Polarimetry of Li-rich giants

被引：0
|
作者：
Pereyra, A. [1 ]
Castilho, B.V. [2 ]
Magalhães, A.M. [1 ]
机构：
[1] Departamento de Astronomia, IAG, Universidade de São Paulo, Rua do Matão 1226, São Paulo, 05508-900, Brazil
[2] Laboratório Nacional de Astrofísica, MCT, CP 21, Itajubá, MG 37500-000, Brazil
来源：
Astronomy and Astrophysics | 1600年 / 449卷 / 01期
关键词：
Context. 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? Aims. 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. Methods. 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. Results. 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 25 μm far infrared emission. Analysis of spectral energy distributions for the sample show dust temperatures for the envelopes that tend to be between 190 and 260 K. We suggest that dust scattering is indeed responsible for the optical intrinsic polarization in Li-rich giants. Conclusions. Our findings indicate that non-spherical envelopes may appear as early as the red giant phase of stellar evolution. © ESO 2006;
D O I：
暂无
中图分类号：
学科分类号：
摘要：
Journal article (JA)
引用
收藏
页码：211 / 222
相关论文
共 50 条
  • [21] Can Li-rich K Giants Eject Shells? Assembling the Lithium Puzzle in K Giants
    de la Reza, R.
    Drake, N. A.
    CIRCUMSTELLAR DYNAMICS AT HIGH RESOLUTION, 2012, 464 : 51 - 58
  • [22] LAMOST/HRS spectroscopic analysis of two new Li-rich giants
    Zhou, Ze-Ming
    Shi, Jian-Rong
    Yan, Hong-Liang
    Hou, Yong-Hui
    Zhang, Kai
    Gao, Qi
    Xu, Xiao-Dong
    Yuan, Hai-Long
    Zhou, Yu-Tao
    Pan, Kaike
    Sang, Zi-Ye
    Zhao, Yong-Heng
    RESEARCH IN ASTRONOMY AND ASTROPHYSICS, 2021, 21 (01)
  • [23] Identifying Li-rich giants from low-resolution spectroscopic survey
    Kumar, Yerra Bharat
    Reddy, Bacham Eswar
    Zhao, Gang
    JOURNAL OF ASTROPHYSICS AND ASTRONOMY, 2018, 39 (02)
  • [24] The Gaia-ESO Survey: properties of newly discovered Li-rich giants
    Smiljanic, R.
    Franciosini, E.
    Bragaglia, A.
    Tautvaisiene, G.
    Fu, X.
    Pancino, E.
    Adibekyan, V.
    Sousa, S. G.
    Randich, S.
    Montalban, J.
    Pasquini, L.
    Magrini, L.
    Drazdauskas, A.
    Garcia, R. A.
    Mathur, S.
    Mosser, B.
    Regulo, C.
    Peralta, R. de Assis
    Hekker, S.
    Feuillet, D.
    Valentini, M.
    Morel, T.
    Martell, S.
    Gilmore, G.
    Feltzing, S.
    Vallenari, A.
    Bensby, T.
    Korn, A. J.
    Lanzafame, A. C.
    Recio-Blanco, A.
    Bayo, A.
    Carraro, G.
    Costado, M. T.
    Frasca, A.
    Jofre, P.
    Lardo, C.
    de laverny, P.
    Lind, K.
    Masseron, T.
    Monaco, L.
    Morbidelli, L.
    Prisinzano, L.
    Sbordone, L.
    Zaggia, S.
    ASTRONOMY & ASTROPHYSICS, 2018, 617
  • [25] Identifying Li-rich giants from low-resolution spectroscopic survey
    Yerra Bharat Kumar
    Bacham Eswar Reddy
    Gang Zhao
    Journal of Astrophysics and Astronomy, 2018, 39
  • [26] Spectroscopic study of two new super Li-rich red clump K giants
    Singh, Raghubar
    Reddy, Bacham E.
    Kumar, Yerra Bharat
    MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 2019, 482 (03) : 3822 - 3830
  • [27] ON INFRARED EXCESSES ASSOCIATED WITH LI-RICH K GIANTS (vol 150, 123, 2015)
    Rebull, Luisa M.
    Carlberg, Joleen K.
    Gibbs, John C.
    Deeb, J. Elin
    Larsen, Estefania
    Black, David V.
    Altepeter, Shailyn
    Bucksbee, Ethan
    Cashen, Sarah
    Clarke, Matthew
    Datta, Ashwin
    Hodgson, Emily
    Lince, Megan
    ASTRONOMICAL JOURNAL, 2016, 152 (02):
  • [28] Li gradients for Li-rich cathodes
    Michael F Toney
    Nature Energy, 2019, 4 : 1014 - 1015
  • [29] Two New Super Li-rich Core He-burning Giants: A New Twist to the Long Tale of Li Enhancement in K Giants
    Kumar, Yerra Bharat
    Singh, Raghubar
    Reddy, B. Eswar
    Zhao, Gang
    ASTROPHYSICAL JOURNAL LETTERS, 2018, 858 (02)
  • [30] Searching for Li-rich giants in a sample of 12 open clusters Li enhancement in two stars with substellar companions
    Delgado Mena, E.
    Tsantaki, M.
    Sousa, S. G.
    Kunitomo, M.
    Adibekyan, V.
    Zaworska, P.
    Santos, N. C.
    Israelian, G.
    Lovis, C.
    ASTRONOMY & ASTROPHYSICS, 2016, 587
12345