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Variable Stars

Variable Stars. in the. Survey. Andrzej Udalski Warsaw University Observatory. OGLE: The Optical Gravitational Lensing Experiment (1992 - ….) Four Phases of the OGLE Project. OGLE-I (1992-1995). 1 m Swope telescope at LCO. ~2 million stars observed. Microlensing

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Variable Stars

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  1. Variable Stars in the Survey Andrzej Udalski Warsaw University Observatory

  2. OGLE: The Optical Gravitational Lensing Experiment (1992 - ….)Four Phases of the OGLE Project • OGLE-I (1992-1995). 1 m Swope telescope at LCO. ~2 million stars observed. Microlensing • OGLE-II (1997-2000). 1.3 m Warsaw telescope. ~40 million stars observed. Variable and non-Variable Stars in GB, MC • OGLE-III (2001– 2009). 8k x 8k mosaic CCD. ~200 million stars observed (GB, GD, MC). Extrasolar Planets, Microlensing • OGLE-IV (2010– ….). 32-chip 256 Mpixel mosaic CCD. Billion stars regularly monitored http://ogle.astrouw.edu.pl

  3. Las Campanas Observatory, Chile

  4. OGLE-IV: 2010 – …. • 32 chip 256 Mpixel mosaic CCD camera (+ 2 chips for guiding) • 2048 x 4102 pixel E2V 44-82 DD CCD detectors (15 mm). • 1.4 square degrees field (~7 Moon disks), scale – 0.26”/pixel • 20 sec. reading time • First light September 7, 2009 • Regular observations since March 4/5, 2010 • 30-50 TB of raw data per year • ~3 mmag accuracy (DIA photometry since 2001)

  5. OGLE-IV Nowa Kamera Mozaikowa

  6. OGLE-IV Sky

  7. OGLE-IV 2013 BLG SKY Cadence: red – ~30 epochs/night yellow – ~10 epochs/night green– ~3 epochs/night blue – ~1 epoch/night cyan – ~1 epoch /2 nights

  8. Current O-IV MC Survey – 600 square degrees

  9. OGLE-IV Galactic Disk (l<0)

  10. Non-Variable Stars • ~billion stars monitored – VI CMDs • O-III Photometric Maps: LMC – 35 million stars, SMC – 6.2 million stars, GB – 380 million stars, GD – 9 million stars • Structure studies • Reddening maps

  11. Variable Stars Geometrical Physical

  12. New Classes of Variable Objects: Microlensing Phenomena Bohdan Paczyński (1940—2007)

  13. GravitationalMicrolensing

  14. OGLE-I #1 Microlenses: Discovery of the first events toward the GB (1993).

  15. Microlensing: Three Main Scientific Channels • Search for Dark Matter • Galactic Structure • Extrasolar Planets – Planetary Microlensing

  16. First Binary Microlensing (1994)

  17. Main Potential of Microlensing • Full status and characterization of exoplanets in regions located 0.5—10 AU from Host Stars (the regions at and behind the Snow Line) • Status of exoplanets around wide range of types of Host Stars • Discovery of low mass planets from the ground

  18. 2012 Planetary Microlensing

  19. Free-Floating Planets • Microlensing event characteristic time: tE~sqrt(Mlens) • tE< 2 days – lensing object has planetary mass • High cadence observations needed for detection : (OGLE-IV: 18-60 min.) • MOA and OGLE data from 2006-2007: 10 short-lived microlensing events of likely planetary mass. No trace of host stars: population of unbound (FFP) or very distant exoplanets. • OGLE-IV data much better suited : ~50 events/season with tE< 2 days (shortest corespond statistically to a few Earth mass objects) • Origin: gravitational interactions – stellar encounters, ejection of planets during planetary system formation

  20. OGLE Variable Star Statistics OIII-CVS: OGLE-III Catalog of Variable Stars (Soszyński et al. 2013, Acta Astronomica 63, 21; Part XV) (Pietrukowicz et al. 2013, Acta Astronomica 63, 115; Part XVI) LMC: 3361 Classical Cepheids, 280 Pop. II Cepheids, 24906 RR Lyrae stars, 2786 Delta Scuti, 91995 LPVs, 26121 Eclipsing Binaries SMC: 4630 Classical Cepheids, 43 Pop II Cepheids, 2475 RR Lyrae stars, 19384 LPVs Galactic Bulge: 16836 RR Lyrae (~400 from SGR Dwarf Galaxy), 32 Classical Cepheids, 357 Pop II Cepheids, 232406 LPVs Galactic Disk: ~30000 (11 600 Eclipsing binaries, 40 DNe) Total > 400000

  21. OGLE Pulsating Stars

  22. Cepheids in the MCs Hubble constant determination is based on OGLE PL relations

  23. Cepheids in the SMC

  24. RR Lyrae Stars in the LMC

  25. RR Lyrae Stars in the SMC

  26. MC: LPVs

  27. Delta Scuti in the LMC

  28. Classical Cepheids in the Magellanic Clouds SMC LMC Magellanic Bridge

  29. RR Lyrae Stars in the Magellanic Clouds SMC Magellanic Bridge LMC

  30. Eclipsing Stars (Great distance indicators)

  31. Distance to the LMC

  32. Transiting Planets

  33. Transiting OGLE Exoplanets (2001– 2004)

  34. Ellipsoidal Variables on Eccentric Orbits model

  35. X-ray Sources Optical Counterparts (XROM System)

  36. R CrB (RCOM System)

  37. OGLE-IV Transient Detection System

  38. Quasars Behind the Magellanic Clouds • Candidates selected based on long term variability in the OGLE-III data, IR brightness and X-ray detection • Spectroscopic campaigns for confirmation (AAT) • Spectacular results: >700 new quasars behind the MCs (the farthest at z=3.99)

  39. GB Cepheids

  40. GB RR Lyrae

  41. Galactic Bulge – Structure

  42. GB LPVs

  43. Galactic Disk Survey • VI Photometry of the strip -3<b<+3 around the Galactic Disk (210<l<360); several epochs; VI maps up to I~22 mag • Shallow (I<18.5 mag) variability survey: 100-150 epoch per field (2013-2014 observing seasons) • Test O-III Galactic Disk: >7 square degrees (high cadence O-III planetary transit fields) in Carina: ~30 000 variable stars: 20 CEP, 50 RRL, 800 DSCT, 11600 ECL, 14000 RSCVn, 40 DNe, 100 UVCET

  44. OGLE-CEP-0227 • 2008 r.: discovery of OGLE-CEP-0227 • 2009-2010: high precision spectroscopy, • ARAUCARIA MCeph = 4.14 ± 0.05 M☼ MPul = 3.98 ± 0.29 M☼ Cepheid pulsation mass in agreement with measured dynamical mass

  45. A RR Lyrae Star in Eclipsing System in the BLG? Odkrycie – OGLE (prof. Igor Soszyński, 2010 r.) Follow up – Araucaria (prof. Grzegorz Pietrzyński, 2011 r.)

  46. Nova Scorpii 2008 (V1309 SCO) – OGLE • Star in the fields regularly observed since 2001 • Unique possibility of tracing the star behavior before eruption

  47. V1309 Sco – Conclusions • First observations of the stellar merger • Next candidate: OGLE-2002-BLG-360

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