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[vsnet-obs 748] Re: Double-peaked max. of AY Lyr
- Date: Tue, 11 Jul 1995 08:41:59 +0200 (METDST)
- To: vsnet-obs@kusastro.kyoto-u.ac.jp
- From: Erik Kuulkers <erik@xray.estec.esa.nl>
- Subject: [vsnet-obs 748] Re: Double-peaked max. of AY Lyr
- In-Reply-To: <199507102225.AAA22638@nic.INbe.net> from "Tonny Vanmunster" at Jul 11, 95 00:25:32 am
- Reply-To: vsnet-obs@kusastro.kyoto-u.ac.jp
- Sender: owner-vsnet-obs@kusastro.kyoto-u.ac.jp
>
> A few days ago, Lasse Jensen listed some of his AY Lyr observations,
> that clearly indicate the existence of a double-peaked maximum.
>
> Double-peaked maxima, although not at all common, have been observed
> and/or suspected in a number of UGSU-type dwarf novae. Some examples
> recently were quoted in the CVC's.
>
> I think there is no sound theoretical explanation yet for the observed
> behaviour ...
>
> Regards,
> Tonny
>
The double peak is caused by a normal outburst just preceding the
superoutburst. The first peak always lasts in the order of a few days, and
resemble the normal outbursts. Just when the normal outbursts declines
in brightness the superoutburst starts, causing the second peak. Then
the "normal" superoutburst features appear, such as superhumps.
It is thought that normal outbursts always precede a superoutbursts.
When the normal outburst is very close to the start of a superoutburst,
one can not distinguish the two outbursts any more, and just one
peak occurs, as is normally the case.
One thinks that the normal outbursts trigger the superoutbursts.
A few people have modeled this behaviour.
Regards,
Erik Kuulkers
References: