A-A+
Which of the following did Leavitt's work prov
问题详情
Which of the following did Leavitt"s work provide astronomers with the means of determining？
A．The absolute brightness of any observable Cepheid variable.
B．The apparent brightness of any object at a given distance from an observer.
C．The distance from earth of any galaxy containing an observable Cepheid variable.
D．Both A and C此题为多项选择题。请帮忙给出正确答案和分析，谢谢！
参考答案
正确答案：D
解析：本题的四个选项中，只有D项为正确答案。这可从文中倒数第二段的“…the absolute brightness of a Cepheid variable could be determined by measuring its periodicity…．If we know the absolute brightness of the star and how bright it appears from the earth，we can tell how far it must be”推知，即造父变星的绝对亮度可以通过测量其周期性来确定；如果知道星体的绝对亮度以及从地球上观察到的表面亮度，我们就能够知道它与地球的实际距离。
