[vsnet-alert 24256] Re: SU UMa: lack of outbursts

[Robin Leadbeater]

A low resolution (R~500) spectrum at 20200503.972
https://britastro.org/specdb/data_graph.php?obs_id=6447&legend_pos=ne
(To faint in quiescence to time resolve anything during an orbital period 
with my equipment)

Robin

-----Original Message----- 
From: Taichi Kato
Sent: Sunday, May 03, 2020 6:19 AM
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Subject: [vsnet-alert 24251] SU UMa: lack of outbursts

SU UMa: lack of outbursts

   As already reported in vsnet-alert 24190 (Apr. 17),
there have been no outbursts in SU UMa recently.

ASAS-SN data:
https://asas-sn.osu.edu/light_curves/f40af148-0984-4e25-835d-617e7c6d87e3

   Could this be a standstill, or a special state of
quiescence without causing thermal instability?

   Such a state appears to be very rare (at least not
seen in the last 25 years).  I remember the instance
in 1986, when SU UMa was targeted to search for
superhumps but the system didn't undergo outbursts
at all as planned (and resulting a delay in detection
of superhumps in this prototype star).
There was also an interval without normal outbursts
in 1990.  No time-resolved photometry or spectroscopy
were obtained at that time.  Although I'm not sure
what signal may be present, observations of such
a state would be interesting (any superhumps,
positive or negative?) 


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