科研之友
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摘要
Since the discovery of lambda Bootis stars, a permanent confusion about their classification can be found in literature. This group of non-magnetic, Population I, metal-poor A to F-type stars, has often been used as some sort of trash can for %26quot;exotic%26quot; and spectroscopically dubious objects. Some attempts have been made to establish a homogeneous group of stars which share the same common properties. Unfortunately, the flood of %26quot;new%26quot; information (e.g. UV and IR data) led again to a whole zoo of objects classified as lambda Bootis stars, which, however, are apparent non-members. %26lt;br%26gt;To overcome this unsatisfying situation, a spectral atlas of well established lambda Bootis stars for the classical optical domain was compiled. It includes intermediate dispersion (40 and 120 angstrom mm(-1)) spectra of three lambda Bootis, as well as appropriate MK standard stars. Furthermore, %26quot;suspicious%26quot; objects, such as shell and Field Horizontal Branch stars, have been considered in order to provide to classifiers a homogeneous reference. %26lt;br%26gt;As a further step, a high resolution (8 angstrom mm(-1)) spectrum of one %26quot;classical%26quot; lambda Bootis star in the same wavelength region (3800 - 4600 angstrom) is presented. In total, 55 lines can be used for this particular star to derive detailed abundances for nine heavy elements (Mg, Ca, Sc, Ti, Cr, Mn, Fe, Sr and Ba).
- 出版日期2014
