J/A+A/707/A241 Young stellar group around Sh 2-295 (Correa-Rodrigues+, 2026)
A closer look at the young stellar group around Sh 2-295.
Correa-Rodrigues J.V., Gregorio-Hetem J.
<Astron. Astrophys. 707, A241 (2026)>
=2026A&A...707A.241C 2026A&A...707A.241C (SIMBAD/NED BibCode)
ADC_Keywords: Stars, pre-main sequence ; Spectral types ; Equivalent widths ;
Optical
Keywords: stars: formation - stars: fundamental parameters -
stars: low-mass - stars: pre-main sequence -
stars: variables: T Tauri, Herbig Ae/Be
Abstract:
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.
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 HII region Sh 2-295.
Our main goal is to verify whether this group is age-mixed and
characterise its physical properties.
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 (λ 6708Å) 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.
We identified 29 TTs, including six new members of the association and
three classical TTs. The equivalent width of the LiI absorption line
suggests an age of 8.1+2.1-3.8Myr, while optical photometric data
indicate stellar ages ranging from ∼1 to 14Myr. Younger stars are
concentrated around Sh 2-295, whereas the older ones are more widely
dispersed. 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.
Description:
This work focuses on the identification of low-mass pre-main-sequence
stars in the vicinity of the star FZ CMa and associated with the HII
region Sh 2-295. We analysed spectra obtained with the Gemini
multi-object spectrograph (GMOS) on the Gemini telescope. We
identified 29 T Tauri stars showing spectroscopic features typically
observed at this evolutionary stage (e.g. LiI absorption line at
6708Å and Hα emission line). The 29 objects are listed along
with literature data, and also their parameters derived from the GMOS
spectra and the best-matching Gaia DR3 counterparts within 1 arcsec
separation, adopting RUWE<1.4. A list of seven objects exhibiting
Hα emission but non-detected LiI absorption is also provided.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 114 29 List of T Tauri stars identified and parameters
derived in this work
tableb1.dat 65 7 List of objects with Halpha emission but no
LiI (6708Å) absorption detected
tabled1.dat 66 29 List of spectral types derived for each source
in table2.dat using different methods
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
J/A+A/609/A127 : X-ray sources in CMa OB1 (Santos-Silva+, 2018)
J/AJ/161/133 : Astrometry & photometry for CMa R1 members
(Gregorio-Hetem+, 2021)
J/ApJS/262/7 : 886 nearby star clusters (He+, 2022)
J/A+A/630/A90 : Halpha emission-line stars in Canis Major (Pettersson+, 2019)
J/ApJS/249/18 : The ZTF catalog of periodic variable stars (Chen+, 2020)
J/ApJ/827/96 : WISE census of YSOs in Canis Major (Fischer+, 2016)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- 2MASS 2MASS identifier
18- 36 I19 --- GaiaDR3 ? Gaia DR3 identifier
38- 40 A3 --- n_2MASS Notes on individual objects (1)
42- 45 F4.2 0.1nm EWLi Equivalent width of the LiI (6708Å) line
47- 52 F6.2 0.1nm EWHa Equivalent width of the Halpha line.
Negative values indicate emission
54- 55 I2 --- SNR Signal-to-noise ratio of the spectra used.
57- 60 A4 --- SpType Estimated spectral type
62- 65 I4 K Teff Estimated effective temperature
67- 69 I3 K e_Teff Estimated uncertainty associated with
effective temperature
71- 74 F4.2 mag AV Estimated extinction
76- 79 A4 --- Class Classification
81- 85 F5.2 Myr b_Age ? Estimated lower end of the age range
88- 92 F5.2 Myr B_Age ? Estimated upper end of the age range
94- 98 A5 --- CMaX X-ray source identification according to
Santos-Silva et al. 2018, Cat. J/A+A/609/A127
100-105 A6 --- IRClass Infrared classification
107-109 A3 --- n_IRClass Notes on Infrared classification (2)
111-114 F4.1 % P ? Membership probability (3)
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Note (1): Notes as follows:
c = Members of vdBergh92 (He et al., 2022ApJS..262....7H 2022ApJS..262....7H, Cat. J/ApJS/262/7)
d = Ha emission objects (Pettersson et al., 2019A&A...630A..90P 2019A&A...630A..90P,
Cat. J/A+A/630/A90)
e = RS Canum Venaticorum-type system (Chen et al., 2020ApJS..249...18C 2020ApJS..249...18C,
Cat. J/ApJS/249/18)
Note (2): Notes as follows:
a = Classification from Santos-Silva et al., 2018A&A...609A.127S 2018A&A...609A.127S,
Cat. J/A+A/609/A127
f = Classification from Fischer, 2016ApJ...827...96F 2016ApJ...827...96F, Cat, J/ApJ/827/96
Note (3): Membership probability from Gregorio-Hetem et al.,
2021AJ....161..133G 2021AJ....161..133G, Cat. J/AJ/161/133
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Byte-by-byte Description of file: tableb1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 A16 --- 2MASS 2MASS identifier
17 A1 --- f_2MASS [)] ) if not an 2MASS identifier
19- 37 I19 --- GaiaDR3 Gaia DR3 identifier
39 A1 --- n_2MASS Notes on individual objects (1)
41- 47 F7.3 0.1nm EWHa Equivalent width of the Halpha line.
Negative values indicate emission
49- 53 F5.2 mag Gmag G Gaia magnitude
55- 59 F5.2 mag BPmag BP Gaia magnitude
61- 65 F5.2 mag RPmag RP Gaia magnitude
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Note (1): Notes as follows:
a = Object without 2MASS counterpart for which we adopted an identification
following the same nomenclature
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Byte-by-byte Description of file: tabled1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 A16 --- 2MASS 2MASS identifier
18- 21 A4 --- SpType Spectral type adopted
23- 31 A9 --- L18 Spectral type estimated by comparison with
Luhman et al. (2018AJ....156...76L 2018AJ....156...76L,
Cat. J/AJ/156/78) spectra
33- 36 A4 --- C24 Spectral type estimated by comparison with
Claes et al. (2024A&A...690A.122C 2024A&A...690A.122C) spectra
38- 46 A9 --- TiO(J07) Spectral type estimated by using
the TiO index from Jeffries et al.
(2007MNRAS.376..580J 2007MNRAS.376..580J, Cat. J/MNRAS/376/580)
48- 56 A9 --- TiO(6800) Spectral type estimated by using
the TiO 6800 index from Herczeg et al.
(2014ApJ...786...97H 2014ApJ...786...97H, Cat. J/ApJ/786/97)
58- 66 A9 --- TiO(7140) Spectral type estimated by using
the TiO 7140 index from Herczeg et al.
(2014ApJ...786...97H 2014ApJ...786...97H, Cat. J/ApJ/786/97)
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Acknowledgements:
Joao Victor Correa Rodrigues, jv.crodrigues27(at)gmail.com
(End) J.V. Correa Rodrigues [Univ. de Sao Paulo], P. Vannier [CDS] 27-Jan-2026