2015A&A...578A.109M


C.D.S. - SIMBAD4 rel 1.7 - 2019.11.18CET16:15:53

2015A&A...578A.109M - Astronomy and Astrophysics, volume 578A, 109-109 (2015/6-1)

Surface abundances of ON stars.

MARTINS F., SIMON-DIAZ S., PALACIOS A., HOWARTH I., GEORGY C., WALBORN N.R., BOURET J.-C. and BARBA R.

Abstract (from CDS):

Massive stars burn hydrogen through the CNO cycle during most of their evolution. When mixing is efficient or when mass transfer in binary systems occurs, chemically processed material is observed at the surface of O and B stars. ON stars show stronger lines of nitrogen than morphologically normal counterparts. Whether this corresponds to the presence of material processed through the CNO cycle is not known. Our goal is to answer this question. We performed a spectroscopic analysis of a sample of ON stars with atmosphere models. We determined the fundamental parameters as well as the He, C, N, and O surface abundances. We also measured the projected rotational velocities. We compared the properties of the ON stars to those of normal O stars. We show that ON stars are usually rich in helium. Their CNO surface abundances are fully consistent with predictions of nucleosynthesis. ON stars are more chemically evolved and rotate - on average - faster than normal O stars. Evolutionary models including rotation cannot account for the extreme enrichment observed among ON main sequence stars. Some ON stars are members of binary systems, but others are single stars as indicated by stable radial velocities. Mass transfer is therefore not a simple explanation for the observed chemical properties. We conclude that ON stars show extreme chemical enrichment at their surface, consistent with nucleosynthesis through the CNO cycle. Its origin is not clear at present.

Abstract Copyright:

Journal keyword(s): stars: massive - stars: abundances - stars: evolution - stars: atmospheres

VizieR on-line data: <Available at CDS (J/A+A/578/A109): stars.dat sp/*>

Simbad objects: 20

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Number of rows : 20

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 HD 12323 SB* 02 02 30.1267578900 +55 37 26.377362418 7.95 8.87 8.92     ON9.2V 164 0
2 HD 13268 * 02 11 29.7002216680 +56 09 31.717631935 7.48 8.24 8.18     ON8.5IIIn 159 0
3 HD 14633 SB* 02 22 54.2920198726 +41 28 47.723244543 6.14 7.26 7.47     ON8.5V 205 0
4 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 5387 1
5 HD 47129 SB* 06 37 24.0417003671 +06 08 07.376246443 5.23 6.11 6.06     O8I+O7.5III 366 0
6 HD 48279 ** 06 42 40.54719 +01 42 58.2571 7.26 8.03 7.86     O8V+F2V 137 0
7 HD 89137 * 10 15 40.0856062390 -51 15 24.090337747 7.02 7.93 7.97 8.82   ON9.7II(n) 83 1
8 HD 91651 bC* 10 33 30.2995844296 -60 07 40.038449715 7.96 9.64 9.52 9.51   ON9.5IIIn 87 0
9 HD 102415 * 11 46 54.4038347193 -61 27 46.985374046 8.51 9.44 9.35 9.67   ON9IIInn 34 0
10 HD 105056 s*b 12 05 49.8805966991 -69 34 22.993604342 6.57 9.07 8.74 8.45   ON9.7Iae 119 1
11 HD 117490 * 13 32 08.5984445366 -60 48 55.483502747 8.13 8.94 8.92 9.52   ON9.5IIInn 29 0
12 HD 123008 s*b 14 07 30.6440577747 -64 28 08.780113899 8.58 10.00 9.50 9.44   ON9.2Iab 98 0
13 * zet Oph Be* 16 37 09.5390545 -10 34 01.529471 1.73 2.58 2.56 2.46 2.50 O9.2IVnn 1709 2
14 HD 150574 * 16 44 07.2106897294 -46 08 29.843997832 8.01 8.74 8.50 9.30   ON9III(n) 55 0
15 HD 191423 * 20 08 07.1135734619 +42 36 21.963024228 7.43 8.19 8.03     ON9II-IIInn 98 0
16 HD 191781 s*b 20 09 50.5815085623 +45 24 10.485607388 10.1 10.06 9.53     ON9.7Iab 58 0
17 V* V2011 Cyg SB* 20 12 33.1205906584 +40 16 05.442931142 7.32 7.85 7.55     O4.5V(n)((f)) 192 0
18 BD+36 4063 EB* 20 25 40.6038664794 +37 22 27.051633013 10.93 10.67 9.656     ON9.7Ib 40 0
19 HD 201345 * 21 07 55.4153633777 +33 23 49.226678368   7.611 7.764     ON9.2IV 157 0
20 * 14 Cep SB* 22 02 04.5726568485 +58 00 01.308560227 4.77 5.551 5.542     O9IV(n)var+B1:V: 238 0

    Equat.    Gal    SGal    Ecl

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2019.11.18-16:15:53

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