ATOMIUM: A high-resolution view on the highly asymmetric wind of the AGB star π1Gruis: I. First detection of a new companion and its effect on the inner wind

被引：23

作者：

Homan, Ward ^{[1
]}

Montarges, Miguel ^{[1
]}

Pimpanuwat, Bannawit ^{[2
]}

Richards, Anita M. S. ^{[2
]}

Wallstrom, Sofia H. J. ^{[1
]}

Kervella, Pierre ^{[4
]}

Decin, Leen ^{[1
,3
]}

Zijlstra, Albert ^{[2
]}

Danilovich, Taissa ^{[1
]}

de Koter, Alex ^{[1
,5
]}

Menten, Karl ^{[6
]}

Sahai, Raghvendra ^{[7
]}

Plane, John ^{[3
]}

Lee, Kelvin ^{[8
]}

Waters, Rens ^{[5
]}

Baudry, Alain ^{[9
]}

Tat Wong, Ka ^{[10
]}

Millar, Tom J. ^{[11
]}

Van de Sande, Marie ^{[1
]}

Lagadec, Eric ^{[12
]}

Gobrecht, David ^{[1
]}

Yates, Jeremy ^{[13
]}

Price, Daniel ^{[14
]}

Cannon, Emily ^{[1
]}

Bolte, Jan ^{[1
]}

De Ceuster, Frederik ^{[1
,13
]}

Herpin, Fabrice ^{[9
]}

Nuth, Joe ^{[15
]}

Philip Sindel, Jan ^{[1
]}

Kee, Dylan ^{[1
]}

Grey, Malcolm D. ^{[2
,19
]}

Etoka, Sandra ^{[2
]}

Jeste, Manali ^{[6
]}

Gottlieb, Carl A. ^{[16
]}

Gottlieb, Elaine ^{[20
,21
]}

McDonald, Iain ^{[2
]}

El Mellah, Ileyk ^{[17
]}

Mueller, Holger S. P. ^{[18
]}

机构：

[1] Katholieke Univ Leuven, Inst Astron, Celestijnenlaan 200D B2401, B-3001 Leuven, Belgium

[2] Univ Manchester, Dept Phys & Astron, JBCA, Manchester M13 9PL, Lancs, England

[3] Univ Leeds, Sch Chem, Leeds LS2 9JT, W Yorkshire, England

[4] Univ Paris Diderot, UPMC, CNRS, LESIA,UMR 8109,Observ Paris,PSL, Paris, France

[5] Univ Amsterdam, Astron Inst Anton Pannekoek, Sci Pk 904,POB 94249, NL-1090 GE Amsterdam, Netherlands

[6] Max Planck Inst Radioastron, Hugel 69, D-53121 Bonn, Germany

[7] CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA

[8] Harvard Smithsonian Ctr Astrophys, Radio & Geoastron Div, 60 Garden St, Cambridge, MA 02138 USA

[9] Univ Bordeaux, CNRS, Lab Astrophys Bordeaux, B18N,Allee Geoffroy St Hilaire, F-33615 Pessac, France

[10] Inst Radioastron Millimetr, 300 Rue Piscine, F-38406 St Martin Dheres, France

[11] Queens Univ Belfast, Sch Math & Phys, Astrophys Res Ctr, Univ Rd, Belfast BT7 1NN, Antrim, North Ireland

[12] Univ Cote Azur, Lab Lagrange, Observ Cote Azur, CNRS, Blvd Observ,CS 34229, F-06304 Nice 4, France

[13] UCL, Dept Phys & Astron, Gower St, London WC1E 6BT, England

[14] Monash Univ, Sch Phys & Astron, Clayton, Vic 3800, Australia

[15] NASA, Solar Syst Explorat Div, Goddard Space Flight Ctr, Code 690, Greenbelt, MD 20771 USA

[16] Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA

[17] Ctr Math Plasma Astrophys, Celestijnenlaan 200B, B-3001 Leuven, Belgium

[18] Univ Cologne, Phys Inst 1, Zulpicher Str 77, D-50937 Cologne, Germany

[19] Natl Astron Res Inst Thailand, 260 Moo 4, Chiangmai 50180, Thailand

[20] Harvard Univ, Sch Engn & Appl Sci, Cambridge, MA 02138 USA

[21] Harvard Univ, Dept Earth & Planetary Sci, 20 Oxford St, Cambridge, MA 02138 USA

来源：

ASTRONOMY & ASTROPHYSICS | 2020年 / 644卷

基金：

英国科学技术设施理事会; 欧盟地平线“2020”;

关键词：

line: profiles; stars: AGB and post-AGB; submillimeter: stars; circumstellar matter; BIPOLAR PREPLANETARY NEBULAE; MASS-LOSS; S-STARS; CIRCUMSTELLAR ENVELOPES; PLANETARY-NEBULA; ELECTRIC-DIPOLE; BINARY-SYSTEMS; DUSTY WINDS; RED GIANTS; SIO;

D O I：

10.1051/0004-6361/202039185

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

The nebular circumstellar environments of cool evolved stars are known to harbour a rich morphological complexity of gaseous structures on different length scales. A large part of these density structures are thought to be brought about by the interaction of the stellar wind with a close companion. The S-type asymptotic giant branch (AGB) star pi (1)Gruis, which has a known companion at similar to 440 au and is thought to harbour a second, closer-by (< 10 au) companion, was observed with the Atacama Large Millimeter/submillimeter Array as part of the ATOMIUM Large programme. In this work, the brightest CO, SiO, and HCN molecular line transitions are analysed. The continuum map shows two maxima, separated by 0.04<double prime> (6 au). The CO data unambiguously reveal that pi (1)Gru's circumstellar environment harbours an inclined, radially outflowing, equatorial density enhancement. It contains a spiral structure at an angle of similar to 38 +/- 3 degrees with the line-of-sight. The HCN emission in the inner wind reveals a clockwise spiral, with a dynamical crossing time of the spiral arms consistent with a companion at a distance of 0.04 '' from the AGB star, which is in agreement with the position of the secondary continuum peak. The inner wind dynamics imply a large acceleration region, consistent with a beta-law power of similar to 6. The CO emission suggests that the spiral is approximately Archimedean within 5 '', beyond which this trend breaks down as the succession of the spiral arms becomes less periodic. The SiO emission at scales smaller than 0.5 '' exhibits signatures of gas in rotation, which is found to fit the expected behaviour of gas in the wind-companion interaction zone. An investigation of SiO maser emission reveals what could be a stream of gas accelerating from the surface of the AGB star to the companion. Using these dynamics, we have tentatively derived an upper limit on the companion mass to be similar to 1.1 M-circle dot.

引用

页数：18

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