U Gem in outburst

Information about outbursts of eruptive stars, Be activity, ...
Francois Teyssier
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U Gem in outburst

Post by Francois Teyssier »

The cataclysmic U Gem has been detected in outburst
It could be still on the rising
Max mag ~ 9
François
Francois Teyssier
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Re: U Gem in outburst

Post by Francois Teyssier »

Tonight spectrum
Broad absorptions for H beta and H gamma
_ugem_20150221_986_fteyssier.png
_ugem_20150221_986_fteyssier.png (18.68 KiB) Viewed 9457 times
François Teyssier
Paolo Berardi
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Re: U Gem in outburst

Post by Paolo Berardi »

François, congratulations for your great spectra (I also see the recent Nova Cyg 2014 observation)! During last U Gem outburst, Vmag remained brighter than 10 for about ten days. Unlike in the previous case, this ouburst occurred in a favourable moment to follow the decline phase.

Ciao!
Paolo
Francois Teyssier
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Re: U Gem in outburst

Post by Francois Teyssier »

Thank you Paolo

U Gem is now at its maximum luminosity
The spectrum looks flat at a first on raw images, but ...

clearly the double peak of the disk in rotation
_ugem_20150223_764_fteyssier.png
_ugem_20150223_764_fteyssier.png (18.39 KiB) Viewed 9409 times
and a crop on Ha
_ugem_20150223_764_ha.png
_ugem_20150223_764_ha.png (12.73 KiB) Viewed 9409 times
with v.sin i ~ 1000 km/s

The disk turns fast !

François
Francois Teyssier
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Re: U Gem in outburst

Post by Francois Teyssier »

Spectre du 24-02
Begening of the decline
_ugem_20150224_759_fteyssier.png
_ugem_20150224_759_fteyssier.png (17.51 KiB) Viewed 9354 times
Note the complexe shape of Balmer lines

The V/R ration of H alpha has changed, in comparison to the previous spectrum (rotation of the disk)
A series of several hours should show the V/R evolution ... (for the next outburst)

Cloudy weather tonight, unfortunatly ...

François
Joan Guarro Flo
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Re: U Gem in outburst

Post by Joan Guarro Flo »

Hi:
Is the U Gem in the 20150225.
J.Guarro.
Attachments
_ugem_20150225_840_J. Guarro.png
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Francois Teyssier
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Re: U Gem in outburst

Post by Francois Teyssier »

During the decline

Noisy, but interesting shape pf H alpha and H beta
_ugem_20150304_776_fteyssier.png
_ugem_20150304_776_fteyssier.png (20.74 KiB) Viewed 9205 times
François Teyssier
Francois Teyssier
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Re: U Gem in outburst

Post by Francois Teyssier »

Tonight spectrum
_ugem_20150305_774_fteyssier.png
_ugem_20150305_774_fteyssier.png (21.92 KiB) Viewed 9196 times
François
Francois Teyssier
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Re: U Gem in outburst

Post by Francois Teyssier »

Nive emission from the disk
See also He I (5876 and 6678)
_ugem_20150306_781_fteyssier.png
_ugem_20150306_781_fteyssier.png (22.5 KiB) Viewed 9168 times
François
Peter Somogyi
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Re: U Gem in outburst

Post by Peter Somogyi »

Nearly started before Francois's last spectra, a 5 hours exposure (with some technical breaks):
_ugem_20150306_793_psomogyi.png
Animated gif of every 2 x 20 minute exposures - except last that was 3 x 20 min:
_ugem_20150306_793_981_psomogyi.gif
_ugem_20150306_793_981_psomogyi.gif (80.31 KiB) Viewed 9140 times
Ref. star was: 79-Gem, taken only 4 times (using averages in between).
Interesting to see the continuum temporary rise while Balmer remains almost there, showing other features.
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