The eclipsing accreting white dwarf Z chameleontis as seen with TESS

Court, JMC; Scaringi, S; Rappaport, S; Zhan, Z; Littlefield, C; Castro Segura, N; Knigge, C; Maccarone, T; Kennedy, M; Szkody, P; Garnavich, P

doi:10.1093/mnras/stz2015

The eclipsing accreting white dwarf Z chameleontis as seen with TESS

Court, JMC; Scaringi, S; Rappaport, S; Zhan, Z; Littlefield, C; Castro Segura, N; Knigge, C; Maccarone, T; Kennedy, M; Szkody, P; Garnavich, P

Authors

JMC Court

Dr Simone Scaringi simone.scaringi@durham.ac.uk
Associate Professor

S Rappaport

Z Zhan

C Littlefield

N Castro Segura

C Knigge

T Maccarone

M Kennedy

P Szkody

P Garnavich

Abstract

We present results from a study of TESS observations of the eclipsing dwarf nova system Z Cha, covering both an outburst and a superoutburst. We discover that Z Cha undergoes hysteretic loops in eclipse depth – out-of-eclipse flux space in both the outburst and the superoutburst. The direction that these loops are executed in indicates that the disc size increases during an outburst before the mass transfer rate through the disc increases, placing constraints on the physics behind the triggering of outbursts and superoutbursts. By fitting the signature of the superhump period in a flux-phase diagram, we find the rate at which this period decreases in this system during a superoutburst for the first time. We find that the superhumps in this source skip evolutionary stage ‘A’ seen during most dwarf nova superoutbursts, even though this evolutionary stage has been seen during previous superoutbursts of the same object. Finally, O–C values of eclipses in our sample are used to calculate new ephemerides for the system, strengthening the case for a third body in Z Cha and placing new constraints on its orbit.

Citation

Court, J., Scaringi, S., Rappaport, S., Zhan, Z., Littlefield, C., Castro Segura, N., …Garnavich, P. (2019). The eclipsing accreting white dwarf Z chameleontis as seen with TESS. Monthly Notices of the Royal Astronomical Society, 488(3), 4149-4160. https://doi.org/10.1093/mnras/stz2015

Journal Article Type	Article
Acceptance Date	Jul 11, 2019
Online Publication Date	Jul 31, 2019
Publication Date	2019-09
Deposit Date	Dec 31, 2020
Publicly Available Date	Apr 9, 2021
Journal	Monthly Notices of the Royal Astronomical Society
Print ISSN	0035-8711
Electronic ISSN	1365-2966
Publisher	Royal Astronomical Society
Peer Reviewed	Peer Reviewed
Volume	488
Issue	3
Pages	4149-4160
DOI	https://doi.org/10.1093/mnras/stz2015

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Copyright Statement
This article has been accepted for publication in Monthly notices of the Royal Astronomical Society. ©: 2019 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.