AG Dra in outburst

[Francois Teyssier]

Dear All,



Symbiotic star AG Dra is going into outburst. See ATel 7582



Steve Shore (University of Pisa) asks for spectra of AG Dra, especially in the region of Raman lines



"We have a winner, AG Dra is in outburst. Observations in the region

around the Raman lines, especially now and soon, will be very (!!!)

important. The last major outburst saw the lines disappear, we may get

this again. "



About Raman Lines, see for example :

http://www.astronomie-amateur.fr/feuill ... _7088.html





Spectra at low and high resolution must be sent to francoismathieu.teyssier at bbox.fr for inclusion in ARAS Data base

http://www.astrosurf.com/aras/Aras_Data ... /AGDra.htm

Bonnes observations,

François Teyssier











ATel #7582: The symbiotic binary and super-soft X-ray source AG Dra is going into outburst





The symbiotic binary and super-soft X-ray source AG Dra is going into outburst

ATel #7582; U. Munari (INAF Padova-Asiago), G. L. Righetti, U. Sollecchia, F. Castellani (ANS Collaboration)
on 1 Jun 2015; 10:49 UT



The yellow symbiotic binary and luminous super-soft X-ray source AG Dra is on a steep rise in optical brightness, after seven years of flat quiescence following the 2006-08 multi-maxima outburst episode (Munari et al. 2009, PASP 121, 1070). We are tightly monitoring AG Dra both photometrically and spectroscopically with various ANS Collaboration telescopes and the Asiago 1.22m and 1.82m telescopes. On March 8.923 UT, when the current brightening begun, we measured B=11.301, V=9.885, Rc=9.005, and Ic=8.367, while our last measurement on May 29.883 UT provides B=10.989, V=9.683, Rc=8.822, and Ic=8.228. The start of what looks like as a new outburst episode is marked by a significant lowering of the usually very high ionization conditions: the HeII 4686 / Hbeta ratio has declined from 0.83 in Nov 2014 to 0.67 on May 29.86 UT, and the ratio between OVI Raman scattering at 6830, 7088 and HeI 6678, 7065 has lowered from 3.80 to 1.58. The profiles of emission lines are still broadly similar to those of quiescence, in particular no P-Cyg absorption has yet appeared.


AG Dra is a yellow symbiotic binary, with an orbital period of 550 days and a pulsation one of 355 days (Galis et al. 1999, A&A 348, 533). The high galactic latitude, large radial velocity (-135 km/s) and low metallicity of the K giant donor star ([Fe/H]=-1.3, Smith et al. 1996, A&A 315, 179), point to a partnership of AG Dra with the Galactic Halo. The luminous super-soft X-ray emission was discovered by ROSAT (Greiner et al. 1997, A&A 322, 576). AG Dra went through 3 major outburst periods during the last 50 years, in 1980-82, 1994-96 and 2006-08, each showing multiple maxima. These maxima have either been of the "cool" (probably related to an expansion and cooling of the white dwarf photosphere, with decline/disappearance of high ionization features) and of the "hot" type (probably caused by an enhancement in the wind from the white dwarf, with no reduction in the ionization degree; Gonzalez-Riestra et al. 1999, A&A 347, 478; Skopal et al. 2009, A&A 507, 1531; Shore et al. 2010, A&A 510, A70). During previous outbursts, the X-ray and the optical/UV brightness have been anti-correlated.

[Paolo Berardi]

Hi all, yesterday observations (2 may).

H-alpha (R~16000):



Neutral helium and Raman lines (R~6000):



François, I'll send you all FITS profile.

Paolo

[Tim Lester]

AG Dra for June 3rd compared to my last shot on March 24th (corrected for heliocentric radial velocity).

_agdra_Ha_tlester.png (7.5 KiB) Viewed 8314 times

Tim

[Peter Somogyi]

Fresh material from the day before yesterday (25cm, LHires 2400/mm, 35um slit, 2x2 bin) compared to previous.

Minor H-alpha change:

AGDra_Ha.png (20.56 KiB) Viewed 8251 times

Raman feature:

AGDra_Raman.png (22.61 KiB) Viewed 8251 times

2 hours exposure in total.
Lots of telluric lines I guess (not removed), not just noise.

I don't see any real change.

[Nico Montigiani]

Hi to all.
This is our AG Dra spectrum center on the Raman lines.

AG Dra - 20150606 -zoom- AAF.png (12.63 KiB) Viewed 8222 times

Nico
Associazione Astrofili Fiorentini

[Peter Somogyi]

Taken on Friday night (2x2 bin, ATIK 414 EXm, R~12000, LHiresIII 2400/mm, 35um slit, 25cm Newton):

_agdra_20150612_878_psomogy_Ha.png (14.06 KiB) Viewed 8141 times

I see here again some little change.

_agdra_20150612_921_psomogyi_Raman.png (24.56 KiB) Viewed 8141 times

If there was a change, it is lost in the noise.

Is it still in outburst?

Cheers,
Peter

[Tim Lester]

AG Dra for 2015-08-09 compared to my last result on 2015-06-11 (R=9000)

_agdra_Ha.png (7.46 KiB) Viewed 7943 times

Tim