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    An ultra-high-resolution study of the interstellar medium in the direction of α Ophiuchi

    Crawford, Ian (2001) An ultra-high-resolution study of the interstellar medium in the direction of α Ophiuchi. Monthly Notices of the Royal Astronomical Society 327 (3), pp. 841-848. ISSN 0035-8711.

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    I present very high resolution graphic and graphic observations of interstellar Ca II absorption lines towards eight early-type stars situated within 15° of α Oph on the sky. I confirm an earlier result that the interstellar structure responsible for the anomalously strong Ca II absorption towards α Oph has a spatial extent of ≲1 pc (and is probably very much smaller). Many discrete interstellar absorption components are apparent in these high-resolution data, but while several have velocities in the range expected for the local interstellar medium (LISM), no convincing detections of either the local interstellar cloud (LIC), or the so-called G cloud, were made. In the former case, I argue that the relatively weak LIC components are masked by components arising in more distant clouds, but which have LISM-like velocities owing to the pervasive influence of outflow from the Sco-Cen association. The non-detection of the G cloud is more problematical, and I tentatively argue that, previous claims notwithstanding, this feature does not extend to galactic latitudes as high as +15° in this direction.


    Item Type: Article
    School: Birkbeck Faculties and Schools > Faculty of Science > School of Natural Sciences
    Depositing User: Sarah Hall
    Date Deposited: 12 Aug 2019 13:17
    Last Modified: 02 Aug 2023 17:53


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