Symbiotic Nova V1413 Aql high state

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Symbiotic Nova V1413 Aql high state

Postby Francois Teyssier » Wed Jul 11, 2018 5:57 am

Spectroscopic coverage highly recommended
François



http://www.astronomerstelegram.org/?read=11079

The symbiotic nova AS 338 (=V1413 Aql) has gone into outburst in 1981 (Schulte-Ladbeck 1985, Msngr 39, 3), and has not yet returned to quiescence after 36 years. The preceding quiescence was characterized by a mean B=15.7 mag brightness, with a large amplitude modulation caused by irradiation of the M5III giant by the WD companion in a 434 day orbit (Munari 1992, A&A 257, 163). The quiescence spectrum was dominated by strong emission lines betraying high ionization conditions, with HeII 4686 at half the intensity of Hbeta, [FeVII], [NeV] and Raman scattered OVI at 6825 Ang (Allen 1984, PASAu 5, 369). In outburst the spectrum of AS 338 lost and never regained the higher ionization emission lines, with a bright hot continuum dominating optical spectra. The light-curve changed from one dominated by irradiation to deep eclipses of the outbursting WD, while preserving the 434.3 day period and its phasing.
The mean brightness level of AS 338 during the outburst is slowly varying, in a way possibly resembling the long term behavior of MWC 560 (=V694 Mon; Munari et al. 2016, NewA 49, 43). After the initial peak reached at V~10.5 in 1983, which was followed by an extremely tedious decline to V~13.2 by 1992, the nova underwent two large re-brightening in 1995 (reaching V~11.0) and 2010 (at V~11.5), declining to a minimum V~13.7 in between. A rise toward a new maximum seems now underway.
We are keeping AS 338 under strict monitoring since 2005, collecting BVRI photometry with various ANS Collaboration telescopes and low- and high-res spectra with the Asiago 1.22m and Varese 0.61m telescopes. After an unusual profile for the last eclipse (centered on 2017 July 7 when we measured B=15.274, V=14.682, R=12.952, I=11.668), the star levelled off and it was measured at B=14.453, V=13.743, R=12.381, I=11.270 on 2017 Dec 6.7, after which it begun a steep rise in brightness bringing it to B=13.175 on Dec 16.7 and B=12.645 V=11.863, R=11.080, I=10.287 on Dec 19.7 (UT), for a mean rise in the B band of 0.18 mag/day. Even larger are the associated spectral changes. High emission lines (in particular HeII 4686 Ang), which have been absent or at most very weak throughout the 36 years of the outburst, including the bright phases of 1995 and 2010, were barely traceable also on our spectrum for 2017 Nov 30, taken just a few days before the onset of the current steep rise in brightness. A new spectrum taken on 2017 Dec 20.7, show now instead a bright 4640 NIII complex and a prominent HeII 4686, about half the intensity of Hbeta, plus stronger than ever HeI lines.
This symbiotic nova is obviously worth a strict monitoring to trace if the current steep rise in brightness will mature into a full flagged third bright phase, following those of 1995 and 2010, and if the spectral evolution will confirm the "hot" nature of the present event compared to the "cool" type of the previous two, an alternance already seen in AG Dra.
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Re: Symbiotic Nova V1413 Aql high state

Postby Tim Lester » Fri Jul 13, 2018 6:38 pm

Here is my try at V1413 Aql with echelle spectroscopy. Difficult as the current V Mag is approx. 12.5 to 13 according to AAVSO.

v1413aql_20180712_107_tlester_1.png

v1413aql_20180712_107_tlester_2.png


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Re: Symbiotic Nova V1413 Aql high state

Postby Francois Teyssier » Sat Jul 14, 2018 7:15 am

A difficult target at that luminosity. Good result!
The long term AAVSO lightcurve, with 1995 and 2015 outbursts
V1413Aql.PNG
V1413Aql.PNG (17.42 KiB) Viewed 835 times



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Re: Symbiotic Nova V1413 Aql high state

Postby Vincent Bouttard » Thu Jul 26, 2018 2:03 pm

Hi,

A spectrum of V1413 Aql last night at low resolution (Alpy600 + Newton 250 F/4 + Atik 460EX, 12 x 300s,R = 606)

V1413Aql_20180725_920.png
V1413Aql_20180725_920.png (7.75 KiB) Viewed 743 times


Start of exposure at 22h TU (H = +61 deg.)
End of exposure at 23h TU (H = +62 deg.)
Reference star : HD182919 (A0V) at H = +63 deg.

Vincent
VBO @ ARAS database : Newtonian 250 mm F/4 / Alpy600 / Atik 460EX
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Re: Symbiotic Nova V1413 Aql high state

Postby Francois Teyssier » Thu Jul 26, 2018 4:51 pm

The variations of this star are impressive (even for a symbiotic)
A monitoring at higher cadency (say at least one/month) should be very welcome.

V1413Aql.PNG
V1413Aql.PNG (68.78 KiB) Viewed 727 times


J'attends ton spectre avec impatience, Vincent

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