2015A&A...576A..56M


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.05CEST07:11:56

2015A&A...576A..56M - Astronomy and Astrophysics, volume 576A, 56-56 (2015/4-1)

The first stars: CEMP-no stars and signatures of spinstars.

MAEDER A., MEYNET G. and CHIAPPINI C.

Abstract (from CDS):

The CEMP-no stars are ``carbon-enhanced-metal-poor'' stars that in principle show no evidence of s- and r-elements from neutron captures. We try to understand the origin and nucleosynthetic site of their peculiar CNO, Ne-Na, and Mg-Al abundances. We compare the observed abundances to the nucleosynthetic predictions of AGB models and of models of rotating massive stars with internal mixing and mass loss. We also analyze the different behaviors of α- and CNO-elements, as well the abundances of elements involved in the Ne-Na and Mg-Al cycles. We show that CEMP-no stars exhibit products of He-burning that have gone through partial mixing and processing by the CNO cycle, producing low 12C/13C and a broad variety of [C/N] and [O/N] ratios. From a 12C/13C vs. [C/N] diagram, we conclude that neither the yields of AGB stars (in binaries or not) nor the yields of classic supernovae can fully account for the observed CNO abundances in CEMP-no stars. Better agreement is obtained once the chemical contribution by stellar winds of fast-rotating massive stars is taken into account, where partial mixing takes place, leading to various amounts of CNO being ejected. The [(C+N+O)/H] ratios of CEMP-no stars vary linearly with [Fe/H] above [Fe/H]=-4.0 indicating primary behavior by (C+N+O). Below [Fe/H]=-4.0, [(C+N+O)/H] is almost constant as a function of [Fe/H], implying very high [(C+N+O)/Fe] ratios up to 4 dex. In view of the timescales, such abundance ratios reflect more individual nucleosynthetic properties, rather than an average chemical evolution. The high [(C+N+O)/Fe] ratios (as well as the high [(C+N+O)/α-elements]) imply that stellar winds from partially mixed stars were the main source of these excesses of heavy elements now observed in CEMP-no stars. The ranges covered by the variations of [Na/Fe], [Mg/Fe], and [Al/Fe] are much broader than for the α-elements (with an atomic mass number above 24) and are comparable to the wide ranges covered by the CNO elements. Nevertheless, the ratios [Na/N] and [Mg/Al] are about constant for CEMP-no stars of different [Fe/H]. This is consistent with the view that the Ne-Na and Mg-Al cycles were significantly operating in the source stars. The very different properties of CNO, Ne-Na, and Mg-Al elements from those of α-elements further support the idea that these elements (which all give to CEMP-no stars their peculiarities) originate in slow stellar winds of massive stars experiencing partial mixing. CEMP-no stars present a wide variety in the [C/Fe], [N/Fe], [O/Fe], [Na/Fe], [Mg/Fe], [Al/Fe], and [Sr/Fe] ratios. We show that back-and-forth, partial mixing between the He- and H-regions may account for this variety. Some s-elements, mainly of the first peak, may even be produced by these processes in a small fraction of the CEMP-no stars. We propose a classification scheme for the CEMP-no and low-s stars, based on the changes in composition produced by these successive back-and-forth mixing motions.

Abstract Copyright:

Journal keyword(s): stars: abundances - stars: Population III - stars: massive - stars: carbon

CDS comments: object 53327-2044-515 is SDSS J014036.22+234458.1 in SIMBAD. Object Segue 1-7 is [NWG2010] Seg1 7 in SIMBAD.

Simbad objects: 44

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Number of rows : 44

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 HE 0007-1832 Pe* 00 09 52.7814403998 -18 16 12.276852284     15.46     CEMP-no 19 0
2 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 9440 1
3 BPS CS 22166-0016 Pe* 00 58 23.8414780886 -14 47 06.881569381   13.34 12.75 12.324 11.898 ~ 18 0
4 HE 0057-5959 Pe* 00 59 53.9858308128 -59 43 29.745940196   16.4       CEMP-no 29 0
5 HE 0107-5240 Pe* 01 09 29.1554552993 -52 24 34.203535506   15.89 15.07 15.10 14.283 CEMP-no 228 0
6 SDSS J014036.21+234458.1 Pe* 01 40 36.2206962306 +23 44 58.204189219   15.6       CEMP-no 32 0
7 HE 0146-1548 Pe* 01 48 34.7216176944 -15 33 24.493790664   16.406 15.725 15.193 14.658 CEMP-no 14 0
8 BPS CS 22958-0042 Pe* 02 01 07.4296353198 -57 16 58.851945318   14.037 14.52 14.222 13.902 CEMP-no 35 0
9 BD+44 493 Pe* 02 26 49.7388403813 +44 57 46.526253277   9.63 9.11     CEMP-no 82 0
10 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 5665 1
11 SMSS J031300.36-670839.3 Pe* 03 13 00.3747490864 -67 08 39.336567558           CEMP-no 84 0
12 G 77-61 Pe* 03 32 38.0871477505 +01 58 00.010460312   15.60 13.90 12.9   dC-J_CH5 124 0
13 2MASS J04442200-4513542 C* 04 44 22.0060297382 -45 13 54.233994954 13.219 13.51 12.989 12.672 12.372 CEMP-s 22 0
14 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 14826 1
15 HE 0557-4840 Pe* 05 58 39.2661082631 -48 39 56.890701762   16.16 15.45 14.991   CEMP-no 81 0
16 2MASS J10042805-0258141 * 10 04 28.0585341221 -02 58 14.198482047   15.695 14.913 14.495 14.050 ~ 6 0
17 SDSS J100814.44+160501.1 RB? 10 08 14.4416905347 +16 05 01.188764402           ~ 19 1
18 HE 1012-1540 Pe* 10 14 53.4754858508 -15 55 53.171904692     14.04     CEMP-no 30 0
19 UCAC4 427-054095 Pe* 11 53 06.6089448606 -04 45 03.484251112     14.91     CEMP-no 25 0
20 HE 1201-1512 Pe* 12 03 37.0450878463 -15 29 33.235237621   14.2       CEMP-no 16 0
21 HE 1300+0157 Pe* 13 02 56.2444113387 +01 41 52.080881619   14.536 14.11 13.678 13.261 CEMP-no 40 0
22 HE 1300-2201 Pe* 13 03 17.3213523004 -22 17 37.978293961     15.469   14.772 CEMP-no 12 0
23 BPS BS 16929-0005 Pe* 13 03 29.4750923367 +33 51 09.243677482 14.109 14.228 13.610 13.208 12.766 CEMP-no 33 0
24 HE 1300-0641 Pe* 13 03 34.1329709575 -06 57 20.869199156     14.804   13.929 CEMP-no 14 0
25 BPS CS 22877-0001 Pe* 13 13 55.3726645896 -12 11 41.664182839   12.78 12.38 11.695 11.218 CEMP-no 34 0
26 HE 1327-2326 Pe* 13 30 05.9395582011 -23 41 49.699027289 13.761 14.01 13.55 13.50 12.803 CEMP-no 214 0
27 HE 1330-0354 Pe* 13 33 10.6752281912 -04 10 05.803050230   15.248 15.000 14.730 14.380 CEMP-no 16 0
28 HE 1410+0213 Pe* 14 13 06.5623968167 +01 59 21.912907907   14.29 13.25 12.734 12.297 dC-H 21 0
29 2MASS J14215106-1338135 * 14 21 51.0678047673 -13 38 13.410092314   14.802 14.708 14.176 13.713 ~ 9 0
30 HE 1506-0113 Pe* 15 09 14.2926751829 -01 24 56.730409770   15.4       CEMP-no 21 0
31 BPS CS 22878-0027 Pe* 16 37 35.8437255100 +10 22 07.754675906   14.86 14.35 14.45   ~ 22 0
32 BPS CS 22885-0096 Pe* 20 20 51.1729562140 -39 53 30.235406812   14.02 13.33     CEMP-no 82 0
33 BPS CS 30314-0067 Pe* 20 52 50.9876997217 -34 19 40.549001966   12.98 11.85 11.175 10.583 CEMP-no 27 0
34 BPS CS 29498-0043 Pe* 21 03 52.1197489072 -29 42 50.344264361   14.8 13.72 13.013 12.406 CEMP-no 87 0
35 BPS CS 30322-0023 * 21 30 32.1818570433 -46 16 24.615679322   13.473 12.166 11.498 10.908 ~ 46 0
36 HE 2139-5432 Pe* 21 42 42.4475156604 -54 18 42.968678598   15.9       CEMP-no 26 0
37 BPS CS 22956-0028 SB* 21 44 48.7079276715 -63 22 09.738970394   13.317 13.0     CEMP-s 23 0
38 HE 2142-5656 Pe* 21 46 20.50080 -56 42 18.0080   14.4       CEMP-no 11 0
39 HE 2202-4831 Pe* 22 06 06.00020 -48 16 53.0089   16.3       CEMP-no 12 0
40 BPS CS 29502-0092 Pe* 22 22 35.9981441327 -01 38 27.624102360   12.64 11.87 11.365 10.862 CEMP-no 44 0
41 HE 2247-7400 Pe* 22 51 19.60360 -73 44 21.0051   14.4       CEMP-no 11 0
42 BPS CS 22945-0017 Pe* 23 20 55.6263860111 -63 15 36.787084717   14.83 14.44 14.50   ~ 20 0
43 HE 2323-0256 Pe* 23 26 29.8073543039 -02 39 58.037206596   15.12 14.36   13.358 CEMP-no 171 0
44 HE 2356-0410 Pe* 23 59 13.1417869434 -03 53 48.220053208   14.39 13.60 13.164 12.713 CEMP-no 81 0

    Equat.    Gal    SGal    Ecl

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2020.07.05-07:11:56

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