Atomic hydrogen in AGB circumstellar environments. A case study : X HerReport as inadecuate

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1 LERMA - Laboratoire d-Etude du Rayonnement et de la Matière en Astrophysique 2 L3AB - Laboratoire d-astrodynamique, d-astrophysique et d-aéronomie de bordeaux 3 OASU - Observatoire aquitain des sciences de l-univers 4 LAB - Laboratoire d-Astrophysique de Bordeaux Pessac 5 GEPI - Galaxies, Etoiles, Physique, Instrumentation

Abstract : We report the detection of the Hi line at 21 cm from the circumstellar shell around the AGB star X Her using the position-switching technique with the Nan¸cay RadioTelescope. At the star position the line shows 2 components: i a broad one FWHM 13 kms?1 centered at ?72.2 kms?1, and ii a narrow one FWHM 4 kms?1 centered at ?70.6 kms?1. Our map shows that the source associated to the broad component is asymmetric with material flowing preferentially towards the North-East. This source extends to 10? 0.4 pc from the star in that direction. On the other hand, the narrow component is detected only at the star position and indicates mate-rial flowing away from the observer. The total mass of atomic hydrogen is 6.5 10?3 M? which, within a factor 2, agrees with the estimate obtained from IRAS data at 60 ?m

Keywords : radio lines: stars. stars: late- type stars: mass-loss radio lines: stars ISM: planetary nebulae: general stars: AGB and post-AGB stars: circumstellar matter

Author: E. Gardan - E. Gerard - T. Le Bertre -



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