Antaeus: a retrograde group of tidal debris in the Milky Way’s disk plane. (arXiv:2206.10404v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Oria_P/0/1/0/all/0/1">Pierre-Antoine Oria</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tenachi_W/0/1/0/all/0/1">Wassim Tenachi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ibata_R/0/1/0/all/0/1">Rodrigo Ibata</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Famaey_B/0/1/0/all/0/1">Benoit Famaey</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yuan_Z/0/1/0/all/0/1">Zhen Yuan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Arentsen_A/0/1/0/all/0/1">Anke Arentsen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Martin_N/0/1/0/all/0/1">Nicolas Martin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Viswanathan_A/0/1/0/all/0/1">Akshara Viswanathan</a>
We present the discovery of a wide retrograde moving group in the disk plane
of the Milky Way using action-angle coordinates derived from the textit{Gaia}
DR3 catalog. The structure is identified from a sample of its members that are
currently almost at the pericenter of their orbit and are passing through the
Solar neighborhood. The motions of the stars in this group are highly
correlated, indicating that the system is probably not phase mixed. With a
width of at least 1.5 kpc and with a probable intrinsic spread in metallicity,
this structure is most likely the wide remnant of a tidal stream of a disrupted
ancient dwarf galaxy (age $sim 12$ Gyr, $langle {rm [Fe/H]} rangle sim
-1.74$). The structure presents many similarities (e.g. in energy, angular
momentum, metallicity, and eccentricity) with the Sequoia merging event.
However, it possesses extremely low vertical action $J_z$ which makes it unique
even amongst Sequoia dynamical groups. As the low $J_z$ may be attributable to
dynamical friction, we speculate that the these stars may be the remnants of
the dense core of the Sequoia progenitor.
We present the discovery of a wide retrograde moving group in the disk plane
of the Milky Way using action-angle coordinates derived from the textit{Gaia}
DR3 catalog. The structure is identified from a sample of its members that are
currently almost at the pericenter of their orbit and are passing through the
Solar neighborhood. The motions of the stars in this group are highly
correlated, indicating that the system is probably not phase mixed. With a
width of at least 1.5 kpc and with a probable intrinsic spread in metallicity,
this structure is most likely the wide remnant of a tidal stream of a disrupted
ancient dwarf galaxy (age $sim 12$ Gyr, $langle {rm [Fe/H]} rangle sim
-1.74$). The structure presents many similarities (e.g. in energy, angular
momentum, metallicity, and eccentricity) with the Sequoia merging event.
However, it possesses extremely low vertical action $J_z$ which makes it unique
even amongst Sequoia dynamical groups. As the low $J_z$ may be attributable to
dynamical friction, we speculate that the these stars may be the remnants of
the dense core of the Sequoia progenitor.
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