A closer look at the young stellar group around Sh 2-295

Universidade de São Paulo, Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Rua do Matão 1226, São Paulo, SP, 05508-090, Brazil

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Received: 30 August 2025
Accepted: 23 December 2025

Abstract

Context. Star formation is governed by multiple physical processes, making it inherently complicated. One excellent example is the Canis Major OB1/R1 association, whose complex history of star formation is related to different episodes. Three supernova (SN) events potentially altered the environment and impacted star formation and stellar evolution.

Aims. Prior investigations revealed two stellar groups of different ages associated with GU CMa and Z CMa. This work focusses on identifying the low-mass young stellar population near FZ CMa, located between these two groups and spatially related to the H II region Sh 2-295. Our main goal is to verify whether this group is age-mixed and characterise its physical properties.

Methods. We analysed multi-object spectroscopic data acquired with Gemini/GMOS to search for typical features of T Tauri stars (TTs) and to determine their spectral types. Lithium absorption line (λ6708 Å) was used as a youth indicator, while Hα emission was investigated to probe accretion activity. We also derived ages based on optical photometry from Gaia DR3 and compared the projected spatial distribution to diffuse infrared emission.

Results. We identified 29 TTs, including six new members of the association and three classical TTs. The equivalent width of the Li I absorption line suggests an age of 8.1_−3.8^+2.1 Myr, while optical photometric data indicate stellar ages ranging from ~1 to 14 Myr. Younger stars are concentrated around Sh 2-295, whereas the older ones are more widely dispersed.

Conclusions. We increased the number of known TTs related to the CMa association. Our results support a scenario of multiple star formation episodes, including a younger group that may have been triggered by the expansion of Sh 2-295. The influence of SN events appears limited in this context.