Open AccessAtomic hydrogen in asymptotic giant branch circumstellar environments. A case study: X Her
Author(s) -
Gardan E.,
Gérard E.,
Le Bertre T.
Publication year - 2006
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2005.09709.x
Subject(s) - physics , asymptotic giant branch , astrophysics , full width at half maximum , telescope , line (geometry) , star (game theory) , astronomy , position (finance) , optics , stars , geometry , mathematics , finance , economics
We report the detection of the H i line at 21 cm from the circumstellar shell around the asymptotic giant branch star X Her using the position‐switching technique with the Nançay Radio Telescope. At the star position, the line shows two components: (i) a broad one [full width at half‐maximum (FWHM) ∼ 13 km s −1 ] centred at −72.2 km s −1 and (ii) a narrow one (FWHM ∼ 4 km s −1 ) centred at ∼−70.6 km s −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 arcmin (∼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 material flowing away from the observer. The total mass of atomic hydrogen is ∼6.5 × 10 −3 M ⊙ which, within a factor of 2, agrees with the estimate obtained from IRAS data at 60 μm.