PNV J19150199+0719471 in Aql

[Francois Teyssier]

Outburst detected in Aquila :



CCD image by Koichi Itagaki of PNV J19150199+0719471:
http://www.k-itagaki.jp/images/pnv-aql.jpg


Today Koichi Itagaki's (Yamagata, Japan) discovery of
a possible magnitude 10.8 nova in Aquila was reported.
Please have a look!
http://www.cbat.eps.harvard.edu/unconf/ ... 19471.html


Should be a Cataclysmic WZ Sge type according to Patrick Schmeer on CBA list .
Spectroscopy requested

PNV J19150199+0719471

Newly discovered probable WZ Sge-type dwarf
nova in Aquila, currently at magnitude V=10.6
(discoverer: Koichi Itagaki (Yamagata, Japan)).
http://www.cbat.eps.harvard.edu/unconf/ ... 52504.html

Astrometry and photometry by Enrique de Miguel:
R.A. 19:15:02.047 decl. +07:19:46.78 (J 2000.0)
2013 June 1.01 UT, V = 10.56, B = 10.40 (private message).

The blue colour and the large proper motion indicate that
PNV J19150199+0719471 (= IPHAS J191502.09+071947.6?)
is probably a dwarf nova in outburst (Taichi Kato,
vsnet-alert 15768).

According to the PPMXL catalog this object has a
large proper motion:
pmRA = -97.4 mas/yr and pmDE = -93.8 mas/yr.

PNV J19150199+0719471 is probably not a nova but
a nearby WZ Sge-type dwarf nova in outburst.
Spectroscopy and time-resolved photometry are strongly
recommended.

[Martin Dubs]

Hello Francois,

based on your alert, Thomas Eversberg and his team at IAC80 on Teide took some time from the WR campaign to observe the suspected nova with the echelle spectrograph. I had the opportunity to reduce the spectrum with ISIS. Lothar Schanne also reduced the spectrum with MIDAS. We both get the same result, shown below.
The spectrum of H-alpha seems to be consistent (I am no expert on dwarf novae) with a dwarf nova of WZ Sge type, with a double peak indicating a radial velocity of 3.6 A or +/-82 km/sec. Some other lines He 6678 and 3 additional at 6590 (Carbon?) can also be seen.
More to follow.

Regards, Martin

[Francois Teyssier]

Excellent
Thank you for forewarding the alert
Congratulations to the team at Teide
This obviously a cataclysmic in outburst with emission in the absorption line
And double pic (disk)
Francois

[Martin Dubs]

Hello Francois,

looking a bit closer at the spectra above I noticed that most lines except H-alpha correspond to lines also present in the sky background, recorded earlier. Apparently the removal of blaze function of this very weak signal with a dark sky at 2400 m altitude does not work very well for the merged echelle spectrum, a common problem. But it is sufficient for the comparison of the emission lines in both spectra.

comparison of nova spectrum with sky background, scaled and shifted for clarity

comparisonnovaAql_sky.png (17.37 KiB) Viewed 16348 times

sky: 1x600sec
nova: 3x600sec

Regards, Martin

[Robin Leadbeater]

Here is a quick look tonight (20min with Alpy) I have an hour total which I will reduce properly later today

Cheers
Robin

[Francois Teyssier]

Nice spectrum Robin. Waiting for the full treatment.
He I 5876 seems obvious.

The lines in cataclysmics stars in outburst are not numerous.
Here's a list (main lines in bold) from Warner 1995 ("La Bible des cataclysmiques")



All the lines are formed in the accretion disk. Contribution of the WD and red companion is negligible
The contents of the disk are solar type material (materail escaping from the main sequence star throw Lagrangian point and orbiating around the white dawrf) which explains la nature of the few lines detected in a CV (H, He, C, N)
The line profile is explained by the formation of the line in an heterogeneous disk, with different temperatures depending of the distance from the WD : from "low" (5000 K) to "high" (15000 K) : some parts create broad absorption while others create narrower emission. Thus, the typical profiles of narrow emission components in broader absorption. The ratio is different for each line and varies rom day to day. For Higher excitation lines such He II of CIII/NIII, there's essentially emission.

Note that a superouturst lasts about 10 days (magnitude declines of about 1 mag) before a steeper decrease.

Best regards

François

[Martin Dubs]

Hello all,

in my previous post I assigned the narrow lines to the sky background as they appear in that spectrum as well. This is not correct, as Lothar Schanne pointed out, they are caused by the memory effect of the CCD and are actually lines from the preceeding ThAr calibration, so mostly Ar lines and the He I line at 6678. The nova lines are much broader and double peaked, barely visible besides H-alpha. Detected are the He I at 5876 A and H-beta at 4861 A.

Martin

[Christian Buil]

An observation from the center of Paris (V. Desnoux St Charles observatory) !





Very first light of a production Alpy 600 (the setup is not optimal,
because the C9.25 telescope work at f/10 i.e. lost of 2-3x of the
potential flux - but in consequence, light
pollution is not very critical, ... )

The spectrum (noisy, but the Halpha emission is clearly visible + more) :



In the same fisrt light session, a spectrum of CH Cyg:



Christian

[Robin Leadbeater]

Here is my reduced spectrum from last night 3x 1200 sec alpy 600 C11 ~f6.3 (The focal reducer works much better now it is at its design distance )
The drop off at the blue end compared with Christian's spectrum is probably due to atmospheric extinction as the target was at much lower elevation than the reference star I used to calculate the instrument response.

Robin

[Martin Dubs]

Hello,

here another spectrum from IAC80 at Teide (the last one), in comparison with the spectrum from the previous night. Care was taken to avoid the memory image of the ThAr calibration, exposure time 5x600 sec (previous spectrum 3x600 sec):

spectra of nova Aql compared with previous night.

comparison novaAql 24h.png (13.37 KiB) Viewed 16210 times

Unfortunately the telescope is reserved for the WR campaign, so no more spectra wil be produced. For a study of the rotating disk structure a full time campaign would probably be necessary, which cannot be done since the WR stars and the nova cannot be observed at differnt times, rising at around the same time.
But it gave me the opportunity to learn something about a new type of object.

Regards, Martin