J/A+A/626/A35 NGC 247 young stellar population (Rodriguez+, 2019)
The young stellar population in NGC 247.
Main properties and hierarchical clustering.
Rodriguez M.J., Baume G., Feinstein C.
<Astron. Astrophys. 626, A35 (2019)>
=2019A&A...626A..35R 2019A&A...626A..35R (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby ; H II regions ; YSOs
Keywords: stars: early-type - stars: luminosity function, mass function -
galaxies: individual: NGC 247 - galaxies: star formation -
galaxies: star clusters: general
Abstract:
We seek to investigate the characteristics of the young stellar
population in the spiral galaxy NGC 247. In particular, we focused our
attention in its hierarchical clustering distributions and the
properties of the smallest groups.
We used multiband Hubble Space Telescope (HST) data from three fields
covering more than half of NGC 247 to select the young population.
Then, through the path linkage criterion (PLC), we found compact young
star groups and estimated their fundamental parameters, such as their
stellar densities, sizes, number of members, and luminosity function
(LF) slopes. We also performed a fractal analysis to determinate the
clustering properties of this population. We built a stellar density
map and dendrograms corresponding to the galactic young population to
detect large structures and depict their main characteristics.
We detect 339 young star groups, for which we compute a mean radius of
∼60pc and a maximum size distribution between 30 and 70pc. We also
obtain LF slopes with a bimodal distribution showing peaks at ∼0.1
and ∼0.2. We identify several candidates for HII regions that follow
an excellent spatial correlation with the young groups found by the
PLC. We observe that the young populations are hierarchically
organized, wherein the smaller and denser structures are within larger
and less dense structures. We notice that all these groups present a
fractal subclustering, following the hierarchical distribution
observed in the corresponding stellar density map. For the large young
structures observed in this map, we obtain a fractal dimension of
∼1.6-1.8 using the perimeter-area relation and cumulative size
distribution. These values are consistent with a scenario of
hierarchical star formation.
Description:
File table3 contains the main parameters of the 339 young stellar
groups detected in NGC 247
File table4 contains coordinates and size of the candidates to HII
regions in NGC 247
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 116 339 Main parameters of young stellar groups in NGC 247
table4.dat 30 23 Candidates to HII regions
list.dat 87 1 Information on fits image
fits/* . 1 fits image
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See also:
J/AJ/136/1770 : VI light curves of NGC 247 Cepheids (Garcia-Varela+, 2008)
J/ApJ/694/1237 : BVRI light curves of NGC 247 Cepheids (Madore+, 2009)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- Name Identification (ASNNN)
7- 17 F11.8 deg RAdeg Right ascension (J2000)
19- 30 F12.8 deg DEdeg Declination (J2000)
32- 36 F5.2 kpc DistGC Galactocentric distance
38- 43 F6.2 pc Radius Radius
45- 48 I4 --- Ng Number of stars inside the group radius
50- 52 I3 --- Nbg Number of bright blue stars inside the
group radius
54- 56 I3 --- Nd Number of stars after field decontamination
58- 60 I3 --- Nbd Number of bright blue stars after
field decontamination
62- 66 F5.2 mag F606Wmag F606W value of the brightest blue star
68- 75 F8.5 pc-3 rho Stellar density in stars/pc3
77- 81 F5.2 --- Gamma ?=- Luminosity function slope
83- 86 F4.2 --- e_Gamma ?=- Luminosity function slope error
88- 91 F4.2 --- m Mean edge length in a minimum spanning tree
93- 96 F4.2 --- e_m Error of m
98-101 F4.2 --- s Mean separation of the stars in the group
103-106 F4.2 --- e_s Error of s
108-111 F4.2 --- Q Q parameter
113-116 F4.2 --- e_Q Error of the Q parameter
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Seq [1/23] Identification number
4- 5 I2 h RAh Right ascension (J2000)
7- 8 I2 min RAm Right ascension (J2000)
10- 14 F5.2 s RAs Right ascension (J2000)
16 A1 --- DE- Declinaiton sign (J2000)
17- 18 I2 deg DEd Declinaiton (J2000)
20- 21 I2 arcmin DEm Declinaiton (J2000)
23- 26 F4.1 arcsec DEs Declinaiton (J2000)
28- 30 F3.1 arcmin Diam Diameter
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 22 I3 --- Nx Number of pixels along X-axis
24- 26 I3 --- Ny Number of pixels along Y-axis
28- 31 I4 Kibyte size Size of FITS file
33- 52 A20 --- FileName Name of FITS file, in subdirectory fits
54- 87 A34 --- Title Title of the FITS file
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Acknowledgements:
Maria Jimena Rodriguez, jimenaro(at)fcaglp.unlp.edu.ar
(End) Patricia Vannier [CDS] 10-Apr-2019