The double Blue Straggler sequence in NGC2173: a field contamination artefact
Journal
Date Issued
2019
Author(s)
Abstract
Here we discuss the case of the double Blue Straggler Star (BSS) sequence
recently detected in the young stellar cluster NGC 2173 in the Large Magellanic
Cloud by Li et al (2018). In order to investigate this feature we made use of
two HST sets of observations, one (the same one used by Li et al.) probing the
cluster central regions, and the other sampling the surrounding field. We
demonstrate that when field star decontamination is applied, ~40% of BSS
population selected by Li et al. turns out to be composed by field stars
interlopers. This contamination mainly affects one of the two sequences, which
therefore disappears in the decontaminated colour-magnitude diagram. We analyse
the result of tens different decontamination realisations: in none of them we
find evidence of a double BSS sequence. Hence we conclude that NGC 2173
harbours a normal single (poorly populated) BSS sequence and that particular
care needs to be devoted to the field decontamination process in any study
aimed at probing stellar population features or star counts in the LMC
clusters.
Volume
621
Start page
A45
Issn Identifier
0004-6361
Ads BibCode
2019A&A...621A..45D
Rights
open.access
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