1. Periodic Variables and Gyrochronology in NGC2301 Tuguldur Sukhbold

2. Dr.Steve Howell NOAO Howell et. al. (2005), Tonry et.al.(2005) Search for Planetary Occultation in Open Cluster NGC2301

3. Open Cluster Formed in the same Gas cloud Loosely Gravitationaly Bound Few 1000 stars Few Hundred My

4. Why “Open”?

5. NGC2301

6. Howell et.al.(2005)

7. University of Hawaii 88” (2.2m) 14 days

8. Planetary Occultation

11. Light Curve

12. Why non-continuous?

13. Phase Plot “Raw” Light Curve Phased Light Curve

14. Stat.Analysis of 4078stars Tonry et.al.(2005) Prob.periodicity ; Prob.exoplanet….

15. Goal 1: Find Eclipsing Binaries (EBs) So that I can measure the distance

16. What is EB

17. Contact EB

18. How can I measure the Distance? Take Spectra => Measure Doppler Shifts => Derive Radial Velocity Curve => Find Mass, Radius of Component Stars => Distance

19. Radial Velocity Curve M=m-5(logD L -1) Berg et.al.(2001)

20. Pool of data of 4078

21. EBs are periodic variables => find Periodic Variables first and then look for EBs in the list

22. Used prob.periodicity P=1-P f Decreasing Probability of Periodicity ------------------------------->

23. 2 Rejected Stars Variables, but not periodic on the time-sclale of 14day observing run

24. EB ~ Unequal Minima

25. Found 5 candidates!!! :D SE292

26. Notice!

27. Periods are Extremely short!!! 0.24-0.34days ~ 6-8hours! Same Mass, Circular Orbit: Crude Radial Velocity Estimation: ~200km/sec!!!

28. Assuming real EBs are they real Members?

29. CMD isochrones, Yi et.al.(2003)

30. CMD of NGC 2301 Yale Isochrones, Yi et.al.(2003)

31. Grubissich & Prugathofer (1962) Cluster Apparent Radius ~18 arcminutes

32. Goal 2: Gyrochronology How old is the cluster? How “well” does Gyrochronology work?

33. Skumanich Law Andrew Skumanich, 1972

34. Sydney Barnes (2003)

36. Empirical Isochrones I sequence C sequence

37. Population (time)

38. Meibom et.al.(2008) – M35

39. Color Conversion (B-V)  (B-R) Values from Cox (2000)

40. Period – Color Plane for NGC2301 200My

41. Filtering: 7 stars (B-R) < 1.00 5 stars EBs 10 stars Pulsators

42. Left with 116 stars: Still mess…

43. Previously Determined Ages ~164My – Unknown Method /WEBDA/ 250+/-45My – Kim et.al.(2001) ~205My – Kharchenko et.al.(2006)

44. Isochrones of Previous ages:

45. What can I do? 1) Fit Isochrones on subjectively defined sequence regions 2) Direct application of Skumanich Relation

46. 1. Isochrone Fits Only on I sequence, because contamination in C sequence  P Nyquist ------------------------------

47. P=5.5(B-R)-4.5

48. P=6.5(B-R)-4.5

49. PNPN

50. Grubissich & Prugathofer (1962) Cluster Apparent Radius ~18 arcminutes

51. Central Region on CMD

52. Period-Color diagram – Central Region

53. Same Criteria lines P=6.5(B-R)-4.5 P=3

54. 220My 96My

55. 2. Direct Application of Skumanich Meibom et.al.(2008)

56. Hyades Cluster ~625My

57. --------------------------

58. So how old is this cluster? I don’t know…?? 196My 177My 205My 164My 96My 250My 220My

59. Same Criteria Lines,

60. Contamination about ~ 12% ~8stars, but in the interval of only

61. What I did From the data set of Howell et.al.(2005) and Tonry et.al.(2005): o found 138 periodic variables o including 5 EB candidates in the field of NGC2301 Analysis of Period-Color diagram o Gyro-age isochrone fits on available data o Proposed a direct application of Skumanich Law o Roughly estimated contamination in the data set

62. Future With Dr.Steve around ~November, WYIN 3.5m Telescope, HYDRA Spectrograph This summer with Dr.Meakin, 3D Hydrodynamical simulations, TYCHO code

63. References Barnes, S. A. 2003, ApJ, 586, 464 Cox, A.N. 2000, in Allen’s Astrophysical Quantities, 4th Edition,(Springer, AIP Press) Grubissich, G. and Purgathofer, A., 1962, Z. Astrophys. 54, 41 Howell, S. B., VanOutryve, C., Tonry, J., et al., 2005, PASP, 117, 1187 Kharchenko N. V., Piskunov A. E., Roeser S.,et al. R.-D., 2005, A&A, 438, 1163 Kim, S. L., Chun, M.Y., Park, B. G., et al., 2001, A&A, 371, 571 Meibom S., Mathieu R. D., Stassun K. G., 2008, ApJ, Skumanich, A. 1972, ApJ, 171, 565 Tonry, J. L., Howell, S. B., Everett, M. E., et al., 2005, PASP, 117, 281 Yi, S. K., Kim, Y., & Demarque, P. 2003, ApJS, 144, 259