2014A&A...566A.116R


Query : 2014A&A...566A.116R

2014A&A...566A.116R - Astronomy and Astrophysics, volume 566A, 116-116 (2014/6-1)

On helium-dominated stellar evolution: the mysterious role of the O(He)-type stars.

REINDL N., RAUCH T., WERNER K., KRUK J.W. and TODT H.

Abstract (from CDS):

About a quarter of all post-asymptotic giant branch (AGB) stars are hydrogen-deficient. Stellar evolutionary models explain the carbon-dominated H-deficient stars by a (very) late thermal pulse scenario where the hydrogen-rich envelope is mixed with the helium-rich intershell layer. Depending on the particular time at which the final flash occurs, the entire hydrogen envelope may be burned. In contrast, helium-dominated post-AGB stars and their evolution are not yet understood. A small group of very hot, helium-dominated stars is formed by O(He)-type stars. A precise analysis of their photospheric abundances will establish constraints to their evolution. We performed a detailed spectral analysis of ultraviolet and optical spectra of four O(He) stars by means of state-of-the-art non-LTE model-atmosphere techniques. We determined effective temperatures, surface gravities, and the abundances of H, He, C, N, O, F, Ne, Si, P, S, Ar, and Fe. By deriving upper limits for the mass-loss rates of the O(He) stars, we found that they do not exhibit enhanced mass-loss. The comparison with evolutionary models shows that the status of the O(He) stars remains uncertain. Their abundances match predictions of a double helium white dwarf (WD) merger scenario, suggesting that they might be the progeny of the compact and of the luminous helium-rich sdO-type stars. The existence of planetary nebulae that do not show helium enrichment around every other O(He) star precludes a merger origin for these stars. These stars must have formed in a different way, for instance via enhanced mass-loss during their post-AGB evolution or a merger within a common-envelope (CE) of a CO-WD and a red giant or AGB star. A helium-dominated stellar evolutionary sequence exists that may be fed by different types of mergers or CE scenarios. It appears likely that all these pass through the O(He) phase just before they become WDs.

Abstract Copyright:

Journal keyword(s): stars: AGB and post-AGB - stars: evolution - stars: fundamental parameters - stars: abundances

CDS comments: Fig.24 HS 1820+72090 misprint for HS 1830+7209

Simbad objects: 34

goto Full paper

goto View the references in ADS

Number of rows : 34
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 KPD 0005+5106 WD* 00 08 18.1703149584 +51 23 16.598370912 11.80 13.04 13.32 13.53   DOZ1 118 0
2 ACO 48 ClG 00 31 11 +12 32.6           ~ 9 0
3 PG 0038+199 WD* 00 41 35.3383561824 +20 09 16.907246244   13.82       DO1 38 0
4 PG 0046+078 WD* 00 48 37.8852581712 +08 02 44.860028568   15.59 15.590     DO 19 0
5 EGGR 900 WD* 01 11 06.5712757896 +10 21 38.183132772   14.86       DO 41 1
6 EGGR 901 WD* 01 12 23.0598244080 +11 23 36.100360788   15.15 15.40 15.69   DOZ.7 41 0
7 HS 0111+0012 WD* 01 13 46.7761796520 +00 28 28.644373920   14.59 14.9     DO 32 0
8 BD+37 442 HS* 01 58 33.4346638392 +38 34 23.842803324   9.69 9.92     sdOHe 62 0
9 PG 0237+116 WD* 02 40 06.6387356664 +11 48 28.043483364   15.12       DO 20 0
10 RX J0503.9-2854 WD* 05 03 55.5148810152 -28 54 34.631077500 12.29 13.55 13.58     DO 97 0
11 PN K 1-27 PN 05 57 02.1748457640 -75 40 22.478040120     16.04 16.27 16.41 sdOHe 83 0
12 SDSS J075732.18+184329.3 WD* 07 57 32.1835598448 +18 43 29.334223524   18.0   18.9   PG1159/O(He) 8 0
13 CD-45 5058 HS* 09 20 10.1317907208 -45 31 54.942917700 9.81 11.03 11.33 11.62   sdO 51 0
14 BD+37 1977 HS* 09 24 26.3929652664 +36 42 53.295009624   9.86 10.15     sdO 43 0
15 PG 1034+001 WD* 10 37 03.8002625256 -00 08 19.118365188 11.589 12.863 13.228 13.383 13.587 DO 111 0
16 V* DN Leo Pu* 10 38 55.2343433712 +10 03 48.486337812   9.76 9.93     Bp 141 0
17 ESO 320-28 PN 11 52 29.2564204824 -42 17 38.943700548           ~ 54 0
18 V* GW Vir WD* 12 01 45.9731868264 -03 45 40.628670300   14.87 15.04     DOQZ1 475 0
19 V* DY Cen RC* 13 25 34.0847063328 -54 14 43.129581792     12.00     C-Hd/B5-6Ie 90 0
20 CD-46 8926 HS* 13 53 08.2139106408 -46 43 42.314548008   11.04 11.30     sdO 38 0
21 SDSS J141812.51-024426.8 WD* 14 18 12.5146423632 -02 44 27.002517540           PG1159/O(He) 10 0
22 HS 1522+6615 WD* 15 22 56.6956117920 +66 04 42.031760016   16.4       DO 24 0
23 V* R CrB RC* 15 48 34.4154827352 +28 09 24.295852440 6.44 6.31 5.71 5.26 5.08 G0Iep 768 0
24 HD 144941 pA* 16 09 24.5513020968 -27 13 38.184011148 9.45 10.17 10.02     B8 85 1
25 LSE 259 HS* 16 53 54.5759529408 -56 01 54.753819672     12.54     sdO 31 0
26 SDSS J171916.96+365326.7 WD* 17 19 16.9660623048 +36 53 26.754215676   17.7   18.3   PG1159/O(He) 7 0
27 SDSS J172854.34+361958.6 WD* 17 28 54.3428839824 +36 19 58.616747292   16.8   17.2   PG1159/O(He) 9 0
28 HD 160641 HS* 17 41 51.5791786632 -17 53 48.462200880 9.15 10.01 9.85 10.08 9.59 sdOC9.5II-IIIHe40 120 0
29 IC 4663 PN 17 45 28.6295081208 -44 54 17.987147856           [WN3] 94 0
30 HS 1830+7209 WD* 18 30 04.7117378448 +72 11 35.945177640   16.1   17.1   DO 11 0
31 PN GJJC 1 PN 18 36 22.820 -23 55 18.26       13.52 12.44 ~ 95 0
32 CD-51 11879 HS* 19 02 11.7428660328 -51 30 09.561616380   11.44 11.55     sdO 35 0
33 PG 2158+082 HS* 22 01 02.2829193744 +08 30 47.912089716   12.8 13.38 13.49   sdO2VIIIHe40 15 0
34 HS 2209+8229 WD? 22 08 25.8763154304 +82 44 51.409027968   16.0       DO/sdO 13 0

To bookmark this query, right click on this link: simbad:objects in 2014A&A...566A.116R and select 'bookmark this link' or equivalent in the popup menu


2022.05.23-12:57:23

© Université de Strasbourg/CNRS

    • Contact