Circumstellar Gas Around the Peculiar $\lambda$ Bootis Stars

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Session 83 -- Circumstellar Gas and Dust
Display presentation, Wednesday, 11, 1995, 9:20am - 6:30pm

[83.07] Circumstellar Gas Around the Peculiar $\lambda$ Bootis Stars

David A. Bohlender (CFHT)

A survey of northern $\lambda$ Boo stars has been carried out in order to search for evidence of circumstellar gas around this small group of peculiar, metal-deficient early A stars. We have discovered shell lines suggestive of circumstellar material superimposed on the broad photospheric Na I D lines of several program stars. These observations raise the total number of $\lambda$ Boo stars which show evidence for circumstellar gas or dust to approximately one-half of the entire class and provide additional strong support for the suggestion that the abundance peculiarities of the $\lambda$ Boo stars arise because they are currently accreting their atmospheres from circumstellar gas which has been metal depleted by selective condensation into grains. In addition, a sequence of spectra of the Ca II K line for at least one object has resulted in the first discovery of spectrum variability among the $\lambda$ Boo stars.

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