Spatially resolved stellar populations and emission line properties in nearby galaxies with J-PLUS

II. Results for the M51 group and the first comparison with the M101 group

¹ Instituto de Astrofísica de Andalucía (CSIC), PO Box 3004, 18080, Granada, Spain
² Departamento de Física, Universidade Federal de Santa Catarina, PO Box 476, 88040-900, Florianópolis, SC, Brazil
³ Centro de Estudios de Física del Cosmos de Aragón (CEFCA), Plaza San Juan 1, 44001, Teruel, Spain
⁴ Unidad Asociada CEFCA-IAA, CEFCA, Unidad Asociada al CSIC por el IAA y el IFCA, Plaza San Juan 1, 44001, Teruel, Spain
⁵ Instituto de Astrofísica de Canarias, La Laguna, 38205, Tenerife, Spain
⁶ Departamento de Astrofísica, Universidad de La Laguna, 38206, Tenerife, Spain
⁷ Observatório Nacional – MCTI (ON), Rua Gal. José Cristino 77, São Cristóvão, 20921-400, Rio de Janeiro, Brazil
⁸ University of Michigan, Department of Astronomy, 1085 South University Ave., Ann Arbor, MI, 48109, USA
⁹ Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo, 05508-090, São Paulo, Brazil
¹⁰ Donostia International Physics Centre (DIPC), Paseo Manuel de Lardizabal 4, 20018, Donostia-San Sebastián, Spain
¹¹ IKERBASQUE, Basque Foundation for Science, 48013, Bilbao, Spain

^★ Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 16 September 2025
Accepted: 15 March 2026

Abstract

Aims. We aim to characterize the spatially resolved stellar population and emission-line properties of galaxies in the M51 group using the same methodology previously applied to the M101 group, ultimately seeking to understand how environmental processes shape the physical properties of galaxies by comparing the results obtained for different groups.

Methods. Properties were derived by applying the ALSTAR spectral fitting code to multiband datacubes from the Javalambre Photometric Local Universe Survey (J-PLUS) data.

Results. We present spatially resolved maps of the main stellar population and emission-line properties for the M51 group galaxies. The interacting pair M51a/b displays clearly distinct properties: M51a features prominent star-forming spiral arms, while its companion is essentially an early-type retired galaxy. M63 exhibits significant asymmetries in its stellar age, dust attenuation, and Hα equivalent width distributions, showing signs of outside-in quenching, likely due to a past interaction. Relations between physical properties and the stellar mass surface density (Σ_★) were investigated. The age–Σ_★ and nebular metalicity–Σ_★ relations are flatter than those in the M101 group. Also, unlike in the less dynamically evolved M101 group, all galaxies align with the resolved star-forming main sequence, with the exception of M51b, which has all the traits of a retired galaxy.

Conclusions. The M51 group presents signatures of more advanced dynamical evolution than the M101 group. This is evidenced by flattened age and nebular metallicity gradients, enhanced dust content, and signs of environmental quenching in some members. In contrast, the less dynamically evolved M101 group largely preserves its primordial inside-out formation signatures. While these findings suggest that group mass and interactions play a role in shaping galaxy evolution even in low-mass environments, the comparison of two systems is evidently limited by small-number statistics. This comparative study underscores the power of J-PLUS data for conducting detailed IFS-like studies of galaxies in the nearby Universe.