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Approximate RA 21 04 05.0 DEC +46 31 13.0

The bright WZ Sge-type dwarf nova TCPJ21040470+4631129 was discovered on July 12, 2019. There have been several rebrighenings and a second super outburst. See Atel# 12947, Atel#13009 for more details. A number of our ARAS group have been participating in the investigation by taking spectra and/ or photometry.

Dr. Vitaly Neustroev, an astrophysicist at University of Oulu in Finland has kindly asked for new spectra and BVRI photometry on this target as part of a continuing investigation. He reports that after having gone faint, this target is bright again with a magnitude of approximately 10.8 on 20191209.93. It is not certain whether this current event is a rebrightening or a super outburst. This event phase could end within days so quick followup is highly necessary.

So it should be a good target for Alpy, LISA and I would think Echelle spectrographs. Please submit spectrum to the ARAS database.

Per Eric W. Weissstein (http://scienceworld.wolfram.com/astrono ... fNova.html ) Dwarf Novae are a class of nova and cataclysmic variable that have multiple observed eruptions ranging in brightness from 2 to 5 magnitudes. Outburst intervals for each object are quasi-periodic, but within the DN family, intervals can range from days to decades. The lifetime of an outburst is typically from 2 to 20 days and is related to the outburst interval. DN outbursts are usually attributed to the release of gravitational energy resulting from an instability in the accretion disk or by sudden mass-transfers through the disk.

Please note that the artifact in my spectrum at about 4358Å is not real but probably HgI light pollution that I have not figured out yet how to remove from the spectrum.

Here is a spectrum I took last night with a Shelyak LISA.

Thank you.
Woody Sims

Here is another spectrum of this WZ Sge dwarf nova taken about 16 hours after Woody's. It is a composite of 24 300 sec integrations taken with a LISA (R~1000) on a C11 scope. I have flux calibrated the spectrum using a concurrently measured mean V magnitude of 10.99. The level of the continuum flux is almost identical to a spectrum I recorded on 24 July as it was fading from its first superoutburst.
I also recorded the following BVRcIc photometry over 2.6 hrs before it disappeared behind some trees. The light curve shows modulation at a period of around 0.055 d which is consistent with the superhump period found during the earlier superoutburst indicating that this may indeed be another superoutburst.
Observations have been sent to Vitaly Neustroev and the ARAS database.

David

Congratulations!
There's also a spectrum obtained by Paolo Berardi at R = 5000.

I moved the topic to the Cataclysmic Stars section as the outburst is not a nova event.

The terminology is confusing since it is based on the photometric behavior well before than the phenomena were understand.
Moreover, the *same* system can produce 3 kinds of events :
- dwarf nova outburst: instability of the accretion disk, heating from ~ 5000 to 20000 K (producing a hot, blue continuum). Frequency from a few days to a few years. Delta mag 1 to 8.
- nova outburst: nuclear runaway in the accreted envelop at the surface of the white dwarf and expulsion of an ejecta. Frequency from several years (recurrent novae) to thousands (?) of years.
- supernova type Ia: explosion of the white dwarf when its mass Chandrasekar limit (~ 1.4 solar mass). Frequency: 1/system as the WD is almost destroyed during the event. Note: this scenario is still an hypothesis because the mass balance during accretion phase and novae event remains uncertain, i.e. does the white dwarf gains or looses mass. This is a very important subject of research: calculation of the mass of the ejecta.

This is the very basic scheme.

Eric W. Weissstein's page is very confused and doesn't help.

François

Sorry for the delay...

My spectrum (sum) of H-alpha region




A single 600s frame profile for the time-resolved spectroscopy



Clear sky!

Paolo

Forrest Sims wrote:Approximate RA 21 04 05.0 DEC +46 31 13.0

Dwarf Novae are a class of nova and cataclysmic variable that have multiple observed eruptions ranging in brightness from 2 to 5 magnitudes.

This is a WZ Sge type so typically will have a much larger brightness increase than this >7 magnitudes

Cheers
Robin

Hi all,

Vitaly Neustroev recently alerted us to the need for photometry and spectroscopy for TCP J21040470+4631129 to cover the period before during and after planned HST observation for the night of April 9/10. But the HST plan changed as TCP J21040470+4631129 has just gone into another superoutburst. David Boyd was able to get photometry on it on the night of March 28 and again on March 31. The V magnitude went from 15.408+/- 0.053 to 10.826+/- 0.018. In this magnitude range it is well in the reach of Alpy and LISA spectrographs. Here is a spectrum from this morning taken with my LISA.

Woody Sims

Excellent!
I recall the summary of observations of this very peculiar dwarf nova written by David this last issue of the newsletter:
http://www.astrosurf.com/aras/novae/Inf ... 019-04.pdf

François

This is also the subject of AAVSO alert 703 where there has been separate request from Dr. Juan Echevarria (Instituto de Astronomia, UNAM) for spectra covering H alpha (also posted via spectro-l)
https://www.aavso.org/tcp-j210404704631 ... gn-2020-02

(Woody - your spectrum would qualify)

Cheers
Robin

Robin,
We are closely working with Vitaly Neustroev since the begining of the outburst with already 3 ATels
and of course the preparation of a publication when the current active state will be over.

https://ui.adsabs.harvard.edu/abs/2019A ... N/abstract
https://ui.adsabs.harvard.edu/abs/2019A ... N/abstract
https://ui.adsabs.harvard.edu/abs/2019A ... N/abstract

François

Francois Teyssier wrote:Robin,
We are closely working with Vitaly Neustroev since the begining of the outburst with already 3 ATels

Yes but the universe is still open to everyone and the ARAS policy is our results are available to anyone who wants to use them or is this a private arrangement ?

Robin