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Stellar variability monitoring in open clusters with mini-SONG

Stellar variability monitoring in open clusters with mini-SONG. X.B. Zhang National Astronomical Observatories, Chinese Academy of Sciences. contents. Mini-SONG Overview Main Science goals Interesting subjects concerned Predicted results. Mini-SONG Overview.

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Stellar variability monitoring in open clusters with mini-SONG

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  1. Stellar variability monitoring in open clusters with mini-SONG X.B. Zhang National Astronomical Observatories, Chinese Academy of Sciences

  2. contents • Mini-SONG Overview • Main Science goals • Interesting subjects concerned • Predicted results

  3. Mini-SONG Overview • A global photometry system; • Shares the sites and operation net-work with the North SONG.

  4. Instruments & parameters: • Double-tube 50 cm reflector; • F/9.5 • equatorial mount; • 2k×2k CCD; • SDSS or Johnson filters

  5. Capability & utilities: • FOV: 20’×20’ ; image scale of 0.6”/pixel; • Photometry precision: • 0.008 mag for V=15 and 0.011mag for V=16 ( 1 single exposure); • 0.003, 0.005 mag for V=15, 16 respectively (10 exposures combined). • Time-resolution: 1 min.; • Duty-cycle: > 40%; • Two-color simultaneously.

  6. Main Science goals • Multi-color photometric survey of open clusters; • To obtain the unique multi-color CMDs of about 300 nearby open clusters and determine the basic parameters by isochrone fitting, by single site. • Stellar variability monitoring in open clusters; • Long-term, time-series photometry on about 20-30 selected clusters, each with a time span longer than 1 month. • Follow-up photometry of ToOs such as GRB, SN etc.

  7. Why open clusters? • More effective for denser stars; • The same evolution history and environment of member stars; • Definite parameters known from other ways;

  8. The probable mini-SONG OC targets • 337 OCs collected as the initial candidates, each with the modest coordinates, distance modulus (brightness) and diameters (http://www.univie.ac.at/webda/webda.html),

  9. Interesting subjects concerned • Eclipsing binaries • Basic data: fraction & distributions in mass ratio, orbital period etc.; • Test the theory of stellar evolution; • Effects of mass transfer and angular momentum loss, constraints to the model of binary evolution.

  10. Example. 1 V12 in NGC188, a detached binary discovered by Zhang et al. (2002, 2004) Zhang, et al., 2002, 2004 Meibom et al., 2009

  11. Zhang, Deng & Lu, 2009 Example. 2 TX Cnc, a W UMa star In the praesepe cluster

  12. Pulsating stars: • Detect and compile the complete sample of several types of pulsating stars, SPB, b Cephei, d Scuti etc.; • Blue & red edges of the instability stripe for each types of variables based on large-sample study. • Comparison asteroseismic study with known physical parameters.

  13. Example. 3 12 d Scuti variables in NGC6811 Luo & Zhang et al., 2009

  14. Example. 4: 18 SPBs in NGC7654 Luo, Zhang & Han, 2011

  15. Transit searching for Jupiter-like planets; • Detailed by Prof. Zhou • Stellar eruptive events. • CVs, flares of late-type stars

  16. Predicted results • Unique, high-precision CMDs and basic physical parameters will be determined for about 300 nearby open clusters,; • Light variability of tens of thousands of stars be monitored by continuous, long-term photometry, a discovery of hundreds to thousands of variables in various types is expected; • Transits and some other unexpected events

  17. Thanks! xzhang@nao.cas.cn

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