The Complexity of the Cetus Stream Unveiled from the Fusion of STREAMFINDER and StarGO

Abstract

We combine the power of two stream-searching tools, STREAMFINDER and StarGO applied to the Gaia EDR3 data, to detect stellar debris belonging to the Cetus stream system that forms a complex, nearly polar structure around the Milky Way. In this work, we find the southern extensions of the northern Cetus stream as the Palca stream and a new southern stream, which overlap on the sky but have different distances. These two stream wraps extend over more than ∼100° on the sky (−60° < δ < +40°). The current N-body model of the system reproduces both as two wraps in the trailing arm. We also show that the Cetus system is confidently associated with the Triangulum/Pisces, Willka Yaku, and the recently discovered C-20 streams. The association with the ATLAS-Aliqa Uma stream is much weaker. All of these stellar debris are very metal-poor, comparable to the average metallicity of the southern Cetus stream with [Fe/H] = −2.17 ± 0.20. The estimated stellar mass of the Cetus progenitor is at least 105.6 M ⊙, compatible with Ursa Minor or Draco dwarf galaxies. The associated globular cluster with similar stellar mass, NGC 5824 very possibly was accreted in the same group infall. The multi-wrap Cetus stream is a perfect example of a dwarf galaxy that has undergone several periods of stripping, leaving behind debris at multiple locations in the halo. The full characterization of such systems is crucial to unravel the history of the assembly of the Milky Way, and importantly, to provide nearby fossils to study ancient low-mass dwarf galaxies.

Gastro Library. I. The Simulated Chemodynamical Properties of Several Gaia–Sausage–Enceladus-like Stellar Halos

“…Using the same line of reasoning as above, we can use our models to identify substructures which are not associated to the GSE merger event. For example, besides Heracles (see Section 5.3), we argue that LMS-1/Wukong (Naidu et al 2020;Yuan et al 2020b) and Cetus (Newberg et al 2009;Yuan et al 2019Yuan et al , 2022) also most likely have distinct progenitors other than the GSE. Malhan et al (2022) showed that both substructures have J z ≈ 2000 kpc km s −1 , meaning they have large vertical excursions.…”

A Ghost in Boötes: The Least-Luminous Disrupted Dwarf Galaxy

“…Our prior expectation was that the majority of pairs would reside in known streams, since stellar streams span tens of degrees on the sky and have a significantly enhanced probability of hosting comoving stars within a few degrees of each other. Groups #1 and #2 could securely be associated with the Cetus stream based on their sky position and kinematics (Newberg et al 2009;Yuan et al 2022). Group #3 was likewise strongly associated with the Orphan stream (Belokurov et al 2007a;Koposov et al 2019).…”

The Pristine survey – XVI. The metallicity of 26 stellar streams around the Milky Way detected with the STREAMFINDER in Gaia EDR3

“…14 ). After verification with known structures, it became apparent that this structure corresponds to the Pisces-T riangulum (Psc-T ri) that, at a distance of ∼ 30 kpc (Bonaca, Geha & Kalli v ayalil 2012 ;Martin et al 2013 ;Yuan et al 2022 ), is located at the very edge of the STREAMFINDER exploration. Martin et al ( 2013 ) determine an average metallicity for this stream from 11 stars and find [Fe/H] −2.2, which is in very good agreement with our measurement using Pristine and further confirms that the few stars we identify in the STREAMFINDER sample belong to Psc-Tri.…”