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Twenty Years of Microlensing Observations From the Andrzej Udalski Warsaw University Observatory Perspective.

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Presentation on theme: "Twenty Years of Microlensing Observations From the Andrzej Udalski Warsaw University Observatory Perspective."— Presentation transcript:

1 Twenty Years of Microlensing Observations From the Andrzej Udalski Warsaw University Observatory Perspective

2 Bohdan Paczyński (19402007)

3 Gravitational Microlensing toward the Galactic Bulge

4 Planetary Microlensing

5 Search for Gravitational Microlenses MACHO Project – Mt. Stromlo, Australia (1992 – 1999) EROS Project – ESO, Chile (1992 – 2002) MOA Project – Mt. Johns, New Zealand (1997– …) OGLE Project – Las Campanas, Chile (1992 – …)

6 Twenty One Years of the OGLE Survey

7 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

8 Las Campanas Observatory, Chile

9 Discovery of the First Microlensing Events – September 1993

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

11 First Binary Microlensing (1994)

12 Fine Microlensing Effects

13 Early Warning System (EWS – 1994)


15 Follow-Up Microlensing Projects < 2001 PLANET GMAN MOA >= 2001 microFuN PLANET Robonet MindSTEP

16 Three Main Channels Search for Dark Matter Galactic Structure Extrasolar Planets – Planetary Microlensing

17 Dark Matter – MACHO in the Galactic Halo

18 OGLE-2005-SMC-001

19 OGLE MC Microlensing

20 Current O-IV MC Survey – 600 square degrees

21 LMC SMC Magellanic Bridge Classical Cepheids in the Magellanic Clouds

22 LMC SMC Magellanic Bridge RR Lyrae Stars in the Magellanic Clouds

23 Stellar Populations in the Magellanic Bridge

24 OGLE-IV Transient Detection System

25 Galactic Structure Optical depth for microlensing toward CG High resolution spectroscopy of highly microlensed bulge dwarfs Microlensing in the Galactic disk

26 Gravitational Microlensing Optical Depth probably the best way to constrain the internal structure of the Milky Way The recent models of the Galactic Bulge: Kerins,Robin,Marshall (2010) OGLE >~10000 microlenses 3.2±0.8 (OGLE3 2007) 2.4±0.4 (MACHO 2000) 2.6±0.8 (MOA 2003)

27 Optical Depth

28 Microlensing in the Galactic Disk

29 OGLE-IV Galactic Disk (l<0)

30 Planetary Microlensing

31 OGLE-III Hardware and Software (2001) 1.3 m OGLE telescope at Las Campanas Observatory, Chile 8192 x 8192 pixel mosaic CCD camera (0.26 arcsec/pixel scale): 0.5 x 0.5 sq. degree Data Pipeline: photometry derived with image subtraction method (accuracy up to 3 mmag for the brightest stars over a few months long observing run)

32 Transiting OGLE Exoplanets

33 Planetary Microlensing O-III ~600 microlensing events per year in real time since 2002. Short-lived anomaly in the light curve of a typical single mass microlensing event.

34 OGLE-2003-BLG-235/MOA-2003-BLG-53 First Planetary Microlensing Planet/star mass ratio: q~0.004

35 OGLE-2005-BLG-71 Planet/star mass ratio: q~0.007

36 OGLE-2005-BLG-390 Planet/star mass ratio: q~0.00008. Mass of the planet: ~6 Earth masses. The least massive planet at the discovery

37 MOA-II Survey (2006– …)

38 Microlensing Planets – results ~30 microlensing planets found since the first announcement in 2004 (~20 published so far) First cool super-Earths of 3-10 Earth masses: low mass planets are common OGLE-2006-BLG-109: analog of the solar system (multiplanetary system: Jupiter+Saturn like) First estimations of the frequency of planets at and behind the snow line 2003– 2007: the discovery rate 0-1 exoplanets per season 2007–2010: the discovery rate of 2-4 exoplanets per season

39 Main Potential of Microlensing Full status and characterization of exoplanets in regions located 0.510 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

40 Second Generation Planetary Microlensing Survey Survey and Follow-up in one Network of 12-m class telescopes over the globe with large field (>1 square degs) cameras Monitoring of the most microlensing efficient parts of the Galactic bulge with the cadence of ~15 minutes No missing planets, easier estimation of survey statistics Estimations: A network of three 1.32 m telescopes: the detection of 14 Earth mass planets, 1015 super- Earths, 100 Jupiter mass planets per year Five year long survey should provide resonable large sample of planets for estimation of the census of exoplanets down to Earth mass at orbits of 0.510 AU

41 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 m). 1.4 square degrees field, 0.26/pixel 20 sec. reading time First light September 7, 2009 Regular observations since March 4/5, 2010


43 OGLE-IV Nowa Kamera Mozaikowa

44 OGLE-IV 2012 BLG SKY Cadence: red – up to 30 epochs/night yellow – up to 10 epochs/night green – up to 3 epochs/night blue – ~1 epoch/night cyan – ~1 epoch /2 nights

45 Real Time Microlensing: OGLE-IV 58 O-IV fields analyzed in real time including all very high and high cadence Statistics for 2012 BLG season: ~1700 on-line detections (~20 in O-I, ~60/season in O-II, ~600/season in O-III) Total number of OGLE-IV microlensing fields: 107 – they will be gradually included to EWS

46 OGLE-IV planetary microlenses 2010 Commissioning Mode MOA-2010-BLG-117MOA-2010-BLG-328 MOA-2010-BLG-477MOA-2010-BLG-523

47 2012 Planetary Microlensing

48 Free-Floating Planets Microlensing event characteristic time: t E =R E /v tr R E ~sqrt(M lens ) t E ~sqrt(M lens ) t E < 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 : preliminary estimation – 2011 season: ~40 events with t E < 2 days (shortest corespond statistically to a few Earth mass objects) Origin: gravitational interactions – stellar encounters, ejection of planets during planetary system formation

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

50 Prospects for Planetary Microlensing Field: Bright New facilities: Bisdee Tier Tasmania, LCOGT Network, KMNet Space Missions: WFIRST, EUCLID

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