U Gem in outburst

Information about outbursts of eruptive stars, Be activity, ...

U Gem in outburst

Postby Francois Teyssier » Sat Feb 21, 2015 11:52 pm

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

Postby Francois Teyssier » Sun Feb 22, 2015 1:31 am

Tonight spectrum
Broad absorptions for H beta and H gamma

_ugem_20150221_986_fteyssier.png
_ugem_20150221_986_fteyssier.png (18.68 KiB) Viewed 4272 times


François Teyssier
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Re: U Gem in outburst

Postby Paolo Berardi » Sun Feb 22, 2015 11:56 am

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!
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Re: U Gem in outburst

Postby Francois Teyssier » Mon Feb 23, 2015 9:03 pm

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 4224 times


and a crop on Ha

_ugem_20150223_764_ha.png
_ugem_20150223_764_ha.png (12.73 KiB) Viewed 4224 times


with v.sin i ~ 1000 km/s

The disk turns fast !

François
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Re: U Gem in outburst

Postby Francois Teyssier » Wed Feb 25, 2015 6:50 pm

Spectre du 24-02
Begening of the decline
_ugem_20150224_759_fteyssier.png
_ugem_20150224_759_fteyssier.png (17.51 KiB) Viewed 4169 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
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Re: U Gem in outburst

Postby Joan Guarro Flo » Thu Feb 26, 2015 8:21 pm

Hi:
Is the U Gem in the 20150225.
J.Guarro.
Attachments
_ugem_20150225_840_J. Guarro.png
_ugem_20150225_840_J. Guarro.png (6.49 KiB) Viewed 4137 times
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Re: U Gem in outburst

Postby Francois Teyssier » Thu Mar 05, 2015 5:26 pm

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 4020 times


François Teyssier
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Re: U Gem in outburst

Postby Francois Teyssier » Thu Mar 05, 2015 8:38 pm

Tonight spectrum

_ugem_20150305_774_fteyssier.png
_ugem_20150305_774_fteyssier.png (21.92 KiB) Viewed 4011 times


François
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Re: U Gem in outburst

Postby Francois Teyssier » Fri Mar 06, 2015 9:19 pm

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 3983 times


François
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Re: U Gem in outburst

Postby Peter Somogyi » Mon Mar 09, 2015 9:33 pm

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 3955 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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