TY - JOUR
T1 - ATOMIUM: The astounding complexity of the near circumstellar environment of the M-type AGB star R Hydrae
T2 - I. Morpho-kinematical interpretation of CO and SiO emission
AU - Homan, Ward
AU - Pimpanuwat, Bannawit
AU - Herpin, Fabrice
AU - Danilovich, Taissa
AU - McDonald, Iain
AU - Wallström, Sofia H.J.
AU - Richards, Anita M.S.
AU - Baudry, Alain
AU - Sahai, Raghvendra
AU - Millar, Tom J.
AU - De Koter, Alex
AU - Gottlieb, C. A.
AU - Kervella, Pierre
AU - Montargès, Miguel
AU - Van De Sande, Marie
AU - Decin, Leen
AU - Zijlstra, Albert
AU - Etoka, Sandra
AU - Jeste, Manali
AU - Müller, Holger S.P.
AU - Maes, Silke
AU - Malfait, Jolien
AU - Menten, Karl
AU - Plane, John
AU - Lee, Kelvin
AU - Waters, Rens
AU - Wong, Ka Tat
AU - Lagadec, Eric
AU - Gobrecht, David
AU - Yates, Jeremy
AU - Price, Daniel
AU - Cannon, Emily
AU - Bolte, Jan
AU - De Ceuster, Frederik
AU - Nuth, Joe
AU - Philip Sindel, Jan
AU - Kee, Dylan
AU - Gray, Malcolm D.
AU - El Mellah, Ileyk
N1 - Funding Information:
Acknowledgements. We would like to thank the Italian ARC Node, and in particular R. Laing for providing the scripts that were used to analyse the continuum. This paper makes use of uses the following ALMA data: ADS/JAO.ALMA#2018.1.00659.L, ‘ATOMIUM: ALMA tracing the origins of molecules forming dust in oxygen-rich M-type stars’. ALMA is a partnership of ESO (representing its member states), NSF (USA), and NINS (Japan), together with NRC (Canada), NSC and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NR.A.O, and NAOJ. W. H. acknowledges support from the Fonds de la Recherche Scientifique (FNRS) through grant 40000307. S. H. J. W., L. D., M. M., D. G. acknowledge support from the ERC consolidator grant 646758 AEROSOL. T. D. acknowledges support from the Research Foundation Flanders (FWO) through grant 12N9920N. T. J. M. is grateful to the STFC for support via grant number ST/P000312/1. J. M. C. P. acknowledges funding from the UK STFC (grant number ST/T000287/1) M. V. dS. acknowledges support from the Research Foundation Flanders (FWO) through grant 12X6419N. S. E. acknowledges funding from the UK Science and Technology Facilities Council (STFC) as part of the consolidated grant ST/P000649/1 to the Jodrell Bank Centre for Astrophysics at the University of Manchester. C. A. G. acknowledges support from NSF grant AST-1615847. We acknowledge financial support from ‘Programme National de Physique Stellaire’ (PNPS) of CNRS/INSU, France. We used the SIMBAD and VIZIER databases at the CDS, Strasbourg (France) (http://cdsweb.u-strasbg.fr/), and NASA’s Astrophysics Data System Bibliographic Services. This research made use of IPython (Pérez & Granger 2007), Numpy (van der Walt et al. 2011), Mat-plotlib (Hunter 2007), SciPy (Virtanen et al. 2020), and Astropy (http://www. astropy.org/), a community-developed core Python package for Astronomy (Astropy Collaboration 2013).
Publisher Copyright:
© ESO 2021.
PY - 2021/7/20
Y1 - 2021/7/20
N2 - Evolved low- to intermediate-mass stars are known to shed their gaseous envelope into a large, dusty, molecule-rich circumstellar nebula which typically develops a high degree of structural complexity. Most of the large-scale, spatially correlated structures in the nebula are thought to originate from the interaction of the stellar wind with a companion. As part of the ATOMIUM large programme, we observed the M-type asymptotic giant branch (AGB) star R Hydrae with the Atacama Large Millimeter/submillimeter Array. The morphology of the inner wind of R Hya, which has a known companion at ∼3500 au, was determined from maps of CO and SiO obtained at high angular resolution. A map of the CO emission reveals a multi-layered structure consisting of a large elliptical feature at an angular scale of ∼10″ that is oriented along the north-south axis. The wind morphology within the elliptical feature is dominated by two hollow bubbles. The bubbles are on opposite sides of the AGB star and lie along an axis with a position angle of ∼115°. Both bubbles are offset from the central star, and their appearance in the SiO channel maps indicates that they might be shock waves travelling through the AGB wind. An estimate of the dynamical age of the bubbles yields an age of the order of 100 yr, which is in agreement with the previously proposed elapsed time since the star last underwent a thermal pulse. When the CO and SiO emission is examined on subarcsecond angular scales, there is evidence for an inclined, differentially rotating equatorial density enhancement, strongly suggesting the presence of a second nearby companion. The position angle of the major axis of this disc is ∼70° in the plane of the sky. We tentatively estimate that a lower limit on the mass of the nearby companion is ∼0.65 Mpdbl on the basis of the highest measured speeds in the disc and the location of its inner rim at ∼6 au from the AGB star.
AB - Evolved low- to intermediate-mass stars are known to shed their gaseous envelope into a large, dusty, molecule-rich circumstellar nebula which typically develops a high degree of structural complexity. Most of the large-scale, spatially correlated structures in the nebula are thought to originate from the interaction of the stellar wind with a companion. As part of the ATOMIUM large programme, we observed the M-type asymptotic giant branch (AGB) star R Hydrae with the Atacama Large Millimeter/submillimeter Array. The morphology of the inner wind of R Hya, which has a known companion at ∼3500 au, was determined from maps of CO and SiO obtained at high angular resolution. A map of the CO emission reveals a multi-layered structure consisting of a large elliptical feature at an angular scale of ∼10″ that is oriented along the north-south axis. The wind morphology within the elliptical feature is dominated by two hollow bubbles. The bubbles are on opposite sides of the AGB star and lie along an axis with a position angle of ∼115°. Both bubbles are offset from the central star, and their appearance in the SiO channel maps indicates that they might be shock waves travelling through the AGB wind. An estimate of the dynamical age of the bubbles yields an age of the order of 100 yr, which is in agreement with the previously proposed elapsed time since the star last underwent a thermal pulse. When the CO and SiO emission is examined on subarcsecond angular scales, there is evidence for an inclined, differentially rotating equatorial density enhancement, strongly suggesting the presence of a second nearby companion. The position angle of the major axis of this disc is ∼70° in the plane of the sky. We tentatively estimate that a lower limit on the mass of the nearby companion is ∼0.65 Mpdbl on the basis of the highest measured speeds in the disc and the location of its inner rim at ∼6 au from the AGB star.
KW - Circumstellar matter
KW - Stars: AGB and post-AGB
KW - Submillimeter: stars
UR - http://www.scopus.com/inward/record.url?scp=85111098260&partnerID=8YFLogxK
U2 - 10.1051/0004-6361/202140512
DO - 10.1051/0004-6361/202140512
M3 - Article
AN - SCOPUS:85111098260
SN - 0004-6361
VL - 651
JO - Astronomy & Astrophysics
JF - Astronomy & Astrophysics
M1 - A82
ER -