M. Marengo, N. R. Evans, L. D. Matthews, G. Bono, P. Barmby, D. L. Welch, M. Romaniello, K. Y. L. Su, G. G. Fazio, D. Huelsman
We found the first direct evidence that the Cepheid class namesake, delta
Cephei, is currently losing mass. These observations are based on data obtained
with the Spitzer Space Telescope in the infrared, and with the Very Large Array
in the radio. We found that delta Cephei is associated with a vast
circumstellar structure, reminiscent of a bow shock. This structure is created
as the wind from the star interacts with the local interstellar medium. We
measure an outflow velocity of ~35.5 km/s and a mass loss rate of ~1E-7 - 1E-6
Mo/yr. The very low dust content of the outflow suggests that the wind is
possibly pulsation-driven, rather than dust-driven as common for other classes
of evolved stars.
View original:
http://arxiv.org/abs/1112.0619
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