Population I Cepheids and star formation history of the Large Magellanic Cloud

• A bimodal frequency-period distribution for Cepheids has been found in the LMC.
• A new period-age relation has been derived for the LMC Population I Cepheids.
• We show that a major star formation event took place in LMC at ∼125–200 Myr ago.

In this paper we study the Cepheids distribution in the Large Magellanic Cloud (LMC) as a function of their ages using data from the OGLE III photometric catalogue. To determine age of the Pop I Cepheids, we derived a period – age (PA) relationship using the Cepheids found in the LMC star clusters. We find two peaks in the period distribution at logP=0.49±0.01logP=0.49±0.01 and logP=0.28±0.01logP=0.28±0.01 days which correspond to fundamental and first overtone pulsation modes, respectively. Ages of the Cepheids are used to understand star formation scenario in the LMC in last 30–600 Myr. The age distribution of the LMC Cepheids is found to have a peak at log (Age)=8.2±±0.1. This suggests that major star formation event took place at about 125–200 Myr ago which may have been triggered by a close encounter between the SMC and the LMC. Cepheids are found to be asymmetrically distributed throughout the LMC and many of them lie in clumpy structures along the bar. The frequency distribution of Cepheids suggests that most of the clumps are located to the eastern side of the LMC optical center.