[vsnet-chat 1665] Re: On the U Sco outburst

["Jan Hers" <janhers@pixie.co.za>]

> Sorry I found it necessary to temper the spirit by reporting my
> negative observation (which I stand by) just (less than 4 hours)
> preceding the alert and my hint of disbelief. I could hardly
> comprehend the 5 magnitude brightening in that time. 
> 
> What has worried me was the hasty jump to conclusions (in either
> direction) made by some of the respectable VSO members before any
> confirmation took place.... 
> 
> On the event itself:
> Is this fast evolution a known fact for NRs or are these first such
> data?  There is the possibility of a wrong observation from my part,
> but I seriously doubt this to be the case... 
> 
> Could this initial steep rise be identical to that of a SN of Type Ia,
> which is known to rise fast. Would the main difference be that in the
> case of a recurrent nova eruption its total mass is not sufficiently
> large to initiate the 'follow through' ?
> 
Frank M. Bateson  in Publ. 7 of the  VSS, RAS of New Zealand, on discussing
the  1979 outburst of U Sco, remarks:
"No observations were made on the rise, but this was obviously very steep,
and probably occurred in a day or two".  No observations are available of
any rise of U Sco except the one in June 1936, where it is stated:
 "Rose from 10.96 to 8.99 in 2 hours 58 minutes"
Data is available for the outbursts of 1863, 1906, 1936  and 1979, but it
seems very likely that other outbursts have occurred, but have been missed.

Jan Hers

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