Discovery of a detached H I gas shell surrounding α Orionis (original) (raw)
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Abstract
We report the detection of the H I line at 21 cm in the direction of α Orionis (α Ori) with the Nançay Radiotelescope and with the Very Large Array.
The observations confirm the previous detection of H I emission centred on α Ori, but additionally reveal for the first time a quasi-stationary detached shell of neutral atomic hydrogen ∼4 arcmin in diameter (0.24 pc at a distance of 200 pc). The detached shell appears elongated in a direction opposite to the star's space motion.
A simple model shows that this detached atomic gas shell can result from the collision of the stellar wind from α Ori with the local interstellar medium (ISM). It implies that α Ori has been losing matter at a rate of ∼1.2 × 10-6 M⊙ yr-1 for the past 8 × 104 yr.
In addition, we report the detection of atomic hydrogen associated with the far-infrared arc located 6 arcmin north-east of α Ori, which has been suggested to trace the bow shock resulting from the motion of the star through the ISM. We also report the detection by the Galaxy Evolution Explorer of a far-ultraviolet counterpart to this arc.
Publication:
Monthly Notices of the Royal Astronomical Society
Pub Date:
June 2012
DOI:
10.1111/j.1365-2966.2012.20853.x
arXiv:
Bibcode:
Keywords:
- circumstellar matter;
- stars: individual: α Ori;
- stars: mass-loss;
- supergiants;
- radio lines: stars;
- Astrophysics - Solar and Stellar Astrophysics
E-Print:
Accepted for publication in the Monthly Notices