1. Rotational periods of the components in Symbiotic Binary Stars
Radoslav K. Zamanov
Institute of Astronomy, Bulgarian Academy of Sciences
in collaboration with
M.F. Bode (Liverpool, UK),
C.H.F. Melo (ESO, Chile) A. Gomboc (Ljubliana, Slovenia),
R. Bachev, I. K. Stateva, R.Konstantinova-Antova (Sofia, Bulgaria)
03'2012

2. Symbiotic binary star = Red Giant + White Dwarf

3. Symbiotic stars are interacting binaries consisting of red giant transferring mass onto a white dwarf.
We are investigating the projected rotational velocities of the mass donors. Our aims are:
To check theoretical prediction that the red giants in these binaries are co-rotating (for objects with known periods).
To perform comparative analysis and to check if they are faster rotators (comparing with isolated giants and those in wide binary systems).
To give clues for binary periods, individual mass loss rates, select candidates for X-ray observations.

4. Observations:
40 symbiotic stars have been observed with the 2.2m telescope (ESO, La Silla) + FEROS spectrograph at resolution
Our sample:
All objects from the Symbiotic star catalogue with 0h<R.A.<24h, Declination < 00, and brighter than V< 12.5 mag.
From literature -12 northern symbiotics.
Our sample is flux limited, there should be no biases in rotation.

5. ESO – La Silla
Altitude H=2340 m

6. ESO La Silla - 2.2 m telescope
OPTICON gives possibility of the Bulgarian astronomers to use the ESO facilities !!!

7. Observations:
the 2.2m telescope + FEROS spectrograph

8. FEROS spectrograph
The 39 orders cover wavelengths from 3600 A up to 8900 A.

9. the 2.2m telescope + FEROS spectrograph
Observations:
the 2.2m telescope + FEROS spectrograph
- resolution 48000;
dispersion=0.03 A/pixel
- wavelength coverage: 6300 A in a single exposure
(3600 – 8900 AA)
- signal-to-noise ratio = 50; exposure=30 min; V=12 mag;
Comparison – 2.0m telescope Rozhen, Coude spectrograph
0.2 A/px, A in one exposure, S/N=50, exposure=30 min; V=11.3

10. Fig. Theoretical spectrum and spectra of a few symbiotic in the near IR: wavelength 8760-8850 AA

11. Fig. Numerical mask and spectra of a few symbiotic in
Wavelength interval AA.

12. To measure the projected rotational velocity (v sin i)
we used the CCF method and numerical template. The width of the CCF is connected (calibrated for FEROS) with the v sin i.
Two examples of the Cross-Correlation Function and the fitting gaussian.
Left – AS 316 – v sin i = 9.8 ± 1.5 km/s
Right – rapid rotator V417 Cen – v sin i = 75 ± 7.5 km/s

13. Fig. Check of our methods.
The measurements of v-sin-i
with FWHM and CCF methods are in good agreement.

14. On the basis of their infrared (IR) properties, the symbiotic stars have been classified into stellar continuum (S) and dusty (D or D' ) types.
IR types
S-type - stellar continuum mass donor is K-M giant
D-type - dusty mass donor is Mira
D'-type – dusty mass donor is F-G giant

15. D' type [km/s] [km/s] HD 330036 D' F8III 107.0 160 67%
v sin i Vcrit critical
[km/s] [km/s]
HD D' F8III %
Hen S,D' K1III
StHa190 D' G4III/IV %
V417 Cen D' G9Ib-II %
AS D' F9III

16. Comparison with catalogs
de Medeiros et al. (2002) rotation of Ib supergiant stars
16 supergiant stars G8-K0 Ib-II, v sin i = 1-20 km/s.
V417 Cen (G9Ib) km/s extreme case of very fast rotation.
The catalogue of rotational velocities for evolved stars (de Medeiros et al. 1999) catalogue of rotational velocities for evolved stars
100 K1III 90% - vsini< 8 km/s, only 5% - vsini>20 km/s
Hen km/s is in the top 5.
F8III-F9III - 5 objects – km/s
AS 201 (25 km/s) is well within in this range.
HD (107 km/s) is an extremely fast rotator.
G3,G4,G5 III-IV – 60 objects - <24 km/s
StHa190 (105 km/s) - is again an extremely fast rotator.

17. D’-type symbiotics are characterized by an earlier spectral type giant (F-K) and lower dust temperatures. Rotational velocities have been measured for five such stars (Zamanov et al. 2006).
Four of these five objects appeared to be very fast rotators, compared with the catalogues of v sini for the corresponding spectral types. At least three of them rotate at a substantial fraction (≥ 0.5) of the critical velocity. Hence, in D’-type symbiotics, the cool components rotate faster than the isolated giants of the same spectral class (as predicted by Soker 2002).
As a result of rapid rotation, they must have larger mass loss rate, probable enhanced in the equatorial regions. In addition, as a result of the fast rotation, magnetic activity is expected to exist in these giants.

18. The rotational period of the red giant versus the orbit period for 17 symbiotic stars in our sample with known orbital periods (all they are S-type).
The solid line represents synchronization (Porb=Prot).
Among these 17 objects there are 3, which deviate considerably from co-rotation:
MWC560, CD
and RS Oph.

19. Possible reasons for non co-rotation:
MWC highly eccentric orbit e=0.70 (+/- 0.05)
CD highly eccentric orbit e>0.5 ?
RS Oph ???.

20. Fig. v sin i versus the spectral type:
symbiotic stars – red crosses,
black – single giants.

21. Isolated giants spectral classes K2-K5 III (238 objects from catalogues of v sin i)
K2-K5 III giants in symbiotic stars
(7 objects, our measurements)
Results:
238 K2III-K5III stars: v sin i = km/s mean v sin i =1.70 km/s)
The K giants in symbiotic stars: v sin i = km/s mean v sin i =7.42 km/s)
The Koslmogorov-Smirnov test gives a probability of 10-4 (K-S statistics =0.60)
K-giant mass donors of symbiotic stars rotate faster than isolated K-giants !!!

22. Isolated giants spectral classes M2-M5 III
(12 objects from catalogues of v sin i)
M2-M5 III giants in symbiotic stars
(28 objects, our measurements mostly)
isolated M giants: < v sin i < 18 km/s (mean vsini=5.54 km/s)
M-giants in symbio 3.0 < v sin i < 52 km/s (mean vsini=9.07 km/s)
The tests gives a probability of that both distributions are coming from the same parent population.

23. Isolated giants spectral classes M2-M5 III
(12 objects from catalogues of v sin i)
M2-M5 III giants in symbiotic stars
(28 objects, our measurements mostly)
isolated M giants: < v sin i < 18 km/s (mean vsini=5.54 km/s)
M-giants in symbio 3.0 < v sin i < 52 km/s (mean vsini=9.07 km/s)
The tests gives a probability of that both distributions are coming from the same parent population.

24. Isolated giants spectral classes M2-M5 III
(12 objects from catalogues of v sin i)
M2-M5 III giants in symbiotic stars
(28 objects, our measurements mostly)
isolated M giants: < v sin i < 18 km/s (mean vsini=5.54 km/s)
M-giants in symbio 3.0 < v sin i < 52 km/s (mean vsini=9.07 km/s)
The tests gives a probability of that both distributions are coming from the same parent population.

25. Results of statistical tests:
mean v sin i
field symbiotic Kolmogorov-Smirnov
K2III-K5III km/s km/s (KS statistics =0.90)
M0III-M6III (KS statistics =0.60)
M0III – M4III (KS statistics =0.64)
M0III – M3III (KS statistics =0.83)
M4III-M6III (KS statistics =0.44)

26. Mean v sin i mean v sin i field symbiotic Kolmogorov-Smirnov
M0III-M6III (KS statistics =0.60)
field symbiotics
km/s (N) km/s (N)
M0-M1 III ±1.9 (23) 9.9± 2.6 (2)
M1.5-M2 III ±4.1 (14) 8.3± 1.1 (3)
M2.5-M3 III (8) (4)
M3.5-M4 III (3) (7)
M4.5-M5 III (5) (9)
M5.5-M6 III (4) (6)

27. Discussion:
The reasons for faster rotation in giants in symbiotic systems could be:
- synchronization, if the time spent by the mass-losing star on the giant branch is longer than the synchronization time. In all symbiotic systems with orbital period Porb ≤ 100 years tidal interaction overcomes the angular momentum loss by the wind (Soker 2002).
- accretion during the MS phase of the present red giant: the more massive star in the system, the present WD, had transferred material at the stage when it had been red giant.
- backflowing material: hot component prevents part of the mass blown by the giant from acquiring the escape velocity for the binary system. This fraction of mass may acquire angular momentum, and if it is accreted back by the giant, it spins-up its envelope.
- angular momentum dredge-up when convective envelope approaches the core region of the giant.
- planet engulfment during the giant phase.

28. CONCLUSIONS:
We have measured the projected rotational velocities of 40 symbiotic stars (v sin i) by the means of CCF and FWHM.
Among 16 symbiotics with known orbit and rotation, there is only one (RS Oph) which is very likely not synchronized.
Our results show that the mass donors in the symbiotic stars rotate faster than isolated giants. The faster rotation is undoubted for D’-type (yellow) symbiotics and for those harbouring K-giant as mass donor. For those with M giant it is valid till M4III.
FUTURE WORK:
To strengthen our results, more data on M-type isolated giants and more
v sin i measurements of K-type mass donors in symbiotics are desirable. We intend to expand our sample with northern and fainter symbiotic stars.

29. Open questions:
1. Is there a bimodal distribution of v sin i of the isolated giants?
2. Hen rotates very fast v sin i = 52 km/s
M5III - R=139 Rsun, and mass 1-3 Msun, Vcrit=40-60 km/s.
What is this object? a monster? or just an error somewhere?
3. Is there a connection between the rotation of the red giant and the density of the circum binary nebula and mass accretion rate?

30. What is the rotation of the white dwarfs in symbiotic stars?

31. What is the rotation of the white dwarfs in symbiotic stars?

32. MWD RWD dM TNR P rot [MꙨ] [km] [MꙨ] [] 0.2 14000 1.47e-2 67 sec
e min
e min
e min
e min
e min
e min
e min
e h
e h
e h
e days

33. Rotation of the mass donors in symbiotic stars
Zamanov R.K., Bode M.F., Melo C.H.F., Stateva I.K., Bachev R., Gomboc A., Konstantinova-Antova R., Stoyanov, K. A.
Rotational velocities of the giants in symbiotic stars - III. Evidence of fast rotation in S-type symbiotics
2008 MNRAS
Zamanov R. K., Bode M. F., Melo C. H. F., Stateva I.K., Bachev R., Gomboc A., Konstantinova-Antova, R.; Stoyanov, K. A.
2007 MNRAS
Zamanov, R. K.; Bode, M. F.; Melo, C. H. F.; Porter, J.; Gomboc, A.; Konstantinova-Antova, R.
Rotational velocities of the giants in symbiotic stars - I. D'-type symbiotics
2006 MNRAS
Zamanov, R. K.; Konstantinova-Antova, R.; Bode, M. F.; Melo, C. H. F.; Gomboc A., Bachev R.,
Rotation of the mass donors in symbiotic stars
V Bulgarian Serbian astronomical conference
Zamanov R.,
Tidal Interaction in High Mass X-ray Binaries and Symbiotic Stars
2011 BlgAJ Z
    

34. in collaboration with N. A. Tomov (NAO Rozhen, BG),
M.F. Bode (Liverpool, UK),
C.H.F. Melo (ESO, Chile) A. Gomboc (Ljubliana, Slovenia),
R. Bachev, I. K. Stateva,
K.A. Stoyanov, R.Konstantinova-Antova (Sofia, Bulgaria)

35. THE END