2017A&A...608A.145B


Query : 2017A&A...608A.145B

2017A&A...608A.145B - Astronomy and Astrophysics, volume 608A, 145-145 (2017/12-1)

What is the Milky Way outer halo made of? High resolution spectroscopy of distant red giants.

BATTAGLIA G., NORTH P., JABLONKA P., SHETRONE M., MINNITI D., DIAZ M., STARKENBURG E. and SAVOY M.

Abstract (from CDS):

In a framework where galaxies form hierarchically, extended stellar haloes are predicted to be an ubiquitous feature around Milky Way-like galaxies and to consist mainly of the shredded stellar component of smaller galactic systems. The type of accreted stellar systems are expected to vary according to the specific accretion and merging history of a given galaxy, and so is the fraction of stars formed in situ versus accreted. Analysis of the chemical properties of Milky Way halo stars out to large Galactocentric radii can provide important insights into the properties of the environment in which the stars that contributed to the build-up of different regions of the Milky Way stellar halo formed. In this work we focus on the outer regions of the Milky Way stellar halo, by determining chemical abundances of halo stars with large present-day Galactocentric distances, >15kpc. The data-set we acquired consists of high resolution HET/HRS, Magellan/MIKE and VLT/UVES spectra for 28 red giant branch stars covering a wide metallicity range, -3.1≤[Fe/H]≤-0.6. We show that the ratio of α-elements over Fe as a function of [Fe/H] for our sample of outer halo stars is not dissimilar from the pattern shown by MW halo stars from solar neighborhood samples. On the other hand, significant differences appear at [Fe/H]≥-1.5 when considering chemical abundance ratios such as [Ba/Fe], [Na/Fe], [Ni/Fe], [Eu/Fe], [Ba/Y]. Qualitatively, this type of chemical abundance trends are observed in massive dwarf galaxies, such as Sagittarius and the Large Magellanic Cloud. This appears to suggest a larger contribution in the outer halo of stars formed in an environment with high initial star formation rate and already polluted by asymptotic giant branch stars with respect to inner halo samples.

Abstract Copyright: © ESO, 2017

Journal keyword(s): stars: abundances - Galaxy: halo - Galaxy: structure - Galaxy: formation - galaxies: interactions - galaxies: interactions

VizieR on-line data: <Available at CDS (J/A+A/608/A145): tablea1.dat tablea2.dat tablea5.dat tablea6.dat tablea7.dat tablea8.dat tablea9.dat tablea10.dat tablea11.dat>

Simbad objects: 44

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Number of rows : 44
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 M 31 G 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 11798 1
2 NAME Sculptor Dwarf Galaxy G 01 00 09.4 -33 42 32   9.79 8.6 8.81   ~ 1234 4
3 Gaia EDR3 2583930463614175104 * 01 12 09.9646131888 +12 59 53.596150080           ~ 1 0
4 NAME Segue 2 G 02 19 16.0 +20 10 31     15.2     ~ 216 0
5 NAME Sagittarius Stream St* 02 22 +00.0           ~ 758 0
6 NAME Fornax Dwarf Spheroidal G 02 39 59.3 -34 26 57   9.02 7.4     ~ 1613 1
7 [SHM2009] J032611.85-022940.1 * 03 26 11.8615528368 -02 29 40.296792444           ~ 2 0
8 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 16002 1
9 [MNM2003] G223.454+42.974 * 09 42 53.4594918768 +11 03 51.960756240           ~ 2 0
10 [MNM2003] G223.446+43.439 * 09 44 34.0355909904 +11 16 46.961040144           ~ 2 0
11 Gaia EDR3 3870240045978161536 * 10 34 38.2958672352 +10 20 50.447659416           ~ 1 0
12 [MNM2003] G234.396+53.538 * 10 34 46.9993602840 +09 58 23.877050016           ~ 2 0
13 Gaia EDR3 3555759031576592000 * 10 55 17.9601139608 -18 30 28.966365468           ~ 1 0
14 Gaia EDR3 3805383905209904768 * 11 00 25.1127283992 +01 23 43.774497780           ~ 1 0
15 Gaia EDR3 3541034857190323200 * 11 31 08.3361231720 -22 46 03.268424352           ~ 1 0
16 Gaia EDR3 3540980293925905664 * 11 31 12.4267125240 -22 54 32.499919656           ~ 1 0
17 [MNM2003] G278.782+46.819 * 11 44 40.3430065200 -12 53 52.712714724           ~ 2 0
18 Gaia EDR3 3543472886786069248 * 11 45 06.6114720240 -19 11 59.437600224           ~ 1 0
19 Gaia EDR3 3597524088133826048 * 12 08 14.9898628056 -04 24 58.094804052           ~ 1 0
20 [MNM2003] G290.014+48.922 * 12 16 44.5698702744 -13 04 38.780294952           ~ 2 0
21 SDSS J123928.99-025458.4 * 12 39 28.9917889848 -02 54 58.374805932           ~ 2 0
22 2MASS J12490495-0743456 RG* 12 49 04.9611709776 -07 43 45.692091768           ~ 3 0
23 NAME NGP reg 12 51 26.275 +27 07 41.70           ~ 1099 0
24 [SHM2009] J125454.56-022029.4 * 12 54 54.5579806032 -02 20 29.840070840           ~ 3 0
25 [MNM2003] G305.220+61.239 * 12 55 50.5435060440 -01 36 48.478710420           ~ 2 0
26 [SHM2009] J125608.49-021623.8 * 12 56 08.4762766464 -02 16 24.014833644           ~ 3 0
27 [MNM2003] G305.501+60.647 * 12 56 28.6122799488 -02 11 57.041297196           ~ 2 0
28 Gaia EDR3 3957130739070283648 * 13 04 49.8673008240 +24 19 15.623601420           ~ 1 0
29 [MNM2003] G338.849+68.273 * 13 42 14.6085381024 +09 01 11.751945996           ~ 2 0
30 * alf Boo RG* 14 15 39.67207 +19 10 56.6730 2.46 1.18 -0.05 -1.03 -1.68 K1.5IIIFe-0.5 2223 0
31 [MNM2003] G356.702+51.228 * 14 52 50.7592228752 +01 29 46.675836924           ~ 3 0
32 NAME UMi Galaxy G 15 09 11.34 +67 12 51.7   13.60 10.6     ~ 1265 0
33 NAME Dra dSph G 17 20 14.335 +57 55 16.39   12.40 10.6     ~ 1246 1
34 NAME Galactic Center reg 17 45 39.60213 -29 00 22.0000           ~ 12914 0
35 NAME Hercules Aquila Cloud reg 19 04 +06.3           ~ 101 0
36 SDSS J201513.32-113108.9 * 20 15 13.3264017504 -11 31 08.898702276           ~ 2 0
37 SDSS J204728.10+031346.4 * 20 47 28.1112739896 +03 13 46.533956916           ~ 2 0
38 SDSS J220715.59+054550.6 * 22 07 15.5961110136 +05 45 50.549215104           ~ 2 0
39 SDSS J232630.67-102825.4 * 23 26 30.6828268248 -10 28 25.464222624           ~ 3 0
40 SDSS J234152.39-091119.8 * 23 41 52.3966245840 -09 11 19.761320940           ~ 3 0
41 NAME Triangulum-Andromeda Region reg ~ ~           ~ 79 0
42 NAME Orphan Stream St* ~ ~           ~ 223 0
43 NAME Triangulum Stream St* ~ ~           ~ 13 0
44 NAME Virgo Stellar Stream MGr ~ ~           ~ 105 0

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2022.05.28-09:53:02

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