J/A+A/628/A51 Magellanic Clouds reddening map (Joshi+, 2019)
Reddening map and recent star formation in the Magellanic Clouds based on
OGLE IV Cepheids.
Joshi Y.C., Panchal A.
<Astron. Astrophys. 628, A51 (2019)>
=2019A&A...628A..51J 2019A&A...628A..51J (SIMBAD/NED BibCode)
ADC_Keywords: Magellanic Clouds ; Stars, variable ; Reddening
Keywords: method: data analysis - surveys - stars: variables: Cepheids -
Magellanic Clouds - galaxies: star formation
Abstract:
The reddening maps of the Large Magellanic Cloud (LMC) and Small
Magellanic Cloud (SMC) are constructed using the Cepheid
period-luminosity (P-L) relations. We examine reddening distribution
across the LMC and SMC through large data sets 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. 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 were analysed for their P-L relations. We converted the period of
FO Cepheids to the corresponding period of FU Cepheids before
combining the two modes of Cepheids. Both galaxies were divided into
small segments and combined FU and FO P-L diagrams were drawn in two
bands for each segment. The reddening analysis was performed on 133
segments covering a total area of about 154.6deg2 in the LMC and 136
segments covering a total area of about 31.3deg2 in the SMC. By
comparison with well-calibrated P-L relations of these two galaxies,
we determined reddening E(V-I) in each segment and equivalent
reddening E(B-V) assuming the normal extinction law. The period-age
relations were used to derive the age of the Cepheids. Reddening maps
were constructed using reddening values in different segments across
the LMC and SMC. 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)=0.466mag is traced in the region
centred at RA∼85.13deg, DEC~-69.34deg which is in close vicinity
of the star forming HII region 30 Doradus. In the SMC, maximum
reddening of E(V-I)=0.189mag is detected in the region centred at
RA∼12.10deg, DEC~-73.07deg. The mean reddening values in the LMC and
SMC are estimated as E(V-I)LMC=0.113±0.060mag,
E(B-V)LMC=0.091±0.050mag, E(V-I)SMC=0.049±0.070mag, and
E(B-V)SMC=0.038±0.053mag. The LMC reddening map displays
heterogeneous distribution having small reddening in the central
region and higher reddening towards the eastern side of the LMC bar.
The SMC has relatively small reddening in its peripheral regions but
larger reddening towards the south-west region. In these galaxies, we
see evidence of a common enhanced Cepheid population at around 200 Myr
ago which appears to have occurred due to a close encounter between
the two clouds.
Description:
Using the OGLE-IV catalogue of Fundamental-mode and First-overtone
mode Cepheids, we estimated the reddening in large number of
small-size segments in LMC and SMC using the well-calibrated P-L
relations. Using the reddening information in small segments
throughout LMC and SMC, we constructed reddening maps in these two
nearby galaxies. In our earlier paper (2014NewA...28...27J 2014NewA...28...27J), we
derived period-age relations for the Cepheids in the LMC which was
used to study their age distribution using the OGLE-III catalogue of
Fundamental-mode and First-overtone mode Cepheids. We carried out
similar analysis for the SMC in our follow-up study
(2016RAA....16...61J 2016RAA....16...61J). In this paper, we used reddening estimations,
spatial distribution, age and spatio-temporal distributions of
classical Cepheids to understand the recent star formation in the
Magellanic Clouds.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 51 133 Reddening in 133 different segments of the LMC
table3.dat 51 136 Reddening in 136 different segments of the SMC
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See also:
J/AcA/65/297 : OGLE4 LMC and SMC Cepheids (Soszynski+, 2015)
Byte-by-byte Description of file: table1.dat table3.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- ID Segment ID
6- 9 F4.1 kpc X X center of the box
12- 15 F4.1 kpc Y Y center of the box
18- 22 F5.2 deg RAdeg Right ascension (J2000.0)
25- 30 F6.2 deg DEdeg Declination (J2000.0)
32- 37 F6.3 mag E(V-I) Reddening E(V-I)
39- 44 F6.3 mag E(B-V) Reddening E(B-V)
47- 51 F5.3 mag e_E(V-I) Error in Reddening E(V-I)
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Acknowledgements:
Yogesh C. Joshi, yogesh(at)aries.res.in
References:
Joshi & Joshi, 2014NewA...28...27J 2014NewA...28...27J
Population I Cepheids and star formation history of the Large Magellanic Cloud
Joshi, Mohanty & Joshi, 2016RAA....16...61J 2016RAA....16...61J
Population I Cepheids and understanding star formation history of the
Small Magellanic Cloud
(End) Yogesh C. Joshi [ARIES, India], Patricia Vannier [CDS] 02-Jul-2019