2017A&A...598A..54H


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.04CEST15:33:41

2017A&A...598A..54H - Astronomy and Astrophysics, volume 598A, 54-54 (2017/2-1)

Something borrowed, something blue: The nature of blue metal-poor stars inferred from their colours and chemical abundances.

HANSEN C.J., JOFRE P., KOCH A., McWILLIAM A. and SNEDEN C.S.

Abstract (from CDS):

Blue metal-poor (BMP) stars are main sequence stars that appear bluer and more luminous than normal turnoff stars. They were originally singled out by using B-V and U-B colour cuts.Early studies found that a larger fraction of field BMP stars were binaries compared to normal halo stars. Thus, BMP stars are ideal field blue straggler candidates for investigating internal stellar evolution processes and binary interaction. In particular, the presence or depletion in lithium in their spectra is a powerful indicator of their origin. They are either old, halo blue stragglers experiencing internal mixing processes or mass transfer (Li-depletion), or intermediate-age, single stars of possibly extragalactic origin (2.2dex halo plateau Li). However, we note that internal mixing processes can lead to an increased level of Li. Hence, this study combines photometry and spectroscopy to unveil the origin of various BMP stars. We first show how to separate binaries from young blue stars using photometry, metallicity and lithium. Using a sample of 80 BMP stars (T>6300K), we find that 97% of the BMP binaries have V-Ks0<1.08±0.03, while BMP stars that are not binaries lie above this cut in two thirds of the cases. This cut can help classify stars that lack radial velocities from follow-up observations. We then trace the origin of two BMP stars from the photometric sample by conducting a full chemical analysis using new high-resolution and high signal-to-noise spectra. Based on their radial velocities, Li, α and s- and r-process abundances we show that BPS CS22874-042 is a single star (A(Li)=2.38±0.10dex) while with A(Li)=2.23±0.07dex CD-48 2445 is a binary, contrary to earlier findings. Our analysis emphasises that field blue stragglers can be segregated from single metal-poor stars, using (V-Ks) colours with a fraction of single stars polluting the binary sample, but not vice versa. These two groups can only be properly separated by using information from stellar spectra, illustrating the need for accurate and precise stellar parameters and high-resolution, high-S/N spectra in order to fully understand and classify this intriguing class of stars. Our high-resolution spectrum analysis confirms the findings from the colour cuts and shows that CS 22874-042 is single, while CD -48 2445 is most likely a binary. Moreover, the stellar abundances show that both stars formed in situ; CS 22874-042 carries traces of massive star enrichment and CD -48 2445 shows indications of AGB mass transfer mixed with gases ejected possibly from neutron star mergers.

Abstract Copyright: © ESO, 2017

Journal keyword(s): stars: abundances - blue stragglers - binaries: general - stars: fundamental parameters - stars: Population II - galaxies: halos

VizieR on-line data: <Available at CDS (J/A+A/598/A54): table4.dat>

Simbad objects: 80

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Number of rows : 80

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 BPS CS 22876-0021 * 00 01 03.7766453873 -33 48 15.747165111   14.79 14.48     ~ 6 0
2 SB 68 PM* 00 12 00.8361200147 -33 59 50.435371163   13.48 13.12     A 12 0
3 BPS BS 17570-0063 Pe* 00 20 36.1934507252 +23 47 37.625665043   14.84 14.51     ~ 24 0
4 BPS CS 29527-0015 Pe* 00 29 10.6813715074 -19 10 07.306464364   14.61 14.24     CEMP-no 52 0
5 Ton S 162 V* 00 31 25.7499934882 -23 57 26.804381216   14.36 14.14     A 11 0
6 BD+23 74 PM* 00 32 43.3276727068 +24 13 21.383820726   10.01 9.88     A2 7 0
7 GD 625 PM* 00 35 50.8975081181 -17 57 00.562183894   14.42 14.04 14.21   ~ 10 0
8 GD 629 * 00 37 44.6846360806 -20 08 11.108935811   14.74 14.41 14.62   ~ 8 0
9 CD-24 266 BS* 00 40 47.9313778053 -24 07 34.183052519   12.955 12.656 12.441 12.216 CEMP-s 90 0
10 CD-31 306 BS* 00 50 15.7694437410 -30 59 56.199734557   12.73 12.72     F3VkA2mA2 30 0
11 TYC 5270-1900-1 * 00 51 07.3623871072 -11 08 31.848403955   11.70 11.52     ~ 9 0
12 BPS CS 22166-0004 * 00 52 11.4384230210 -11 04 39.950062505   13.25 13.08     ~ 6 0
13 BPS CS 22166-0041 PM* 01 10 56.3582749276 -13 42 43.418841045   14.68 14.36     ~ 7 0
14 BPS CS 22174-0008 * 01 11 45.4632754876 -10 40 03.840385737   13.90 13.62     ~ 5 0
15 BPS CS 29518-0024 * 01 17 12.1148984153 -32 26 57.860332235   14.73 14.52     ~ 6 0
16 BPS CS 29518-0043 * 01 18 38.3021781706 -30 41 02.851142792 14.730 14.94 14.57     ~ 24 0
17 BPS CS 22946-0011 SB* 01 19 11.6732860036 -19 23 58.130561980   14.28 13.95     ~ 11 0
18 [PS72] 298 SB* 01 22 45.5840948446 -28 24 29.884215518   14.57 14.26     A1w 13 0
19 HD 8554 PM* 01 24 42.3024685450 +07 00 05.209635632   9.86 9.57     F0 10 0
20 BPS CS 22953-0037 Pe* 01 25 06.6511385034 -59 16 00.741420364   14.01 13.64   13.13 CEMP-no 40 0
21 BPS CS 22174-0040 * 01 28 40.5133770013 -07 24 04.233660942   13.40 13.18     B8.3 9 0
22 BPS CS 22175-0034 * 02 20 21.5102848036 -10 38 08.938022811   12.97 12.60     ~ 9 0
23 BPS CS 31061-0032 Pe* 02 38 43.3010009273 +03 19 02.564348687   14.30 13.90 13.581 13.290 ~ 26 0
24 BPS CS 22963-0013 PM* 02 53 53.7577333381 -06 42 17.792322000   13.82 13.51     ~ 8 0
25 LP 831-70 PM* 03 06 05.4387006390 -22 19 17.833596144   11.97 11.80     ~ 44 0
26 LP 772-81 PM* 03 14 53.7607737107 -14 43 53.824643284   14.13 13.79     ~ 8 0
27 CD-33 1173 Pe* 03 19 35.3161303154 -32 50 43.157841051   11.272 10.902 10.421 10.152 CEMP 46 0
28 BPS CS 22177-0009 Pe* 04 07 40.6490023717 -25 02 43.969982222   14.67 14.27     ~ 30 0
29 Cl Melotte 25 OpC 04 26 54.00 +15 52 00.0           ~ 2654 0
30 BD+03 740 HB* 05 01 16.6227347580 +04 06 37.023779331 9.97 10.17   9.6   sdF0 158 0
31 CD-48 2445 PM* 06 41 26.6604067723 -48 13 14.891279167   10.94 10.54     F8 22 0
32 BD+24 1676 PM* 07 30 41.2663867705 +24 05 10.250742299   11.15   10.4   F 104 0
33 BD+25 1981 PM* 08 44 24.6897133760 +24 47 47.745336304   9.65   9.1   F0 127 0
34 HE 0926-0508 Pe* 09 28 55.3516802855 -05 21 40.489677426 12.410 12.34 12.194 11.895 11.617 ~ 13 0
35 BD+09 2190 PM* 09 29 15.5616421382 +08 38 00.469417390   11.54   10.8   sdA5 115 0
36 HD 84937 PM* 09 48 56.09801 +13 44 39.3237 8.49 8.68 8.32 7.97 7.70 F8Vm-5 717 0
37 BD-13 3442 Pe* 11 46 50.6526364381 -14 06 43.453858029   10.662 10.274     CEMP 91 0
38 HD 106038 PM* 12 12 01.3690548564 +13 15 40.620671155 10.45 10.630 10.162 9.851 9.539 F6wl 169 0
39 HD 109443 PM* 12 34 46.7276299946 -23 28 32.251885330   9.61 9.25     F0V 23 0
40 BD+51 1817 SB* 13 08 39.1022369959 +51 03 59.234697018       10.0   sdF6 22 0
41 BPS BS 16554-0041 Pe* 14 00 54.4741225648 +22 46 42.087338110 14.317 14.548 14.230     ~ 22 0
42 BPS CS 22874-0009 * 14 34 23.1650238622 -26 17 37.593258136   13.92 13.58     ~ 16 0
43 BPS CS 22874-0042 PM* 14 38 01.9318806667 -24 58 44.506900006   14.34 13.91     ~ 7 0
44 BPS CS 22874-0034 * 14 38 26.8316713980 -23 14 48.535054704   14.73 14.49     ~ 5 0
45 V* KT Lib SX* 14 39 19.9964388944 -20 50 31.716422153   12.98 12.72     ~ 12 0
46 HD 135449 Pe* 15 16 10.3878351858 -32 53 33.077182122   9.78 9.46     F/Gw 44 0
47 BPS CS 22890-0069 SB* 15 24 12.2845615795 +03 05 06.391386798   12.93 12.71     ~ 10 0
48 HD 142575 PM* 15 55 02.8362623172 +05 04 12.163144327   9.00   8.4   F0 60 0
49 BPS CS 22872-0062 * 16 26 37.0240448198 -04 32 54.093923143   14.46 14.05     ~ 7 0
50 NGC 6397 GlC 17 40 42.09 -53 40 27.6   7.39 5.17     ~ 1798 1
51 HD 338529 PM* 19 32 31.9104538188 +26 23 26.116678290   9.72   9.2   B5 196 0
52 BPS CS 22896-0103 * 19 33 15.4722262778 -54 58 51.992037083   14.87 14.54     ~ 7 0
53 TYC 8778-1253-1 * 19 43 44.9027581831 -56 10 08.730611531   12.62 13.03     ~ 5 0
54 BPS CS 22964-0074 PM* 19 49 29.4239137014 -39 42 39.470289475   14.85 14.46     ~ 9 0
55 BPS CS 22964-0214 Pe* 20 05 49.9992351669 -39 27 43.359955626   14.06 13.66     CEMP-no 20 0
56 BPS CS 22873-0139 SB* 20 05 55.15 -59 17 11.4   14.20 13.83     ~ 32 0
57 BPS CS 22885-0048 * 20 19 53.7688232747 -38 56 35.977936786 14.54 14.61 14.27     A 6 0
58 BPS CS 22950-0078 PM* 20 24 57.7984695694 -16 29 57.866598195   15.03 14.62     ~ 8 0
59 BPS CS 22950-0173 PM* 20 35 31.2591932771 -15 53 30.716444601   14.45 14.04     ~ 14 0
60 LP 815-43 PM* 20 38 13.2997980664 -20 26 10.852305467   11.31 10.72     ~ 64 0
61 BPS CS 22880-0058 * 20 43 55.9755196566 -21 36 32.516756689   14.91 14.54     ~ 8 0
62 BPS CS 22880-0073 * 20 48 10.9458296265 -20 59 23.972862920 14.41 14.37 14.05     A 6 0
63 CD-35 14849 PM* 21 33 49.75243 -35 26 14.2322   10.95 10.56 10.59   B8 62 0
64 BPS CS 22956-0028 SB* 21 44 48.7079276715 -63 22 09.738970394   13.317 13.0     CEMP-s 23 0
65 BPS CS 22948-0079 * 21 47 29.2119011185 -39 25 19.275689425   14.07 13.72     ~ 9 0
66 BPS CS 30327-0064 PM* 21 49 06.9242753099 -37 27 52.524735144 13.95 14.10 13.76 13.85   A 9 0
67 BPS CS 22960-0058 HB* 22 16 05.8811027290 -42 26 42.797861480   13.91 13.50 13.57   A 6 0
68 CD-24 17504 Pe* 23 07 20.2536159873 -23 52 35.956455668   12.51 12.18     CEMP-no 82 0
69 BPS CS 22888-0031 Pe* 23 11 32.4788632961 -35 26 42.874207261   15.31 14.90     CEMP-no 33 0
70 BPS CS 22941-0012 Pe* 23 28 29.7281389544 -32 48 46.511567976   12.75 12.45     ~ 14 0
71 BPS CS 22941-0005 SB* 23 29 52.8370812791 -35 13 03.815404086   14.88 14.61     ~ 9 0
72 BPS CS 22966-0011 Pe* 23 35 07.0484328903 -30 22 54.279012782 14.694 14.97 14.55     ~ 26 0
73 BPS CS 22894-0029 * 23 42 14.6212201912 -00 51 32.656396592 14.60 14.66 14.37     A 6 0
74 BPS CS 29496-0024 * 23 43 38.5869603656 -31 48 18.363808207   14.28 14.02     ~ 7 0
75 V* BX Scl SX* 23 43 54.4552644084 -28 18 34.625979560   13.82 13.56     A 40 0
76 BPS CS 22966-0054 PM* 23 49 51.5785222631 -29 08 21.448332014   14.71 14.43     ~ 7 0
77 V* BY Scl SX* 23 51 32.2400306003 -25 45 46.664469252   14.05 13.85     A0 19 0
78 BPS CS 22876-0008 PM* 23 55 21.3721683572 -34 48 01.104854593   14.24 13.95     ~ 7 0
79 BPS CS 29517-0021 HB* 23 58 09.0930438615 -14 51 47.257477050   13.918 13.6     A 5 0
80 BPS CS 22874-0024 * ~ ~           ~ 1 0

    Equat.    Gal    SGal    Ecl

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2020.07.04-15:33:41

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