Volume 491, Number 1, November III 2008Diagnostics of interstellar hydrogen in the heliosphere
|Page(s)||229 - 238|
|Section||Interstellar and circumstellar matter|
|Published online||01 October 2008|
The Antares emission nebula and mass loss of Scorpii A*
Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany e-mail: email@example.com
Accepted: 25 August 2008
Aims. The Antares nebula is a peculiar emission nebula seen in numerous  lines and in radio free-free emission, probably associated with the H ii region caused by α Sco B in the wind of α Sco A. High-resolution spectra with spatial resolution were used to study the emission line spectrum, the physical nature of the nebula and to determine the mass-loss rate of the M supergiant α Sco A.
Methods. The Antares nebula was mapped with long-slit (10″) and high-resolution (R = 80 000) spectra using UVES at the VLT. The resulting 2-D images were used to reconstruct a 3-D picture of the H ii region and its absolute location in space relative to α Sco A.
Results. We found that the Antares nebula shows, in addition to numerous [Fe ii] lines, the Balmer line recombination spectrum Hα, H up to H10, and [N ii] 6583/6548 Å, Hα and [N ii] with the same extent as seen in cm radio free-free emission. Combining velocity information from optical and GHRS/HST spectra with Hα velocities, the H ii region is found to be located ~215 AU behind the plane of the sky of α Sco A. From the Hα/[N ii] intensity ratio and the non-visibility of the [O ii] 3726/3729 Å lines we estimate a low mean electron temperature of = 4900 K and an N abundance enhanced by a factor of ~3 due to the CNO cycle in α Sco A. The shape and size of the H ii region yield a mean mass-loss rate of (1.05 ± 0.3) 10-6 yr-1. The [Fe ii] lines originate predominantly at the edges (rear and front) of the H ii region. UV continuum pumping as well as collisional excitation seem to be responsible for the observed iron lines.
Key words: binaries: visual / circumstellar matter / stars: mass-loss / stars: late-type
© ESO, 2008
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.