Symbiotic Type Star Spectroscopy
 Shelyak Alpy 600 & 80mm f/6 APO
Jim Ferreira, Livermore CA




CH Cygni, Symbiotic Star, Alpy 600



CI Cygni, Symbiotic Star, Alpy 600
CI Cygni is a symbiotic star, a combination of both a hot 'B' type star and a much cooler 'M' type giant star.  The pair of stars are surrounded
by a cloud of H and He.
  The hot 'B' star ionizes portions of the cloud producing the emission peaks present in the above spectra.


Chi Cygni, Alpy 600 spectrograph
Chi Cygni is a Mira type variable star with a 407 day period, spectra recorded post-2014-maxima while star at ~8.0 magnitude


AG Peg spectra, Symbiotic Star, Alpy 600
AG Peg is a spectroscopic binary consisting of a WN6 Wolf-Rayet type star and a M III red giant


V0694 Mon spectroscopy, Alpy 600

V694 Mon [MWC 560] is a 'symbiotic' binary system consisting of a M type star and white dwarf.  Earlier this year the system brightened from ~12.7 magnitude to 8.8 magnitude, undergoing an outburst associated with the accretion disk around the white dwarf. Stellar winds on the M star move matter away from its surface, a portion of which is drawn into an accretion disk around its binary companion white dwarf.  The white dwarf accretion disk is quite large, perhaps 1 AU in diameter and produces powerful polar jets.  One of the jets is pointed almost directly at us so radial velocity measurements represent close to actual outflow velocity.  At its peak, outflow velocity can reach 6000 km/s, more than twice the velocity of a nova eruption.  My spectra nicely show the blue shifted absorption trough nexgt to the promient HI and FeII emission peaks produced by the polar jet outflow.  Doppler shift measurements of H-alpha and H-beta (see below) suggest an outflow velocity of -2200 to -2500 km/s, which is in line with what is being published right now by other amateurs and professionals. 

 

The litereature, A&A 377, 206{240 (2001), Spectroscopic Monitoring Of The Jet In The Symbiotic Star MWC560 (V0694 Mon), suggests hours to days variations. The changes are primarily variations in the optical density of the low velocity and higher velocity portions of the polar jet. The jet velocity closest to the accretion disk is a few hundred km/s, farther up the jet velocities increase to 2000 to 3000+ km/s. Since we are not actually looking straight down the jet, instead at an inclination of 15 to 20 degrees, the absorption troughs reveal jet velocities at different depths. Very cool!


V0694 Mon, Doppler 4861, Alpy 600
V0694 Mon spectra, radial velocities for 4861 Angstrom

V0694 Mon, Doppler 6563A, Alpy 600
V0694 Mon spectra, radial velocities for 6563 Angstrom

V0694 Mon, MWC 560 spectra, Alpy 600
V0694 Mon [MWC 560] spectra, 31 Mar & 02 Apr 2016, Alpy 600 spectrograph.  Spectra line intensities for both days are essentially identical.

V0694 Mon spectrum, Alpy 600
V0694 Mon [MWC 560] spectra, 06 Apr 2016, Alpy 600 spectrograph.  Spectrum continues to be essentially identical to previous spectra.

Comparison of V0694 Mon [MWC 560] spectra from 2016 April and 2017 January

Recently revisited V0694 Mon [MWC 560], a Symbiotic Binary system involving a M3.5-5 III main sequence giant star and a white dwarf star surrounded by an accretion disk fed by the larger M star companion.   Last February (2016) it underwent an outburst and in a matter of days increased in brightness to 8.8 magnitude, 4 magnitudes brighter than its quiescent state of 12.7 magnitude.  Shortly after, it began to quickly fade to its present brightness of ~9.8 magnitude.  The brightening was the result of an outburst on the accretion disk around the white dwarf.  Stellar winds on the M star move matter away from its surface, a portion of which is drawn into an accretion disk around its binary companion white dwarf.  The white dwarf accretion disk is quite large, perhaps 1 AU in diameter and produces powerful polar jets.  One of the polar jets is pointed almost directly at us so radial velocity measurements represent close to actual outflow velocity.  A build up of mass on the accretion disk caused the outburst.  At its peak, polar jet outflow velocity reached 6000 km/s, more than twice the velocity of a nova eruption.  Sadly, I was not able to record spectra of the initial outburst, but my spectra from 2016 March and April show the blue shifted absorption produced by the polar jet next to prominent emission lines. 

Doppler shift measurements of the 2016 April spectrum for H-alpha, H-beta and several Fe II lines suggest an outflow velocity, at that time, of 2200-2500 km/s.  My 2017 January 28 spectrum record blue shift absorption for H-alpha and H-beta that translate to 1800 km/s...give or take, not surprising as the system slowly returns to its quiescent state.  Of particular interest, though, is that Doppler measurements for the prominent Iron lines, Fe II 4924A, 5018A and 5169A, in the 2017 January spectrum remain much the same as the 2016 April blue shifts -- roughly 2000 km/s.  Further, the shape of the absorption troughs are significantly different......still going through the literature to understand what is going on there.  Reading suggests that the Fe II lines are produced in the accretion disk and not directly associated with the polar jet out flow.

Further reading and valuable input from French spectroscopist, Francois Teyssier, have provided some answers regarding the curious behavior of the Fe II absorption troughs in my two spectra. Indeed, the Fe II emission lines are produced primarily in the accretion disk, also, though lesser so, in the hotter base of the polar jet itself. The Fe II absorption troughs are produced solely in the jet, near the base of the jet where temperature is highest.

The significant difference in the Fe II absorption profiles in the two spectrum is the result of variations in the polar jet density and velocity near the base. The literature models for the polar jets tend to leave the impression that the jet flow is constant, like the solid stream of water out of a garden hose, but the reality is, the jet is more like the stream out of a garden hose that has air in the line. Random spits and sputters over time. Both the Balmer line absorption and Fe II absorption can vary significantly due to velocity and gas density variations in the jet. These variations can be traced back to the source, which is the flow of gas from the cooler companion M star feeding the accretion disk. Flow variation occurs over days, even hours, not over months as I initially assumed comparing my two spectra.

I'm still not clear on why the Fe II absorption troughs indicate higher jet velocity than the Balmer line absorption, but the none homogeneous nature of the jet does help to explain the variations in the shape of the absorption troughs. Still much to learn.


V0694 Mon 20016 - 20017, Alpy 600

Comparison spectra -- 2016 April  and 2017 January

V0694 Mon 2016-2017, Alpy 600





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