2000A&A...362..984V


Query : 2000A&A...362..984V

2000A&A...362..984V - Astronomy and Astrophysics, volume 362, 984-1003 (2000/10-3)

Near-infrared and Brγ observations of post-AGB stars.

VAN DE STEENE G.C., VAN HOOF P.A.M. and WOOD P.R.

Abstract (from CDS):

In this article we report further investigations of the IRAS selected sample of Planetary Nebula (PN) candidates that was presented in Van de Steene & Pottasch (1993A&A...274..895V). About 20% of the candidates in that sample have been detected in the radio and/or Hα and later confirmed as PNe. Here we investigate the infrared properties of the IRAS sources not confirmed as PNe. We observed 28 objects in the N-band of which 20 were detected and 5 were resolved, despite adverse weather conditions. We obtained medium resolution Brγ spectra and we took high resolution JHKL images of these 20 objects. We critically assessed the identification of the IRAS counterpart in the images and compared our identification with others in the literature. High spatial resolution and a telescope with very accurate pointing are crucial for correct identification of the IRAS counterparts in these crowded fields. Of sixteen positively identified objects, seven show Brγ in absorption. The absorption lines are very narrow in six objects, indicating a low surface gravity. Another six objects show Brγ in emission. Two of these also show photospheric absorption lines. All emission line sources have a strong underlying continuum, unlike normal PNe. In another three objects, no clear Brγ absorption or emission was visible. The fact that our objects were mostly selected from the region in the IRAS color-color diagram where typically PNe are found, may explain our higher detection rate of emission line objects compared to previous studies, which selected their candidates from a region between AGB and PNe. The objects showing Brγ in emission were re-observed in the radio continuum with the Australia Telescope Compact Array. None of them were detected above a detection limit of 0.55mJy/beam at 6cm and 0.7mJy/beam at 3cm, while they should have been easily detected if the radio flux was optically thin and Case B recombination was applicable. It is suggested that the Brγ emission originates in the post-Asymptotic Giant Branch (post-AGB) wind, and that the central star is not yet hot enough to ionize the AGB shell. We measured the JHKL magnitudes of the objects and present their infrared spectral energy distributions. They are typical for post-AGB stars according to the scheme of van der Veen et al. (1989A&A...226..108V). We also constructed various color-color diagrams using the near-infrared and IRAS magnitudes. No distinction can be made between the objects showing Brγ in emission, absorption, or a flat spectrum in the near and far-infrared color-color diagrams. The near-infrared color-color diagrams show evidence for a very large range of extinction, which in part is of circumstellar origin. Near-infrared versus far-infrared color-color diagrams show trends that are consistent with the expected evolution of the circumstellar shell. This sample of post-AGB stars show a larger range in color and are generally redder and closer to the galactic plane than the ones known so far. The properties of most of these objects are fully consistent with the assumption that they are post-AGB stars that have not evolved far enough yet to ionize a significant fraction of their circumstellar material.

Abstract Copyright:

Journal keyword(s): stars: AGB and post-AGB - stars: circumstellar matter - stars: evolution - ISM: dust, extinction - ISM: planetary nebulae: general - infrared: stars

CDS comments: Table 1: IRAS 13428-6531 misprint for 13427-6531, p. 986: calibrators not identified

Simbad objects: 36

goto View the references in ADS

Number of rows : 36
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 RAFGL 618 pA* 04 42 53.6242032600 +36 06 53.400902220   16.32   12.59   C-rich 981 0
2 HD 44179 pA* 06 19 58.2185496 -10 38 14.706068 9.51 9.33 9.02     B9Ib/II 735 0
3 IRAS 10256-5628 pA* 10 27 35.2259757072 -56 44 19.801926816           F5I 10 0
4 IRAS 11159-5954 pA? 11 18 07.1578985232 -60 10 38.510377464           ~ 5 0
5 IRAS 11387-6113 pA* 11 41 08.7104227704 -61 30 17.334303228           A3Ie 12 0
6 IRAS 13356-6249 pA* 13 39 06.3052579368 -63 04 44.265180432           ~ 13 0
7 IRAS 13416-6243 pA* 13 45 07.2573421656 -62 58 16.835990124           G1I 42 0
8 IRAS 13428-6232 Em* 13 46 20.581 -62 47 59.78           ~ 29 0
9 IRAS 13427-6531 PN? 13 46 25.70 -65 46 24.4           ~ 15 0
10 IRAS 13529-5934 pA? 13 56 24.59 -59 48 57.1           ~ 11 0
11 IRAS 14325-6428 pA* 14 36 34.3740180048 -64 41 31.082196876   12.56 12.00     F5I 19 0
12 CD-53 5736 pA* 14 52 28.7255749920 -54 17 42.825195636   11.66 10.94     A0Ie 20 0
13 IRAS 15066-5532 pA* 15 10 26.6785573008 -55 44 12.035535144           ~ 12 0
14 IRAS 15144-5812 pA* 15 18 21.9091371984 -58 23 11.936248476           ~ 12 0
15 IRAS 15154-5258 PN 15 19 08.76 -53 09 49.8   16.2       [WO4]pec 62 0
16 IRAS 15310-6149 pA? 15 35 17.1330515448 -61 59 04.222013352   14.35 13.54     F0Ve 12 0
17 IRAS 15544-5332 pA? 15 58 18.830 -53 40 39.84           ~ 13 0
18 IRAS 15553-5230 pA* 15 59 10.90 -52 38 37.1           ~ 12 0
19 IRAS 16086-5255 pA* 16 12 30.4680470520 -53 03 09.962106480           ~ 12 0
20 IRAS 16115-5044 s*b 16 15 17.9553965760 -50 52 19.841361852           ~ 22 0
21 IRAS 16127-5021 pA? 16 16 30.25 -50 28 57.6           ~ 6 0
22 IRAS 16130-4620 pA* 16 16 42.84 -46 27 55.3           ~ 11 0
23 OH 335.832 +1.434 OH* 16 24 33.9561534432 -47 21 30.140946792           ~ 11 0
24 IRAS 16279-4757 pA* 16 31 38.7381067320 -48 04 05.637444456           M3II 39 0
25 IRAS 16328-4517 pA? 16 36 25.7317277592 -45 24 03.651457680           ~ 6 0
26 IRAS 16345-5001 pA? 16 38 21.75 -50 07 50.9           ~ 4 0
27 IRAS 16594-4656 pA* 17 03 10.0705512504 -47 00 27.731886516           B7 85 0
28 IRAS 17009-4154 pA* 17 04 29.6093682792 -41 58 38.632672956           ~ 15 0
29 OH 345.05 -1.86 pA* 17 12 22.806 -42 25 09.82           ~ 32 0
30 IRAS 17234-4008 pA* 17 26 56.1268486440 -40 11 02.210386128           ~ 15 0
31 Hen 3-1475 PN 17 45 14.1819342984 -17 56 46.778166204   13.84 12.87     B7e 193 0
32 PN MaC 1-12 PN 18 21 21.1085584532 -08 31 42.537249789           ~ 24 0
33 IRAS 18231-1047 PN 18 25 58.08960 -10 45 28.7280           ~ 19 0
34 PN MA 13 PN 18 30 30.3940394160 -07 27 38.178410436           ~ 20 0
35 PN VV 201 PN 18 42 56.979 -11 06 53.10           ~ 60 0
36 [D75b] Em* 21-021 PN 21 29 58.4711786760 +51 04 00.323924520   15.66 14.20 13.89   O7(f)/[WC11] 235 0

To bookmark this query, right click on this link: simbad:objects in 2000A&A...362..984V and select 'bookmark this link' or equivalent in the popup menu


2022.05.28-03:10:48

© Université de Strasbourg/CNRS

    • Contact