[vsnet-alert 25492] Re: SS Cyg: standstill

[Mariko Kimura]

Let me add more information.
I'd like to extract orbital light curve at this standstill state of SS 
Cyg if possible.  I'm using Rc-band data to do this.
Also, B-V color is helpful to investigate what region is bright in the 
disk.
Rc-band time-resolved photometry and B and V-band monitoring are helpful 
at least for my study.

- Mariko

On 2021/03/03 16:15, Mariko Kimura wrote:
> Thank you for your suggestions.
> At least for me, filtered photometry (U, B, V, R, I) is helpful.
>
> - Mariko
>
> On 2021/03/03 12:23, Brian Skiff wrote:
>>       Since this event is on-going and occurring on a genuinely 
>> bright target, would Kato-san or others suggest the most useful 
>> observations to be made?  I think it would be useful to be a little 
>> prescriptive about what is to be done with these very many cv 
>> outbursts.  It seems that the opportunity exists in this case to do 
>> something more use diagnostic than simple unfiltered photometry (i.e. 
>> the usual thing).  Would having, say, U, V, I, or Sloan z (= Paschen 
>> decrement) time-series photometry be helpful?  Time-resolved H-alpha 
>> spectroscopy?  Helium lines?  Polarization?  Spectra in the near-IR?
>>
>>
>> \Brian
>>
>>
>>
>> On Mar 2, 2021, at 5:42 PM, Taichi Kato 
>> <tkato at kusastro.kyoto-u.ac.jp> wrote:
>>
>> Re: SS Cyg: standstill
>>
>>> Akazawa-san and Kasai-san reported their latest observations.
>>> The standstill in SS Cyg seems to be accompanied by oscillatory
>>> variations even at this moment.  Their timescale is around a week.
>>> It would be important to see if SS Cyg enters Z Cam-type standstill
>>> with constant luminosity or repeats oscillations.
>>    It has been documented that some standstills are
>> associated with a hint of mini-outbursts occurring
>> within the standstill at the normal interval
>> frequency (Szkody and Mattei 1984, PASP 96, 988).
>> So, the presence of low-amplitude oscillations
>> may not be a surprise.
>>
>>    It would be noteworthy that the outburst preceding
>> this standstill had a "shoulder" in the light curve
>> at the end of 2020 Dec., particularly evident in
>> Akawaza-san's light curve.  This phenomenon indicates
>> that the disk radius reached the tidal truncation
>> radius during this outburst.  The angular momentum
>> of the disk was maximal during this outburst.
>> The present standstill appears (to me) to be a result
>> of the insufficient removal of the disk mass and angular
>> momentum during this outburst (SS Cyg-type -- currently
>> an ironical term -- outbursts reaching the tidal truncation
>> radius are usually long ones, but this one lacked
>> the flat-topped portion).
>>
>>    The presence of oscillations during the standstill
>> somewhat reminds me of IW And stars.  The present
>> phenomenon might provide a clue in understanding
>> the IW And-type phenomenon and SS Cyg-type phenomenon
>> as a whole.
>