High Speed Scanner: Digital Access to a Sky-Century

现在，设计和建造一种高速扫描仪系统是可行的，它可以在30秒内将记录在玻璃板(8x10英寸)上的天文图像数字化到高光度精度。这使得在平板上数字保存大量档案数据成为可能，这反过来又使得对许多类天文物体的时间变异性研究能够前所未有地追溯到整整一个世纪以前。持续时间最长、覆盖范围最广的天文板块是哈佛大学天文台的60万个天文板块。通过将一个世纪的恒星数据数字化并在高速网络上提供服务而成为可能的宇宙“时光机”意味着可以研究天体物理学中的一些关键问题。三个例子包括：可以研究造父变星脉动周期的长期变化，这是天文距离尺度的宇宙标尺，其中周期变化测量可以揭示这些发光恒星内部的核心对流条件，人们对此知之甚少；在非常年轻的恒星中，可以在十到世纪的时间尺度上观察到恒星的演化，这可能是将周围圆盘中的剩余物质转化为行星的诞生；在双星系统中的白矮星、中子星和黑洞中，从双星伴星中吸积物质，可变性是规律，而不是例外，因此可以通过亮度变化来研究它们，这些变化的结果指向了银河系中这些最极端恒星的形成和演化。不仅已知的现象和问题可以解决，而且很可能会发现新的和意想不到的现象。更广泛的影响。这项研究有助于提高公众对宇宙不是静态的认识。进化和变化是规律，而不是例外。这对科学教育的影响可能很大：通过在项目网站上展示从类星体变化到造父变星脉动变化，再到新形成的恒星和行星系统变化的附近例子，学生们可以更好地理解当前天文学的兴奋。对动态宇宙的物理理解甚至比一成不变的天空更具诱惑力。

It is now feasible to design and build a high speed scanner system that can digitize astronomical images recorded on glass plates (8 x 10 in) to high photometric accuracy in under 30 sec. This makes possible the digital preservation of large volumes of archival data on plates which in turn enables time variability studies of many classes of astronomical objects to extend back a full century in time as never before possible. The longest duration set of astronomical plates, and with the largest amount of coverage, are contained in the 600,000 plates of the Harvard College Observatory. The cosmic "time machine" made possible by digitizing and serving a century of stellar data on high speed networks means that a number of key problems in astrophysics can be investigated. Three examples include: Long-term changes in the pulsation periods of Cepheid variable stars, the cosmic yardsticks of the astronomical distance scale, can be studied where period change measurements can reveal the poorly understood conditions of core convection in the interiors of these luminous stars; Stellar evolution can be observed on decade to century timescales in very young stars, which may be converting their left over material in surrounding disks into the birth of planets; In white dwarfs, neutron stars and black holes in binary systems, accreting matter from the binary companion, variability is the rule rather than the exception so they may be studied by the brightness changes, results of which point to the formation and evolution of these most extreme stars in the Galaxy. Not only can known phenomena and problems be addressed, but there is the very likely discovery of new and unexpected phenomena. Broader Impacts. This research is helping to increase public awareness that the universe is not static. Evolution and change are the rule, not the exception. The impact on science education can be large: by showing on the project website segments of the ``cosmic movie" from quasar variations to Cepheid variable pulsation changes to nearby examples of change in newly-forming stars and planet systems, students can better understand the excitement of current astronomy. Physical understanding of the dynamic universe is even more enticing than the immutable sky.