236
11 The Kapteyn Universe
he should choose Kohlschütter’s side. On the other hand, Adams was also a
hothead, who has had similar problems with others. For example, he openly
resisted the fact that so many European astronomers were given jobs in the
United States which, according to him, actually belonged to Americans.
Almost immediately after the previous clash there was another run-in with
Adams. After Kohlschütter had left California at the outbreak of the war,
he continued his program of radial velocities with the originally Swedish
astronomer Gustaf Strömberg (1882–1962). He was appointed at Mount Wilson in 1917 and continued the work with Adams on the relationship between
radial velocity and absolute magnitude or luminosity. Strömberg wrote two
manuscripts on this subject, one with himself as sole author and the other
with Adams. Kapteyn did not object to the result itself, but he did object
to the way in which average distances were estimated in these manuscripts.
Kapteyn had derived a formula for this, which indicated how the average parallax of stars depended on the mean and apparent brightness (magnitude) and
proper motion. Strömberg and Adams had adjusted his formula and Kapteyn
was outraged that they dared to question his equation. George Hale responded
to the matter by asking Kapteyn to write an extensive argumentation of the
case, which he did; Frederick Seares reviewed the case as an independent referee. Seares solved the case again with great tact. The article of Strömberg
by himself was published as part of the publications of Mount Wilson, but
not—as was usual—first in a professional magazine which would sent it to
anonymous experts for review. Strömberg admitted in his article that he had
followed an incorrect procedure in the earlier manuscript with Adams. Seares
ultimately blamed everything partly on Strömberg’s poor English, but above
all blamed himself for his own inattentiveness. Kapteyn and Adams would
never work together again. Kapteyn is certainly to blame for his inflexible attitude; it is incorrect to put the blame for everything on Adams. But Adams was
easily offended. After Kapteyn’s death, his successor Pieter van Rhijn also got
into trouble with Adams, who felt (unnecessarily, in my opinion) offended by
certain passages in van Rhijn’s publications.
Incidentally, Strömberg’s work led to the discovery of an important concept
called ‘asymmetric drift’. The stars in the disk of the Galaxy move systematically
around the center, the rotation of the Galaxy. If stars were to move in circular
orbits, they would have to do so at a speed that produces a centrifugal force
that would exactly compensate for the gravitational attraction of the matter in
the Galaxy as a whole. But the stars also move relative to each other and do
not move in circular orbits. The result is that for such an equilibrium between
the forces, a lower collective velocity around the center will suffice than in the
case of pure circular orbits. You can also look at it in terms of energy. There
is a potential energy due to gravitation, and that needs to be compensated by
11 The Kapteyn Universe
he should choose Kohlschütter’s side. On the other hand, Adams was also a
hothead, who has had similar problems with others. For example, he openly
resisted the fact that so many European astronomers were given jobs in the
United States which, according to him, actually belonged to Americans.
Almost immediately after the previous clash there was another run-in with
Adams. After Kohlschütter had left California at the outbreak of the war,
he continued his program of radial velocities with the originally Swedish
astronomer Gustaf Strömberg (1882–1962). He was appointed at Mount Wilson in 1917 and continued the work with Adams on the relationship between
radial velocity and absolute magnitude or luminosity. Strömberg wrote two
manuscripts on this subject, one with himself as sole author and the other
with Adams. Kapteyn did not object to the result itself, but he did object
to the way in which average distances were estimated in these manuscripts.
Kapteyn had derived a formula for this, which indicated how the average parallax of stars depended on the mean and apparent brightness (magnitude) and
proper motion. Strömberg and Adams had adjusted his formula and Kapteyn
was outraged that they dared to question his equation. George Hale responded
to the matter by asking Kapteyn to write an extensive argumentation of the
case, which he did; Frederick Seares reviewed the case as an independent referee. Seares solved the case again with great tact. The article of Strömberg
by himself was published as part of the publications of Mount Wilson, but
not—as was usual—first in a professional magazine which would sent it to
anonymous experts for review. Strömberg admitted in his article that he had
followed an incorrect procedure in the earlier manuscript with Adams. Seares
ultimately blamed everything partly on Strömberg’s poor English, but above
all blamed himself for his own inattentiveness. Kapteyn and Adams would
never work together again. Kapteyn is certainly to blame for his inflexible attitude; it is incorrect to put the blame for everything on Adams. But Adams was
easily offended. After Kapteyn’s death, his successor Pieter van Rhijn also got
into trouble with Adams, who felt (unnecessarily, in my opinion) offended by
certain passages in van Rhijn’s publications.
Incidentally, Strömberg’s work led to the discovery of an important concept
called ‘asymmetric drift’. The stars in the disk of the Galaxy move systematically
around the center, the rotation of the Galaxy. If stars were to move in circular
orbits, they would have to do so at a speed that produces a centrifugal force
that would exactly compensate for the gravitational attraction of the matter in
the Galaxy as a whole. But the stars also move relative to each other and do
not move in circular orbits. The result is that for such an equilibrium between
the forces, a lower collective velocity around the center will suffice than in the
case of pure circular orbits. You can also look at it in terms of energy. There
is a potential energy due to gravitation, and that needs to be compensated by