2024MNRAS.530.4712A

Query : 2024MNRAS.530.4712A

2024MNRAS.530.4712A - Mon. Not. R. Astron. Soc., 530, 4712-4729 (2024/June-1)

The oldest stars with low neutron-capture element abundances and origins in ancient dwarf galaxies.

ANDALES H.D., SANTOS FIGUEIREDO A., FIENBERG C.G., MARDINI M.K. and FREBEL A.

Abstract (from CDS):

We present a detailed chemical abundance and kinematic analysis of six extremely metal-poor (-4.2 ≤ [Fe/H] ≤-2.9) halo stars with very low neutron-capture abundances ([Sr/H] and [Ba/H]) based on high-resolution Magellan/MIKE spectra. Three of our stars have [Sr/Ba] and [Sr/H] ratios that resemble those of metal-poor stars in ultra-faint dwarf galaxies (UFDs). Since early UFDs may be the building blocks of the Milky Way, extremely metal-poor halo stars with low, UFD-like Sr and Ba abundances may thus be ancient stars from the earliest small galactic systems that were accreted by the proto-Milky Way. We label these objects as Small Accreted Stellar System (SASS) stars, and we find an additional 61 similar ones in the literature. A kinematic analysis of our sample and literature stars reveals them to be fast-moving halo objects, all with retrograde motion, indicating an accretion origin. Because SASS stars are much brighter than typical UFD stars, identifying them offers promising ways towards detailed studies of early star formation environments. From the chemical abundances of SASS stars, it appears that the earliest accreted systems were likely enriched by a few supernovae whose light element yields varied from system to system. Neutron-capture elements were sparsely produced and/or diluted, with r-process nucleosynthesis playing a role. These insights offer a glimpse into the early formation of the Galaxy. Using neutron-capture elements as a distinguishing criterion for early formation, we have access to a unique metal-poor population that consists of the oldest stars in the universe.

Abstract Copyright: © 2024 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society.

Journal keyword(s): nuclear reactions, nucleosynthesis, abundances - stars: abundances - stars: Population II - Galaxy: halo - galaxies: dwarfs

Status at CDS : Large table(s) will be appraised for possible ingestion in VizieR.

Simbad objects: 72

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Number of rows : 72
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 2MASS J00061720+1057419 Pe* 00 06 17.2023422184 +10 57 41.854295088           ~ 7 0
2 HE 0008-3842 Pe* 00 10 56.0380483968 -38 26 10.033424268   14.531 13.372 12.722 12.064 ~ 8 0
3 SMSS J003327.36-491037.9 Pe* 00 33 27.3724152168 -49 10 37.891125012           ~ 4 0
4 BPS CS 30339-0073 Pe* 00 34 52.2289856016 -36 55 29.891258904     14.75     ~ 13 0
5 SMSS J004037.56-515025.2 Pe* 00 40 37.5651110832 -51 50 25.141528212           ~ 7 0
6 HE 0044-2459 RG* 00 46 35.8758070056 -24 43 02.290921248   14.49 13.87 13.92 12.948 ~ 26 0
7 CD-38 245 Pe* 00 46 36.1954514592 -37 39 33.555030480   12.733 11.929 13.39 10.996 KIIvw 233 0
8 HE 0048-6408 Pe* 00 50 45.2846592720 -63 51 50.416091208   13.52 12.48 12.29   ~ 15 0
9 CD-30 298 RG* 00 58 43.8709169280 -30 05 57.717373920   11.43 10.83     F6Vwl 66 1
10 HE 0057-5959 Pe* 00 59 53.9857261680 -59 43 29.745171408   16.4       CEMP-no 39 0
11 HE 0104-5300 Pe* 01 06 51.9165053832 -52 44 10.577875704   14.382 13.550 13.038 12.518 CEMP-no 18 0
12 HE 0107-5240 Pe* 01 09 29.1555567432 -52 24 34.202039148   15.89 15.07 15.10 14.283 CEMP-no 250 0
13 HE 0124-0119 Pe* 01 26 58.5792560424 +01 35 15.359701704   13.902 12.671 12.499   ~ 19 0
14 HE 0139-2826 Pe* 01 41 36.8114907696 -28 11 02.828648508   14.42 13.74 13.81   CEMP-no 8 0
15 BD+44 493 Pe* 02 26 49.7390353632 +44 57 46.523771136   9.63 9.11 9.073   CEMP-no 116 0
16 SMSS J023147.96-575341.7 Pe* 02 31 47.9645500584 -57 53 41.639412876           CEMP-no 7 0
17 HE 0239-1340 Pe* 02 41 42.3721546152 -13 28 10.603797240   14.73 13.97 13.566 13.080 CEMP-no 64 0
18 BPS CS 22963-0004 Pe* 02 56 46.5715607688 -04 51 17.421404184   15.51 14.98     ~ 30 0
19 HE 0302-3417 Pe* 03 04 28.4444210809 -34 06 04.581186242   11.797 10.876 10.756 9.560 CEMP-no 18 0
20 UCAC4 115-002803 Pe* 03 13 00.3747928560 -67 08 39.336144504   15.442 14.753 14.639   CEMP-no 122 0
21 2MASS J03142084-1035112 Pe* 03 14 20.8495451808 -10 35 11.277788028   13.54 12.73 12.204 11.693 KIIvw 73 0
22 SMSS J031556.09-473442.1 Pe* 03 15 56.1041622792 -47 34 42.109333248           ~ 5 0
23 HE 0316+0214 Pe* 03 19 09.2348269680 +02 24 54.195148980     15.541   14.332 ~ 6 0
24 NAME Reticulum II G 03 35 42.1 -54 02 57           ~ 375 0
25 HE 0344-0243 Pe* 03 46 50.0746257936 -02 34 13.338977520   15.986 15.239 15.189   ~ 6 0
26 HE 0411-5725 Pe* 04 12 05.1903072408 -57 17 59.420310720   16.524 15.753 15.774   ~ 6 0
27 HE 0557-4840 Pe* 05 58 39.2660594064 -48 39 56.890252404   16.144 15.466 15.336   CEMP-no 92 0
28 SMSS J085924.06-120104.9 Pe* 08 59 24.0472976736 -12 01 04.930033764           ~ 6 0
29 HE 0926-0546 Pe* 09 29 27.9598753848 -05 59 43.433385756   14.983 14.265 14.169   ~ 11 0
30 HE 0945-1435 Pe* 09 47 50.6778824184 -14 49 06.861774900   15.73 15.23 15.35   CEMP-mp 14 0
31 HE 1012-1540 Pe* 10 14 53.4753516864 -15 55 53.172437448   14.721 14.043 14.034   CEMP-no 43 0
32 UCAC3 215-112497 Pe* 10 29 15.1489854864 +17 29 27.924626724   17.424 16.708   15.98 sdA 120 0
33 TYC 4928-1438-1 Pe* 11 18 35.8831613496 -06 50 45.020130180   12.577 11.606 10.822 10.099 CEMP-no 32 0
34 NAME Leo IV LSB 11 32 57.0 -00 32 00     15.1     ~ 419 1
35 HE 1201-1512 Pe* 12 03 37.0449862176 -15 29 33.236334924   14.2       CEMP-no 27 0
36 2MASS J12482275+2056440 Pe* 12 48 22.7519584056 +20 56 44.029766004   13.88 13.4 13.115 12.706 ~ 25 0
37 HE 1300+0157 Pe* 13 02 56.2443901392 +01 41 52.080457056   14.536 14.11 13.678 13.261 CEMP-no 48 0
38 2MASS J13132688-0019415 Pe* 13 13 26.8884339336 -00 19 41.336280264           CEMP-no 37 0
39 HE 1310-0536 Pe* 13 13 31.1856437856 -05 52 12.533926152   15.055 14.347 13.829   CEMP-no 38 0
40 HE 1320+0139 Pe* 13 22 50.6004129672 +01 23 42.949936212   16.72 16.08 15.40   F5 12 0
41 HE 1347-1025 Pe* 13 50 22.3970330568 -10 40 18.942310344   15.727 15.013     ~ 15 0
42 HE 1356-0622 Pe* 13 59 30.3168806616 -06 36 34.904583792   14.995 14.268 14.313   ~ 16 0
43 HD 122563 Pe* 14 02 31.8455084952 +09 41 09.944391876 7.47 7.10 6.19 5.37 4.79 G8:III:Fe-5 920 0
44 HE 1416-1032 Pe* 14 19 37.4725374048 -10 46 10.232878368   15.777 14.984 14.729   ~ 8 0
45 HE 1424-0241 Pe* 14 26 40.3306297920 -02 54 27.487168164   15.892 15.45 14.887 14.54 ~ 40 0
46 2MASS J14543927+0421380 Pe* 14 54 39.2685981792 +04 21 38.099145888   13.02 12.32 11.849 11.376 ~ 53 0
47 HE 1523-0901 Pe* 15 26 01.0697532504 -09 11 38.885639784   12.37 11.50 10.476 9.863 CEMP 93 0
48 BPS BS 16084-0160 Pe* 16 28 50.7923247984 +54 37 06.886218324   13.94 13.12 12.630 12.103 ~ 22 0
49 NAME Galactic Center reg 17 45 39.60213 -29 00 22.0000           ~ 16269 0
50 SMSS J184226.25-272602.7 Pe* 18 42 26.2432169784 -27 26 02.952830868           ~ 5 0
51 SMSS J184825.29-305929.7 Pe* 18 48 25.2926849136 -30 59 29.594883984           CEMP-no 7 0
52 BPS CS 22891-0200 Pe* 19 35 19.0776472464 -61 42 24.374080224   14.77 13.93   12.79 CEMP-no 45 0
53 BPS CS 22885-0096 Pe* 20 20 51.1730095656 -39 53 30.234972840   14.02 13.33     CEMP-no 96 0
54 BPS CS 22943-0137 Pe* 20 26 29.0087260776 -43 00 42.661173708 14.670 15 14.47     ~ 19 0
55 BPS CS 30492-0016 Pe* 21 04 49.7578631664 -40 14 48.080316768   14.34 13.89     ~ 12 0
56 2MASS J21584227-2029156 Pe* 21 58 42.2746240680 -20 29 15.746399232   14.1 13.156 12.692 12.225 CEMP-no 12 0
57 BPS CS 22960-0048 Pe* 22 17 01.5646398192 -45 12 16.965506844 15.445 15.64 14.96 14.558 14.059 CEMP-no 15 0
58 BPS CS 22892-0052 Pe* 22 17 01.6558764360 -16 39 27.051026544   14.03 13.20 13.06 12.19 KIIvw 472 0
59 2MASS J22214882+0228448 Pe* 22 21 48.8262598080 +02 28 44.867730936 13.291 13.4 12.74 12.325 12.013 ~ 46 0
60 2MASS J22422683-5004009 Pe* 22 42 26.8476804960 -50 04 00.914721852   16.239 15.846 15.576 15.240 CEMP-mp 18 0
61 HE 2248-3345 Pe* 22 51 44.7838586784 -33 29 25.392693912   15.387 14.682 14.257 13.768 ~ 5 0
62 HE 2249-1704 Pe* 22 51 49.7146486550 -16 49 00.474168558   16.360 15.258 14.956   ~ 7 0
63 2MASS J23065518-5740335 PM* 23 06 55.1834886264 -57 40 33.520694664   13.8       ~ 3 0
64 HE 2304-4153 Pe* 23 07 05.6946070176 -41 37 30.076128300   17.154 16.330 15.829 15.302 ~ 6 0
65 CD-24 17504 Pe* 23 07 20.2534619736 -23 52 35.954286096   12.51 12.18     CEMP-no 94 0
66 HE 2318-1621 Pe* 23 21 21.5631300312 -16 05 05.628387156   13.38 12.73 12.67   CEMP-no 19 0
67 2MASS J23215820-5211431 Pe* 23 21 58.1901363600 -52 11 43.204631172   14.3       CEMP-no 13 0
68 BPS CS 22949-0048 Pe* 23 26 07.4169241824 -05 50 06.903492036   14.48 13.67 13.154 12.639 CEMP-no 38 0
69 HE 2331-7155 Pe* 23 34 36.1728318744 -71 38 50.939495232   14.73   13.82   CEMP-no 13 0
70 HE 2334-0604 RG* 23 37 28.6873103640 -05 47 56.594641632   14.03 13.28 12.768 12.249 KIIvw 74 0
71 2MASS J23434113-6019223 Pe* 23 43 41.1306862440 -60 19 22.441054080   13.7 12.788 12.255 11.707 ~ 6 0
72 NAME Tuc III G 23 56.6 -59 36           ~ 229 0

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