VARSTARS · Variable Stars in Current and Future Large Scale Observing Surveys

Variable Stars in Current and Future Large Scale Observing Surveys

In the project we exploited the time-domain astronomical datasets in preparation for future all-sky monitoring space mission Gaia. ASAS, OGLE and SDSS databases were used as training sets and various types of variable stars were studied. This included microlensing events, supernovae, R Corona Borealis-type stars, FU Orionis-type stars and dwarf and classical novae. These types of variable-transient objects were identified and used for studying their properties in the context of their rapid classification within the Gaia data flow. The template light curves of each of the type were extracted from the available real data and were fed into the simulations of the Gaia data. This yielded the estimated rates of these objects detectable during the Gaia mission (Wyrzykowski et al. 2011a). Microlensing events were searched for in the microlensing-dedicated survey OGLE, which for last two decades continuously monitors dense regions of the sky. We found candidates for microlensing events in the Magellanic Clouds and the Galactic Centre. These events were also used for constraining the amount of dark matter present in the form of compact objects. Our studies (Wyrzykowski et al. 2009, 2010, 2011b, 2011c) confirmed that a negligible fraction of the Galactic halo dark matter mass is encompassed in compact objects of sub-solar masses. Dwarf novae and classical novae are commonly found in the microlensing datasets and often cause confusion with genuine microlensing events. We derived templates for dwarf novae using OGLE events which turned out to be dwarf novae and exhibited multiple brightening episodes (Skowron et al. 2009). R Corona Borealis and FU Orionis stars are very rare and change over long time-scales. Therefore they will be easily detectable with Gaia, which should provide a complete census of these stars in our Galaxy. We studied these stars using ASAS long term monitoring data from the entire sky as well as OGLE data and discovered a number of new previously unknown examples of these stars (Tisserand et al. 2010). Supernovae were studied primarily with the SDSS Stripe82 dataset, which covered about 300 square degrees of the sky monitored over 5 years. We used the supernovae previously identified in this data and also searched for new missed objects and found a handful of interesting candidates (Wyrzykowski, Kostrzewa in preparation). Tests of detectability of supernovae with Gaia were performed and revealed Gaia should detect about 6000 supernovae and be able to classify them almost immediately after the discovery. In the course of the project the Researcher attended several meetings and conferences related to the project. Among them were Microlensing Workshops in Paris (2009) and Salerno (2011), where the Researcher presented his research on microlensing and its connection to Gaia. In 2011 the Researcher attended the Symposium of the International Astronomical Union in Oxford on transient astrophysical phenomena and presented Gaia transients science to the international community as well as chaired the workshop on microlensing-past and future. The Researcher also visited the Warsaw University Astronomical Observatory several times during the project to build and maintaining the scientific links with that institution. Also, the Researcher invited and collaborated with the following people from Warsaw: Bogumil Pilecki, Jan Skowron, Radoslaw Pilecki, Marcin Sokolowski, Zuzanna Kostrzewa. The Researcher initiated and organised two workshops (in 2010 and 2011) concentrated on detection and studies of transient variable stars with Gaia. These were held in the Institute of Astronomy in Cambridge and each time attracted about 50 scientists from around the world who are currently actively involved in the field and are interested in Gaia mission. On a final note, the reintegration into the Warsaw University was fully successful as the Researcher obtained a tenure-track position at the Astronomical Observatory which commences in 2012. The ERG had a huge impact on this as it allowed the Researcher to extend his own duties in Cambridge with the activities which linked with Warsaw. The collaboration initiated is likely to last through next years when Gaia mission operates.

Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз