Symbiotic StHa 169 in outburst

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

Symbiotic StHa 169 in outburst

Post by Francois Teyssier »

http://www.astronomerstelegram.org/?read=9036

The symbiotic star StHa 169 is in outburst, possibly the first ever noted for this object. On Apr 25.9 UT we have measured U=13.133, B=13.617, V=12.823, Rc=11.963, Ic=11.108. Mean quiescence values from the UBVRI photometric catalog of symbiotic stars by Henden and Munari (2008, BaltA 17, 293) are U=16.27 B=15.32 V=13.68, Rc=12.64, Ic=11.54, thus the event is currently showing an amplitude of 3.1 mag in U, 1.7 mag in B, and 0.9 mag in V band. Similar quiescence values characterized our 2009-2015 photometric data, the Kepler satellite observations (Ramsay et al. 2014, MNRAS 442, 489) and the ASAS monitoring of this object (Pigulski et al. 2009, AcA 59, 33).

A spectrum of StHa 169 in outburst has been obtained with the Asiago 1.22m telescope + B&C spectrograph on May 6.93 UT, covering from 3300 to 8000 Ang at 2.31 Ang/pix dispersion. Compared with similar spectra recorded during the 2010-2015 quiescence period, a strong blue continuum now completely overwhelms the M giant absorption spectrum short of 6000 Ang, and the Balmer continuum is now in a much stronger emission. The [NeV] 3426 and the OVI Raman scattering at 6825 Ang, that were weakly present in quiescence, are gone. The emission lines have largely increased their integrated flux. Hbeta flux is 9.3x10(-13) erg/cm2sec, or 6.9 times the average value in quiescence, and HeII 4686 flux is 3.0x10(-13) erg/cm2sec, or 4.4 times the quiescence. The Hbeta/HeII ratio has increased from the average 2.0 of the quiescence to present 3.1 value. The width of emission lines remains sharp with no sign of a P-Cyg profile, and their radial velocity stays close to the mean -92 km/s characterizing quiescence.


A nice target for Alpy, Lisa, Dados 200 l/mm ...

François
David Boyd
Posts: 161
Joined: Wed Dec 11, 2013 5:50 pm

Re: Symbiotic StHa 169 in outburst

Post by David Boyd »

Here is a flux calibrated spectrum of StHa 169 taken last night 12th May. It was relatively faint at V=12.92, B-V=0.88. Unfortunately clouds stopped the run after only 25 mins so the result is quite noisy but the Balmer, He I and He II emission lines are clear.

David
_stha169_20160512_926_D.Boyd_flux.png
_stha169_20160512_926_D.Boyd_flux.png (43.44 KiB) Viewed 5844 times
Francois Teyssier
Posts: 1520
Joined: Fri Sep 23, 2011 1:01 pm
Location: Rouen
Contact:

Re: Symbiotic StHa 169 in outburst

Post by Francois Teyssier »

Nice, despite the low SNR.
Perhaps a new trial this week-end ?
All the best
François
David Boyd
Posts: 161
Joined: Wed Dec 11, 2013 5:50 pm

Re: Symbiotic StHa 169 in outburst

Post by David Boyd »

Here is another flux calibrated spectrum of the symbiotic star StHa 169 taken on 14th May. This was a 75 min run with improved SNR. The star has faded slightly to V=12.98. Measuring the spectrum with ISIS gives Hbeta flux as 9.9x10(-13) erg/cm2/sec and HeII 4686 flux as 3.2x10(-13) erg/cm2/sec. The Hβ/He II line ratio is 3.1.
_stha169_20160514_915_D.Boyd_flux.png
_stha169_20160514_915_D.Boyd_flux.png (29.16 KiB) Viewed 5794 times
This spectrum of StHa 169 during the current outburst is very different from the optical spectrum published in Downes & Keyes, AJ, 96, 777 (1988) (below) which was the basis of StHa 169 being classified as a symbiotic star.
Downes & Keyes spectrum 1988.png
Downes & Keyes spectrum 1988.png (47.24 KiB) Viewed 5800 times
According to Ramsay, Hakala & Howell, MNRAS 442, 489 (2014) the cool component is a pulsating red giant with spectral type around M2III. The nature of the hot component is less clear. They argue that is it not a white dwarf but possibly an A0V star.

David
Peter Somogyi
Posts: 420
Joined: Sun Jul 13, 2014 8:56 am

Re: Symbiotic StHa 169 in outburst

Post by Peter Somogyi »

Had this star a sleeper project for the 2nd half of the night:
asdb_stha169_20160521_941.png
Had some veils meanwhile, basically slept it over.
Comparing to David Boyd's data from 05.14, doing gauss filter of 2.5/ISIS showing only a minor drop of Balmer and HeII 4686 as a difference, otherwise everything very similar (note that my LHires gets defocused in H-gamma). Had to use 1 sec exposures, that is my typical limit for slit-based guiding (means a star roughly at 13 mag, +/-0.5).
I can measure an EW ratio of Hb/HeII of 3.5 in ISIS.

Peter
Francois Teyssier
Posts: 1520
Joined: Fri Sep 23, 2011 1:01 pm
Location: Rouen
Contact:

Re: Symbiotic StHa 169 in outburst

Post by Francois Teyssier »

Excellent results, Peter and David, on that faint target
All the best,
François
Post Reply