2006A&A...449..211P


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.05CEST05:49:03

2006A&A...449..211P - Astronomy and Astrophysics, volume 449, 211-222 (2006/4-1)

Polarimetry of Li-rich giants.

PEREYRA A., CASTILHO B.V. and MAGALHAES A.M.

Abstract (from CDS):

Protoplanetary nebulae typically present non-spherical envelopes. The origin of such geometry is still controversial. There are indications that it may be carried over from an earlier phase of stellar evolution, such as the AGB phase. But how early in the star's evolution does the non-spherical envelope appear? Li-rich giants show dusty circumstellar envelopes that can help answer that question. We study a sample of fourteen Li-rich giants using optical polarimetry in order to detect non-spherical envelopes around them. We used the IAGPOL imaging polarimeter to obtain optical linear polarization measurements in V band. Foreground polarization was estimated using the field stars in each CCD frame. After foreground polarization was removed, seven objects presented low intrinsic polarization (0.19-0.34)% and two (V859 Aql and GCSS 557) showed high intrinsic polarization values (0.87-1.16)%. This intrinsic polarization suggests that Li-rich giants present a non-spherical distribution of circumstellar dust. The intrinsic polarization level is probably related to the viewing angle of the envelope, with higher levels indicating objects viewed closer to edge-on. The correlation of the observed polarization with optical color excess gives additional support to the circumstellar origin of the intrinsic polarization in Li-rich giants. The intrinsic polarization correlates even better with the IRAS 25µm far infrared emission. Analysis of spectral energy distributions for the sample show dust temperatures for the envelopes that tend to be between 190 and 260K. We suggest that dust scattering is indeed responsible for the optical intrinsic polarization in Li-rich giants. Our findings indicate that non-spherical envelopes may appear as early as the red giant phase of stellar evolution.

Abstract Copyright:

Journal keyword(s): polarization - stars: circumstellar matter - infrared: stars - stars: late type - stars: evolution

Simbad objects: 20

goto Full paper

goto View the reference in ADS

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 V* V341 Car LP* 07 56 50.9465103624 -59 07 32.759315630 10.62 8.33 6.25     M1II 70 0
2 HD 90082 * 10 22 07.4539316271 -61 51 00.660584073   9.12 7.47     M3III 13 0
3 HD 95799 * 11 02 25.1092401545 -58 45 37.377549640   8.960 7.94 7.395 6.906 G8III 29 0
4 V* V530 Car s*r 11 04 29.1553812844 -62 57 43.727817020   10.46 8.26     M2+Iab 22 1
5 V* R Vir Mi* 12 38 29.9337975491 +06 59 19.025590708 10.26 9.04 7.48 5.62 3.91 M3.5-7e 189 0
6 V* RU Vir C* 12 47 18.4075712853 +04 08 41.364022128   14.75 9.00     C8,1e 164 0
7 HD 112127 C* 12 53 55.7454142679 +26 46 47.984571519 9.56 8.14 6.88 5.97 5.39 C-R4IIIb 138 0
8 HD 120602 * 13 50 24.6782891653 +05 29 50.002618344   6.892 5.993     K0 40 0
9 IRAS 13539-4153 TT* 13 56 57.2668777596 -42 08 09.865923001   14.40 12.80 12.33   K 18 0
10 HD 124649 * 14 16 22.0960850651 -53 19 36.625664469   9.50 7.84     K4III 6 0
11 HD 146850 * 16 19 00.4167225599 -14 52 22.145494376 9.41 7.46 5.94     K3IIICNVp 37 0
12 V* V385 Sct S* 18 26 59.1541815762 -14 41 48.762521853           S 24 0
13 HD 176588 * 19 01 09.5031107555 -04 26 20.287792125   8.57 6.88     K4/5III 22 0
14 IRAS 19012-0747 * 19 03 58.1 -07 42 36           ~ 11 0
15 GSC2 S300232037086 * 19 06 23.7584187208 -00 21 22.448038695   15.7 14.1     ~ 6 0
16 HD 178168 * 19 07 32.7655878417 -02 29 54.648610319   10.79 8.96     K3/4 11 0
17 V* V859 Aql LP* 19 31 01.2269176135 +05 23 53.495279070   11.64 10.39     ~ 22 0
18 HD 190664 PM* 20 06 12.2152512672 -04 04 41.503941036   7.616 6.469     K0III 12 0
19 V* AU Cap RS* 21 21 29.6767611622 -15 09 21.778452239   9.22 8.01     K2III 28 0
20 HD 203252 * 21 21 35.6702960350 -17 54 34.612810081   10.64 9.42     K0III 3 0

    Equat.    Gal    SGal    Ecl

To bookmark this query, right click on this link: simbad:objects in 2006A&A...449..211P and select 'bookmark this link' or equivalent in the popup menu


2020.07.05-05:49:03

© Université de Strasbourg/CNRS

    • Contact