, J. E. and Vanderburg, A. and Quinn, S. and Johnson, C. I. and Latham, D. W. and Torres, G. and Gary, B. L. and Tan, T. G. and Johnson, M. C. and Burt, J. and Kristiansen, M. H. and Jacobs, T. L. and LaCourse, D. and Schwengeler, H. M. and Terentev, I. and Bieryla, A. and Esquerdo, G. A. and Berlind, P. and Calkins, M. L. and Bento, J. and Cochran, W. D. and Karjalainen, M. and Hatzes, A. P. and Karjalainen, R. and Holden, B. and Butler, R. P. (2018) Occultations from an Active Accretion Disk in a 72-day Detached Post-Algol System Detected by K2. The Astrophysical Journal, 854 (2):109. pp. 1-18. ISSN 1538-4357

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Disks in binary systems can cause exotic eclipsing events. MWC 882 (BD -22 4376, EPIC 225300403) is such a disk-eclipsing system identified from observations during Campaign 11 of the K2 mission. We propose that MWC 882 is a post-Algol system with a B7 donor star of mass in a 72-day orbit around an A0 accreting star of mass . The disk around the accreting star occults the donor star once every orbit, inducing 19-day long, 7% deep eclipses identified by K2 and subsequently found in pre-discovery All-Sky Automated Survey and All Sky Automated Survey for Supernovae observations. We coordinated a campaign of photometric and spectroscopic observations for MWC 882 to measure the dynamical masses of the components and to monitor the system during eclipse. We found the photometric eclipse to be gray to ≈1%. We found that the primary star exhibits spectroscopic signatures of active accretion, and we observed gas absorption features from the disk during eclipse. We suggest that MWC 882 initially consisted of a ≈3.6 M o donor star transferring mass via Roche lobe overflow to a ≈2.1 M o accretor in a ≈7-day initial orbit. Through angular momentum conservation, the donor star is pushed outward during mass transfer to its current orbit of 72 days. The observed state of the system corresponds with the donor star having left the red giant branch ∼0.3 Myr ago, terminating active mass transfer. The present disk is expected to be short-lived (102 yr) without an active feeding mechanism, presenting a challenge to this model.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Faculty/School / Institute/Centre: No Faculty
Faculty/School / Institute/Centre: No Faculty
Date Deposited: 28 Jan 2022 00:03
Last Modified: 02 Feb 2022 05:06
Uncontrolled Keywords: accretion; accretion disks; binaries: eclipsing; stars: evolution; Astrophysics - Solar and Stellar Astrophysics
Fields of Research (2008): 02 Physical Sciences > 0201 Astronomical and Space Sciences > 020110 Stellar Astronomy and Planetary Systems
Fields of Research (2020): 51 PHYSICAL SCIENCES > 5101 Astronomical sciences > 510109 Stellar astronomy and planetary systems
Socio-Economic Objectives (2008): E Expanding Knowledge > 97 Expanding Knowledge > 970102 Expanding Knowledge in the Physical Sciences
Socio-Economic Objectives (2020): 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280120 Expanding knowledge in the physical sciences
Identification Number or DOI: https://doi.org/10.3847/1538-4357/aaa9b9
URI: http://eprints.usq.edu.au/id/eprint/45054

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