TY - JOUR
T1 - ED-2
T2 - A cold but not so narrow stellar stream crossing the solar neighbourhood
AU - Balbinot, E.
AU - Helmi, A.
AU - Callingham, T.
AU - Matsuno, T.
AU - Dodd, E.
AU - Ruiz-Lara, T.
N1 - Publisher Copyright:
© 2023 The Authors.
PY - 2023/10/1
Y1 - 2023/10/1
N2 - Context. ED-2 is a stellar stream identified as a compact group in integrals-of-motion space in a local sample of halo stars from the third Gaia data release. Aims. We investigate its nature and possible association with known halo substructures. Methods. We explored the current properties of ED-2 members in phase-space and also analysed the expected distribution via orbit integration. In addition, we studied the metallicity of ED-2 using APOGEE DR17 and LAMOST DR8 (and re-calibrated DR3). Results. ED-2 forms a compact group in the x-z (or R-z) plane, showing a pancake-like structure as it crosses the solar neighbourhood. Dynamically, it is most similar to the globular clusters NGC 3201 and NGC 6101 and to the stellar streams Ylgr and Phlegethon. However, its orbit is sufficiently different for none of these objects to likely be the ED-2 progenitor. We also find ED-2 to be quite metal poor: all of its stars have [Fe=H] < -2:42, with a median [Fe=H] = -2:60+0:20-0:21. At this low metallicity, it is unlikely that ED-2 stems from any known globular cluster. Instead, ED-2 seems to be in a similar category as the recently discovered Phoenix and C-19 stellar streams. We find that ED-2 members are scattered across the whole sky, which is due to its current orbital phase. We predict that as this object moves to its next apocentre, it will acquire an on-sky morphology that is similar to that of cold stellar streams. Finally, because ED-2 is nearing pericentre, we predict that additional members found below the plane will have high radial velocities of close to ∼500 km s-1 in the present-day direction of the globular cluster NGC 6101.
AB - Context. ED-2 is a stellar stream identified as a compact group in integrals-of-motion space in a local sample of halo stars from the third Gaia data release. Aims. We investigate its nature and possible association with known halo substructures. Methods. We explored the current properties of ED-2 members in phase-space and also analysed the expected distribution via orbit integration. In addition, we studied the metallicity of ED-2 using APOGEE DR17 and LAMOST DR8 (and re-calibrated DR3). Results. ED-2 forms a compact group in the x-z (or R-z) plane, showing a pancake-like structure as it crosses the solar neighbourhood. Dynamically, it is most similar to the globular clusters NGC 3201 and NGC 6101 and to the stellar streams Ylgr and Phlegethon. However, its orbit is sufficiently different for none of these objects to likely be the ED-2 progenitor. We also find ED-2 to be quite metal poor: all of its stars have [Fe=H] < -2:42, with a median [Fe=H] = -2:60+0:20-0:21. At this low metallicity, it is unlikely that ED-2 stems from any known globular cluster. Instead, ED-2 seems to be in a similar category as the recently discovered Phoenix and C-19 stellar streams. We find that ED-2 members are scattered across the whole sky, which is due to its current orbital phase. We predict that as this object moves to its next apocentre, it will acquire an on-sky morphology that is similar to that of cold stellar streams. Finally, because ED-2 is nearing pericentre, we predict that additional members found below the plane will have high radial velocities of close to ∼500 km s-1 in the present-day direction of the globular cluster NGC 6101.
KW - Galaxy: halo
KW - Galaxy: kinematics and dynamics
UR - http://www.scopus.com/inward/record.url?scp=85175013848&partnerID=8YFLogxK
U2 - 10.1051/0004-6361/202347076
DO - 10.1051/0004-6361/202347076
M3 - Article
AN - SCOPUS:85175013848
SN - 0004-6361
VL - 678
JO - Astronomy and Astrophysics
JF - Astronomy and Astrophysics
M1 - A115
ER -