OB stellar associations in the Large Magellanic Cloud: Survey of young stellar systems

Gouliermis, D. A.; Kontizas, M.; Kontizas, E.; Korakitis, R.

doi:10.1051/0004-6361:20030483

Cited by 31 publications

(40 citation statements)

References 53 publications

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“…We compared our results with those derived in a number of studies of other galaxies, M101 and LMC (B98, Kennicut, Stetson 1996, BKS), LMC (Gouliermis et al 2003), M33, M31, SMC (Battinelli et al 1996), NGC 6822 (Karampelas et al 2009;Gouliermis et al 2010), and HST galaxies .…”

Section: Comparison With Previous Investigationsmentioning

confidence: 93%

“…The increase in Nmin leads to identifying larger groups than when using lower Nmin values. Gouliermis et al (2003) report an average size of associations of 86 pc for LMC, and a peak in the size distribution at 70 pc, and a number of studies for different galaxies was also presented as well where the average size of the associations varied from 65-93 pc. For NGC 6822 Gouliermis (2010) gives a lower average of 68 pc.…”

Section: Comparison With Previous Investigationsmentioning

confidence: 99%

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Star forming regions in a sample of HST spiral galaxies

Drazinos

Kontizas

Karampelas

et al. 2013

A&A

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Aims. 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. Methods. 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. Results. 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.

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Section: Comparison With Previous Investigationsmentioning

confidence: 93%

Section: Comparison With Previous Investigationsmentioning

confidence: 99%

Star forming regions in a sample of HST spiral galaxies

Drazinos

Kontizas

Karampelas

et al. 2013

A&A

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“…Stellar (volume) density has been proposed as a crucial parameter for the distinction between stellar systems of different self-binding strength (Kontizas et al 1999;Gouliermis et al 2003) on both theoretical (Bok 1934;Spitzer 1958) and observational (Blaauw 1964;Lada & Lada 1991) grounds. This indicates that stellar density, expressed here in terms of observed "column" density, is an important intrinsic parameter of stellar groupings.…”

Section: Correlations Of Other Parameters With Sizementioning

confidence: 99%

Hierarchical star formation across the grand-design spiral NGC 1566

Gouliermis

Elmegreen²,

Elmegreen

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We investigate how star formation is spatially organized in the grand-design spiral NGC 1566 from deep HST photometry with the Legacy ExtraGalactic UV Survey (LEGUS). Our contour-based clustering analysis reveals 890 distinct stellar conglomerations at various levels of significance. These star-forming complexes are organized in a hierarchical fashion with the larger congregations consisting of smaller structures, which themselves fragment into even smaller and more compact stellar groupings. Their size distribution, covering a wide range in length-scales, shows a power-law as expected from scale-free processes. We explain this shape with a simple "fragmentation and enrichment" model. The hierarchical morphology of the complexes is confirmed by their mass-size relation which can be represented by a powerlaw with a fractional exponent, analogous to that determined for fractal molecular clouds. The surface stellar density distribution of the complexes shows a log-normal shape similar to that for supersonic non-gravitating turbulent gas. Between 50 and 65 per cent of the recentlyformed stars, as well as about 90 per cent of the young star clusters, are found inside the stellar complexes, located along the spiral arms. We find an age-difference between young stars inside the complexes and those in their direct vicinity in the arms of at least 10 Myr. This timescale may relate to the minimum time for stellar evaporation, although we cannot exclude the in situ formation of stars. As expected, star formation preferentially occurs in spiral arms. Our findings reveal turbulent-driven hierarchical star formation along the arms of a grand-design galaxy.

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“…The algorithms usually follow two strategies: (i) a search for statistically significant peaks (over 2 or 3σ) in maps of stellar density (Kontizas et al 1996;Gouliermis et al 2003); or (ii) the Path Linkage Criterion Method (Battinelli 1991) also known as the friends-of-friends algorithm. The use of pattern recognition (Feitzinger & Braunsfurth 1984) is less common.…”

Section: Automatic Search Of Ob Associationsmentioning

confidence: 99%

The young stellar population of IC 1613

García¹,

Herrero

Vicente³

et al. 2009

A&A

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Context. Determining the parameters of massive stars is crucial to understand many processes in galaxies and the Universe, since these objects are important sources of ionization, chemical enrichment and momentum. 10m class telescopes enable us to perform detailed quantitative spectroscopic analyses of massive stars in other galaxies, sampling areas of different metallicity. Relating the stars to their environment is crucial to understand the physical processes ruling their formation and evolution. Aims. In preparation for the new instrumentation planned for the Gran Telescopio CANARIAS (GTC), our goal is to build a list of massive star candidates in the metal-poor irregular galaxy IC 1613. The catalogue must have very high astrometric accuracy, suitable for the current generation of multi-object spectrographs. A census of OB associations in this galaxy is also needed, to provide important additional information about the age and environment of the candidate OB stars. Methods. From observations taken with the Wide Field Camera (WFC) at the Isaac Newton Telescope (INT), we have built an astrometric and photometric catalogue of stars in IC 1613. Candidate blue massive stars are preselected by their colors. A friendsof-friends algorithm is developed to find their clustering in the galaxy. While a common physical origin for all the members of the associations cannot be ensured, this is a necessary first step to place candidate OB stars in a population context. Results. We have produced a deep catalogue of targets in IC 1613 that covers a large field of view. To achieve high astrometric accuracy, a new astrometric procedure was developed for the INT-WFC data. We also built a catalogue of OB associations in IC 1613 and found that they concentrate in the central regions, especially in the H ii bubbles. The study of extinction confirms that it is patchy, with local values of color-excess above the foreground value.

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OB stellar associations in the Large Magellanic Cloud: Survey of young stellar systems

Cited by 31 publications

References 53 publications

Star forming regions in a sample of HST spiral galaxies

Star forming regions in a sample of HST spiral galaxies

Hierarchical star formation across the grand-design spiral NGC 1566

The young stellar population of IC 1613

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