Legacy ExtraGalactic UV Survey with The Hubble Space Telescope: Stellar Cluster Catalogs and First Insights Into Cluster Formation and Evolution in NGC 628<sup>∗</sup>

Adamo, Angela; Ryon, J. E.; Messa, Matteo; Kim, Hwi; Grasha, Kathryn; Cook, D.; Calzetti, Daniela; Lee, Janice; Whitmore, Bradley C.; Elmegreen, Bruce G.; Úbeda, Leonardo; Smith, L. J.; Bright, Stacey N.; Runnholm, Axel; Andrews, Jennifer E.; Fumagalli, Michele; Gouliermis, D. A.; Kahre, L.; Nair, Preethi; Thilker, David A.; Walterbos, R. A. M.; Wofford, Aida; Aloisi, Alessandra; Ashworth, G.; Brown, Thomas M.; Chandar, Rupali; Christian, C. A.; Cignoni, M.; Clayton, Geoffrey C.; Dale, Daniel A.; Mink, S. E. de; Dobbs, Clare; Elmegreen, D. M.; Evans, A. S.; Gallagher, John S.; Grebel, Eva K.; Herrero, A.; Hunter, Deidre A.; Johnson, K. E.; Kennicutt, Robert C.; Krumholz, Mark R.; Lennon, D. J.; Levay, K.; Martin, Christopher; Nota, A.; Östlin, Göran; Pellerin, Anne; Prieto, J. L.; Regan, Michael W.; Sabbi, E.; Sacchi, Elena; Schaerer, D.; Schiminovich, David; Shabani, F.; Tosi, M.; Dyk, Schuyler D. Van; Zackrisson, Erik

doi:10.3847/1538-4357/aa7132

Cited by 133 publications

(353 citation statements)

References 89 publications

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“…At the distance of NGC 3938, such a cluster could be unresolved. To that end, we considered stellar clusters in a galaxy similar to NGC 3938, those in NGC 628 (M74; also a nearly face-on Sc galaxy, but closer to us at 10.19 Mpc; Jang & Lee 2014), which Adamo et al (2017) studied (see also Grasha et al 2015). We considered the , with the SN position indicated by a white circle with radius equal to the 0.26 pixel rms astrometric uncertainty.…”

Section: The Nature Of the Progenitor Candidatementioning

confidence: 99%

SN 2017ein and the Possible First Identification of a Type Ic Supernova Progenitor

Dyk

Zheng

Brink

et al. 2018

ApJ

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We have identified a progenitor candidate in archival Hubble Space Telescope (HST) images for the Type Ic supernova (SN Ic) SN 2017ein in NGC 3938, pinpointing the candidate's location via HST Target of Opportunity imaging of the SN itself. This would be the first identification of a stellar-like object as a progenitor candidate for any SN Ic to date. We also present observations of SN 2017ein during the first ∼49 days since explosion. We find that SN 2017ein most resembles the well-studied SN Ic SN 2007gr. We infer that SN 2017ein experienced a total visual extinction of A V ≈1.0-1.9 mag, predominantly because of dust within the host galaxy. Although the distance is not well known, if this object is the progenitor, it was likely of high initial mass, ∼47-48 M e if a single star, or ∼60-80 M e if in a binary system. However, we also find that the progenitor candidate could be a very blue and young compact cluster, further implying a very massive (>65 M e ) progenitor. Furthermore, the actual progenitor might not be associated with the candidate at all and could be far less massive. From the immediate stellar environment, we find possible evidence for three different populations; if the SN progenitor was a member of the youngest population, this would be consistent with an initial mass of ∼57 M e . After it has faded, the SN should be reobserved at high spatial resolution and sensitivity, to determine whether the candidate is indeed the progenitor.

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Section: The Nature Of the Progenitor Candidatementioning

confidence: 99%

SN 2017ein and the Possible First Identification of a Type Ic Supernova Progenitor

Dyk

Zheng

Brink

et al. 2018

ApJ

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“…Here is worth mentioning that the power-law shape of extragalactic cluster mass functions is interpreted as the product of hierarchy in both space and time (e.g., Messa et al 2018), in agreement with the idea that compact clusters are (the densest) parts of larger hierarchical stellar structures. These mass functions do not seem to follow a power-law across their entire dynamic range, but there is a confirmed dearth of clusters at high masses (e.g., Adamo et al 2017). Indications that the mass limit of the cluster mass function truncation may depend on the galactic environment (Johnson et al 2017) suggest a clear relation between the formation of clusters (as the high density peaks of the hierarchy) and the global star formation properties of their host galaxies.…”

Section: Discussionmentioning

confidence: 99%

Unbound Young Stellar Systems: Star Formation on the Loose

Gouliermis¹

2018

PASP

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Unbound young stellar systems, the loose ensembles of physically related young bright stars, trace the typical regions of recent star formation in galaxies. Their morphologies vary from small few pc-size associations of newly formed stars to enormous few kpc-size complexes composed of stars few 100 Myr old. These stellar conglomerations are located within the disks and along the spiral arms and rings of star-forming disk galaxies, and they are the active star-forming centers of dwarf and starburst galaxies. Being associated with star-forming regions of various sizes, these stellar structures trace the regions where stars form at various length-and timescales, from compact clusters to whole galactic disks. Stellar associations, the prototypical unbound young systems, and their larger counterparts, stellar aggregates, and stellar complexes, have been the focus of several studies for quite a few decades, with special interest on their demographics, classification, and structural morphology. The compiled surveys of these loose young stellar systems demonstrate that the clear distinction of these systems into welldefined classes is not as straightforward as for stellar clusters, due to their low densities, asymmetric shapes and variety in structural parameters. These surveys also illustrate that unbound stellar structures follow a clear hierarchical pattern in the clustering of their stars across various scales. Stellar associations are characterized by significant sub-structure with bound stellar clusters being their most compact parts, while associations themselves are the brighter denser parts of larger stellar aggregates and stellar complexes, which are members of larger superstructures up to the scale of a whole star-forming galaxy. This structural pattern, which is usually characterized as self-similar or fractal, appears to be identical to that of star-forming giant molecular clouds and interstellar gas, driven mainly by turbulence cascade. In this short review, I make a concise compilation of our understanding of unbound young stellar systems across various environments in the local universe, as it is developed during the last 60 years. I present a factual assessment of the clustering behavior of star formation, as revealed from the assembling pattern of stars across loose stellar structures and its relation to the interstellar medium and the environmental conditions. I also provide a consistent account of the processes that possibly play important role in the formation of unbound stellar systems, compiled from both theoretical and observational investigations on the field.

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“…Here, we provide a short overview of the selection criteria, as we use these catalogs to select young star clusters for our analysis. A full description of the selection methods, photometry, and derivation of cluster masses, ages, and reddening via SED fitting are given in Adamo et al (2017) and Cook et al (2019).…”

Section: Star Cluster Catalogsmentioning

confidence: 99%

H α morphologies of star clusters: a LEGUS study of H ii region evolution time-scales and stochasticity in low-mass clusters

Hannon

Lee

Whitmore

et al. 2019

Monthly Notices of the Royal Astronomical Society

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The morphology of HII regions around young star clusters provides insight into the timescales and physical processes that clear a cluster's natal gas. We study ∼700 young clusters (≤10Myr) in three nearby spiral galaxies (NGC 7793, NGC 4395, and NGC 1313) using Hubble Space Telescope (HST ) imaging from LEGUS (Legacy Extra-Galactic Ultraviolet Survey). Clusters are classified by their Hα morphology (concentrated, partially exposed, no-emission) and whether they have neighboring clusters (which could affect the clearing timescales). Through visual inspection of the HST images, and analysis of ages, reddenings, and stellar masses from spectral energy distributions fitting, together with the (U-B), (V-I) colors, we find: 1) the median ages indicate a progression from concentrated (∼3 Myr), to partially exposed (∼4 Myr), to no Hα emission (>5Myr), consistent with the expected temporal evolution of HII regions and previous results. However, 2) similarities in the age distributions for clusters with concentrated and partially exposed Hα morphologies imply a short timescale for gas clearing ( 1Myr). Also, 3) our cluster sample's median mass is ∼1000 M , and a significant fraction (∼20%) contain one or more bright red sources (presumably supergiants), which can mimic reddening effects. Finally, 4) the median E(B-V) values for clusters with concentrated Hα and those without Hα emission appear to be more similar than expected (∼0.18 vs. ∼0.14, respectively), but when accounting for stochastic effects, clusters without Hα emission are less reddened. To mitigate stochastic effects, we experiment with synthesizing more massive clusters by stacking fluxes of clusters within each Hα morphological class. Composite isolated clusters also reveal a color and age progression for Hα morphological classes, consistent with analysis of the individual clusters.

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Legacy ExtraGalactic UV Survey with The Hubble Space Telescope: Stellar Cluster Catalogs and First Insights Into Cluster Formation and Evolution in NGC 628^∗

Cited by 133 publications

References 89 publications

SN 2017ein and the Possible First Identification of a Type Ic Supernova Progenitor

SN 2017ein and the Possible First Identification of a Type Ic Supernova Progenitor

Unbound Young Stellar Systems: Star Formation on the Loose

H α morphologies of star clusters: a LEGUS study of H ii region evolution time-scales and stochasticity in low-mass clusters

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Legacy ExtraGalactic UV Survey with The Hubble Space Telescope: Stellar Cluster Catalogs and First Insights Into Cluster Formation and Evolution in NGC 628∗

Cited by 133 publications

References 89 publications

SN 2017ein and the Possible First Identification of a Type Ic Supernova Progenitor

SN 2017ein and the Possible First Identification of a Type Ic Supernova Progenitor

Unbound Young Stellar Systems: Star Formation on the Loose

H α morphologies of star clusters: a LEGUS study of H ii region evolution time-scales and stochasticity in low-mass clusters

Contact Info

Product

Resources

About

Legacy ExtraGalactic UV Survey with The Hubble Space Telescope: Stellar Cluster Catalogs and First Insights Into Cluster Formation and Evolution in NGC 628^∗