Final Report Summary - OGLEIV (Optical Gravitational Lensing Experiment: New Frontiers in Observational Astronomy)
The OGLE-IV long-term large-scale photometric sky survey started regular observations in March 2010. Since then it has been regularly monitoring thousands of square degrees of the most stellar dense regions of the sky containing over a billion of objects. Currently OGLE-IV is the largest sky variability survey worldwide. During the period of 2010-2014 the OGLE-IV survey has collected over 300 000 wide-field images, i.e. over 150 Terabytes of raw photometric data.
The OGLE-IV project consists of a series of long-term sky surveys covering the main astrophysical laboratories like the Galactic center, Magellanic System (Magellanic Cloud and Magellanic Bridge) and Galactic disk and short-term surveys aiming for example, at the discovery of new massive solar system objects. The collected images are reduced and analyzed in real time what allows real time monitoring of known variable objects and early discovery of unique objects like gravitational microlensing events (over 2000 per year) or transient objects (about 200 supernovae per year).
During the OGLEIV project research in many fields of modern astrophysics has been conducted. The main scientific outcome includes:
* significant increase of the detection rate of exoplanets with the gravitational microlensing technique (several tens during the years 2010-2014). The sample contains unique systems like OGLE-2013-BLG-0341 – an Earth-mass circumprimary exoplanet in a binary stellar system, the first Uranus-like exoplanet, also in a binary system (OGLE-2008-BLG-092) and several cases of rare systems with Jupiter-mass planets orbiting low mass stars.
* Discovery of an enigmatic population of free-floating exoplanets.
* First assessments of the frequency of the Galactic exoplanets of wide range of masses (from super-Earths to Jupiter-mass objects) orbiting their hosts at 1-5 AU. Joint observational campaign with the Spitzer satellite aiming at the determination of the distribution of exoplanets in the Galaxy.
* Final ruling out low mass compact objects as the main component of the dark matter in the halo of the Milky Way. Studies of the Galactic structure with gravitational microlensing.
* Discovery and analysis of huge samples of variable stars of all types. For example, complete census of pulsating RR Lyrae type stars in the Galactic center (over 38 000 objects used for the Galactic center structure studies), full census of pulsating Cepheids and RR Lyrae stars in the Magellanic System, huge samples of eclipsing stars, pulsating red giants and other variable objects. The OGLE collection of variable stars counts currently over 500 000 classified periodic stars and this is the largest uniform data set of variables worldwide.
* Discovery of hundreds of rare unique variable stars: pulsating stars in eclipsing systems and other non-standard eclipsing stars, merger of main sequence stars, optical counterparts of X-ray sources, and many others.
* Most precise determination of the distance to the Large Magellanic Cloud with the OGLE eclipsing stars. The LMC distance is the base of the extragalactic distance scale.
* The most extensive so far studies of stellar populations in the Magellanic System – the discovery of the continuous stream of young stellar population between the Magellanic Clouds. Studies of the Galactic structure with red giant stars. Studies of interstellar extinction toward the Galactic center.
* Discovery of new large transneptunian objects, e.g. 2010 EK 139 with diameter of ~500 km – promising candidate for a dwarf planet.
The OGLE-IV project consists of a series of long-term sky surveys covering the main astrophysical laboratories like the Galactic center, Magellanic System (Magellanic Cloud and Magellanic Bridge) and Galactic disk and short-term surveys aiming for example, at the discovery of new massive solar system objects. The collected images are reduced and analyzed in real time what allows real time monitoring of known variable objects and early discovery of unique objects like gravitational microlensing events (over 2000 per year) or transient objects (about 200 supernovae per year).
During the OGLEIV project research in many fields of modern astrophysics has been conducted. The main scientific outcome includes:
* significant increase of the detection rate of exoplanets with the gravitational microlensing technique (several tens during the years 2010-2014). The sample contains unique systems like OGLE-2013-BLG-0341 – an Earth-mass circumprimary exoplanet in a binary stellar system, the first Uranus-like exoplanet, also in a binary system (OGLE-2008-BLG-092) and several cases of rare systems with Jupiter-mass planets orbiting low mass stars.
* Discovery of an enigmatic population of free-floating exoplanets.
* First assessments of the frequency of the Galactic exoplanets of wide range of masses (from super-Earths to Jupiter-mass objects) orbiting their hosts at 1-5 AU. Joint observational campaign with the Spitzer satellite aiming at the determination of the distribution of exoplanets in the Galaxy.
* Final ruling out low mass compact objects as the main component of the dark matter in the halo of the Milky Way. Studies of the Galactic structure with gravitational microlensing.
* Discovery and analysis of huge samples of variable stars of all types. For example, complete census of pulsating RR Lyrae type stars in the Galactic center (over 38 000 objects used for the Galactic center structure studies), full census of pulsating Cepheids and RR Lyrae stars in the Magellanic System, huge samples of eclipsing stars, pulsating red giants and other variable objects. The OGLE collection of variable stars counts currently over 500 000 classified periodic stars and this is the largest uniform data set of variables worldwide.
* Discovery of hundreds of rare unique variable stars: pulsating stars in eclipsing systems and other non-standard eclipsing stars, merger of main sequence stars, optical counterparts of X-ray sources, and many others.
* Most precise determination of the distance to the Large Magellanic Cloud with the OGLE eclipsing stars. The LMC distance is the base of the extragalactic distance scale.
* The most extensive so far studies of stellar populations in the Magellanic System – the discovery of the continuous stream of young stellar population between the Magellanic Clouds. Studies of the Galactic structure with red giant stars. Studies of interstellar extinction toward the Galactic center.
* Discovery of new large transneptunian objects, e.g. 2010 EK 139 with diameter of ~500 km – promising candidate for a dwarf planet.