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NGC 147 Corroborates the Break in the Stellar Mass–Stellar Metallicity Relation for Galaxies

Zhuang, Zhuyun and Kirby, Evan N. and Leethochawalit, Nicha and de los Reyes, Mithi A. C. (2021) NGC 147 Corroborates the Break in the Stellar Mass–Stellar Metallicity Relation for Galaxies. Astrophysical Journal, 920 (1). Art. No. 63. ISSN 0004-637X. doi:10.3847/1538-4357/ac1340.

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The stellar mass–stellar metallicity relation (MZR) is an essential approach to probing the chemical evolution of galaxies. It reflects the balance between galactic feedback and gravitational potential as a function of stellar mass. However, the current MZR of local dwarf satellite galaxies (M* ≲ 10⁸ M_⊙; measured from resolved stellar spectroscopy) may not be reconcilable with that of more massive galaxies (M* ≳ 10^(9.5) M_⊙; measured from integrated-light spectroscopy). Such a discrepancy may result from a systematic difference between the two methods, or it may indicate a break in the MZR around 10⁹ M_⊙. To address this question, we measured the stellar metallicity of NGC 147 from integrated light using the Palomar Cosmic Web Imager. We compared the stellar metallicity estimates from integrated light with measurements from resolved stellar spectroscopy and found them to be consistent within 0.1 dex. On the other hand, the high-mass MZR overpredicts the metallicity by 0.6 dex at the mass of NGC 147. Therefore, our results tentatively suggest that the discrepancy between the low-mass MZR and high-mass MZR should not be attributed to a systematic difference in techniques. Instead, real physical processes cause the transition in the MZR. In addition, we discovered a positive age gradient in the innermost region and a negative metallicity gradient from the resolved stars at larger radii, suggesting a possible outside-in formation of NGC 147.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Zhuang, Zhuyun0000-0002-1945-2299
Kirby, Evan N.0000-0001-6196-5162
Leethochawalit, Nicha0000-0003-4570-3159
de los Reyes, Mithi A. C.0000-0002-4739-046X
Additional Information:© 2021. The American Astronomical Society. Received 2021 May 28; revised 2021 July 2; accepted 2021 July 8; published 2021 October 13. The authors acknowledge the constructive feedback from the anonymous referee, which helped us improve the manuscript. We thank Yuguang Chen, Donal O'Sullivan, and James (Don) Neill for useful discussions on PCWI data reduction and covariance correction. We gratefully thank the staff at the Palomar Observatory, including support astronomers Carolyn Heffner and Kevin Rykoski, and telescope operator Kajsa Peffer, for assisting in the observations. This material is based on work supported by the National Science Foundation (NSF) under grant No. AST-1847909. E.N.K. gratefully acknowledges support from a Cottrell Scholar Award administered by the Research Corporation for Science Advancement. M.A.C.d.l.R. acknowledges the financial support of the NSF Graduate Research Fellowship Program. We are grateful to the many people who have worked to make the Keck Telescope and its instruments a reality and to operate and maintain the Keck Observatory. The authors wish to extend special thanks to those of Hawaiian ancestry, on whose sacred mountain we are privileged to be guests. Without their generous hospitality, none of the observations presented herein would have been possible. This research has made use of the Keck Observatory Archive, which is operated by the W. M. Keck Observatory and the NASA Exoplanet Science Institute, under a contract with the National Aeronautics and Space Administration. Facilities: Hale (CWI) - , Keck II (DEIMOS) - . Software: CWITools (O'Sullivan & Chen 2020), FSPS (Conroy et al. 2009), alf (Conroy et al. 2018), MPFIT (Markwardt 2012), Astropy (Astropy Collaboration et al. 2013, 2018), NumPy (Harris et al. 2020), SciPy (Virtanen et al. 2020), pPXF (Cappellari 2017).
Group:Astronomy Department
Funding AgencyGrant Number
Cottrell Scholar of Research CorporationUNSPECIFIED
NSF Graduate Research FellowshipUNSPECIFIED
Subject Keywords:Local Group; Galaxy abundances; Metallicity; Chemical abundances; Stellar abundances; Dwarf elliptical galaxies
Issue or Number:1
Classification Code:Unified Astronomy Thesaurus concepts: Local Group (929); Galaxy abundances (574); Metallicity (1031); Chemical abundances (224); Stellar abundances (1577); Dwarf elliptical galaxies (415)
Record Number:CaltechAUTHORS:20211014-170544433
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Official Citation:Zhuyun Zhuang et al 2021 ApJ 920 63
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:111423
Deposited By: George Porter
Deposited On:18 Oct 2021 22:50
Last Modified:18 Oct 2021 22:50

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