2020A&A...642A.227A


Query : 2020A&A...642A.227A

2020A&A...642A.227A - Astronomy and Astrophysics, volume 642A, 227-227 (2020/10-1)

The CARMENES search for exoplanets around M dwarfs. Rubidium abundances in nearby cool stars.

ABIA C., TABERNERO H.M., KOROTIN S.A., MONTES D., MARFIL E., CABALLERO J.A., STRANIERO O., PRANTZOS N., RIBAS I., REINERS A., QUIRRENBACH A., AMADO P.J., BEJAR V.J.S., CORTES-CONTRERAS M., DREIZLER S., HENNING T., JEFFERS S.V., KAMINSKI A., KURSTER M., LAFARGA M., LOPEZ-GALLIFA A., MORALES J.C., NAGEL E., PASSEGGER V.M., PEDRAZ S., RODRIGUEZ LOPEZ C., SCHWEITZER A. and ZECHMEISTER M.

Abstract (from CDS):

Due to their ubiquity and very long main-sequence lifetimes, abundance determinations in M dwarfs provide a powerful and alternative tool to GK dwarfs to study the formation and chemical enrichment history of our Galaxy. In this study, abundances of the neutron-capture elements Rb, Sr, and Zr are derived, for the first time, in a sample of nearby M dwarfs. We focus on stars in the metallicity range - 0.5≥[Fe/H]≥+0.3, an interval poorly explored for Rb abundances in previous analyses. To do this we use high-resolution, high-signal-to-noise-ratio, optical and near-infrared spectra of 57 M dwarfs observed with CARMENES. The resulting [Sr/Fe] and [Zr/Fe] ratios for most M dwarfs are almost constant at about the solar value, and are identical to those found in GK dwarfs of the same metallicity. However, for Rb we find systematic underabundances ([Rb/Fe]<0.0) by a factor two on average. Furthermore, a tendency is found for Rb - but not for other heavy elements (Sr, Zr) - to increase with increasing metallicity such that [Rb/Fe]≥0.0 is attained at metallicities higher than solar. These are surprising results, never seen for any other heavy element, and are difficult to understand within the formulation of the s- and r-processes, both contributing sources to the Galactic Rb abundance. We discuss the reliability of these findings for Rb in terms of non-LTE (local thermodynamic equilibrium) effects, stellar activity, or an anomalous Rb abundance in the Solar System, but no explanation is found. We then interpret the full observed [Rb/Fe] versus [Fe/H] trend within the framework of theoretical predictions from state-of-the-art chemical evolution models for heavy elements, but a simple interpretation is not found either. In particular, the possible secondary behaviour of the [Rb/Fe] ratio at super-solar metallicities would require a much larger production of Rb than currently predicted in AGB stars through the s-process without overproducing Sr and Zr.

Abstract Copyright: © ESO 2020

Journal keyword(s): nuclear reactions, nucleosynthesis, abundances - stars: abundances - stars: late-type

Simbad objects: 61

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Number of rows : 61
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 BD+44 4548 PM* 00 05 10.8891772602 +45 47 11.639549811   11.45   9.2   M2Ve 143 0
2 V* GX And Er* 00 18 22.8849667932 +44 01 22.637271919   10.120   7.3   M2V 473 0
3 Wolf 1056 PM* 00 38 59.0436387491 +30 36 58.387293197   12.60   10.6   M2.5V 81 0
4 G 172-30 PM* 00 57 02.6919576431 +45 05 09.790903101   13.19 11.972 11.568   M3.0Ve 33 0
5 Wolf 44 PM* 01 01 20.0490626127 +61 21 56.681939701   12.26 10.87     M2.0Ve 74 1
6 Ross 318 Er* 01 02 32.2350866427 +71 40 47.334297514   11.736   9.1   M3.0Ve 136 0
7 BD+61 195 PM* 01 02 38.8679928575 +62 20 42.172837073   11.439   8.7   M1.5V 210 0
8 G 3-14 PM* 01 43 20.1788090313 +04 19 17.962195740 13.64 12.45 10.915 9.879 8.614 M2V 127 0
9 G 244-37 PM* 01 51 51.1324314626 +64 26 05.922097987       11.036   M2.5Ve 44 0
10 G 244-47 PM* 02 01 35.3406953145 +63 46 11.995703079       10.630   M2.5Ve 56 0
11 BD+02 348 PM* 02 12 20.9874569826 +03 34 32.230562527 12.552 11.477 10.042 9.092 7.988 M1V 161 0
12 BD+47 612 PM* 02 22 14.6440695182 +47 52 48.110234827   10.85   9.104   M0V 120 0
13 BD+19 381 PM* 02 35 53.3068796400 +20 13 11.583339035 13.32 12.138 10.628 9.611 8.403 M3V 62 0
14 V* VX Ari Er* 02 44 15.5094178798 +25 31 24.117029188 13.363 12.141 10.563 9.49 8.115 dM3 192 0
15 Ross 364 PM* 02 56 34.4247155101 +55 26 14.099190043       9.6   M1.0Ve 67 0
16 HD 275122 PM* 03 18 07.4803977050 +38 15 07.436514092   11.75 10.280 9.821 8.2 M1.5Ve 87 0
17 G 245-71 PM* 03 21 21.7794053122 +79 58 02.154836577       10.2   M2.0Ve 60 0
18 G 77-46 PM* 03 21 46.9231319786 -06 40 24.217353522   12.49 11.314 10.981 9.47 M2V 42 0
19 HD 23453 Er* 03 46 20.1399146634 +26 12 55.821894034   11.05   9.237   M1V 109 0
20 Ross 567 PM* 03 53 10.4353664994 +62 34 08.067755803       11.084   M3.0Ve 33 0
21 LSPM J0422+1031 PM* 04 22 31.9877737107 +10 31 18.797504258   14.0   12.154   M3.5Ve 26 0
22 HD 28343 Er* 04 29 00.1237376701 +21 55 21.719015238 10.988 9.688 8.300 7.446 6.656 M0.5V 169 0
23 HD 232979 Er* 04 37 40.9307425963 +52 53 37.011042661   10.006 8.648 8.750   M0.5V 159 0
24 BD-11 916 PM* 04 37 41.8658538225 -11 02 19.970320151 13.041 11.838 10.331 9.327 8.137 M1V 111 0
25 HD 285968 PM* 04 42 55.7753203198 +18 57 29.394344631 12.668 11.49 9.951 8.931 7.702 M2.5V 275 2
26 L 736-30 PM* 04 53 49.9799241551 -17 46 24.309239662 13.598 12.443 10.894 9.876 8.671 M3V 86 0
27 BD+49 1280 PM* 04 58 50.5747915458 +49 50 57.433438137   11.6   9.373   M0.0Ve 70 0
28 G 85-52 PM* 05 12 42.2265962548 +19 39 56.356342775 13.493 12.308 10.746 9.728 8.529 M0V 79 0
29 HD 36395 PM* 05 31 27.3958475290 -03 40 38.021551815 10.626 9.443 7.968 6.996 5.913 M1.5Ve 447 0
30 V* V2689 Ori RS* 05 36 30.9904303980 +11 19 40.331999226 11.508 10.276 8.898 7.963 7.140 K6V 121 0
31 HD 233153 PM* 05 41 30.7305969608 +53 29 23.290085020   11.31   9.343   M1.0V 163 0
32 G 222-11 PM* 06 10 19.8463571757 +82 06 24.324656398   12.214   9.5   M2.5V 100 0
33 HD 42581 Er* 06 10 34.6152510171 -21 51 52.658021185 10.801 9.607 8.125 7.164 6.121 M1V 417 0
34 HD 265866 PM* 06 54 48.9577150656 +33 16 05.438570309   11.47   9.650   M3V 191 0
35 G 250-33 PM* 07 04 25.9411009163 +68 17 19.657102324     11.99 11.460   M3.0Ve 48 0
36 G 112-21 PM* 07 28 45.4390299123 -03 17 53.305913300 14.298 13.023 11.456 10.351 8.954 M3V 64 0
37 GJ 3452 PM* 07 35 21.8791845108 +54 50 58.972178689   12.93 11.325 10.868   M2.5Ve 46 0
38 BD-02 2198 PM* 07 36 07.0798477777 -03 06 38.791356409 12.551 11.347 9.871 8.925 7.891 M1.0V 45 0
39 G 113-20 PM* 08 16 07.9814381592 +01 18 09.267240612 12.824 11.63 10.091 9.071 7.851 M2.0V 105 0
40 UCAC4 470-039415 PM* 08 29 21.9129006489 +03 55 09.342036923     11.437 11.036   M2.5Ve 18 0
41 G 234-37 PM* 08 35 49.0405629090 +68 04 09.127093660   13.420   11.1   M3.0Ve 46 0
42 G 234-57 PM* 09 13 23.849448 +68 52 30.70416   12.77 11.17 10.76   M2.5V 34 0
43 LP 427-16 PM* 09 14 03.1837557572 +19 40 05.772518977   13.5   11.753   M3.0Ve 23 0
44 HD 79210 Er* 09 14 22.7754519714 +52 41 11.792840757   9.388   6.8   K7V 266 0
45 HD 79211 Er* 09 14 24.6830609365 +52 41 10.906120364   7.966   6.8   M0V 247 0
46 L 749-34 PM* 09 16 20.6445638249 -18 37 32.901570289   12.58 10.739 10.326   M2V 38 0
47 Ross 85 PM* 09 41 10.3603705950 +13 12 34.424857126 13.097 11.891 10.370 9.371 8.182 M2.5V 110 0
48 G 236-1 PM* 09 42 34.8412757372 +70 02 01.965486742   11.86 10.58 9.53 8.24 M2.5V 80 0
49 BD+44 2051 PM* 11 05 28.5769490063 +43 31 36.386948721 11.440 10.270   7.9   M1.0Ve 281 0
50 LP 733-99 LM* 11 20 06.1044739405 -10 29 46.725680797   12.734 11.250 10.887   M2.0V 37 0
51 L 758-108 PM* 12 11 11.7598897837 -19 57 38.069257626 14.475 13.276 11.709 10.619 9.253 dM3.0 56 1
52 Wolf 418 PM* 12 32 16.2123465292 +12 10 45.705930709       10.1   K4 21 0
53 GrW 170817 GWE 13 09 48.0850 -23 22 53.343           ~ 1154 0
54 BD+18 2776 PM* 13 45 05.0809131163 +17 47 07.568400085 12.325 11.192 9.750 8.863 8.003 M1V 107 0
55 HD 119850 Er* 13 45 43.7754528655 +14 53 29.473195472 10.989 9.894 8.50 7.465 6.363 M2V 303 0
56 * 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 2193 0
57 V* OT Ser PM* 15 21 52.9325996324 +20 58 39.910979308 12.662 11.522 10.003 8.993 7.843 M1.0V 115 0
58 G 202-48 PM* 16 25 24.6233091302 +54 18 14.765751243   11.78 10.07 9.66   M1.5V 169 0
59 NAME rho Oph A Cloud MoC 16 26 26.4 -24 22 33           ~ 258 1
60 1SWASP J181725.16+482201.8 BY* 18 17 25.1255751303 +48 22 02.331325999   12.81 11.37 10.91   dM2.0 30 0
61 HD 216899 PM* 22 56 34.8047291749 +16 33 12.353727149 11.323 10.143 8.638 7.657 6.542 M1.5Ve 246 0

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2021.09.18-01:41:46

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