2020A&A...634A..72S


Query : 2020A&A...634A..72S

2020A&A...634A..72S - Astronomy and Astrophysics, volume 634A, 72-72 (2020/2-1)

An empirical metallicity tracer in CEMP and C-normal stars.

SINGH D., HANSEN C.J., BYRGESEN J.S., REICHERT M. and REGGIANI H.M.

Abstract (from CDS):

Context. Deriving the metallicity, [Fe/H], in low-resolution spectra of carbon-enhanced metal-poor (CEMP) stars is a tedious task that, owing to the large number of line blends, often leads to uncertainties on [Fe/H] exceeding 0.25 dex. The CEMP stars increase in number with decreasing [Fe/H] and some of these are known to be bona fide second generation halo stars. Hence, knowing their [Fe/H] is important for tracing the formation and chemical evolution of the Galaxy. Aims. Here, we aim to improve the [Fe/H] measurements in low-resolution spectra by avoiding issues related to blends. In turn, we improve our chemical tagging in such spectra at low metallicities. Methods. We developed an empirical way of deriving [Fe/H] in CEMP (and C-normal) stars that relates the equivalent width (EW) of strong lines, which remain detectable in lower resolution, metal-poor spectra, such as X-shooter spectra to [Fe/H]. Results. The best [Fe/H] tracers are found to be Cr I and Ni I, which both show strong transitions in spectral regions that are free of molecular bands (between ∼5200-6800Å, a region accessible to most surveys). We derive different relations for dwarfs and giants. The relations are valid in the ranges ~-3<[Fe/H]< -0.5 and 10<EW<800mÅ (Cr) or [Fe/H]>-3.2 and EW>5mÅ (Ni), depending on the trace element and line as well as the stellar evolutionary stage. Conclusions. The empirical relations are valid for both CEMP and C-normal stars and have been proven to be accurate tracers in a sample of ∼400 stars (mainly giants). The metallicities are accurate to within ±∼0.2dex depending on the sample and resolution, and the empirical relations are robust to within 0.05-0.1dex. Our relations will improve the metallicity determination in future surveys, which will encounter a large number of CEMP stars, and will greatly speed up the process of determining [Fe/H] as the EWs only need to be measured in two or three lines in relatively clean regions compared to dealing with numerous blended Fe lines.

Abstract Copyright: © ESO 2020

Journal keyword(s): stars: abundances - stars: carbon - stars: Population II - techniques: spectroscopic

Simbad objects: 83

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Number of rows : 83
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 HE 2358-4640 Pe* 00 00 50.9112333552 -46 23 31.346424996   14.3       CEMP-mp 5 0
2 * 85 Peg SB* 00 02 10.3487193861 +27 04 54.599101714 6.47 6.42 5.75 5.16 4.73 G5VbFe-2 534 0
3 HE 0002-1037 Pe* 00 05 23.0071596768 -10 20 24.702251820   14.74 13.68 13.59   CEMP-rs 7 0
4 BPS CS 30324-0063 Pe* 00 22 44.8620794952 -17 24 29.140962984   13.824 12.887     CEMP-no 19 0
5 SKB 2 Pe* 00 41 39.8197621944 -26 18 54.460585116   13.338 12.221 11.704 11.321 CEMP-s 89 0
6 SCMS 1023 RG* 01 00 12.5294537376 -33 43 01.362185616   19.23 18.125   16.897 ~ 18 0
7 HE 0059-6540 Pe* 01 01 18.1549967400 -65 23 56.383503936   14.26   13.19   CEMP-rs 3 0
8 GD 678 PM* 01 06 40.6174103712 -24 58 41.889812448   14.38 14.01 13.668 13.375 CEMP-no 21 0
9 BPS CS 31082-0001 Pe* 01 29 31.1311443552 -16 00 45.495314460 12.527 12.427 11.642 11.189 10.713 CEMP 274 0
10 BD+29 366 PM* 02 10 24.5274364299 +29 48 23.663397433 9.27 9.35 8.77 8.24 7.85 G3 130 0
11 BD-01 306 PM* 02 14 40.2989460555 -01 12 05.123909214 9.60 9.631 9.066 8.712 8.377 G0 140 0
12 HE 0221-3218 Pe* 02 24 03.9522407208 -32 04 57.675410976   17.01 15.60     CEMP-mp 3 0
13 HE 0241-3512 Pe* 02 43 26.7740293632 -35 00 12.129681528   15.17 14.00 13.305 12.773 CEMP-s 6 0
14 HD 17820 PM* 02 51 58.3551725257 +11 22 11.940361848 8.85 8.92   8.0   G5 105 0
15 HE 0253-6024 Pe* 02 55 06.4464459168 -60 12 16.739351172   15.10 13.50   11.992 CEMP-s 5 0
16 HE 0315+0000 Pe* 03 17 39.0100103112 +00 11 04.600281192     15.516   14.506 ~ 13 0
17 HE 0317-4705 Pe* 03 18 45.2582795640 -46 54 39.574798200   13.71 12.55 12.41   CEMP-rs 3 0
18 HE 0338-3945 Pe* 03 39 55.0068570984 -39 35 42.902896452   15.753 15.333 15.098 14.787 CEMP-r/s 36 0
19 HE 0400-2030 Pe* 04 02 14.8021418088 -20 21 53.533679904   14.921 14.033 13.605 13.164 CEMP-s 18 0
20 HE 0408-1733 Pe* 04 11 06.0266169456 -17 25 39.745266096   13.511 12.335     CEMP-mp 10 0
21 HE 0414-0343 Pe* 04 17 16.4631860496 -03 36 31.388697180   12.23 11.04     CEMP-r/s 13 0
22 HE 0430-4901 Pe* 04 31 31.1369700144 -48 54 41.518597500     14.572   13.770 CEMP-s 13 0
23 HE 0442-1234 Pe* 04 44 51.7052109360 -12 28 45.533823744     12.914   11.672 ~ 14 0
24 HE 0448-4806 Pe* 04 49 33.0494670384 -48 01 08.312761272   13.45 12.35     CEMP-s 8 0
25 HE 0450-4902 Pe* 04 51 43.2538838712 -48 57 25.202919240   16.23 15.84 15.90   CEMP-s 7 0
26 HE 0516-2515 Pe* 05 18 09.4817384592 -25 12 24.992694432   15.57 13.90 12.634 11.953 CEMP-no 7 0
27 CD-25 3416 PM* 06 37 14.6317376664 -25 21 39.798513720   10.29 9.63     G5 41 0
28 BD+24 1676 PM* 07 30 41.2662525096 +24 05 10.248524088   11.15   10.4   F 118 0
29 HD 64606 SB* 07 54 34.1880221064 -01 24 44.300470716 8.32 8.165 7.433 7.007 6.569 K0V 239 0
30 SDSS J091243.72+021623.6 Pe* 09 12 43.7229065184 +02 16 23.716384212           CEMP-s 22 0
31 BD-03 2764 PM* 09 45 37.8300847800 -04 40 28.499674008   11.333 10.849 10.499 10.175 ~ 35 0
32 HD 88725 PM* 10 14 08.3343804089 +03 09 04.671822250 8.34 8.33 7.73 7.24 6.89 G3/5V 185 0
33 NAME SDSS J1036+1212 Pe* 10 36 49.9302859032 +12 12 19.888410852           CEMP-s 25 0
34 BD-13 3442 Pe* 11 46 50.6525751264 -14 06 43.458063768   10.662 10.274     CEMP 100 0
35 HE 1148-0037b Pe* 11 51 14.9726731248 -00 54 11.335035528 13.847 14.018 13.614 13.297 12.946 CEMP-no 10 1
36 BD-04 3208 PM* 12 07 15.0721580835 -05 44 01.612773628   10.40 9.99     A7 141 0
37 HD 106038 PM* 12 12 01.3688687080 +13 15 40.618559661 10.45 10.630 10.162 9.851 9.539 F6wl 182 0
38 HE 1219-0312 Pe* 12 21 34.1430245160 -03 28 39.636260184     15.940   15.043 ~ 38 0
39 HD 108317 Pe* 12 26 36.8319587208 +05 18 09.023783400       7.7   G2IVm-5 160 0
40 HD 111980 SB* 12 53 15.0529661499 -18 31 20.013189741 8.80 8.91 8.38     F7V 164 0
41 Wolf 1492 Pe* 13 40 02.4921849768 -00 02 18.750053436 11.601 11.832 11.451 11.184 10.892 sdF0: 273 0
42 NAME SDSS J1349-0229 Pe* 13 49 13.5415394784 -02 29 42.784646424           CEMP-s 23 0
43 HD 120559 PM* 13 51 40.3987847839 -57 26 08.350982731 8.679 8.647 7.982 7.605 7.217 G7VFe-1.4CH-1 149 0
44 Ross 841 Pe* 14 02 30.0900761861 -05 39 05.181979951   11.508 11.149 10.866 10.576 sdA3 147 0
45 HD 122563 Pe* 14 02 31.8455084952 +09 41 09.944391876 7.47 7.10 6.19 5.37 4.79 G8:III:Fe-5 808 0
46 * 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 2245 0
47 HD 126587 Pe* 14 27 00.3636631296 -22 14 38.992940592   9.88 9.60 8.75   CEMP-no 129 0
48 HE 1431-0245 Pe* 14 33 54.1499119320 -02 58 32.583788724   16.58 15.30   14.223 CEMP-s 6 0
49 HD 128279 Pe* 14 36 48.5108525999 -29 06 46.612858494 8.64 8.63 8.00     Gw 188 0
50 BD+26 2621 PM* 14 54 10.7123241110 +25 33 48.927279437   11.40   10.7   F0 41 0
51 G 66-51 PM* 15 00 50.0690852592 +02 07 37.456745232   11.34   10.1   K0 32 0
52 HD 134113 SB* 15 07 46.5004807478 +08 52 47.202473395   8.83   7.9   F9 120 0
53 HD 134088 PM* 15 08 12.5670605259 -07 54 47.535411110   9.266 9.018     G2/3(V) 108 0
54 BPS CS 30312-0100 Pe* 15 43 31.6557531288 +02 01 17.338042560   13.629 12.916 12.444 11.995 ~ 22 0
55 CD-71 1234 Pe* 16 07 44.6410532021 -71 21 01.360284611   10.81 10.44     ~ 36 0
56 HD 149414 SB* 16 34 42.3538551709 -04 13 44.635969732 10.48 10.37 9.63     G5Ve 192 0
57 HD 161770 PM* 17 47 46.0757369400 -09 36 18.442563336 10.38 10.39 9.71 9.04 8.55 F3V 94 0
58 BD+20 3603 PM* 17 54 43.2306198848 +20 16 16.444611703   10.13   9.6   F0 155 0
59 V* V2564 Oph LP? 18 04 40.0713763656 +03 46 44.716990584 9.53 8.59 7.30 6.24 5.43 F6/7V 252 0
60 HD 179626 PM* 19 13 20.7189797919 -00 35 42.325251766   9.701 9.187 8.844 8.489 F5V 123 0
61 HD 338529 PM* 19 32 31.9104668184 +26 23 26.117367216   9.72   9.2   B5 204 0
62 HD 345957 PM* 20 10 48.1625876064 +23 57 54.510596568   9.36   8.6   G0V: 139 0
63 HD 340279 PM* 20 24 45.4125969504 +25 03 07.109969040   11.23   10.7   A5 99 0
64 BPS CS 22943-0095 Pe* 20 27 29.9870188056 -46 50 56.315093100 11.857 12.063 12.62     ~ 24 0
65 HD 204155 PM* 21 26 42.9050916792 +05 26 29.902289568   9.03   8.1   F7V 123 0
66 HE 2138-1616 Pe* 21 41 16.6096540440 -16 02 39.863733396   14.91 13.90     CEMP-mp 5 0
67 HE 2141-1441 Pe* 21 44 25.6762953072 -14 27 32.869448856   14.63 13.50     CEMP-mp 5 0
68 HE 2144-1832 Pe* 21 46 54.6639160128 -18 18 15.587038476   12.651 10.97 10.471 9.860 CEMP-s 13 0
69 Wolf 1143 PM* 21 55 16.1462515842 +32 38 41.150257734   11.69   10.6   G2V 72 0
70 HE 2153-2323 Pe* 21 56 37.5847822872 -23 09 25.420064616   16.10 14.50   13.403 CEMP-s 8 1
71 HE 2158-5134 Pe* 22 01 31.8889617744 -44 11 49.856208000   15.15 14.51 14.45   CEMP-s 4 1
72 G 126-52 PM* 22 04 13.3810303392 +19 32 54.335372892       10.7   sd:F2 36 0
73 BD+11 4725 SB* 22 05 40.6982164308 +12 22 36.113158501   10.19   9.2   G3 86 0
74 BPS CS 22881-0036 Pe* 22 07 58.4409920904 -40 44 16.477523484   14.42 13.95 13.633 13.278 CEMP-s 37 0
75 HE 2235-5058 Pe* 22 38 07.9560821352 -50 42 41.505459048   13.8       CEMP-s 6 0
76 HE 2250-4229 Pe* 22 53 39.7110580176 -42 13 03.821675880   13.2       CEMP-no 6 0
77 HE 2258-4427 Pe* 23 00 54.3589175328 -44 11 26.927627208           CEMP-s 4 0
78 HE 2310-4523 Pe* 23 13 00.0416103048 -45 07 06.565285596   12.120 11.207 10.55   CEMP-mp 19 0
79 BPS CS 22949-0008 Pe* 23 16 58.7314762776 -03 20 52.625003208   14.61 14.15 13.858 13.545 CEMP-s 20 0
80 HE 2319-5228 Pe* 23 21 58.1901363600 -52 11 43.204631172   14.3       CEMP-no 9 0
81 HE 2339-4240 Pe* 23 41 40.9352924280 -42 24 01.772703180   14.16 13.12 12.98   CEMP-s 3 0
82 HD 222766 PM* 23 43 34.9167361914 -07 55 24.014028099   10.769 10.115 9.728 9.349 G5/6V 78 0
83 HE 2357-2718 Pe* 23 59 58.1284315416 -27 01 37.629391764   14.313 13.078     CEMP-mp 12 0

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2022.11.28-12:28:27

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