Lowell's astronomers carry out research in areas spanning much of modern astrophysics, from studies of tiny icy objects in our own solar system to the structure of distant galaxies. Meet our scientists and learn more about our diverse programs here.
Solar and Stellar Activity Cycles
Wes Lockwood, Jeffrey Hall, and Brian Skiff
Twenty years ago, stimulated by the new knowledge that the Sun’s brightness variations over the 11-year solar cycle were less than 0.1 percent, Lockwood and colleagues began a systematic photometric study of the small brightness fluctuations of sunlike stars of various ages. Using the 21-inch telescope and a dedicated photometer, Brian Skiff observed several dozen sunlike stars for 16 consecutive seasons. Here’s what they found: (1) a majority of sunlike stars have detectable year-to-year variations from as small as 0.3 percent to several percent; (2) the amount of variability decreases with increasing stellar age; and, (3) in comparison with the stars in our survey, the Sun appears to be relatively quiescent. This may turn out to be a very important result in the arena of Sun-climate studies. Many of these same stars have also been observed spectroscopically using Lowell’s Solar-Stellar Spectrograph, an instrument fed by optical fiber from a solar feed and from the 1.1-m J. S. Hall telescope at Anderson Mesa. This program is operated in collaboration with Jeffrey Hall. It is intended to characterize the magnetic activity of these stars AND the Sun on the timescale of the 11-year solar cycle.
Select a program from the list below to read more about it.