Imaging of the Galaxy with pulsating stars
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Principal Investigator: prof. dr hab. Igor Soszyński

Place: Astronomical Observatory of the University of Warsaw

Project duration: 2017-2022


The goal of this research project is to prepare the largest collection of classical pulsating stars (Cepheids, RR Lyrae stars, and delta Scuti stars) in the Milky Way and to use these stars to answer the most fundamental questions about the structure of the Galaxy. How many spiral arms does the Milky Way have? How far does the disk extend? What is the accretion history of the Galaxy? The search for pulsating stars will be based on the huge photometric database obtained by the Optical Gravitational Lensing Experiment (OGLE) which since 2010 monitors brightness of about 900 million stars in the Galactic bulge and disk. Containing about 1012 individual photometric measurements, the OGLE database is currently the world’s best observational material suited for a massive variable star search.

We propose to focus on pulsating stars that populate the Cepheid instability strip in the H-R diagram, since these stars are primary distance indicators, tracers of various stellar populations and laboratories for studying stellar pulsation and evolution. We expect to find several thousand new classical Cepheids - a sample a few times larger that is presently known in the entire Milky Way. These pulsators will be used to delineate the spiral structure of the Galaxy in the regions farther than about 3 kpc from the Sun - currently very poorly sampled with stellar standard candles. Type II Cepheids and RR Lyrae stars are representatives of the oldest stellar population. In our survey we plan to identify thousands of these variables in the Galactic disk – in the regions notoriously avoided by other large-scale sky surveys due to stellar crowding. We will conduct the first ever massive search for anomalous Cepheids in the Galactic field. Thanks to the largest sample of these mysterious stars recently identified by OGLE in the Magellanic System, we developed a method of distinguishing anomalous Cepheids from other pulsating stars based on their light curves shapes. Finally, we expect the discovery of more than ten thousand high-amplitude delta Scuti stars. Such a huge sample will provide new standards for asteroseismic studies.

The OGLE Project
Astronomical Observatory of the University of Warsaw
Faculty of Physics at the University of Warsaw
University of Warsaw
National Science Centre, Poland
Copyright by Igor Soszynski & OGLE Team