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Galaxy And Mass Assembly: galaxy morphology in the green valley, prominent rings, and looser spiral arms

Smith, Dominic; Haberzettl, Lutz; Porter, L. E.; Porter-Temple, Ren; Henry, Christopher P.A.; Holwerda, Benne; López-Sánchez, R.; Phillipps, Steven; Graham, Alister W.; Brough, Sarah; Pimbblet, Kevin A.; Liske, Jochen; Kelvin, Lee S.; Robertson, Clayton D.; Roemer, Wade; Walmsley, Michael; O’Ryan, David; Géron, Tobias


Dominic Smith

Lutz Haberzettl

L. E. Porter

Ren Porter-Temple

Christopher P.A. Henry

Benne Holwerda

R. López-Sánchez

Steven Phillipps

Alister W. Graham

Sarah Brough

Jochen Liske

Lee S. Kelvin

Clayton D. Robertson

Wade Roemer

Michael Walmsley

David O’Ryan

Tobias Géron


Galaxies fall broadly into two categories: star-forming (blue) galaxies and quiescent (red) galaxies. In between, one finds the less populated 'green valley'. Some of these galaxies are suspected to be in the process of ceasing their star formation through a gradual exhaustion of gas supply, or already dead and experiencing a rejuvenation of star formation through fuel injection. We use the Galaxy And Mass Assembly (GAMA) database and the Galaxy Zoo citizen science morphological estimates to compare the morphology of galaxies in the green valley with those in the red sequence and blue cloud. Our goal is to examine the structural differences within galaxies that fall in the green valley, and what brings them there. Previous results found that disc features such as rings and lenses are more prominently represented in the green-valley population. We revisit this with a similar sized data set of galaxies with morphology labels provided by the Galaxy Zoo for the GAMA fields based on new Kilo-Degree Survey (KiDS) images. Our aim is to compare the results from expert classification qualitatively with those of citizen science. We observe that ring structures are indeed found more commonly in green-valley galaxies compared with their red and blue counterparts. We suggest that ring structures are a consequence of disc galaxies in the green valley actively exhibiting the characteristics of fading discs and evolving disc morphology of galaxies. We note that the progression from blue to red correlates with loosening spiral-arm structure.


Smith, D., Haberzettl, L., Porter, L. E., Porter-Temple, R., Henry, C. P., Holwerda, B., …Géron, T. (2022). Galaxy And Mass Assembly: galaxy morphology in the green valley, prominent rings, and looser spiral arms. Monthly notices of the Royal Astronomical Society, 517(3), 4575-4589.

Journal Article Type Article
Acceptance Date Jul 28, 2022
Online Publication Date Nov 3, 2022
Publication Date 2022-12
Deposit Date Dec 8, 2022
Publicly Available Date Dec 9, 2022
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Oxford University Press
Peer Reviewed Peer Reviewed
Volume 517
Issue 3
Pages 4575-4589
Keywords Galaxies: bar; Galaxies: bulges; Galaxies: disc; Galaxies: evolution; Galaxies: spiral; Galaxies: star formation
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