NOAO Astronomer Helmut Abt turns 90
Image credit: NOAO/AURA/NSF
The recipient in 1952 of the first doctoral degree in astrophysics awarded by Caltech for his work on the nature of W Virginis stars, Abt has studied stellar binarity, stellar rotation, and many other topics involving stellar spectroscopy. He has also made numerous contributions to NOAO and to the astronomical community.
The author of more than 200 refereed publications, Abt’s most important scientific contributions are an extensive series of papers that established the basic properties of B-G main sequence stars and guided subsequent developments in theories of binary star formation and the dynamics of stellar atmospheres. Specifically, Abt and co-workers found that the frequency of binaries is similar for stars with spectral types B through G—a result that suggests that binaries form in a similar way throughout this mass range. This work also showed that the majority of main sequence stars have one or more companions. Based on rotational velocities and spectral types for 1700 A-type stars, Abt concluded that all rapid rotators are normal and that most slow rotators show spectral anomalies: they are either peculiar A stars or metallic-line A stars. This work led to the conclusion that the apparent abundance anomalies are due to diffusion in stable atmospheres where rotational mixing is absent.
In the 1950’s Abt helped to select the site for a national astronomical observatory by conducting an aerial site survey and by exploring potential sites by Jeep, pack horse, and on foot. The committee eventually selected Kitt Peak as the best site. From 1971-1999, Abt served as Managing Editor for the Astrophysical Journal. From 1980 onward, his interest in the quantitative analysis of publication practices in astronomy led to a series of papers on topics such as the relative value of smaller aperture telescopes, the productivity of astronomers as a function of age, and the half-life of astronomical publications.