Reddening map and recent star formation in the Magellanic Clouds based
  on OGLE IV Cepheids
  In the present study, we examine reddening distribution across the LMC and
SMC through largest data on Classical Cepheids provided by the OGLE Phase IV
survey. The V and I band photometric data of 2476 fundamental mode (FU) and
1775 first overtone mode (FO) Cepheids in the LMC and 2753 FU and 1793 FO
Cepheids in the SMC are analyzed for their Period-Luminosity (P-L) relations.
We convert period of FO Cepheids to corresponding period of FU Cepheids before
combining the two modes of Cepheids. The reddening analysis is performed on 133
segments covering a total area of about 154.6 deg^2 in the LMC and 136 segments
covering a total area of about 31.3 deg^2 in the SMC. By comparing with well
calibrated P-L relations of these two galaxies, we determine reddening E(V-I)
in each segment. Using reddening values in different segments across the LMC
and SMC, reddening maps are constructed. We find clumpy structures in the
reddening distributions of the LMC and SMC. From the reddening map of the LMC,
highest reddening of E(V-I) = 0.466 mag is traced in the region centered at RA
~ 85.13 deg, DEC ~ -69.34 deg which is in close vicinity of the star forming
HII region 30 Doradus. In the SMC, maximum reddening of E(V-I) = 0.189 mag is
detected in the region centered at RA ~ 12.10 deg, DEC ~ -73.07 deg. The mean
reddening values in the LMC are estimated as E(V-I) = 0.113+/-0.060 mag and
E(B-V) = 0.091+/-0.050 mag; and that in the SMC are E(V-I) = 0.049+/-0.070 mag
and E(B-V) = 0.038+/-0.053 mag. The period-age relations are used to derive the
age of the Cepheid populations in the LMC and SMC. We investigate age and
spatio-temporal distributions of Cepheids to understand the recent star
formation history in the Magellanic Clouds (MCs) and found an evidence of a
common enhanced Cepheid population in the MCs at around 200 Myr ago which
appears to have occurred due to close encounter between the two clouds.
