Microlensing observations of event OGLE 2005-BLG-390 have provided evidence that the lens star, presumably an M-dwarf with 0.2 Solar masses, is orbited by a planet with only about 5 Earth masses (uncertain within a factor of two) at 3 AU with a period of 10 years. This discovery was reported as the joint effort of three independent microlensing campaigns (PLANET/RoboNet, OGLE, and MOA) in a Letter to Nature.

The event OGLE 2005-BLG-390 was reported by the OGLE Early-Warning System (EWS) on 11-Jul 2005, and was then monitored with the telescopes constituting the PLANET/RoboNet network. The light curve initially followed the characteristic brightening expected for a single isolated lens star and a point-like source star, which in this case is a G2-4 giant, and reached a peak magnification of about 3 on 31-Jul. However, on 10-Aug, an anomalous rise by 0.15 mag was observed by PLANET/RoboNet with the Danish 1.54m at ESO LaSilla (Chile), while an OGLE point from this night showed the same trend. By succeeding in monitoring the second half of this anomaly, lasting about half a day, with the Perth 0.6m (West Australia), and previously obtaining a dense coverage of the peak region of the event, we were able to conclude that the lens star is orbited by a low-mass planet, which is designated OGLE 2005-BLG-390Lb. The MOA collaboration was able to identify the source star on its frames and confirmed the observed deviation.

Press releases The listed institutions have indicated that a press release will be issued at the time of discovery announcement.

Scientific Documentation

• Letter to Nature (Nature 439, 437-440, 26-Jan-2006)
• Web documentation
  • by PLANET (planet.iap.fr)
  • by OGLE (ogle.astrouw.edu.pl)
  • by Perth Observatory (www.wa.gov.au/perthobs)

Figures and Animations

• Graphs, Photos and Figures
  • True-colour image of the field around OGLE 2005-BLG-390 (Image credit: Jean-Philippe Beaulieu)
  • Light curve of OGLE 2005-BLG-390 with collected data - pdf, gif, eps (Planet Collaboration)
  • Animated Danish 1.54m frame (credit Daniel Kubas)
  • Lecture Slides from press briefing at Perth.
  • Extrasolar planet properties summary - pdf, gif, eps. (Image credit: Keith Horne, Andrew Williams)
  • The sky above Perth Observatory during the planetary discovery,10/8/2005 at 1am,
  • showing the lens - jpg,png. (Image Credit: Andrew Williams)
  
  
• Artist views
  • Artist's view of OGLE 2005-BLG-390Lb gif (created by ESO)
  • Artist view 4000x3000 JPEG. (Image credit: G.Bacon, STScI )
  • Artist view 800x600 JPEG. (Image credit: G.Bacon, STScI)
  
  
• Videos
  • Simple sketch of a planetary event mov (credit ESO)
  
  
  • Simulations of lensing as seen from an imaginary, nano-arcsecond resolution telescope:
    Variation of images as lens star and planet pass by (4 animations by Andrew Williams & David Bennett)
     
    
    • Whole microlensing event (~40 days).
      Lens star position shown green, Einstein ring in blue, source star position (assuming no lensing) shown in red.
      Images of background giant star in yellow. See Planet page for more information.
      • 1280x720 pixel mpeg4
      • 720x576 pixel broadcast-ready mpeg2
      •  
    • Zoomed inview of the two-day period covering the planetary anomaly.
      The planet is shown as a blue dot in front of the distorted images of the background giant star.
      • 1200x900 pixel mpeg4
      • 720x576 pixel broadcast-ready mpeg2
      •  
    • Adaptive view, showing whole (40-day) microlensing event, but zooming in and slowing down
      for the 2-day planetary anomaly.    Planet shown as a blue dot.
      • 1280x720 pixel mpeg4
      • 720x576 pixel broadcast-ready mpeg2
      •  
    • Comparison of the planetary deviation part of the light curve to the case of a planet that is 3 times more massive. AVI
    
     
    • Mosaic and all still frames from the zoomed-in planetary anomaly, 3000x3000 pixel
  
  

Please see the press releases for contact persons in your local area.
Enquiries about the contents of this page should be made to Dr. Beaulieu
       Beaulieu@iap.fr (prefered)        or: +33 1 44 32 81 19

The PLANET collaboration 2005 :

Institut d'Astrophysique de Paris (Paris, France): Dr. Jean-Philippe Beaulieu, Dr Arnaud Cassan, Esperanza de Santa Cecilia Corrales Cosmeli, Morgan Desort, Dr. Jean-Baptiste Marquette

University of St Andrews (St Andrews, United Kingdom): Dr. Martin Dominik, Prof. Keith Horne

Observatoire Midi-Pyrénées (Toulouse, France): Dr. Pascal Fouqué

CEA DAPNIA/SPP Saclay (Gif-sur-Yvette, France): Dr. Christian Coutures

Niels Bohr Institutet (Copenhagen, Denmark): Dr. Uffe G. Jørgensen, Christian Vinter, Kristian Woller

Universität Heidelberg (Heidelberg, Germany): Prof. Joachim Wambsganss

Universität Potsdam (Potsdam, Germany): Dijana Dominis

Technical University of Vienna (Vienna, Austra): Dr Jadzia Donatowicz

European Southern Observatory (Santiago, Chile): Dr. Stephane Brillant, Dr. Daniel Kubas

Space Telescope Science Institute (Baltimore, MD, USA): Dr. Kailash C. Sahu

University of Notre Dame (Notre Dame, IN, USA): Prof. David P. Bennett

University of Florida (Gainsville, FL, USA): Dr. Stephen R. Kane

Lawrence Livermore National Laboratory (Livermore, CA, USA): Dr. Kem H. Cook

McDonald Observatory (Fort Davis, TX, USA): Dr. John A. R. Caldwell

University of Washington (Seattle, WA, USA): Chris Laws

University of Canterbury (Christchurch, New Zealand): Dr. Michael D. Albrow, Dr. Karen R. Pollard

University of Tasmania (Hobart, TAS, Australia): Dr. Stefan Dieters, Dr. John Greenhill, Dr. Kym Hill

Mt Stromlo Observatory (Weston Creek, ACT, Australia): Dr. Penny D. Sackett

Perth Observatory (Bickley, WA, Australia): Dr. Ralph Martin, Dr. Andrew Williams

South African Astronomical Observatory (Cape Town, South Africa): Dr. John W. Menzies

Boyden Observatory (Bloemfontein, South Africa): Hannes Calitz, Dr. Matie Hoffman, Prof. Pieter Meintjes

The RoboNet collaboration:

Liverpool John Moores University (Liverpool, United Kingdom): Prof. Mike Bode, Dr. Daniel Bramich, Dr. Martin Burgdorf, Dr. Iain Steele

University of St Andrews (St Andrews, United Kingdom): Dr. Martin Dominik, Prof. Keith Horne

Queen's University Belfast (Belfast, United Kingdom): Colin Snodgrass

The OGLE collaboration:

Obserwatorium Astronomiczne Unversytetu Warszawaskiego (Warsaw, Poland): Prof. Marcin Kubiak, Dr. Grzegorz Pietrzynski, Dr. Igor Soszynski, Olaf Szewczyk, Dr. Michal K. Szymanski, Prof. Andrzej Udalski, Lukasz Wyrzykowski

Universidad de Concepcion (Concepcion, Chile): Dr. Grzegorz Pietrzynski, Dr. Igor Soszynski

Princeton University (Princeton, NJ, USA): Prof. Bohdan Paczynski

Jodrell Bank Observatory (Macclesfield, United Kingdom): Lukasz Wyrzykowski

The MOA collaboration:

Massey University (Auckland, New Zealand): Dr. Ian Bond

University of Auckland (Auckland, New Zealand): Tui Britton, Paul Tristram, Prof. Philip Yock

Victoria University (Victoria, New Zealand): Aarno Korpela, Dr. Denis Sullivan

University of Canterbury (Christchurch, New Zealand): Alan Gilmore, Prof. John Hearnshaw. Pam Kilmartin

Nagoya University (Nagoya, Japan): Prof. Fumio Abe, Prof. Yoshitaka Itow, Kouki Kamiya, Prof. Kimiaki Masuda, Prof. Yutaka Matsubara, Masatoshi Motomura, Prof. Yasushi Muraki, Shunsaku Nakamura, Chihiro Okada, Dr. Takashi Sako, Prof. Shuji Sato, Mitsuhiro Sasaki, Tomohiro Sekiguchi, Dr. Tsutomo Yoshioka

Nagano National College of Technology (Nagano, Japan): Prof. Kouji Ohnishi

Jodrell Bank Observatory (Macclesfield, United Kingdom): Dr. Nicholas Rattenbury

University of Notre Dame (Notre Dame, IN, USA): Prof. David P. Bennett