J/MNRAS/479/961 Young star groups in NGC 253 (Rodriguez+, 2018)
Identification and analysis of the young population in the starburst
galaxy NGC 253.
Rodriguez M.J., Baume G., Feinstein C.
<Mon. Not. R. Astron. Soc., 479, 961-972 (2018)>
=2018MNRAS.479..961R 2018MNRAS.479..961R (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby ; Associations, stellar ; Photometry, HST ;
Optical
Keywords: stars: early-type - stars: luminosity function, mass function -
galaxies: individual: NGC 253 - galaxies: star clusters: general -
galaxies: structure - galaxies: star formation
Abstract:
We present a study of the young population in the starburst galaxy
NGC 253. In particular, we focused our attention on searching for
young star groups, obtaining their main properties and studying their
hierarchical organization. For this task, we used multiband images and
their corresponding photometric data obtained with the Advanced Camera
for Surveys of the Hubble Space Telescope (ACS/HST). We first derived
the absorption affecting the different regions of the galaxy. Then, we
applied an automatic and objective searching method over the corrected
data in order to detect young star groups. We complemented this result
with the construction of a stellar density map for the blue young
population. A statistical procedure to decontaminate the photometric
diagrams from field stars was applied over the detected groups and we
estimated their fundamental parameters. As a result, we built a
catalogue of 875 newly identified young groups with their main
characteristics, including coordinates, sizes, estimated number of
members, stellar densities, luminosity function (LF) slopes and
galactocentric distances. We observed that these groups delineate
different structures of the galaxy, and they are the last step in the
hierarchical way in which the young population is organized. From
their size distribution, we found they have typical radii of
∼40-50pc. These values are consistent with those found in other
nearby galaxies. We estimated a mean value for the LF slope of 0.21
and an average density of 0.0006 star/pc3 for the identified young
groups, taking into account stars earlier than B6.
Description:
The images used in this work were acquired from the Hubble Legacy
Archive1 and were obtained in 2006 September, as part of the programme
GO-10915 (principal investigator: J. Dalcanton), during HST Cycle 15.
These observations correspond to five fields of NGC 253, and were
carried out with the wide-field camera (WFC) of the Advanced Camera
for Surveys (ACS).
We performed an automatic analysis of the detected young star groups
using a numerical code developed in fortran 95. This code allowed the
study of selected groups in a systematic and homogeneous way. The code
estimated the basic parameters of each group detected by the PLC,
their sizes, densities, and number of object members, and built their
CMDs and LFs, with their corresponding slope values.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
catalog.dat 84 875 Catalogue of young star groups in NGC 253
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Byte-by-byte Description of file: catalog.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- Name Name (ASNNN)
7- 15 F9.6 deg RAdeg Right ascension (J2000)
17- 26 F10.6 deg DEdeg Declination (J2000)
28- 33 F6.2 pc r Radius
35- 38 I4 --- N Number of stars
40- 43 I4 --- Ndct Number of stars belonging to the
decontaminated region
45- 47 I3 --- Ndct-bri Number of bright stars with F606W<24
49- 53 F5.2 mag F606W-bb ?=99.99 F606W value of the brightest blue
object in the group
55- 61 F7.5 pc-3 Density Density (in */pc3)
63- 67 F5.2 --- Gamma LF slope (dlogN/dF606W)
69- 72 F4.2 --- e_Gamma rms uncertainty on Gamma
74- 78 F5.2 kpc dGC Galactocentric distance
80- 84 F5.3 mag Av Characteristic absorption affecting the group
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 28-Apr-2022