The star cluster – field star connection in nearby spiral galaxies

Silva-Villa, E.; Larsen, S. S.

doi:10.1051/0004-6361/201016206

Cited by 97 publications

(119 citation statements)

References 63 publications

(90 reference statements)

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“…Right: Γ vs. star formation rate (SFR) surface density. Open blue diamonds correspond to the samples from Goddard et al (2010), green triangles to Adamo et al (2011), and red squares to Silva-Villa & Larsen (2011). The cyan crosses correspond to the sample of Cook et al (2012).…”

Section: Discussionmentioning

confidence: 99%

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A Starburst in the Core of a Galaxy Cluster: The Dwarf Irregular NGC 1427a in Fornax

Mora

Chanamé

Puzia

2015

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Gas-rich galaxies in dense environments such as galaxy clusters and massive groups are affected by a number of possible types of interactions with the cluster environment, which make their evolution radically different than that of field galaxies. The dwarf irregular galaxy NGC 1427A, presently infalling toward the core of the Fornax galaxy cluster for the first time, offers a unique opportunity to study those processes at a level of detail not possible to achieve for galaxies at higher redshifts, when galaxy-scale interactions were more common. Using the spatial resolution of the Hubble Space Telescope/Advanced Camera for Surveys and auxiliary Very Large Telescope/ FORS1 ground-based observations, we study the properties of the most recent episodes of star formation in this gas-rich galaxy, the only one of its type near the core of the Fornax cluster. We study the structural and photometric properties of young star cluster complexes in NGC 1427A, identifying 12 bright such complexes with exceptionally blue colors. The comparison of our broadband near-UV/optical photometry with simple stellar population models yields ages below~4 10 6 years and stellar masses from a few 1000 up to~´ M 3 10 4 , slightly dependent on the assumption of cluster metallicity and initial mass function. Their grouping is consistent with hierarchical and fractal star cluster formation. We use deep Hα imaging data to determine the current star formation rate in NGC 1427A and estimate the ratio, Γ, of star formation occurring in these star cluster complexes to that in the entire galaxy. We find Γ to be among the largest such values available in the literature, consistent with starburst galaxies. Thus a large fraction of the current star formation in NGC 1427A is occurring in star clusters, with the peculiar spatial arrangement of such complexes strongly hinting at the possibility that the starburst is being triggered by the passage of the galaxy through the cluster environment.

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Section: Discussionmentioning

confidence: 99%

“…These measurements seem to show that the cluster formation efficiency (SCFE) increases with S SFR , although with considerable scatter (Cook et al 2012), and there have even been reports of no clear trend at all (Bastian 2008;Silva-Villa & Larsen 2011).…”

Section: Fraction Of Recent Star Formation Occurring In Clustersmentioning

confidence: 99%

A Starburst in the Core of a Galaxy Cluster: The Dwarf Irregular NGC 1427a in Fornax

Mora

Chanamé

Puzia

2015

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“…Hence, two clusters with same physical parameters could host a different number of massive bright stars, resulting in very different integrated colors, especially in the A&A 581, A111 (2015) case of young and low-mass clusters that contain only a few massive bright stars. -SSP models are biased because they do not even match the average of integrated color distributions for star clusters with mass log 10 (M/M ) 4 (see, e.g., Fouesneau & Lançon 2010;Popescu & Hanson 2010;Silva-Villa & Larsen 2011).…”

Section: Introductionmentioning

confidence: 99%

Deriving physical parameters of unresolved star clusters

Meulenaer

Narbutis

Mineikis

et al. 2015

A&A

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Context. When trying to derive the star cluster physical parameters of the M 33 galaxy using broad-band unresolved ground-based photometry, previous studies mainly made use of simple stellar population models, shown in the recent years to be oversimplified. Aims. In this study, we aim to derive the star cluster physical parameters (age, mass, and extinction; metallicity is assumed to be LMC-like for clusters with age below 1 Gyr and left free for older clusters) of this galaxy using models that take stochastic dispersion of cluster integrated colors into account. Methods. We use three recently published M 33 catalogs of cluster optical broad-band photometry in standard UBVRI and in CFHT/MegaCam u * g r i z photometric systems. We also use near-infrared JHK photometry that we derive from deep 2MASS images. We derive the cluster parameters using a method that takes into account the stochasticity problem, presented in previous papers of this series. Results. The derived differential age distribution of the M 33 cluster population is composed of a two-slope profile indicating that the number of clusters decreases when age gets older. The first slope is interpreted as the evolutionary fading phase of the cluster magnitudes, and the second slope as the cluster disruption. The threshold between these two phases occurs at ∼300 Myr, comparable to what is observed in the M 31 galaxy. We also model by use of artificial clusters the ability of the cluster physical parameter derivation method to correctly derive the two-slope profile for different photometric systems tested.

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“…In the present work, we use the Silva-Villa et al catalogue and select class 1 and 2 sources with ages 10 Myr and masses > 5000M⊙. The mass cut was applied in order to limit the effects of stochasticity of the stellar IMF in the broad band properties of the sources (e.g., Barbaro & Bertelli 1977;Fouesneau & Lançon 2010;Silva-Villa & Larsen 2011;de Meulenaer et al 2013). …”

Section: Cluster Cataloguementioning

confidence: 99%

“…The authors acknowledge that their apertures do not cover just individual clusters, but rather contain cluster complexes. In comparison, HST based optical studies typically have aperture sizes of 3-10 pc (e.g., Whitmore et al 2010;Silva-Villa & Larsen 2011). Randriamanakoto et al (2010 have tested the role of resolution in determining the luminosity function index of cluster/complexes, and found that decreasing the resolution led to mildly flatter luminosity functions (∼ 0.1 in the index), however the authors did not investigate how the lower resolution affected the derived cluster/complex properties.…”

Section: Introductionmentioning

confidence: 99%

The effect of spatial resolution on optical and near-IR studies of stellar clusters: implications for the origin of the red excess

Bastian

Adamo

Schirmer

et al. 2014

Monthly Notices of the Royal Astronomical Society

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Recent ground based near-IR studies of stellar clusters in nearby galaxies have suggested that young clusters remain embedded for 7 − 10 Myr in their progenitor molecular cloud, in conflict with optical based studies which find that clusters are exposed after 1 − 3 Myr. Here, we investigate the role that spatial resolution plays in this apparent conflict. We use a recent catalogue of young (< 10 Myr) massive (> 5000 M ⊙ ) clusters in the nearby spiral galaxy, M83, along with Hubble Space Telescope (HST) imaging in the optical and near-IR, and ground based near-IR imaging, to see how the colours (and hence estimated properties such as age and extinction) are affected by the aperture size employed, in order to simulate studies of differing resolution. We find that the near-IR is heavily affected by the resolution, and when aperture sizes > 40 pc are used, all young/blue clusters move red-ward in colour space, which results in their appearance as heavily extincted clusters. However, this is due to contamination from nearby sources and nebular emission, and is not an extinction effect. Optical colours are much less affected by resolution. Due to the larger affect of contamination in the near-IR, we find that, in some cases, clusters will appear to show near-IR excess when large (> 20 pc) apertures are used. Our results explain why few young (< 6 Myr), low extinction (A V < 1 mag) clusters have been found in recent ground based near-IR studies of cluster populations, while many such clusters have been found in higher resolution HST based studies. Additionally, resolution effects appear to (at least partially) explain the origin of the near-IR excess that has been found in a number of extragalactic YMCs.

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The star cluster – field star connection in nearby spiral galaxies

Cited by 97 publications

References 63 publications

A Starburst in the Core of a Galaxy Cluster: The Dwarf Irregular NGC 1427a in Fornax

A Starburst in the Core of a Galaxy Cluster: The Dwarf Irregular NGC 1427a in Fornax

Deriving physical parameters of unresolved star clusters

The effect of spatial resolution on optical and near-IR studies of stellar clusters: implications for the origin of the red excess

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