J/A+A/701/A228 Sagittarius stream with RRLs from Gaia DR3 (Muraveva+, 2025)
Exploring the Sagittarius stream with RR Lyrae stars from Gaia Data Release 3.
Muraveva T., Bellazzini M., Garofalo A., Clementini G., Monti L.,
Valentini M.L.
<Astron. Astrophys. 701, A228 (2025)>
=2025A&A...701A.228M 2025A&A...701A.228M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Abundances, [Fe/H] ; Stars, distances ; Optical
Keywords: techniques: photometric - surveys - stars: abundances -
stars: variables: RR Lyrae - Galaxy: halo
Abstract:
The Sagittarius (Sgr) dwarf spheroidal galaxy is one of the most
prominent satellites of the Milky Way (MW). It is currently
undergoing tidal disruption, forming an extensive stellar stream that
provides key insights into the assembly history of the MW halo.
Our goal is to investigate the structure and metallicity distribution
of the Sgr stream using RR Lyrae stars (RRLs).
We analyzed RRLs provided in Gaia Data Release 3 (DR3), for which new
estimates of photometric metallicities are available in the
literature, and accurate distances were calculated using the
reddening-free period-Wesenheit-metallicity (PWZ) relation in the Gaia
G, G BP , and GRP bands.
We determine the mean metallicity of RRLs in the Sgr stream to be
[Fe/H]=-1.62±0.01dex. We measure a metallicity gradient as a
function of stripping time from the Sgr progenitor of
0.05±0.02dex/Gyr, indicating that the metal-poor RRLs were stripped
earlier during the accretion process. The far arm is found to be the
most metal-poor structure of the Sgr stream, with a mean metallicity
of [Fe/H]=-1.98±0.37dex, significantly lower than that of the
leading (-1.69±0.31dex) and trailing (-1.64±0.28dex) arms. Our
findings show that the RRLs in the far arm of the Sgr stream exhibit a
bimodal metallicity distribution with peaks at [Fe/H]=-2.4dex and
-1.7dex. The main body of the stream is the most metal-rich structure,
with a mean metallicity of [Fe/H]=-1.58±0.31dex and a radial
gradient of -0.008±0.005 dex/kpc. We find almost negligible
metallicity gradients of (-0.2±0.3)x10-3dex/deg in the trailing
arm and (-1.0±0.5)x10-3dex/deg in the leading arm, in agreement
with previous studies. Finally, we investigate the bifurcation of the
Sgr stream and conclude that the metallicity difference between the
faint and bright branches is not confirmed based on the RRLs in our
sample.
Description:
The paper analyzes the Sagittarius stream using RR Lyrae stars from
Gaia Data Release 3. The files contain catalogs of RR Lyrae stars in
the Sagittarius stream, selected using different approaches.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 76 3865 RRLS-SGR-R22 sample
tablea2.dat 76 2377 RRLS-SGR-MODEL sample
tablea3.dat 76 5296 RRLS-SGR-SELECTION sample
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See also:
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
Byte-by-byte Description of file: tablea1.dat tablea2.dat tablea3.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- GaiaDR3 Gaia DR3 source identifier
21- 28 F8.4 deg RAdeg Right Ascension (ICRS) at Ep=2016.0
30- 37 F8.4 deg DEdeg Declination (ICRS) at Ep=2016.0
39- 45 F7.4 mas/yr pmRA Proper motion in right ascension direction
47- 53 F7.4 mas/yr pmDE Proper motion in declination direction
55- 59 F5.2 [-] [Fe/H] Photometric metallicity
61- 64 F4.2 [-] e_[Fe/H] Uncertainty in photometric metallicity
66- 70 F5.2 kpc Dist Heliocentric distance
72- 76 F5.2 kpc e_Dist Uncertainty in heliocentric distance
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Acknowledgements:
Tatiana Muraveva, tatiana.muraveva(at)inaf.it
(End) Tatiana Muraveva [INAF - OAS Bologna], Patricia Vannier [CDS] 24-Jul-2025