Young star clusters in interacting galaxies – NGC 1487 and NGC 4038/4039

Mengel, Sabine; Lehnert, M. D.; Thatte, Niranjan; Vacca, William D.; Whitmore, Brad; Chandar, Rupali

doi:10.1051/0004-6361:200809649

Cited by 44 publications

(55 citation statements)

References 70 publications

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“…We adopt the definition of Whitmore (2003) who defined "young" as having an age less than 500 Myr and "massive" as having masses ranging from 10 3 M to 10 8 M . Individual YMCs were analyzed in detail by Bastian et al (2006b), Mengel et al (2008), and Bastian et al (2009). The combined dataset of the three publications demonstrates that the median size of YMCs in the mass range between 10 5 M and 10 6 M is about 4 pc.…”

Section: An Eo Formation Scenariomentioning

confidence: 99%

A catalog of extended clusters and ultra-compact dwarf galaxies

Kroupa

2012

A&A

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Context. In the past decade, very extended old stellar clusters with masses in the range from a few 10 4 to 10 8 M and effective radii larger than 10 pc have been found in various types of galaxies in different environments. Objects with masses comparable to normal globular clusters (GCs) are called extended clusters (ECs), while objects with masses in the dwarf galaxy regime are called ultra-compact dwarf galaxies (UCDs). Aims. The paper analyses the observational parameters total luminosity, M V , effective radius, r eff , and projected distance to the host galaxy, R proj , of all known ECs and UCDs and the dependence of these parameters on the type and the total luminosity of their host galaxy. Methods. We searched the available literature to compile a catalog of star clusters with effective radii larger than 10 pc. As there is no clear distinction between ECs and UCDs, both types of objects will be called extended stellar objects -abbreviated "EOs" -in this paper.Results. In total, we found 813 EOs of which 171 are associated with late-type galaxies and 642 EOs associated with early-type galaxies. EOs cover a luminosity range from about M V = −4 to −14 mag. However, the vast majority of EOs brighter than M V = −10 mag are associated with giant elliptical galaxies. At each magnitude extended objects are found with effective radii between 10 pc and an upper size limit, which shows a clear trend: the more luminous the object the larger is the upper size limit. For EOs associated with early-and late-type galaxies, the EO luminosity functions peak at −6.40 mag and −6.47 mag, respectively, which is about one magnitude fainter than the peak of the GC luminosity function. EOs and GCs form a coherent structure in the r eff vs. M V parameter space, while there is a clear gap between EOs and early-type dwarf galaxies. However, there is a small potential overlap at the high-mass end, where the most extended EOs are close to the parameters of some compact elliptical galaxies. We compare the EO sample with the numerical models of a previous paper and conclude that the parameters of the EO sample as a whole can be very well explained by a star cluster origin, where EOs are the results of merged star clusters of cluster complexes.

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Section: An Eo Formation Scenariomentioning

confidence: 99%

A catalog of extended clusters and ultra-compact dwarf galaxies

Kroupa

2012

A&A

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“…Another method that can be used to establish whether the selected complexes are stable is to study their location in wellknown empirical correlations followed by other self-gravitating (Bender et al 1992); open squares in red, dwarf ellipticals (Bender et al 1992;Geha et al 2003); crosses in yellow, dwarf spheroidals (Bender et al 1992); plusses in green, the TDG candidates in Monreal-Ibero et al (2007); diamonds in orange, massive globular clusters in NGC 5128 (Martini & Ho 2004); inverse triangles, globular clusters in the Galaxy (Trager et al 1993) and in M 31 (Dubath & Grillmair 1997); and asterisks in pink, clusters in the Antennae (Mengel et al 2008). …”

Section: Conditions For Self-gravitationmentioning

confidence: 99%

Extranuclear Hα-emitting complexes in low-z(U)LIRGs: precursors of tidal dwarf galaxies?

Miralles-Caballero

Colina

Arribas

2012

A&A

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This paper characterizes the physical and kinematic properties of external massive star-forming regions in a sample of (U)LIRGs. We use high angular resolution ACS images from the Hubble Space Telescope (HST) in F435W (∼B) and F814W (∼I) bands, as well as Hα-line emission maps obtained with integral field spectroscopy. We find 31 external Hα-emitting (i.e., young star-forming) complexes in 11 (U)LIRGs. These complexes have in general similar sizes (from few hundreds of pc to about 2 kpc), luminosities (M F435W < -10.65 and L(Hα) > 10 39 L ), and metallicities (12 + log (O/H) ∼ 8.5-8.7) to extragalactic giant HII regions and TDG candidates found in less luminous mergers and compact groups of galaxies. We assess the mass content and the likelihood of survival as TDGs of the 22 complexes with simple structures in the HST images based on their photometric, structural, and kinematic properties. The dynamical tracers used (radius-σ and luminosity-σ diagrams) indicate that most of the complexes might be self-gravitating entities. The resistance to forces from the parent galaxy is studied by considering the tidal mass of the candidate and its relative velocity with respect to the parent galaxy. After combining the results of previous studies of TDG searches in ULIRGs a total of 9 complexes satisfy most of the applied criteria and thus show a high-medium or high likelihood of survival, their total mass likely being compatible with that of dwarf galaxies. They are defined as TDG candidates. We propose that they probably formed more often during the early phases of the interaction. Combining all data for complexes with IFS data where a significant fraction of the system is covered, we infer a TDG production rate of 0.3 candidates with the highest probabilities of survival per system for the (U)LIRGs class. This rate, though, might decrease to 0.1 after the systems in (U)LIRGs have evolved for 10 Gyr, for long-lived TDGs, which would imply that no more than 5-10% of the overall dwarf population could be of tidal origin.

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“…Other evidence against long duration infant mortality was provided by Mengel et al (2008), who measured the dynamical masses of 9 clusters in the Antennae with ages between 6 and 9 Myr. By comparing their dynamical and photometric mass estimates to models of early cluster evolution (Goodwin & Bastian 2006) they found that all but one of these clusters are stable and bound.…”

Section: Other Considerations Of Cluster Disruptionmentioning

confidence: 99%

Gemini Spectroscopic Survey of Young Star Clusters in Merging/Interacting Galaxies. Iii. The Antennae

Bastian

Trancho

Konstantopoulos

et al. 2009

ApJ

136

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We present optical spectroscopy of 16 star clusters in the merging galaxies NGC 4038/39 ("The Antennae") and supplement this dataset with HST imaging. The age and metallicity of each cluster is derived through a comparison between the observed Balmer and metal line strengths with simple stellar population models. We then estimate extinctions and masses using the photometry. We find that all but three clusters have ages between ∼ 3 − 200 Myr, consistent with the expected increase in the star-formation rate due to the merger. Most of the clusters have velocities in agreement with nearby molecular and Hi gas that has been previously shown to be rotating within the progenitor galaxies, hence star/cluster formation is still taking place within the galactic disks. However, three clusters have radial velocities that are inconsistent with being part of the rotating gas disks, which is surprising given their young (200 − 500 Myr) ages. Interestingly, we find a stellar association with the same colors (V-I) near one of these three clusters, suggesting that the cluster and association were formed concurrently and have remained spatially correlated. We find evidence for spatially distributed cluster formation throughout the duration of the merger. The impact of various assumptions about the star/cluster formation rate on the interpretation of the cluster age distribution are explored, and we do not find evidence for long term "infant mortality" as has been previously suggested. Models of galaxy mergers that include a prescription for star formation can provide an overall good fit to the observed cluster age distribution.

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Young star clusters in interacting galaxies – NGC 1487 and NGC 4038/4039

Cited by 44 publications

References 70 publications

A catalog of extended clusters and ultra-compact dwarf galaxies

A catalog of extended clusters and ultra-compact dwarf galaxies

Extranuclear Hα-emitting complexes in low-z(U)LIRGs: precursors of tidal dwarf galaxies?

Gemini Spectroscopic Survey of Young Star Clusters in Merging/Interacting Galaxies. Iii. The Antennae

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