2019ApJ...881..164Y


C.D.S. - SIMBAD4 rel 1.7 - 2021.05.16CEST20:58:44

2019ApJ...881..164Y - Astrophys. J., 881, 164-164 (2019/August-3)

Revealing the complicated story of the Cetus Stream with StarGO.

YUAN Z., SMITH M.C., XUE X.-X., LI J., LIU C., WANG Y., LI L. and CHANG J.

Abstract (from CDS):

We use a novel cluster identification tool, STARGO, to explore the metal-poor ([Fe/H] < -1.5) outer stellar halo (d > 15 kpc) of the Milky Way using data from Gaia, LAMOST, and SDSS. Our method is built using an unsupervised learning algorithm, a self-organizing map, which trains a 2D neural network to learn the topological structures of a data set from an n-D input space. Using a 4D space of angular momentum and orbital energy, we identify three distinct groups corresponding to the Sagittarius, Orphan, and Cetus Streams. For the first time we are able to discover a northern counterpart to the Cetus Stream (CS). We test the robustness of this new detection using mock data and find that the significance is more than 5σ. We also find that the existing southern counterpart bifurcates into two clumps with different radial velocities. By exploiting the visualization power of STARGO, we attach MW globular clusters (GCs) to the same trained neural network. The Sagittarius stream is found to have five related clusters, confirming recent literature studies, and the CS has one associated cluster, NGC 5824. This latter association has previously been postulated, but can only now be truly confirmed thanks to the high-precision Gaia proper motions and large numbers of stellar spectra from LAMOST. The large metallicity dispersion of the stream indicates that the progenitor cannot be a GC. Given the mean metallicity of the stream, we propose that the stream is the result of a merger of a low-mass dwarf galaxy that is associated with a massive GC (NGC 5824).

Abstract Copyright: © 2019. The American Astronomical Society. All rights reserved.

Journal keyword(s): galaxies: formation - galaxies: halos - galaxies: kinematics and dynamics - methods: data analysis

Simbad objects: 18

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Number of rows : 18

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 NAME Cetus Polar Stream St* 01 31 +01.0           ~ 46 0
2 NAME Whiting 1 GlC 02 02 56.8 -03 15 10           ~ 114 0
3 NAME Sgr Stream St* 02 22 +00.0           ~ 697 0
4 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 5935 1
5 NAME Leo V G 11 31 09.60 +02 13 12.0     16.0     ~ 171 0
6 NAME Leo IV Dwarf Galaxy G 11 32 57.0 -00 32 00     15.1     ~ 335 1
7 NAME Crater Cluster GlC 11 36 16.20 -10 52 38.8           ~ 66 1
8 NAME Crater II Dwarf Galaxy G 11 49 14 -18 24.8           ~ 76 0
9 NGC 5139 GlC 13 26 47.28 -47 28 46.1   6.12 5.33     ~ 3104 0
10 NGC 5824 GlC 15 03 58.612 -33 04 06.70   10.28 9.56     ~ 356 0
11 NAME UMi Galaxy G 15 09 11.34 +67 12 51.7   13.60 10.6     ~ 1214 0
12 NAME SDG G 18 55 03.1 -30 28 42   4.5 3.6     ~ 1836 2
13 M 54 GlC 18 55 03.33 -30 28 47.5           ~ 943 0
14 Cl Arp 2 GlC 19 28 44.11 -30 21 20.3     12.41     ~ 314 0
15 Cl Terzan 8 GlC 19 41 44.41 -33 59 58.1     11.54     ~ 272 0
16 Cl Pal 12 GlC 21 46 38.84 -21 15 09.4     11.89     ~ 465 0
17 NAME Local Group GrG ~ ~           ~ 7264 0
18 NAME Orphan Stream St* ~ ~           ~ 206 0

    Equat.    Gal    SGal    Ecl

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2021.05.16-20:58:44

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