Astronomy Picture of the Day——盖亚构建的M15
Discover the cosmos! Each day a differentimage or photograph of our fascinating universe is featured, along with a briefexplanation written by a professional astronomer.
The Gaia Stars of M15
Image Credit: Robert Vanderbei (PrincetonUniversity), ESA, Gaia, DPAC
Explanation: Messier 15 is a 13 billionyear old relic of the early formative years of our galaxy, one of about 170globular star clusters that still roam the halo of the Milky Way. About 200light-years in diameter, it lies about 35,000 light years away toward theconstellation Pegasus. But this realistic looking view of the ancient globularstar cluster is not a photograph. Instead it's an animated gif imageconstructed from remarkably precise individual measurements of star positions,brightness, and color. The astronomically rich data set used was made by the sky-scanningGaia satellite which also determined parallax distances for 1.3 billion MilkyWay stars. In the animated gif, twinkling stars are M15's identified RR Lyraestars. Plentiful in M15, RR Lyrae stars are evolved pulsating variable starswhose brightness and pulsation period, typically less than a day, are related.
盖亚构建的M15
说明：M15是银河系形成初期形成的，具有130亿年历史的古老遗迹，它是仍然在银河系光晕中漫游的约170个球状星团之一。它的直径约为200光年，位于飞马座方向，距离太阳系约35,000光年。然而，你仔细观察，这幅极具真实感的照片并不是一张静态图像，相反，它是一张gif动态图片，由对恒星位置、亮度和颜色进行非常精确的单独测量值所构成。这个富含天文意义的数据集是由进行巡天任务的盖亚探测器拍摄并制作而成，盖亚还测定了13亿颗银河系恒星的视差距离。在这幅gif图像中，闪烁的恒星是M15内已识别出的天琴座RR型星。在M15内这类恒星数量非常多，是一种演化过的脉动变星，它的亮度与其通常不到一天的脉动周期有关系。
近期文章：
Astronomy Picture of the Day——NGC 1333：英仙座内的恒星孕育场