[vsnet-alert 22671] Re: ASASSN-18yi: superhump period

[Yasuyuki WAKAMATSU]

The ephemeris of eclipses based on the epoch of
2018-10-28 22:06:34 (UTC) and the orbital period of 0.16825 d
is as follows,

2018-11-01 18:59:15
2018-11-01 23:01:33

2018-11-02 03:03:50
2018-11-02 07:06:08
2018-11-02 11:08:25
2018-11-02 15:10:43
2018-11-02 19:13:00
2018-11-02 23:15:18

2018-11-03 03:17:35
2018-11-03 07:19:53
2018-11-03 11:22:10
2018-11-03 15:24:28
2018-11-03 19:26:45
2018-11-03 23:29:03

2018-11-04 03:31:20
2018-11-04 07:33:38
2018-11-04 11:35:55
2018-11-04 15:38:13
2018-11-04 19:40:30
2018-11-04 23:42:48

2018-11-05 03:45:05
2018-11-05 07:47:23
2018-11-05 11:49:40
2018-11-05 15:51:58
2018-11-05 19:54:15
2018-11-05 23:56:33

2018-11-06 03:58:51
2018-11-06 08:01:08
2018-11-06 12:03:26
2018-11-06 16:05:43
2018-11-06 20:08:01

2018-11-07 00:10:18
2018-11-07 04:12:36
2018-11-07 08:14:54
2018-11-07 12:17:11
2018-11-07 16:19:29
2018-11-07 20:21:46

2018-11-08 00:24:04
2018-11-08 04:26:21
2018-11-08 08:28:39
2018-11-08 12:30:57
2018-11-08 16:33:14
2018-11-08 20:35:32

> Re: ASASSN-18yi: superhump period
>
>> The mass ratio estimated from the
>> orbital period and superhump period is 0.338(3) d.
>    This estimate also assumes that current superhumps
> are of stage A.  It is worth noting that the outburst
> started on Oct. 19.  Considering that superhumps were
> not yet apparent on Oct. 26, it took 7 days to develop
> superhumps.  This delay is almost comparable to
> WZ Sge-type dwarf novae.  Outbursts appear to have been
> infrequent as judged from the CRTS and ASAS-SN data.
> This object, despite that it is above the period gap,
> the mass-transfer rate may be as low as in WZ Sge-type
> systems and the disk may have reached the tidal truncation
> radius during the current outburst due to the large
> stored mass in quiescence.  This may explain the flat-top
> shape of the outburst (type B outburst in Osaki & Meyer
> 2003, A&A 401, 325).  The outburst may have lasted
> long enough to enable weak tidal instability to develop.
> During this outburst, both variation of the superhump
> period and the disk radius are very important.
> Detailed observations of eclipses (with higher
> time resolutions) as well as superhumps are desired.
> We may also expect post-superoutburst reberightening(s).
>