Eruption of recurrent nova V3890 Sgr

Alerts and Monitoring of Novae

Eruption of recurrent nova V3890 Sgr

Postby Robin Leadbeater » Tue Aug 27, 2019 11:19 pm

The recurrent nova V3890 Sgr has erupted (mag 6.7) Eruptions occur only
every ~28 years

Robin

-----Original Message-----
From: Patrick Schmeer pasc1312-aavso@yahoo.de via vsnet-alert
Sent: Tuesday, August 27, 2019 10:52 PM
To: vsnet-alert@ooruri.kusastro.kyoto-u.ac.jp ;
vsnet-outburst@ooruri.kusastro.kyoto-u.ac.jp ;
cvnet-outburst@yahoogroups.com ; baavss-alert@yahoogroups.com
Subject: [vsnet-alert 23506] Re: V3890 Sgr eruption

V3890 Sagittarii (NR+E)
https://www.aavso.org/vsx/index.php?vie ... &oid=31590

Congratulations, Alfredo!
This should be the third recorded eruption, which I had expected
for about 2018 March. Previous eruptions occurred on 1962 June 2
and 1990 April 27.

In recent months I observed V3890 Sgr on almost every night
(weather and moonlight permitting). Unfortunately tonight the
sky has been overcast here, and the two previous evenings it
was too cloudy or hazy low above my southern horizon.

Recent ASAS-SN Sky Patrol (Shappee et al. 2014ApJ...788...48S
and Kochanek et al. 2017PASP..129j4502K) data and light curve:
https://asas-sn.osu.edu/light_curves/d0 ... a43085d9a0
SGRV3890 20190827.048 <160g ASN
Failed observations on Aug. 27.76 UT?

AAVSO data:
https://www.aavso.org/apps/webobs/results/?star=V3890 SGR

Confirmation, spectroscopy, and multiband photometry are
urgently required.

Clear skies,
Patrick Am Dienstag, 27. August 2019, 23:12:45 MESZ hat Alfredo Pereira
alfjspereira@gmail.com via vsnet-alert
<vsnet-alert@ooruri.kusastro.kyoto-u.ac.jp> Folgendes geschrieben:

--
V3890 Sgr outburst

This recurrent nova was found in outburst on 2019 Aug. 27.870 UT, mag 6.7
(Alfredo Pereira, Carnaxide, Portugal).

Alfredo Pereira, Carnaxide, Portugal
--
Last edited by Robin Leadbeater on Thu Aug 29, 2019 10:31 pm, edited 1 time in total.
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Re: Eruption of recurrent nova V3980 Sgr

Postby Hamish Barker » Wed Aug 28, 2019 1:26 am

Cool. We have it nearly at zenith here and the star chart seems to show nothing as bright near it so shout be obvious and easy ( famous last words...)
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Re: Eruption of recurrent nova V3980 Sgr

Postby Francois Teyssier » Wed Aug 28, 2019 4:32 pm

I forward a message of Ulisse Munari

I would be interested to gain support from ARAS observers who could monitor
the eruption of the symbiotic stars and recurrent nova V3890 Sgr

18 30 43.29 -24 01 08.9

that has erupted to a peak 7 mag within the last few hours, and immediately
begun to decline. I'm expecially interested in Echelle spectra, to monitor the
evolution of the broad emisison line profiles. I expect a series of very rapid
changes like we have seen in the 2010 eruption of V407 Cyg (see Figure 5 in the paper in attachment), and spectra at a few hours interval would be needed. Low resolution, broad wavelength range spectra will be useful too.


Note the decline -as all recurrent novae with high mass white dwarf- is very fast. This will be the same for the next nova outburst of T CrB and RS Oph






Note: such as all recurrent novae, the decline is very step
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Re: Eruption of recurrent nova V3980 Sgr

Postby umberto sollecchia » Thu Aug 29, 2019 11:11 am

Bonjour à tous, voici le profil de la nova observée la nuit dernière entre nuages et brume.
Umberto

v389sgr_20190828_908_Umberto Sollecchia.png
v389sgr_20190828_908_Umberto Sollecchia.png (45.97 KiB) Viewed 6606 times


Vitesse radiale
v389sgr_20190828_908_V.R._U Sollecchia.png
v389sgr_20190828_908_V.R._U Sollecchia.png (23.54 KiB) Viewed 6606 times
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Re: Eruption of recurrent nova V3980 Sgr

Postby Terry Bohlsen » Thu Aug 29, 2019 11:33 am

My effort from tonight using a Lospec with a 1200l/mm grating. R=4900.
Terry
_v3890sgr_20190829_412_TBohlsen.png
_v3890sgr_20190829_412_TBohlsen.png (6.2 KiB) Viewed 6599 times
Terry Bohlsen
Armidale NSW
Australia
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Re: Eruption of recurrent nova V3980 Sgr

Postby Joan Guarro Flo » Thu Aug 29, 2019 3:46 pm

Good job Umberto and Terry,

This is the vision with NOU_T echelle spectrograph.

Friendly, Joan.
Attachments
_V3890SGR.png
_V3890SGR.png (18.33 KiB) Viewed 6573 times
_V3890SGR2.png
_V3890SGR2.png (16.96 KiB) Viewed 6573 times
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Re: Eruption of recurrent nova V3980 Sgr

Postby Francois Teyssier » Thu Aug 29, 2019 5:23 pm

That's great!
Congratulations to Joan, Umberto and Terry. And also Pavol Dubovsky who sent a nice low resolution spectrum
Page opened: http://www.astrosurf.com/aras/Aras_DataBase/Novae/2019_NovaV3890Sgr.htm
The nova is so fast (classical behavior for a recurrent nova) that changes at 1 hour timescale is highly probable.

V3890Sgr.PNG
V3890Sgr.PNG (4.39 KiB) Viewed 6560 times


Bonne continuation!
François

PS to Joan: could you send me the spectrum asap, please.
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Re: Eruption of recurrent nova V3980 Sgr

Postby Francois Teyssier » Thu Aug 29, 2019 9:23 pm

The spectrum obtained by Pavol (LISA R=1000):

asdb_v3890sgr_20190828_789.png
asdb_v3890sgr_20190828_789.png (24.71 KiB) Viewed 6528 times


f
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Re: Eruption of recurrent nova V3980 Sgr

Postby Robin Leadbeater » Thu Aug 29, 2019 10:27 pm

Joan Guarro Flo wrote:
This is the vision with NOU_T echelle spectrograph.


Wow ! That has to be one of the most remarkable amateur spectra I have ever seen. Where do all those narrow absorption lines superimposed on H alpha come from ? (The companion star or circumsystem material from previous outbursts ?)

Robin

EDIT: of course they are mainly just Telluric lines :oops:
Last edited by Robin Leadbeater on Fri Aug 30, 2019 3:26 pm, edited 1 time in total.
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Re: Eruption of recurrent nova V3890 Sgr

Postby Francois Teyssier » Fri Aug 30, 2019 5:18 am

A few explanations from Steve Shore:

The symbiotic-like recurrent nova V3890 Sgr has been observed again in outburst and it's a chance to go over a few points in the early spectra.
The rise and decline of such novae is very quick, within the first couple of days the nova has declined a few magnitudes. This is far more rapid than normal unless the ejecta are very low mass and that is the case with these systems. The accretion occurs much like a "normal" symbiotic. That is, the white dwarf is surrounded by a disk formed from either a focussed or freely streaming wind from the giant being intercepted by the degenerate. Since this matter carries angular momentum, it forms a disk and the usual dissipation processes there -- so familiar from cataclysmics and symbiotics -- leads the material to drift inward and accumulate on the white dwarf. This is quite ordinary for a massive WD, one near the stability limit, and the usual thermonuclear explosion results when sufficient mass is accreted. That said, the mass of the compact star is much higher than a normal symbiotic, around 1.3 or 1.4 M_sun relative to less than one solar mass for the symbiotics, so the explosion triggers with less accumulation and is thermonuclear, hence very violent.

The total ejection may be as low as 10^-6M_sun, about 1% of a normal non-recurrent nova, but that's where the similarity ends and the profiles you see in the database begin. The ejecta are not in free expansion, although they are ballistic in origin. That is, they are plowing into an external medium instead of being, essentially, in vacuum. This forms a shock on the interface at the front of the expanding matter that heats and sweeps up gas from the wind. The mass of the ejecta change such that within a matter of days it has engulfed and accelerated about as much gas as was thrown out in the explosion. The shock heats the gas by compression, this is very supersonic (into the wind with a sound speed of a few tens of km/s with an expansion velocityexpansion velocity of a few thousand km/s so you have Mach numbers of hundreds). The heating depends on the square of the Mach number so the temperatures in the post-shocked has reach a few million Kelvin. That is the agent responsible for the narrow near-rest velocity line on Halpha and all other profiles: the shock irradiates the environment before it impacts. This stage, the "precursor", is what causes the vapor cloud in an air nuclear explosion (look at the images of the Bikini test, from the 1950s). That recombines when the shock has reached a portion of the wind, on expansion, of sufficiently low density that it is in breakout" and the ionization rapidly drops. The wind periphery, though, doesn't completely recombine so you see [Fe X] and [Fe XII], among other coronal transitions, and the emission from the recombining Balmer and He lines. Those also chow absorption against the shock from the neutral (not photoionized) parts of the wind along the line of sight. In fact, absorption lines (e.g., P Cyg components), will turn over into emission and broaden as the shock expands.

This is well documented for only a few cases and it's very important for understanding the wind environment and getting a handle on how the ejecta pass through the environment. Some of this is discussed, inthe detailed analysis of one nova, for V407 Cyg (https://ui.adsabs.harvard.edu/abs/2011A%26A...527A..98S/abstract) and V3890 Sgr in a less detailed way ( https://ui.adsabs.harvard.edu/abs/1992A%26A...265...71G/abstract). More coming, this is just background. The other systems, several of which you've been monitoring, are RS Oph, T CrB, and V745 Sco.
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