首页     开始     To Survive in the Universe    
Inhabited Sky
    News@Sky     天文图片     收集     论坛     Blog New!     常见问题     新闻     登录  

HD 4646


目录

图像

上传图像

DSS Images   Other Images


相关文章

On the problem of cohabitation between AM and delta-Scuti or 'normal' A stars - A unified theory
A previous interpretation (Baglin, 1972) of the occurrence of deltaScuti variables and Am stars in the same region of the H-R diagram foundan order of magnitude of the maximum rotational velocity that allows thestars to appear as Am. These stars are observed as nonpulsating stars asa consequence of the downward diffusion of helium. For higher rotationalvelocity, the turbulence in the external layers, due to the shearinstability of the meridional circulation, ensures a homogeneouschemical composition. It does not allow the diffusion processes to actefficiently and preserves the ability of the He ionization zone toenergize the pulsations, with the star appearing as a delta Scutivariable. This paper takes an alternate approach, assuming the rotationinduced by the meridional circulation to be time dependent and derivingReynolds and Richardson numbers for this differential rotation. It isshown, among other things, that the differential rotation maintains itsstability even if its Reynolds number is supercritical, as long as thedensity stratification is able to stabilize any perturbation accordingto the Richardson criterion.

提交文章


相关链接

  • - 没有找到链接 -
提交链接


下列团体成员


观测天体数据

星座:仙后座
右阿森松:00h50m03.34s
赤纬:+73°35'18.3"
视星:8.852
距离:189.753 天文距离
右阿森松适当运动:15.3
赤纬适当运动:-6.1
B-T magnitude:9.031
V-T magnitude:8.867

目录:
适当名称   (Edit)
HD 1989HD 4646
TYCHO-2 2000TYC 4308-6-1
USNO-A2.0USNO-A2 1575-00502015
HIPHIP 3902

→ 要求更多目录从vizier