[vsnet-alert 25174] DDE 39 light curve (likely SU UMa star)

Thu Dec 31 21:25:00 JST 2020

ZTF DR4 light curve (Masci et al., 2019):
http://scan.sai.msu.ru/~denis/DDE39-ZTF-DR4-LC.gif

After the outburst to 15.3 detected by ASAS-SN in January 2018
(MJD=58123-58125) the variable has dropped to its lowest level at 19.8m
(M_abs=+11) and showed oscillations between 18-19.5m for the whole year.
Since 2019, the quiescent level has risen to 18.5 with some hints of
activity.

Then there was an outburst to 15.9 on MJD=59125-59126 (2020 Oct. 3-4) in
ZTF Lasair data:
https://lasair.roe.ac.uk/object/ZTF18aabfgpj/

Gaia EDR3 position: 04 02 52.72 +43 55 44.7
Distance 556+/-39 pc, proper motion 37.943 mas/yr, Gmag=18.15+/-0.03
Distance modulus m-M=8.7, M_abs=+9.4 in Gaia band (not taking into account
the extinction)

V=100 km/s appears to be rather large for the average Milky Way star. Got
to search for the possible past components in the surrounding nebula.
Measuring the radial velocity is strongly encouraged while the star is in
outburst.

Wishing the Cataclysmic Variables community the fruitful and productive
2021 year. My personal wishes are for MASTER OT J0426+3541, APA-V1, DDE 196
and DDE 175 to go into outbursts in 2021.

Keep watching!

Denis Denisenko
http://scan.sai.msu.ru/~denis/VarDDE.html