Reddening map and recent star formation in the Magellanic Clouds based on OGLE IV Cepheids

Abstract

Context. The reddening maps of the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) are constructed using the Cepheid Period-Luminosity (P-L) relations. Aims. We examine reddening distribution across the LMC and SMC through largest data on Classical Cepheids provided by the OGLE Phase IV survey. We also investigate the age and spatio-temporal distributions of Cepheids to understand the recent star formation history in the LMC and SMC. Methods. 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 P-L relations. We convert period of FO Cepheids to corresponding period of FU Cepheids before combining the two modes of Cepheids. Both galaxies are divided into small segments and combined FU and FO P-L diagrams are drawn in two bands for each segment. 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 and equivalent reddening E(B − V) assuming the normal extinction law. The period-age relations are used to derive the age of the Cepheids.Results. 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 α ∼ 85 o .13, δ ∼ −69 o .34 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 α ∼ 12 o .10, δ ∼ −73 o .07. The mean reddening values in the LMC and SMC are estimated as E(V − I) LMC = 0.113 ± 0.060 mag, E(B − V) LMC = 0.091 ± 0.050 mag, E(V − I) S MC = 0.049 ± 0.070 mag, and E(B − V) S MC = 0.038 ± 0.053 mag.Conclusions. The LMC reddening map displays heterogeneous distribution having small reddening in the central region and higher reddening towards eastern side of the LMC bar. The SMC have relatively small reddening in peripheral regions but larger reddening towards south-west region. In these galaxies, we see an evidence of a common enhanced Cepheid population at around 200 Myr ago which appears to have occurred due to close encounter between the two clouds.

Axion and neutrino bounds improved with new calibrations of the tip of the red-giant branch using geometric distance determinations

“…The main difference arises from the different extinction value. A thorough summary of recent reddening measurements using different stellar populations in the LMC is provided in Table 2 of Joshi and Panchal [33]. In the same work, they analyzed the reddening distribution across the LMC using Cepheids provided by the OGLE IV survey.…”

OGLE-ing the Magellanic System: Optical Reddening Maps of the Large and Small Magellanic Clouds from Red Clump Stars

“…The majority of stellar population studies require accounting for interstellar extinction in order to acquire precise distances; thus, it is very important to have accurate reddening maps of the Magellanic System. Previous efforts to construct reddening maps employed various tracers such as Red Clump (RC) stars (Udalski et al 1999a(Udalski et al , 1999bSubramaniam 2005;Subramanian & Subramaniam 2009Haschke et al 2011;Tatton et al 2013;Choi et al 2018;Górski et al 2020), classical Cepheids (Inno et al 2016;Joshi & Panchal 2019), or RR Lyrae-type variables (Pejcha & Stanek 2009;Haschke et al 2011;Deb 2017). Interstellar reddening has also been inferred from equivalent widths of spectral lines (Munari & Zwitter 1997), stellar atmosphere fitting (Zaritsky et al 2002(Zaritsky et al , 2004, and through the analysis of spectral energy distributions of background galaxies (Bell et al 2019).…”

The intrinsic reddening of the Magellanic Clouds as traced by background galaxies – II. The Small Magellanic Cloud

“…Of the eight literature maps shown, three (Zaritsky et al 2002;Muraveva et al 2018;Górski et al 2020) show no obvious signs of enhanced levels of reddening associated with the main body of the SMC, when compared with the levels of reddening in regions away from the main body. In contrast, the remaining five maps (Gordon et al 2014, the two realizations of Rubele et al 2018, Joshi &Panchal 2019, andTatton et al submitted) all exhibit clear signs of enhanced reddening in the south-western region of the main body ( RA 0.35, Dec. -0.35 deg) as well as other regions in some cases.…”

“…In this study, we retain the reddening maps of Zaritsky et al (2002, specifically that based on the cool stars), Muraveva et al (2018), Rubele et al (2018), and Tatton et al (submitted), and refer the reader to Paper I for details concerning each of these. Additionally, we include as part of our comparison recent reddening maps produced by Joshi & Panchal (2019) and Górski et al (2020) as well as the dust emission map based on far-IR and submillimetre observations taken as part of the HERschel Inventory of The Agents of Galaxy Evolution (HERITAGE) project (Meixner et al 2013).…”

“…For example, the use of young stellar populations (e.g. young star clusters and Cepheids; Nayak et al 2018;Joshi & Panchal 2019) results in reddening maps with enhanced levels of reddening associated with regions that are actively forming stars and lower levels of reddening in more quiescent regions. In contrast, reddening maps based on older stars [e.g.…”