Ladislav Hric Astronomical Institute

Slovak Academy of Sciences

Our team:

V. BreusP. DubovskýR. GálisN. A. KatyshevaE. KundraS. Yu. Shugarov

KOLOS

Schematic picture of CV – non magnetic system

Schematic picture of CV – the strong magnetic system - Polar

Schematic picture of CV – the moderately magnetic system - intermediate polar

V709 Cas was discovered as an opticalcounterpart of the ROSAT source RX J0028.8+5917 byHaberl & Motch (1995)The soft X-Ray flux was changingwith a period of 312.8 s, which is the spinperiod of the white dwarf

Radial velocity variations showed2 possible orbital periods P = 5.4 h and 4.45 hwhich are one day aliases of each other (Motch 1996)Note to spin and orbital periods, the reprocessing of X-rays at some part of the system that revolves at the binary period gives rise to emission that varies with the beat period, where1/Pbeat = 1/Pspin − 1/PorbitThis synodic counterpart is often called the orbital sideband of the spin frequency.

Kozhevnikov (2001) reported thepresence of strong optical oscillations at thespin period of 312.77 s and it’s orbital sideband of 317.94 s.Bonnet-Bidaud et al. (2001) studied radial velocitiesof the emission lines and published the ephemeris T0 = HJD 2451048.0575(2) + 0.2225(2) x E.

Tamburini et al. (2009) studied the white-light flickeringand reported that the light curve is strongly flickering dominatedwithout any dominating frequency except the orbital motion.

Thorstensen et al. (2010) found the value of the orbitalperiod of the system using radial velocity spectroscopyP= 0d.2222033(7) .

We obtained photometric CCD observations using different telescopes: 50cm AZT-5 (13 nights), 60cm Zeiss-Cassegrain (2 nights), 38cm K-380 (19 nights) at the Crimean Astrophysical Observatory (CrAO), and Crimean Laboratory of Sternberg Astronomical Institute, Nauchny, Crimea, Ukraine, and1m Vihorlat National Telescope(VNT) (22 nights), Celestron 14 (1 night) at the Kolonica Observatory (KO), Slovakia mainly in V and R filters.

10 years of observations

Period analysis

Periodograms near frequrency, that corresponds to thespin period of the white dwarf, exhibit the different highest peaks for different nights of observations in the range from 185 s to 330 s.

Particulary, for data obtained 7. Oct 2010at the 1m VNT we got highest peak that corresponds to the spin period of 311.7(4) s.

Results

Results

Using all determined minima timings, we calculated (O - C) diagram with initial values of period P = 0.2222041 d (Thorstensen et al. 2010) and initial epoch T0 = 2454028.43349 determined for one night from the middle of our data.

We chose the linear fit as the best approximation for the (O - C) data and the resulting orbital period was Porb =0.2222123(6) d.

Results

The new period

Periodograms in the range of 0.002 - 0.02 days exhibit strong peak around the period of 23 minutes (0.016 d). Different nights show different highest peaks in the range from 0.010 d to 0.019 d. We took the average value of Pnew = 0.01645 d, which corresponds to the frequency of 60.79 /day in the periodograms. Finally we took the set of 3 nights.

The period analysis of these data reveals the highest peak at the frequency f = 61.15 /day which corresponds to the newly detected period of Pnew = 0.0163510(3) d.

Periodogram

The new period

The new period

What about the conclusion

It is worth to note that on the published by Norton (1999) and Kozhevnikov (2001) power spectra it is possible to identify the peaks corresponding to our new period. In the paper by Kozhevnikov (2001) the peak is more than two times higher than the spin period. Both authors did not notice this fact in their papers.

These evidences support our opinion, that the period discovered by us is caused by real physical process. One of the possible explanations is the vibration of the accretion stream in the magnetic field of the white dwarf.The explanation of this new period is only speculative and for better understanding it is necessary to get spectroscopic data with higher time resolution.

Our paper

The new data

Photometry of V709 Cas in Stará Lesná and Hlohovec Observatories Date [m/d/year] JD/MJD Duration Filter Instrument START END START END [hours]

10/1/2007 20:20 10/1/2007 23:46 54375.34744 54375.49080 3.441 BVRI 508/2500 G1 10/6/2007 19:35 10/7/2007 0:20 54380.31656 54380.51449 4.750 BVRI 508/2500 G1 10/7/2007 22:10 10/8/2007 0:07 54381.42378 54381.50519 1.954 BVRI 508/2500 G1

12/27/2007 16:43 12/27/2007 20:25 54462.19669 54462.35101 3.704 BVRI 508/2500 G1 2/25/2008 18:10 2/25/2008 20:12 54522.25721 54522.34174 2.029 UBVRI 508/2500 G1 2/26/2008 17:37 2/26/2008 20:16 54523.23461 54523.34494 2.648 UBVRI 508/2500 G1

10/28/2009 21:32 10/28/2009 23:58 55133.39773 55133.49916 2.434 BVRI 508/2500 G1 11/9/2009 17:32 11/9/2009 17:59 55145.23060 55145.24947 0.453 BRI 508/2500 G1

11/18/2009 16:08 11/18/2009 21:16 55154.17291 55154.38612 5.117 BRI 508/2500 G1 11/19/2009 16:34 11/20/2009 4:39 55155.19044 55155.69428 12.092 BRI 508/2500 G1 11/21/2009 18:52 11/22/2009 4:47 55157.28661 55157.69979 9.916 BVRI 508/2500 G1

12/3/2009 16:43 12/4/2009 4:26 55169.19676 55169.68536 11.726 BVRI 508/2500 G1 12/4/2009 16:52 12/4/2009 23:22 55170.20322 55170.47389 6.496 BVRI 508/2500 G1

12/20/2009 16:20 12/20/2009 22:50 55186.18124 55186.45174 6.492 BVRI 508/2500 G1 12/21/2009 16:12 12/21/2009 18:07 55187.17534 55187.25538 1.921 BVRI G1_50cm_SBIG

1/4/2010 17:15 1/4/2010 21:50 55201.21928 55201.41034 4.585 BVRI G1_50cm_SBIG 2/4/2010 16:41 2/4/2010 20:47 55232.19547 55232.36597 4.092 BVRI G1 SBIG Dual Chip

10/7/2010 18:53 10/8/2010 3:30 55477.28700 55477.64631 8.623 V G1_50cm_SBIG 10/8/2010 19:19 10/9/2010 2:16 55478.30527 55478.59472 6.947 V G1_50cm_SBIG 1/28/2011 16:45 1/28/2011 17:34 55590.19793 55590.23244 0.828 BVRI G1_50cm_SBIG

2/2/2011 17:13 2/2/2011 19:36 55595.21781 55595.31713 2.384 BVRI G1_50cm_SBIG 9/6/2011 18:56 9/7/2011 2:33 55811.28904 55811.60678 7.626 BVRI G1_50cm_SBIG

11/18/2013 19:06 11/18/2013 19:14 56615.29622 56615.30177 0.133 BVRI Short! G1_60cm_FLI2 Zeiss 600/7500 12/2/2013 23:47 12/3/2013 2:20 56629.49127 56629.59748 2.549 V G1_60cm_FLI2

2/3/2014 19:25 2/3/2014 20:36 56692.30963 56692.35897 1.184 VN G1_60cm_FLI2 2/13/2014 20:20 2/13/2014 21:20 56702.34266 56702.38841 1.----- N 67 G2_60cm_MI G4-9000 CCD 2/24/2014 17:58 2/24/2014 20:20 56713.24926 56713.34747 2.357 VN long+BRI short G1_60cm_FLI2

10/25/2014 18:00 10/25/2014 19:00 56956.25515 56956.29022 1.----- V 92 B 5 R 9 G1_60cm_FLI ML3041 CCD 11/3/2014 21:00 11/3/2014 22:00 56965.40890 56965.44661 1.----- V 26 R 25 I 30 G2_60cm_MI G4-9000 CCD 6/14/2014 20:27 6/14/2014 21:42 56823.35260 56823.40466 1.249 R Hlohovec, ZC600, SBIG ST-9 6/21/2014 21:01 6/21/2014 21:53 56830.37600 56830.41193 0.862 C Hlohovec, ZC600, SBIG ST-9

The new data

The new data

Spectroscopy of V709 Cas at 6 m Telescope in SAO

Date Sp. Resolution Time resolution Duration Telescope [yyyymmdd]

20141030 5 Å or 15 000 – 17 000 about 5 min 2 – 3 hours BTA 6 m

Acknowledgements

Thank you very much

for your attention