标题： 正常晚B型和汞锰星中的氖丰度 显示英文标题

标题： Neon abundances in normal late-B and mercury-manganese stars

摘要： 我们进行了新的非局部热平衡（Non-LTE）计算，以从7颗正常星和20颗HgMn星的选定Ne I谱线可见区光谱推断氖的丰度。 我们发现，在Teff范围下端可以使用的最佳无强谱线混合的Ne谱线是6402 Å，尽管在这些恒星光谱的红区发现了若干其他潜在有用的Ne I谱线。 正常星的平均氖丰度（log A=8.10）与标准氖丰度（8.08）非常一致。 然而，在HgMn星中，氖几乎普遍缺量，从轻微不足0.1-0.3 dex到超过一个数量级的缺量不等。 在许多情况下，谱线如此之弱，只能确定上限。 最极端的例子是upsilon Her，其缺量至少为1.5 dex。 根据辐射加速计算的结果，这种缺量是定性可预期的，表明氖在光球中的辐射加速非常小，如果混合过程足够弱且没有强烈的恒星风，则预计会发生重力沉降。 根据Landstreet等人（1998）的理论预测，低氖丰度对这种恒星风强度施加了重要限制，如果它们是非湍流的，则必须小于\$10^-14 M_sun每yr。 显示英文摘要

摘要： We make new Non-LTE calculations to deduce abundances of neon from visible-region echelle spectra of selected Ne I lines in 7 normal stars and 20 HgMn stars. We find that the best strong blend-free Ne line which can be used at the lower end of the Teff range is 6402 A, although several other potentially useful Ne I lines are found in the red region of the spectra of these stars. The mean neon abundance in the normal stars (log A =8.10) is in excellent agreement with the standard abundance of neon (8.08). However, in HgMn stars, neon is almost universally underabundant, ranging from marginal deficits of 0.1-0.3 dex to underabundances of an order of magnitude or more. In many cases, the lines are so weak that only upper limits can be established. The most extreme example found is upsilon Her with an underabundance of at least 1.5 dex. These underabundances are qualitatively expected from radiative acceleration calculations, which show that Ne has a very small radiative acceleration in the photosphere and is expected to undergo gravitational settling if mixing processes are sufficiently weak, and there is no strong stellar wind. According to the theoretical predictions of Landstreet et al. (1998), the low Ne abundances place an important constraint on the intensity of such stellar winds, which must be less than $10^-14 M_sun per yr if they are non-turbulent.