J/A+A/553/A87 Star forming regions in HST galaxies sample (Drazinos+, 2013)
Star forming regions in a sample of HST spiral galaxies.
Drazinos P., Kontizas E., Karampelas A., Kontizas M., Dapergolas A.
<Astron. Astrophys., 553, A87-87 (2013)>
=2013A&A...553A..87D 2013A&A...553A..87D
ADC_Keywords: Galaxy catalogs ; Morphology
Keywords: methods: statistical - catalogs - galaxies: structure
Abstract:
The presence of small- and large-scale star formation structures in a
sample of six spiral Hubble Space Telescope (HST) galaxies is
investigated to identify small structures of young stars known as OB
associations and to tell whether they are formed inside larger scale
star forming stellar structures in a hierarchical form. This process
was based on a friend-of-friend (FOF) algorithm applied to the bright,
early type stars above a certain color cutoff limit in order to ensure
that we include main sequence stars. A size criterion was introduced
in order to apply the same algorithm to different types of stellar
structures. Depending on their size, the structures were divided into
the four categories of associations, aggregates, complexes, and
supercomplexes. Star forming structures of the four types mentioned
above are found in all six galaxies of our sample. The majority of the
associations and aggregates (the smaller structures) found are lying
inside larger structures like complexes and supercomplexes, indicating
a hierarchical star formation mechanism.
Description:
The data used for our study were taken using HST/WFPC2 images and
filters F555W(V) and F814W (I). They were retrieved from the HST data
archive and were reduced using the HSTphot photometry package (Dolphin
2000, http://purcell.as.arizona.edu/hstphot/). A method based on a
Friend of Friend algorithm were used to detect young stellar
structures. In each catalogue we give for each structure, the position
of the centre (deg), it's size (pc), the number of stars within the
structure, and it's type as described in the relevant paper.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
ngc925.dat 42 775 NGC 925 young stellar structures
ngc2541.dat 42 690 NGC 2541 young stellar structures
ngc3351.dat 42 560 NGC 3351 young stellar structures
ngc3621.dat 42 944 NGC 3621 young stellar structures
ngc4548.dat 42 832 NGC 4548 young stellar structures
ngc5457.dat 42 710 NGC 5457 young stellar structures
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Byte-by-byte Description of file: ngc*.dat
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Bytes Format Units Label Explanations
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1- 3 I3 -- Index Sequential number within the Group
5- 14 F10.6 deg RAdeg Right ascension (J2000)
16- 25 F10.6 deg DEdeg Declination (J2000)
27- 30 I4 -- Nstars Number of stars in Group
32- 40 F9.3 pc Size Group size (parsec)
42 I1 -- Type [1/4] Type of Group: 1=Association,
2=Aggregate, 3=Complex, 4=Supercomplex
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Acknowledgements:
Petros Drazinos, pdrazinos(at)noa.gr
(End) Petros Drazinos [UOA, Greece], Patricia Vannier [CDS] 18-Feb-2014