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EP Aquarii:A New Picture of the Circumstellar Envelope

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Research in Astronomy and Astrophysics 2024年第3期24卷 83-105页

作者： Pham T.Nhung Do T.Hoai Pierre Darriulat Pham tuan-Anh Pham N.diep Nguyen B.Ngoc tran T.Thai Department of Astrophysics Vietnam National Space CenterVietnam Academy of Science and Technology18Hoang Quoc VietNghia DoCau GiayHa Noivietnam

New analyses of earlier ALMA observations of oxygen-rich AGB star EP Aquarii are presented,which complete a previously published analysis and offer a different interpretation of the morpho-kinematics of the circumstellar *** birth of the equatorial density enhancement(EDE)is shown to occur very close to the star where evidence for rotation has been *** to the star and where outflows have been observed:their interaction with the gas of the nascent EDE is seen to play an important role in the development of the wind and the evolution of its radial velocity from 8 to 10 km s^(-1) on the polar symmetry axis to~2 km s^(-1) at the *** implies complex morpho-kinematics:making reliable interpretations with reasonable confidence is *** particular,it questions an earlier interpretation implying the presence of a white dwarf companion orbiting the star at an angular distance of -0″4 from its *** proposes instead an interpretation in terms of a standard mass ejection associated with a shock wave leaving a void of emission in its *** Doppler velocity wings are seen to consist of two components,the upper velocity end of the global wind,reaching above±12 km s^(-1),and an effective line broadening,confined within 200 mas from the center of the star,reaching above±20 km s^(-1) and interpreted as caused by the pattern of shock waves resulting from the interaction between stellar pulsation and convective cell partition.

关键词： stars AGB and post-AGB-(stars) circumstellar matter-radio lines stars

Contributions of Rotation,Expansion and Line Broadening to the Morphology and Kinematics of the Inner CSE of Oxygen-rich AGB Star R Hya

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Research in Astronomy and Astrophysics 2023年第1期23卷 40-47页

作者： Pham Tuyet Nhung Do Thi Hoai Pierre Darriulat Pham Ngoc diep Nguyen Bich Ngoc tran Thi Thai Pham tuan-Anh Department of Astrophysics Vietnam National Space CenterVietnam Academy of Science and Technology18Hoang Quoc VietNghia DoCau GiayHa NoiVietnam

We use archival ALMA observations of the CO(2-1)and SiO(5-4)molecular line emissions of AGB star R Hya to illustrate the relative contributions of rotation,expansion and line broadening to the morphology and kinematics of the circumstellar envelope(CSE)within some~70 au(~0."5)from the centre of the *** give evidence for rotation and important line broadening to dominate the inner region,within~14 au(~100 mas)from the centre of the *** former is about an axis that projects a few degrees west of north and has a projected rotation velocity of a few km s^(-1).The latter occurs within some 7-14 au(50-100 mas)from the centre of the star,with the line width reaching two to three times its value outside this *** suggest that it is caused by shocks induced by stellar pulsations and convective cell *** show the importance of properly accounting for the observed line broadening when discussing rotation and evaluating the radial dependence of the rotation velocity.

关键词： stars AGB and post-AGB-(stars:)circumstellar matter-radio lines

Morphology and kinematics of the gas envelope of the Mira binary W Aquilae

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Research in Astronomy and Astrophysics 2016年第7期16卷 47-54页

作者： Do Thi Hoai Pham Tuyet Nhung Pham Ngoc diep Nguyen Thi Phuong Pham tuan-Anh Nguyen Thi Thao Pierre Darriulat Department of Astrophysics Vietnam National Satellite CenterVAST

We analyse ALMA observations of the12CO（3-2） emission of the circumstellar envelope（CSE）of the Mira variable binary star W Aql. These provide, for the first time, spatially resolved Doppler velocity spectra of the CSE up to angular distances to the central star ofy nature of the observations（only five minutes in each of～5′′（meaning some 2000 AU）. The explorator two different configurations） does not allow for a detailed modelling of the properties of the CSE but provides important qualitative information on its morphology and kinematics. Emission is found to be enhanced along an axis moving from east/west to north-east/south-west when the angular distance from the central star projected on the plane of the sky increases from zero to four arcseconds. In parallel, the Doppler velocity distribution displays asymmetry along an axis moving from east/west to north-west/south-east. The results are discussed in the context of earlier observations, in particular of the dust morphology.

关键词： stars AGB and post-AGB (stars ) circumstellar matter stars individual(W Aql) stars mass-loss radio lines stars

^(12)CO emission from the Red Rectangle

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Research in Astronomy and Astrophysics 2015年第12期15卷 2213-2228页

作者： Pham tuan Anh Pham Ngoc diep Do Thi Hoai Pham Tuyet Nhung Nguyen Thi Phuong Nguyen Thi Thao Pierre Darriulat Department of Astrophysics Vietnam National Satellite CenterVAST

Observations of an unprecedented quality made by ALMA on the Red Rectangle of CO（3-2） and CO（6-5） emissions are analysed jointly with the aim of obtaining as simple as possible a description of the gas morphology and kinematics. Evidence is found for polar conical outflows and for a broad equatorial torus in rotation and expansion. Simple models of both are proposed. Comparing CO（6-5） and CO（3-2） emissions provides evidence for a strong temperature enhancement over the polar outflows. Continuum emission （dust） is seen to be enhanced in the equatorial region. Observed asymmetries are briefly discussed.

关键词： stars: AGB and post-AGB -- circumstellar matter -- radio-lines: stars-- planetary nebulae: individual (Red Rectangle)

Morphology and kinematics of the gas envelope of the variable AGB star π^1 Gruis

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Research in Astronomy and Astrophysics 2016年第7期16卷 97-104页

作者： Pham Tuyet Nhung Do Thi Hoai Pham Ngoc diep Nguyen Thi Phuong Nguyen Thi Thao Pham tuan Anh Pierre Darriulat Department of Astrophysics Vietnam National Satellite CenterVAST

Observations of the ^12CO（3–2） emission from the circumstellar envelope（CSE） of the variable star π1Gru using the compact array of the ALMA observatory have been recently made accessible to the public. An analysis of the morphology and kinematics of the CSE is presented with a result very similar to that obtained earlier for ^12CO（2–1） emission using the Submillimeter Array. A quantitative comparison is made using their flared disk model. A new model is presented that provides a significantly better description of the data, using radial winds and smooth evolutions of the radio emission and wind velocity from the stellar equator to the poles.

关键词： stars AGB and post-AGB circumstellar matter star individual(π1Gru) stars massloss radio lines stars

Gravitationally lensed extended sources: the case of QSO RXJ0911

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Research in Astronomy and Astrophysics 2013年第7期13卷 803-814页

作者： Do Thi Hoai Pham Tuyet Nhung Pham tuan Anh Frederic Boone Pierre Darriulat Pham Ngoc diep Pham Ngoc Dong Nguyen Van Hiep Nguyen Thi Thao VATLY INST179Hoang Quoc VietCau GiayHanoiVietnam IRAP 14avenue Edouard BelinF31400 ToulouseFrance

After a brief reminder of the mechanism of gravitational lensing of ex- tended sources, the particular case of the host galaxy of QSO RXJ0911, a high red-shift （z - 2.8） quadruply imaged quasar, is explored. The non linearity of the problem, together with the proximity of the source to a cusp of the lens inner caustic, has impor-tant consequences on the dependence of the image appearance on the size and shape of the source. Their expected main features and their interpretation in terms of source extension and shape are investigated in a spirit of simplicity and in preparation for the analysis of high sensitivity and spatial resolution images that will soon be within reach with the completion of the Atacama Large Millimeter/submillimeter Array （ALMA）. In particular, the information on source size carded by relative image brightness is dis-cussed. Extension of the results to other types of quadruply imaged quasars is briefly considered.

关键词： gravitational lensing - galaxies: high-redshift

Morphology of the ^(13)CO(3–2) millimetre emission across the gas disc surrounding the triple protostar GG Tau A using ALMA observations

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Research in Astronomy and Astrophysics 2018年第3期18卷 63-76页

作者： Nguyen Thi Phuong Pham Ngoc diep Anne Dutrey Edwige Chapillon Pierre Darriulat Stéphane Guilloteau Do Thi Hoai Pham Tuyet Nhung Ya-Wen Tang Nguyen Thi Thao Pham tuan-Anh Department of Astrophysics Vietnam National Space CenterVietnam Academy of Science and Technology Graduate University of Science and Technology Vietnam Academy of Science and Technology Laboratoire d’Astrophysique de Bordeaux Université de Bordeaux IRAM F-38406 Saint Martin d’Hères Cedex Academia Sinica Institute of Astronomy and Astrophysics

Observations by the Atacama Large Millimetre/sub-millimetre Array of the dust continuum and ^13 CO（3–2） millimetre emissions of the triple stellar system GG Tau A are analysed,giving evidence for a rotating gas disc and a concentric and coplanar dust ring. The present work complements an earlier analysis（Tang et al.） by exploring detailed properties of the gas disc. A 95% confidence level upper limit of 0.24＂（34 au） is placed on the disc scale height at a distance of 1＂（140 au） from the central stars. Evidence for Keplerian rotation of the gas disc is presented,with the rotation velocity reaching-3.1 km s^-1 at 1＂ from the central stars,and a 99% confidence level upper limit of 9% is placed on relative contribution from a possible in-fall velocity. Variations of the intensity across the disc area are studied in detail and confirm the presence of a hot spot in the south-eastern quadrant. However several other significant intensity variations,in particular a depression in the northern direction,are also revealed. Variations of the intensity are found to be positively correlated to variations of the line width. Possible contributions to the measured line width are reviewed,suggesting an increase of the disc temperature and opacity with decreasing distance from the stars.

关键词： protoplanetary disks - stars low-mass - stars individual (GG Tau A)

ALMA observations of the circumstellar envelope around EP Aqr

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Research in Astronomy and Astrophysics 2019年第3期19卷 97-110页

作者： Pham Thi Tuyet Nhung Do Thi Hoai Pham tuan-Anh Thibaut Le Bertre Pierre Darriulat Pham Ngoc diep Nguyen Thi Phuong Nguyen Thi Thao Jan Martin Winters Department of Astrophysics Vietnam National Space CenterVAST LERMA UMR 8112 CNRS and Observatoire de Paris PSL Research University Graduate University of Science and Technology VAST IRAM 300 rue de la Piscine Domaine Universitaire

Atacama Large Millimetre/sub-millimetre Array(ALMA) observations of CO(1–0) and CO(2–1) emissions from the circumstellar envelope of the asymptotic giant branch(AGB) star EP Aqr have been made with four times better spatial resolution than previously available. They are analysed with emphasis on the de-projection in space of the effective emissivity and flux of matter using as input a prescribed configuration of the velocity field, assumed to be radial. The data are found to display an intrinsic axisymmetry with respect to an axis making a small angle with respect to the line of sight. A broad range of wind configurations, from prolate(bipolar) to oblate(equatorial) has been studied and found to be accompanied by significant equatorial emission. Qualitatively, the effective emissivity is enhanced near the equator to produce the central narrow component observed in the Doppler velocity spectra and its dependence on star latitude generally follows that of the wind velocity with the exception of an omni-present depression near the poles. In particular, large equatorial expansion velocities produce a flared disc or a ring of effective emissivity and mass loss. The effect on the determination of the orientation of the star axis of radial velocity gradients, and possibly competing rotation and expansion in the equatorial disc, is discussed. In general,the flux of matter is found to reach a broad maximum at distances of the order of 500 AU from the *** are given that may be used to favour one wind velocity distribution over another. As a result of the improved quality of the data, a deeper understanding of the constraints imposed on morphology and kinematics has been obtained.

关键词： stars: AGB and post-AGB (stars:) circumstellar matter stars: individual: EP Aqr stars:mass-loss radio lines: stars

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夏黑葡萄在越南北部栽培表现及其技术要点

南方园艺 2019年第6期30卷 34-37页

作者：黄江流 DO THANH TRUNG 唐其展吕荣华 NGUYEN tuan diep CAN VAN TOAN NGUYEN CONG THANH PHUNG DUY HIEU BUI THI THU tranG 黄竟刘淑仪黄芳颖梁芳黄勇策黄克顺广西农业科学院葡萄与葡萄酒研究所广西南宁530007 越南北江农林科技大学越南广西农业科学院国际合作处广西南宁530007 广西无为谷生态农业科技有限公司广西南宁530008

河内、北江等越南北方地区年均温比广西南宁高2℃左右,光温条件比较优越,应越方要求新引入种植比巨峰葡萄早熟优质的无核夏黑葡萄,以期调节产期,满足市场需求。采用广西夏黑葡萄当年种当年收和一年两收栽培技术管理,在越南北部地区于3... 详细信息

河内、北江等越南北方地区年均温比广西南宁高2℃左右,光温条件比较优越,应越方要求新引入种植比巨峰葡萄早熟优质的无核夏黑葡萄,以期调节产期,满足市场需求。采用广西夏黑葡萄当年种当年收和一年两收栽培技术管理,在越南北部地区于3月上旬种植夏黑葡萄,种后4个半月于7月下旬修剪促花,剪后1个月于8月下旬开花,剪后2个月于9日下旬着色,剪后3个月于10月中下旬成熟上市,从种到收获全程9个月,平均每hm^2产量8517.0 kg,实现了当年种植当年投产的目标。为越南葡萄产业增加新的经济增长点。

关键词：夏黑葡萄当年种当年投产栽培表现技术要点