ASASSN-25dc; a new candidate of a WZ Sge-type dwarf nova with the double
superoutburst
ASASSN-25dc was discovered by ASAS-SN on 2025-07-13.09 UTC at g=13.07. This
outburst is also observed by ATLAS, o~15.2 mag on 2025-07-07.8 UTC and
o~13.5 mag on 2025-07-10.9 UTC. The likely counterpart is Gaia
DR3 6129070308813533568 with G~21.0 mag, hence the outburst amplitude is
~7.0 mag.
This system underwent a short dip on 16-17th July, around 14.5 mag, and is
now recovering from the dip.
Lesedi telescope at Sutherland, Josch Hambsh, and Berto Monard have
reported the time-resolved observations of ASASSN-25dc. PDM analysis using
the overall data yields a single-peaked modulation with a period of
0.05991(4) d and an amplitude of 0.03 mag. Combining the 1-mag dip feature
on the light curve and short superhump period, ASASSN-25dc can be a similar
system to double-superoutburst WZ Sge-type dwarf novae, especially the
period-bouncer candidates ASASSN-15jd and ASASSN-16hg (see Kimura et al.
2016,2018).
https://arxiv.org/abs/1604.06344https://arxiv.org/abs/1803.03179
The ongoing second outburst should show the evolution of ordinary
superhumps. The hint of ordinary superhumps is seen in the observations on
17th July. Further time-resolved observations are encouraged.
Best regards,
Yusuke
--
----------------------------------------------
South African Astronomical Observatory, Postdoc fellow
Yusuke TAMPO / ๅไฟ ้ไป
EMAIL: tampo(a)kusastro.kyoto-u.ac.jp
ALT. EMAIL: yusuke(a)saao.ac.za
----------------------------------------------