Call for monitoring of AG Dra by R. Galis & al.

Information about outbursts of eruptive stars, Be activity, ...
Francois Teyssier
Posts: 1520
Joined: Fri Sep 23, 2011 1:01 pm
Location: Rouen
Contact:

Re: Call for monitoring of AG Dra by R. Galis & al.

Post by Francois Teyssier »

The ATel:

The fourth outburst during the present active stage of symbiotic binary AG Dra
ATel #11559; R. Galis, J. Merc (UPJS in Kosice), M. Vrastak (CAS), F. Teyssier, T. Lester, D. Boyd, W. Sims (ARAS Group), L. Leedjarv (Tartu Observatory)
on 22 Apr 2018; 14:23 UT


The symbiotic system AG Dra regularly undergoes quiescent and active stages which consist of several outbursts repeating at about 360d interval (Galis et al. 2017, OEJV 180, 24). After seven years of flat quiescence following the 2006-08 major outbursts, in the late spring of 2015, AG Dra began rising again in brightness toward what appeared to be a new minor outburst (ATel #7582). The recent outburst activity of AG Dra was definitely confirmed by the outbursts in April 2016 and May 2017 (ATel #8975; ATel #10390). The maximal magnitudes (10.7, 9.9 and 10.7 in B filter) rank all these brightenings to the minor outbursts of symbiotic binary AG Dra. Such photometric behavior of the active stage is very unusual. More often, the activity of AG Dra starts with a major outburst, during which the brightness can reach the 8.8 and 8.4 mag in B and V band, respectively. Recent outburst activity resembles the weak activity stage 1963-66 (Hric et al. 2014, MNRAS 443, 1103).
UV and X-ray observations showed that there are two types of outbursts: cool and hot ones (Gonzalez-Riestra et al. 1999, A&A 347, 478). Leedjarv et al. (2016, MNRAS 456, 2558) demonstrated that the outbursts of AG Dra can be clearly distinguished also according to the behavior of the prominent emission lines in optical spectra. High-dispersion spectroscopy confirmed significant increase of equivalent widths (EWs) of the emission lines Hbeta, He II (4686), Halpha, He I (6678), and Raman-scattered O VI (6825) during all three recent outbursts of AG Dra. At the same times, the blue-wing absorption component observed in the profiles of the emission lines He I (6678), H alpha and H beta completely disappeared and HeII/Hbeta flux ratio was higher than 1. Such spectroscopic behavior is typical for the hot outbursts of AG Dra (Munari et a. 2009, PASP 121, 1070; Leedjarv et al. 2016, MNRAS 456, 2558). Here, we report about the onset of a new outburst, the fourth one during the present active stage of AG Dra.
After sharp and short-lasting hot outburst in May 2017 during which magnitudes of AG Dra reached U=10.29, B=10.723, V=9.528, Rc=8.728, and I=8.148 on May 16, 2017 (JD 2457890.439; ATel #10390), the symbiotic binary returned to brightness typical for its quiescence stages (April 2, 2018, JD 2458211.360; U=11.07, B=11.01, V=9.68, Rc=8.80, Ic=8.15, +/- 0.05 in U, 0.03 in B and 0.02 in VRI). Since then, AG Dra has begun a rise in brightness, reaching U=10.82, B=10.95, V=9.67, Rc=8.77, and I=8.13 on April 14, 2018 (JD 2458223.300) and B=10.57, V=9.45, on April 20, 2018 (JD 2458229.329).
As part of ARAS spectroscopic monitoring (link to database below), a mid-resolution spectrum of AG Dra (resolving power 13000, range 4000-7950 Ang) has been obtained with the 31cm telescope on Mill Ridge Observatory, Canada on February 26, 2018 (JD 2458175.883). The ratio HeII/Hbeta was 0.67, EWs were 18.91, 28.11, 97.19, 2.03 and 7.37 Ang for He II (4686), Hbeta, Halpha, He I (6678) and O VI (6825), respectively. For reference, values typical for quiescence of AG Dra are HeII/Hbeta = 0.70, EWs He II 16.5, Hbeta 22.2, Halpha 81.0, He I 1.5 and O VI 6.3 Ang. Low-resolution spectra of AG Dra obtained on April 15, 2018 (JD 2458223.734) and April 18, 2018 (JD 2458227.388) suggested an increase in the ratio of He II/Hbeta. A mid-resolution Echelle spectrum of AG Dra (resolving power 11000, range 4200-7400 Ang) has been obtained on April 20, 2018 (JD 2458229.363) with the 35cm telescope with eShel spectrograph in Rouen, France. The values of the HeII/Hbeta ratio (1.16), as well as EWs of prominent emission lines (He II 37.21, Hbeta 32.20, Halpha 87.97, He I 1.94, O VI 8.72 Ang), confirm that the fourth hot outburst in the present active stage of symbiotic binary AG Dra is in onset.

ARAS Spectral Database

http://www.astronomerstelegram.org/?read=11559


From now, daily monitoring of the event, both low and medium resolution is stongly encourged

Clear skies,

François
James Foster
Posts: 439
Joined: Sun Jan 24, 2016 7:14 am

Re: Call for monitoring of AG Dra by R. Galis & al.

Post by James Foster »

Here is a low resolution spectra of AG Dra (R=870) I imaged on 10Apr18:
Image
Its spectrum is looking more "P Cygni-like" than usual.

Here is a fair-quality LhiresIII Ha spectrum (R=14K) I shot two night ago:
Image
AG Dra's HA line is displaced approximately 2.35A short wards (blue) of the laboratory value of 6562.85A. No RV correction was made and
it looks like the telluric H2O line is a match with the prominent notch in the continuum at 6516.5A


James
James Foster
eShel2-Zwo ASI6200MM Pro
Lhires III (2400/1800/600 ln/mm Grat) Spectroscope
LISA IR/Visual Spectroscope (IR Configured)
Alpy 200/600 with Guide/Calibration modules and Photometric slit
Star Analyzer 200
Christian Buil
Posts: 1431
Joined: Mon Sep 26, 2011 6:59 pm
Contact:

Re: Call for monitoring of AG Dra by R. Galis & al.

Post by Christian Buil »

Two high resolution eShel spectra (at R = 10 000) - moderate exposure time because bad weather conditions (20 mn) :-(

Image
(use of the new CMOS ASI183MM camera)

and

Image

Image

Christian B
Jaroslav Merc
Posts: 27
Joined: Thu May 04, 2017 11:27 am
Location: Prague, Czech Republic
Contact:

The fourth outburst during the present active stage of AG Dr

Post by Jaroslav Merc »

Dear ARAS observers,

according to photometric as well as spectroscopic observations we can confirm that the new outburst of symbiotic system AG Dra is in onset (The Astronomer’s Telegram #11559, http://www.astronomerstelegram.org/?read=11559). It is the fourth hot outburst of this interesting interacting binary during the present active stage.

The previous three outbursts of AG Dra occurred in May 2015, April 2016 and May 2017 (ATel #7582, ATel #8975 and ATel #10390). The maximal magnitudes (10.7, 9.9 and 10.7 in B filter) rank all these brightenings to the minor outbursts of the symbiotic binary. Such photometric behavior of the active stage is very unusual and resembles the weak activity stage 1963–66 (Hric et al. 2014, MNRAS 443, 1103). The onset of new outburst of AG Dra was photometrically confirmed on April 13, 2018 (JD 2 458 222, B = 10.93 +/- 0.02 mag and V = 9.65 +/- 0.02 mag). After next 9 days, the brightness of AG Dra increased by about 0.42 mag and 0.21 mag in B and V filters, respectively. The brightening has occurred after around 340 days after the previous outburst of AG Dra in May 2017 and is still in progress.

The new outburst of AG Dra was confirmed also spectroscopically. Low-resolution spectra of AG Dra obtained by W. Sims on April 15, 2018 (JD 2458223.734) and by D. Boyd on April 18, 2018 (JD 2458227.388) suggested an increase in the ratio of He II/Hbeta. A mid-resolution Echelle spectrum of AG Dra (resolving power 11000, range 4200-7400 Ang) has been obtained on April 20, 2018 (JD 2458229.363) with the 35cm telescope with eShel spectrograph in Rouen, France by F. Teyssier. The increase of the HeII/Hbeta ratio (1.16) as well as equivalent widths of the prominent emission lines (He II 37.21, Hbeta 32.20, Halpha 87.97, He I 1.94, OVI 8.72 Ang) suggest that the outburst is of the hot type (Leedjärv et al. 2016, MNRAS 456, 2558) like the previous three outbursts in the present active stage of AG Dra. Such spectroscopic behavior of the active stage has not been recorded so far. More often, the activity of symbiotic binary AG Dra starts with a major cool outburst followed by a series of lower amplitude events of the hot type.

According to the aforementioned, we kindly ask the ARAS observers for daily spectroscopic monitoring of AG Dra in the coming period as a follow up of photometric observations of this interesting symbiotic system.

Thank you very much in advance.

On behalf of the scientific team,
Rudolf Gális and Jaroslav Merc
James Foster
Posts: 439
Joined: Sun Jan 24, 2016 7:14 am

Re: Call for monitoring of AG Dra by R. Galis & al.

Post by James Foster »

Here is a spectrum of AG Dra I took in the CaK region with my LihersIII (R=4900) last night (23Arp18):
Image
Of course, identification of non-balmer lines is tentative, but it looks like HeI ionization spikes are happening in the near UV.
If anyone is interested, I may go a little deeper in the UV to see if any other interesting activity is happening. I also
have taken near concurrent photometry on this object with a 400mm Nikon lens on a ST-8 (R,V,B) and a C-11 (I,V,B).

James
James Foster
eShel2-Zwo ASI6200MM Pro
Lhires III (2400/1800/600 ln/mm Grat) Spectroscope
LISA IR/Visual Spectroscope (IR Configured)
Alpy 200/600 with Guide/Calibration modules and Photometric slit
Star Analyzer 200
Francois Teyssier
Posts: 1520
Joined: Fri Sep 23, 2011 1:01 pm
Location: Rouen
Contact:

Re: Call for monitoring of AG Dra by R. Galis & al.

Post by Francois Teyssier »

James,
Interesting, but for AG Dra during the outbust, the most important ranges are HeII-Hbeta and the two Raman OVI 6830 and 7080
Of course, your spectra are welcome in the base if you send me the fits
François
Olivier GARDE
Posts: 1243
Joined: Thu Sep 29, 2011 6:35 am
Location: Rhône Alpes FRANCE
Contact:

Re: Call for monitoring of AG Dra by R. Galis & al.

Post by Olivier GARDE »

My last observation of AG Dra taken last night and comparison on several wavelenght with another spectrum taken 4 days ago.
Image

Image
LHIRES III #5, LISA, e-Shel, C14, RC400 Astrosib, AP1600
http://o.garde.free.fr/astro/Spectro1/Bienvenue.html
Francois Teyssier
Posts: 1520
Joined: Fri Sep 23, 2011 1:01 pm
Location: Rouen
Contact:

Re: Call for monitoring of AG Dra by R. Galis & al.

Post by Francois Teyssier »

Very interesting, Olivier
From spectra of the database, one can determine that Raman OVI declined between 04-23 and 04-24
agdra_Ramn.png
agdra_Ramn.png (40.75 KiB) Viewed 7327 times
Daily coverage is strongly expected
François
Christian Buil
Posts: 1431
Joined: Mon Sep 26, 2011 6:59 pm
Contact:

Re: Call for monitoring of AG Dra by R. Galis & al.

Post by Christian Buil »

A spectrum taken the 23.9/04/2018 :

Image

Details of Raman emission :

Image

A VHIRES-MO spectrum at R = 35000 the 24.9/04/2018 :

Image

Image

Image

Christian
Paolo Berardi
Posts: 578
Joined: Thu Sep 29, 2011 10:51 pm

Re: Call for monitoring of AG Dra by R. Galis & al.

Post by Paolo Berardi »

Hi all, I report my 25 April observations with Lhires III and 1200 l/mm grating (spectra sent to François).

Helium / Raman O VI:

Image

Helium / H-beta:

Image

Concerning the trend of the Raman O VI 6830 line, the intensity relative to the continuum in my spectrum (April 25.780) is similar to that of Olivier (April 24.864).

Paolo
Post Reply