Do all barium stars have a white dwarf companion
Do all barium stars have a white dwarf companion
复制标题
DOI：
10.1086/161109
复制
发表时间：
1983-07
期刊：
影响因子：
--
通讯作者：
J. F. Dominy;D. Lambert
中科院分区：
文献类型：
--
作者：
J. F. Dominy;D. Lambert
国际紫外线探测器的短波长，低色散光谱分析了四个钡，两个温和的钡，和一个R-型碳星星，以测试的假设，钡和相关的巨星是由质量转移从伴星现在作为一个白色矮星。早先对温和的钡星星天鹅座Zeta星的一颗白色矮星伴星的初步鉴定得到了证实。对于其他恒星，没有发现可归因于白色矮星的紫外线过量。对可能的白色矮星伴星的热星等和年龄设定了限制。由于钡星在主序星和次巨星之间没有明显的祖先星，因此必须假设质量增加的星星已经在巨星分支上时发生了质量转移。这个限制，以及白色矮星的最小年龄，大于8 × 10的8次方年，对几颗恒星的测定，有效地消除了来自渐近巨星分支星星的质量转移产生钡星星的假设。提出了在双星系统中产生钡星星的其他方法的推测。
International Ultraviolet Explorer short-wavelength, low-dispersion spectra were analyzed for four barium, two mild barium, and one R-type carbon star in order to test the hypothesis that the barium and related giants are produced by mass transfer from a companion now present as a white dwarf. An earlier tentative identification of a white dwarf companion to the mild barium star Zeta Cyg is confirmed. For the other stars, no ultraviolet excess attributable to a white dwarf is seen. Limits are set on the bolometric magnitude and age of a possible white dwarf companion. Since the barium stars do not have obvious progenitors among main-sequence and subgiant stars, mass transfer must be presumed to occur when the mass-gaining star is already on the giant branch. This restriction, and the white dwarf's minimum age, which is greater than 8 x 10 to the 8th yr, determined for several stars, effectively eliminates the hypothesis that mass transfer from an asymptotic giant branch star creates a barium star. Speculations are presented on alternative methods of producing a barium star in a binary system.