2022ApJ...930...47H


Query : 2022ApJ...930...47H

2022ApJ...930...47H - Astrophys. J., 930, 47-47 (2022/May-1)

The GALAH Survey: A New Sample of Extremely Metal-poor Stars Using a Machine-learning Classification Algorithm.

HUGHES A.C.N., SPITLER L.R., ZUCKER D.B., NORDLANDER T., SIMPSON J., DA COSTA G.S., TING Y.-S., LI C., BLAND-HAWTHORN J., BUDER S., CASEY A.R., DE SILVA G.M., D'ORAZI V., FREEMAN K.C., HAYDEN M.R., KOS J., LEWIS G.F., LIN J., LIND K., MARTELL S.L., SCHLESINGER K.J., SHARMA S., ZWITTER T. (The GALAH Collaboration)

Abstract (from CDS):

Extremely metal-poor (EMP) stars provide a valuable probe of early chemical enrichment in the Milky Way. Here we leverage a large sample of ∼600,000 high-resolution stellar spectra from the GALAH survey plus a machine-learning algorithm to find 54 candidates with estimated [Fe/H] <=-3.0, six of which have [Fe/H] <=-3.5. Our sample includes ∼20% main-sequence EMP candidates, unusually high for EMP star surveys. We find the magnitude-limited metallicity distribution function of our sample is consistent with previous work that used more complex selection criteria. The method we present has significant potential for application to the next generation of massive stellar spectroscopic surveys, which will expand the available spectroscopic data well into the millions of stars.

Abstract Copyright: © 2022. The Author(s). Published by the American Astronomical Society.

Journal keyword(s): Galactic archaeology - Stellar abundances - Stellar classification - Classification - CEMP stars - Population II stars - Population III stars - Galaxy stellar content - High resolution spectroscopy

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 - 2024
#notes
1 HE 0048-6408 Pe* 00 50 45.2846592720 -63 51 50.416091208   13.52 12.48 12.29   ~ 12 0
2 UCAC4 132-000788 Pe* 00 53 07.8237605954 -63 45 01.491856643   14.219   13.618   ~ 3 0
3 BPS CS 22953-0003 Pe* 01 02 15.8723379360 -61 43 45.836012208   14.43 13.75 13.339 12.886 KIIvw 70 0
4 HE 0105-6141 Pe* 01 07 37.8492758736 -61 25 17.694026832   14.22 13.64 13.113 12.660 ~ 18 0
5 HE 0124-0119 Pe* 01 26 58.5792560424 +01 35 15.359701704   13.902 12.671 12.499   ~ 11 0
6 SkKM 359 Pe* 01 52 14.6609103648 -72 19 13.036188396   14.46 13.94 13.89   K/M 3 1
7 UCAC4 115-002803 Pe* 03 13 00.3747928560 -67 08 39.336144504   15.442 14.753 14.639   CEMP-no 111 0
8 BPS CS 29529-0089 Pe* 04 14 16.2451959768 -60 09 04.781216196   13.87 13.11     ~ 5 0
9 UCAC4 157-003889 Pe* 04 19 20.0086299745 -58 40 42.359148078   13.145 12.477 12.449   ~ 4 0
10 UCAC4 124-004028 Pe* 04 22 53.1068953430 -65 22 31.295422717   14.607 13.807 13.715   ~ 3 0
11 HE 0433-1008 Pe* 04 35 35.8274994220 -10 02 01.970278109   14.253 13.303 13.140 12.181 ~ 7 0
12 UCAC4 246-005724 Pe* 05 00 36.9542616668 -40 53 12.009739261   13.770 13.356 13.385   ~ 3 0
13 UCAC4 264-006015 Pe* 05 10 08.6113975920 -37 20 19.359351492   13.486 12.900 12.830   ~ 11 0
14 HE 0520-5012 C* 05 21 57.8816124744 -50 10 03.162360504   14.80 13.60 12.857 12.318 C 6 0
15 UCAC4 177-007679 Pe* 06 20 55.9582695091 -54 40 32.570257770   13.815 13.402 13.385   ~ 2 0
16 UCAC4 266-013909 Pe* 07 05 42.1772496927 -36 50 03.512190051   12.899 12.405 12.394   ~ 3 0
17 HE 0926-0508 Pe* 09 28 55.3529041896 -05 21 40.492169352 12.410 12.34 12.194 11.895 11.617 ~ 22 0
18 UCAC4 293-061996 Pe* 10 16 44.0354183984 -31 25 51.068899393   14.173 13.652 13.635   ~ 3 0
19 UCAC4 160-049451 Pe* 10 30 50.0826619436 -58 01 38.203801033   14.251 13.327 13.032   ~ 2 0
20 UCAC4 226-057537 Pe* 11 16 03.7216746792 -44 56 21.204635856   14.422 13.309 13.018   ~ 4 0
21 UCAC4 244-050995 Pe* 11 25 03.9768883453 -41 19 04.908498751   13.966 13.340 13.335   ~ 3 0
22 TYC 4934-700-1 Pe* 11 44 40.8707831640 -04 09 51.268408920   12.053 11.082 10.91   CEMP 13 0
23 HE 1207-3108 Pe* 12 09 53.9936676462 -31 25 10.567641369   12.844 12.242 12.133   ~ 19 0
24 UCAC4 447-053342 Pe* 12 14 19.5650557604 -00 36 48.254145972   14.631 13.995 13.996   ~ 3 0
25 UCAC4 203-066636 Pe* 12 34 56.1132283028 -49 26 13.457555562   13.797 13.351 13.286   ~ 4 0
26 UCAC4 219-067482 Pe* 12 43 02.7963200800 -46 20 12.401870241   13.715 13.279 13.228   ~ 2 0
27 UCAC4 282-067498 Pe* 12 57 51.6144941859 -33 36 21.082954434   14.963 14.006 13.856   ~ 4 0
28 UCAC4 243-063327 Pe* 13 19 00.5001751940 -41 28 09.448717478   13.809 13.093 12.907   ~ 3 0
29 2MASS J13273676-1710384 Pe* 13 27 36.7700176464 -17 10 38.500016124   13.27 12.53     ~ 6 0
30 NGC 5139 602 RG* 13 27 45.0745748544 -47 32 20.109729840 14.45 13.980 12.958     ~ 11 0
31 UCAC4 260-066236 Pe* 13 32 37.1658390395 -38 00 33.024164884   14.560 13.558 13.402   ~ 4 0
32 UCAC4 408-058576 Pe* 13 37 48.8508327672 -08 26 17.605539312   12.767 11.506 11.219 10.146 CEMP 13 0
33 HD 122563 Pe* 14 02 31.8455084952 +09 41 09.944391876 7.47 7.10 6.19 5.37 4.79 G8:III:Fe-5 854 0
34 BD-08 3703 Pe* 14 07 35.5176986112 -09 29 23.464496220   11.56 10.91     ~ 3 0
35 UCAC4 319-072977 Pe* 14 08 34.2574775248 -26 21 50.882757672   13.965 13.505 13.589   ~ 4 0
36 UCAC4 329-069890 Pe* 14 17 59.9600683872 -24 15 46.331782020   13.714 12.802 12.552   CEMP 7 0
37 UCAC4 318-075675 Pe* 14 22 02.0529748511 -26 24 34.988839847   14.534 13.726 13.623   ~ 3 0
38 UCAC4 261-072275 Pe* 14 23 52.3106615887 -37 51 04.933180877   13.793   13.325   ~ 2 0
39 UCAC4 282-073852 Pe* 14 26 10.4396592810 -33 42 48.348127106   13.561 12.736 12.606   ~ 4 0
40 UCAC4 282-074015 Pe* 14 28 12.9600379202 -33 42 11.816066495   13.912 12.863 12.613   ~ 3 0
41 UCAC4 348-073000 Pe* 14 42 07.4439880483 -20 34 48.292641123   14.038 13.184 13.081   ~ 2 0
42 UCAC4 346-071741 Pe* 14 45 14.3231905614 -20 51 55.225814481   14.328 13.439 13.360   ~ 2 0
43 UCAC4 356-072657 Pe* 15 12 47.6648768797 -18 52 08.050251151   14.567 13.439 13.191   ~ 3 0
44 UCAC4 410-061205 Pe* 15 15 29.3487498971 -08 03 32.679673498   13.927   12.933   ~ 3 0
45 TYC 7325-920-1 HB* 15 21 39.9538571520 -35 38 09.321499716   12.940 12.269 12.225 11.343 CEMP 15 0
46 UCAC4 053-017641 Pe* 15 23 06.7366788168 -79 30 07.386741288   14.064 13.156 13.004   ~ 6 0
47 UCAC4 378-073293 Pe* 15 38 04.5332368327 -14 34 01.509584350   14.114 13.479 13.463   ~ 2 0
48 UCAC4 347-075031 Pe* 15 45 28.9204518269 -20 46 44.559791104   14.650 13.807 13.628   ~ 2 0
49 UCAC4 302-083986 SB* 15 57 30.1025796144 -29 39 22.771142172   14.170 13.175 12.937   CEMP 10 0
50 UCAC4 348-079613 Pe* 15 59 55.9906944509 -20 25 57.590991401   14.729 13.354 13.048   ~ 2 0
51 UCAC4 323-084847 Pe* 16 10 06.4228742493 -25 26 44.874066033   16.326 14.170 14.157   ~ 2 0
52 UCAC4 324-082300 Pe* 16 10 31.3839609419 -25 20 15.107147066   15.618 13.184 13.023   ~ 3 0
53 UCAC4 468-055983 Pe* 16 28 21.6746517478 +03 30 52.723252587   14.026 12.759 12.476   ~ 2 0
54 UCAC4 154-195455 Pe* 17 05 29.6778663295 -59 15 16.148422936       13.102   ~ 4 0
55 TYC 6246-355-1 Pe* 17 20 02.7068028912 -20 39 06.364339236   11.96 10.79     ~ 2 0
56 UCAC4 482-067983 Pe* 17 45 24.6514997383 +06 13 28.459804050   13.798 12.690 12.378   ~ 4 0
57 UCAC4 195-177220 SB* 18 08 20.0315466960 -51 04 37.883300340   12.546 11.930 11.898   CEMP 24 0
58 UCAC4 238-176332 Pe* 20 24 34.5151400568 -42 33 33.814043712   13.737 13.044 12.974 12.148 ~ 11 0
59 BPS CS 30314-0177 Pe* 20 40 18.4442379432 -34 31 11.182545912   12.933 12.469 12.433   ~ 6 0
60 UCAC4 390-134367 Pe* 21 11 31.4171905690 -12 07 26.013102080   13.409 12.949 12.948   ~ 3 0
61 BPS CS 30303-0090 Pe* 21 21 42.9132733632 -28 41 16.864046736   13.788 13.361 13.346   ~ 5 0
62 HE 2123-0329 Pe* 21 26 08.9581508400 -03 16 58.787281596   14.089 13.650 13.026   CEMP-no 10 0
63 BPS CS 30322-0023 Pe* 21 30 32.1818994960 -46 16 24.614480388   13.447 12.167 11.902 10.908 CEMP-s 57 0
64 UCAC4 289-214219 Pe* 21 33 40.2230343329 -32 14 44.239570578   13.420 12.783 12.625   ~ 3 0
65 TYC 9107-598-1 Pe* 21 34 02.8351164936 -62 24 20.885716296   13.31 12.59     ~ 8 0
66 UCAC4 059-028498 Pe* 21 56 41.1847609994 -78 23 16.625590905   13.896 13.245 13.177   ~ 3 0
67 BPS BS 17569-0049 Pe* 22 04 58.3605927288 +04 01 32.135832984 14.503 14.263 13.126 13.122 12.259 ~ 34 0
68 UCAC4 157-208544 Pe* 22 09 21.7958407944 -58 37 04.970639136   14.220 13.231 12.983   ~ 6 0
69 UCAC4 464-129364 Pe* 22 16 35.9639920032 +02 46 16.993943220   13.57 12.77 12.57   CEMP-no 8 0
70 BPS CS 22892-0052 Pe* 22 17 01.6558764360 -16 39 27.051026544   14.03 13.20 13.06 12.19 KIIvw 449 0
71 UCAC4 486-137065 Pe* 22 24 24.8642227830 +07 07 16.893894739   14.359 13.260 12.880   ~ 3 0
72 UCAC4 433-122466 Pe* 23 33 25.2263483115 -03 26 05.181579192   12.936 12.404 12.704   ~ 2 0

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