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Star Cluster Formation and Evolution in M101: An Investigation with the Legacy Extragalactic UV Survey

Linden, S. T. and Perez, G. and Calzetti, D. and Maji, S. and Messa, M. and Whitmore, B. C. and Chandar, R. and Adamo, A. and Grasha, K. and Cook, D. O. and Elmegreen, B. G. and Dale, D. A. and Sacchi, E. and Sabbi, E. and Grebel, E. K. and Smith, L. (2022) Star Cluster Formation and Evolution in M101: An Investigation with the Legacy Extragalactic UV Survey. Astrophysical Journal, 935 (2). Art. No. 166. ISSN 0004-637X. doi:10.3847/1538-4357/ac7c07.

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We present Hubble Space Telescope WFC3/UVIS (F275W, F336W) and ACS/WFC optical (F435W, F555W, and F814W) observations of the nearby grand-design spiral galaxy M101 as part of the Legacy Extragalactic UV Survey (LEGUS). Compact sources detected in at least four bands were classified by both human experts and the convolutional neural network StarcNet. Human experts classified the 2351 brightest sources, retrieving Nc = 965 star clusters. StarcNet, trained on LEGUS data not including M101, classified all 4725 sources detected in four bands, retrieving Nc = 2270 star clusters. The combined catalog represents the most complete census to date of compact star clusters in M101. We find that for the 2351 sources with both a visual- and machine-learning classification StarcNet is able to reproduce the human classifications at high levels of accuracy (∼80%–90%), which is equivalent to the level of agreement between human classifiers in LEGUS. The derived cluster age distribution implies a disruption rate of dN/dτ ∝ τ^(−0.45±0.14) over 10^7 < τ < 10^8.5 yr for cluster masses ≥103.55 M_⊙ for the central region of M101 and dN/dτ ∝ τ^(−0.02±0.15) for cluster masses ≥103.38 M_⊙ in the northwest region of the galaxy. The trends we recover are weaker than those of other nearby spirals (e.g., M51) and starbursts, consistent with the M101 environment having a lower-density interstellar medium, and providing evidence in favor of environmentally dependent cluster disruption in the central, southeast, and northwest regions of M101.

Item Type:Article
Related URLs:
URLURL TypeDescription
Linden, S. T.0000-0002-1000-6081
Perez, G.0000-0003-3880-8075
Calzetti, D.0000-0002-5189-8004
Messa, M.0000-0003-1427-2456
Chandar, R.0000-0003-0085-4623
Adamo, A.0000-0002-8192-8091
Grasha, K.0000-0002-3247-5321
Cook, D. O.0000-0002-6877-7655
Elmegreen, B. G.0000-0002-1723-6330
Dale, D. A.0000-0002-5782-9093
Sacchi, E.0000-0001-5618-0109
Sabbi, E.0000-0003-2954-7643
Grebel, E. K.0000-0002-1891-3794
Smith, L.0000-0002-0806-168X
Additional Information:S.T.L. acknowledges partial support from the NASA grant HST GO–15330. Support for program No. 15330 was provided by NASA through a grant from the Space Telescope Science Institute. K.G. is supported by the Australian Research Council through the Discovery Early Career Researcher Award (DECRA) Fellowship DE220100766 funded by the Australian Government. K.G. is supported by the Australian Research Council Center of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), through project number CE170100013. M.M. acknowledges the support of the Swedish Research Council, Vetenskapsradet (internationell postdok grant 2019-00502). Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5–26555. These observations are associated with program No. 13364. Based also on archival data from the following facilities: the NASA/ESA Hubble Space Telescope, and obtained from the Hubble Legacy Archive, which is a collaboration between the Space Telescope Science Institute (STScI), the Space Telescope European Coordinating Facility (ST-ECF/ESA) and the Canadian Astronomy Data Center (CADC/NRC/CSA). Finally, This research has made use of the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.
Funding AgencyGrant Number
Space Telescope Science InstituteHST GO-15330
Australian Research CouncilDE220100766
Australian Research CouncilCE170100013
Swedish Research Council2019-00502
NASANAS 5–26555
NASA/ESA Hubble Space TelescopeUNSPECIFIED
Hubble Legacy ArchiveUNSPECIFIED
Space Telescope Science Institute (STScI)UNSPECIFIED
Space Telescope European Coordinating Facility (ST-ECF/ESA)UNSPECIFIED
Canadian Astronomy Data Center (CADC/NRC/CSA)UNSPECIFIED
NASA/IPAC Extragalactic Database (NED)UNSPECIFIED
Issue or Number:2
Record Number:CaltechAUTHORS:20220908-184102986
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:116638
Deposited By: Donna Wrublewski
Deposited On:07 Sep 2022 22:29
Last Modified:08 Sep 2022 18:41

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