[vsnet-alert 22675] Re: ASASSN-18yi: superhump period

[Yasuyuki WAKAMATSU]

Sorry for my mistake of the ephemeris. I misunderstood the time standard.
A revised ephemeris (UTC) is as follows,

epoch : 2018-10-29 07:06:34 (UTC)
period : 0.16825 d
ephemeris :
2018-11-02 12:03:50
2018-11-02 16:06:08
2018-11-02 20:08:25
2018-11-03 00:10:43
2018-11-03 04:13:00
2018-11-03 08:15:18
2018-11-03 12:17:35
2018-11-03 16:19:53
2018-11-03 20:22:10
2018-11-04 00:24:28
2018-11-04 04:26:45
2018-11-04 08:29:03
2018-11-04 12:31:20
2018-11-04 16:33:38
2018-11-04 20:35:55
2018-11-05 00:38:13
2018-11-05 04:40:30
2018-11-05 08:42:48
2018-11-05 12:45:05
2018-11-05 16:47:23
2018-11-05 20:49:40
2018-11-06 00:51:58
2018-11-06 04:54:15
2018-11-06 08:56:33
2018-11-06 12:58:51
2018-11-06 17:01:08
2018-11-06 21:03:26
2018-11-07 01:05:43
2018-11-07 05:08:01
2018-11-07 09:10:18
2018-11-07 13:12:36
2018-11-07 17:14:54
2018-11-07 21:17:11
2018-11-08 01:19:29
2018-11-08 05:21:46
2018-11-08 09:24:04
2018-11-08 13:26:21
2018-11-08 17:28:39
2018-11-08 21:30:57
2018-11-09 01:33:14
2018-11-09 05:35:32
2018-11-09 09:37:49
2018-11-09 13:40:07


(2018/11/02 2:26), Yasuyuki WAKAMATSU wrote:
> 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).
>>


-- 
若松恭行
京都大学大学院理学研究科宇宙物理学教室
E-Mail:wakamatsu at kusastro.kyoto-u.ac.jp