TY - JOUR
T1 - The eclipsing accreting white dwarf Z chameleontis as seen with TESS
AU - Court, J. M.C.
AU - Scaringi, S.
AU - Rappaport, S.
AU - Zhan, Z.
AU - Littlefield, C.
AU - Castro Segura, N.
AU - Knigge, C.
AU - Maccarone, T.
AU - Kennedy, M.
AU - Szkody, P.
AU - Garnavich, P.
N1 - Funding Information:
CK and NCS acknowledge support by the Science and Technology Facilities Council (STFC), and from STFC grant ST/M001326/1. MK is funded by a Newton International Fellowship from the Royal Society. PS acknowledges support by the National Science Foundation (NSF) grant AST-1514737.
Publisher Copyright:
© 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society
PY - 2019/9/21
Y1 - 2019/9/21
N2 - 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.
AB - 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.
KW - Accretion discs
KW - Cataclysmic variables
KW - Eclipses
KW - Stars: individual: Z Cha
UR - http://www.scopus.com/inward/record.url?scp=85079678736&partnerID=8YFLogxK
U2 - 10.1093/mnras/stz2015
DO - 10.1093/mnras/stz2015
M3 - Article
AN - SCOPUS:85079678736
VL - 488
SP - 4149
EP - 4160
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
SN - 0035-8711
IS - 3
ER -