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1,009 results on '"Circumstellar envelope"'

1. Spatial distributions of 13CO and CS in a carbon-rich AGB star IRC+10216.

Author

Tuo, Juan, Yang, Xiaofeng, Sun, Jixian, Zijlstra, Albert, and Nakashima, Junichi

Subjects
*LOCAL thermodynamic equilibrium, *DISTRIBUTION (Probability theory), *ASYMPTOTIC giant branch stars, *RADIO telescopes, *ASTROCHEMISTRY
Abstract

IRC+10216 is the typical carbon-rich asymptotic giant branch star, and more than 100 species have been observed in its circumstellar envelope so far. The use of interferometric arrays to map molecular emission in this source has been widely reported, but to study the angular extent of molecular emission, singledish mapping must be employed. We report here the mapping of the 13CO J = 1-0 and CS J = 2-1 lines towards IRC+10216 using the 13.7 m mm-wave radio telescope at Purple Mountain Observatory. As far as we know, these maps are the largest published 13CO J = 2-1 and CS J = 2-1 images to date. Both molecules have roughly spherically symmetric distribution, with 13CO having an emission radius of over 80"and CS extending up to ~50". Assuming that the two molecules are in local thermodynamic equilibrium, the column density and fractional abundance relative to H2 for 13CO and the lower limits for CS are obtained. They are 4.35 × 1016 cm-2 and > 4.72 × 1014 cm-2, and 5.25 × 10-5 and > 2.56 × 10-7 for 13CO and CS, respectively. [ABSTRACT FROM AUTHOR]

Published
2024
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2. Spatial distributions of 13CO and CS in a carbon-rich AGB star IRC+10216

Author

Juan Tuo, Xiaofeng Yang, and Jixian Sun

Subjects
asymptotic giant branch star, circumstellar envelope, IRC+10216, molecular line, 13CO, CS, Astronomy, QB1-991, Geophysics. Cosmic physics, QC801-809
Abstract

IRC+10216 is the typical carbon-rich asymptotic giant branch star, and more than 100 species have been observed in its circumstellar envelope so far. The use of interferometric arrays to map molecular emission in this source has been widely reported, but to study the angular extent of molecular emission, single-dish mapping must be employed. We report here the mapping of the 13CO J = 1–0 and CS J = 2–1 lines towards IRC+10216 using the 13.7 m mm-wave radio telescope at Purple Mountain Observatory. As far as we know, these maps are the largest published 13CO J = 2–1 and CS J = 2–1 images to date. Both molecules have roughly spherically symmetric distribution, with 13CO having an emission radius of over 80″and CS extending up to ∼50″. Assuming that the two molecules are in local thermodynamic equilibrium, the column density and fractional abundance relative to H2 for 13CO and the lower limits for CS are obtained. They are 4.35 × 1016 cm−2 and > 4.72 × 1014 cm−2, and 5.25 × 10−5 and > 2.56 × 10−7 for 13CO and CS, respectively.

Published
2024
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3. Molecules in Space

Author

Müller, Holger S. P., Gargaud, Muriel, editor, Irvine, William M., editor, Amils, Ricardo, editor, Claeys, Philippe, editor, Cleaves, Henderson James, editor, Gerin, Maryvonne, editor, Rouan, Daniel, editor, Spohn, Tilman, editor, Tirard, Stéphane, editor, and Viso, Michel, editor

Published
2023
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4. Photochemical origin of SiC2 in the circumstellar envelope of carbon-rich AGB stars revealed by ALMA

Author

Yanan Feng, Xiaohu Li, Tom J. Millar, Ryszard Szczerba, Ke Wang, Donghui Quan, Shengli Qin, Xuan Fang, Juan Tuo, Zhenzhen Miao, Rong Ma, Fengwei Xu, Jingfei Sun, Biwei Jiang, Qiang Chang, Jianchao Yang, Gao-Lei Hou, Fangfang Li, and Yong Zhang

Subjects
asymptotic giant branch stars, mass loss, circumstellar envelope, C-rich, SiC2, AI Vol, Astronomy, QB1-991, Geophysics. Cosmic physics, QC801-809
Abstract

The fact that whether SiC2 is a parent species, formed in the photosphere or as a by-product of high-temperature dust formation, or a daughter species, formed in chemistry driven by the photodestruction of the parent species in the outer envelope, has been debated for a long time. In this study, we analyze the Atacama Large Millimeter Array (ALMA) observations of four SiC2 transitions in the circumstellar envelopes (CSEs) of three C-rich asymptotic giant branch (AGB) stars (AI Vol, II Lup, and RAFGL 4211) and find that SiC2 exhibits an annular, shell-like distribution in these targets, suggesting that SiC2 can be a daughter species in the CSEs of carbon-rich AGB stars. The results may provide important references for future chemical models.

Published
2023
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5. Molecules in Space

Author

Müller, Holger S. P., Gargaud, Muriel, editor, Irvine, William M., editor, Amils, Ricardo, editor, Cleaves, Henderson James (Jim), II, editor, Pinti, Daniele L., editor, Quintanilla, José Cernicharo, editor, Rouan, Daniel, editor, Spohn, Tilman, editor, Tirard, Stéphane, editor, and Viso, Michel, editor

Published
2015
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12. AGB Stars: History, Structure, and Characteristics

Author

Habing, Harm J., Olofsson, Hans, Appenzeller, Immo, editor, Börner, Gerhard, editor, Dopita, Michael A., editor, Harwit, Martin, editor, Kippenhahn, Rudolf, editor, Lequeux, James, editor, Maeder, André, editor, Strittmatter, Peter A., editor, Trimble, Virginia, editor, Habing, Harm J., editor, and Olofsson, Hans, editor

Published
2004
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30. Using spectropolarimetry to determine envelope geometry and test variability models for hot star circumstellar envelopes

Author

Bjorkman, Karen S., Beig, R., editor, Ehlers, J., editor, Frisch, U., editor, Hepp, K., editor, Jaffe, R. L., editor, Kippenhahn, R., editor, Ojima, I., editor, Weidenmüller, H. A., editor, Wess, J., editor, Zittartz, J., editor, Beiglböck, W., editor, Eisenächer, Monika, editor, Wolf, Bernhard, editor, Stahl, Otmar, editor, and Fullerton, Alex W., editor

Published
1999
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31. Исследование многолетней спектральной переменности Ae звезды Хербига HD 36112

Subjects
Physics, 010308 nuclear & particles physics, Resonance, Circumstellar envelope, Astrophysics, 01 natural sciences, Intensity (physics), Planet, 0103 physical sciences, Emission spectrum, Variation (astronomy), 010303 astronomy & astrophysics, Equivalent width, Probable mechanism
Abstract

Представлены результаты многолетних высокодисперсионных спектральных наблюдений (R = 20000) Ае звезды Хербига HD 36112 в области эмиссионных линий Hα и резонансного дублета NaI D. Показано, что параметры эмиссионной линии Hα демонстрируют сложную переменность на нескольких временных шкалах: 1) переменность от ночи к ночи, обусловленную неоднородной структурой околозвездной газовой оболочки; 2) переменность на шкале времени около 1200 суток, характеризующуюся изменением эквивалентной ширины, интенсивности, а также других параметров эмиссии; 3) переменность на шкале времени более 4000 суток, наблюдаемую как многолетний тренд в изменении параметров эмиссионной линии Hα.Мы связываем полученные результаты с изменением физических и кинематических условий во внутренних областях аккреционного диска и ветра. Наиболее вероятным механизмом таких изменений является активно идущий в околозвездном диске звезды процесс планетообразования.

Published
2020
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44. ISO LWS Observations of H2O from R CAS : A Consistent Model For Its Circumstellar Envelope

Author

Truong-Bach, Nguyen-Q-Rieu, Sylvester, R. J., Barlow, M. J., Liu, X. W., Lim, T., Omont, A., Cox, P., Skinner, C. J., Dyson, John, editor, Lamb, Susan A., editor, Cameron, A. G. W., editor, Cherepashchuk, A. M., editor, Fälthammar, C.-G., editor, Kitamura, M., editor, Waters, L. B. F. M., editor, Waelkens, C., editor, van der Hucht, K. A., editor, and Zaal, P. A., editor

Published
1998
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45. Impact of Submerged Macrophytes on Fish-Zooplankton Interactions in Lakes

Author

Jeppesen, Erik, Lauridsen, Torben L., Kairesalo, Timo, Perrow, Martin R., Caldwell, M. M., editor, Heldmaier, G., editor, Lange, O. L., editor, Mooney, H. A., editor, Schulze, E.-D., editor, Sommer, U., editor, Jeppesen, Erik, editor, Søndergaard, Martin, editor, Søndergaard, Morten, editor, and Christoffersen, Kirsten, editor

Published
1998
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47. Mass Loss in AGB Stars

Author

Guélin, M., Lucas, R., Neri, R., Latter, William B., editor, Radford, Simon J. E., editor, Jewell, Philip R., editor, Mangum, Jeffrey G., editor, and Bally, John, editor

Published
1997
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