Non-radial pulsations in RR Lyrae stars from the OGLE photometry

Transcription

1 Non-radial pulsations in RR Lyrae stars from the OGLE photometry Henryka Netzel CATS, 2015 with Nicolaus Copernicus Astronomical Center Rados law Smolec Pawe l Moskalik Wojciech Dziembowski 1 / 39

2 RR Lyrae stars OGLE RR Lyrae stars classical radial pulsators fundamental mode (RRab), first overtone (RRc), both (RRd) typical periods: d P S /P L RRd (F+1O) F+2O log P L Figure: Multi-mode radial pulsations of RR Lyrae stars 2 / 39

3 RR Lyrae stars OGLE Additional frequencies in RR Lyrae stars P S /P L RRd (F+1O) F+2O Gruberbauer et al. (2007) Olech Moskalik (2009) Soszynski et al. (2009) Suveges et al. (2012) Chadid (2012), Szabo et al. (2014) Moskalik et al. (2015) Molnar et al. (2015) Jurcsik et al. (2015) log P L 3 / 39

4 RR Lyrae stars OGLE Non-radial modes in RR Lyrae stars Pulsations in the first overtone mode Additional signal has higher frequency Period ratio P X /P , 0.64 Amplitude of the additional mode 1mmag Subharmonics of the additional mode are present: f 1 2 f X or f 3 2 f X 4 / 39

5 RR Lyrae stars OGLE Theoretical Petersen diagram M: M ; L: L Figure: Moskalik et al. (2015) 5 / 39

6 RR Lyrae stars OGLE Additional frequencies in RR Lyrae stars P x /P 1O RRd (F+1O) F+2O log P 1O Figure: Multi-mode pulsations of RR Lyrae stars P X P 1O / 39

7 RR Lyrae stars OGLE Additional frequencies in RR Lyrae stars P x /P 1O RRd (F+1O) F+2O P S /P L RRd (F+1O) F+2O log P L log P 1O Figure: Multi-mode pulsations of RR Lyrae stars Figure: Multi-mode pulsations of RR Lyrae stars including results from OGLE P X P 1O / 39

8 RR Lyrae stars OGLE Additional frequencies in RR Lyrae stars P x /P 1O RRd (F+1O) F+2O P S /P L RRd (F+1O) F+2O log P L log P 1O Figure: Multi-mode pulsations of RR Lyrae stars Figure: Multi-mode pulsations of RR Lyrae stars including results from OGLE P X P 1O 0.61 P 1O P X / 39

9 RR Lyrae stars OGLE OGLE project Optical Gravitational Lensing Experiment long term project dedicated to the search of dark matter with microlensing events 1.3 meter telescope in Las Campanas, Chile third phase: currently the fourth phase (from 2010) Figure: 9 / 39

10 RR Lyrae stars OGLE RR Lyrae in OGLE-III OGLE-III 4989 RRc and 91 RRd stars (from the Galactic bulge) automatic analysis : stars (3 % of the sample) 10 / 39

11 RR Lyrae stars OGLE RR Lyrae in OGLE-IV OGLE-IV RRc (from the Galactic bulge) / 39

12 RR Lyrae stars OGLE RR Lyrae in OGLE-IV 485 RRc stars with more than 8000 observations from fields 501 and 505 manual analysis : stars (27 % of the sample) and stars 12 / 39

13 Petersen diagram for RR Lyrae stars RRd (F+1O) F+2O P S /P L log P L 13 / 39

14 0.61 stars in the Galactic bulge 14 / 39

15 0.61 stars in the Galactic bulge (zoom in) 15 / 39

16 Petesen diagram for 0.61 stars from Galactic bulge P X /P log P 1 16 / 39

17 Structures observed in power spectra of 0.61 stars 17 / 39

18 Structures observed in power spectra of 0.61 stars 18 / 39

19 Structures observed in power spectra of 0.61 stars A [mag] OGLE-BLG-RRLYR OGLE-BLG-RRLYR f-f x [d -1 ] 19 / 39

20 Three sequences simultaneously 20 / 39

21 Seasonal variability A [mag] OGLE-BLG-RRLYR A [mag] OGLE-BLG-RRLYR P/P 1O P/P 1O 21 / 39

22 Seasonal variability A x [mmag] 9 OGLE-BLG-RRLYR time [day] 22 / 39

23 Power excess OGLE-BLG-RRLYR OGLE-BLG-RRLYR A [mmag] A [mmag] P x /P 1O P x /P 1O 23 / 39

24 Subharmonic frequency range of the additional mode 24 / 39

25 Petersen diagram for RR Lyrae stars RRd (F+1O) F+2O P S /P L log P L 25 / 39

26 Petersen diagram for (zoom in) P 1O /P x KIC log P x 26 / 39

27 Star observed with Kepler f 1 = , P 1 = , additionally 0.61 mode! Figure: Moskalik et al. (2015) 27 / 39

28 0.68 stars in the Galactic bulge 28 / 39

29 0.68 stars in the Galactic bulge 29 / 39

30 Characteristics of the 0.68 stars Pulsations in the first overtone mode Additional signal of frequency lower of unseen fundamental mode Additional signal is always stationary Combination frequencies of the additional frequency and the first overtone mode are present 30 / 39

31 31 / 39

32 and Blazhko effect - OGLE-BLG-RRLYR OGLE-III + OGLE-IV 6042 d modulation period: 3042 d 32 / 39

33 and Blazhko effect - OGLE-BLG-RRLYR OGLE-III + OGLE-IV 6042 d modulation period: 3042 d OGLE-BLG-RRLYR-07653: P B = 1698 ± 4d 33 / 39

34 and Blazhko effect - OGLE-BLG-RRLYR OGLE-BLG-RRLYR-32196: P B = / 39

35 Possible explanations starspots or companion pulsations 35 / 39

36 Possible explanations Figure: Dziembowski and Cassisi (1999) 36 / 39

37 We significantly increased the number of known 0.61 stars three sequences - sometime in one star non-stationary signal Blazhko effect in 0.61 stars complicated subharmonic structure We discovered entirely new group of double-mode RR Lyrae stars stationary signal frequency of the additional mode lower than fundamental frequency detected 0.61 mode and cadidates for Blazhko modulated stars 37 / 39

38 Bibliography Netzel H., Smolec R., Moskalik P., 2015, Double-mode radial-non-radial RR Lyrae stars in the OGLE photometry of the Galactic bulge, Monthly Notices of the Royal Astronomical Society, Volume 447, Issue 2, p Netzel H., Smolec R., Dziembowski W., 2015, Discovery of a new group of double-periodic RR Lyrae stars in the OGLE-IV photometry, Monthly Notices of the Royal Astronomical Society: Letters, Volume 451, Issue 1, p.l25-l29 Netzel H., Smolec R., Moskalik P., 2015, Double-mode radial-non-radial RR Lyrae stars. OGLE-IV photometry of two high cadence fields in the Galactic bulge, accepted for publication in MNRAS 38 / 39

39 Thank you! 39 / 39