Star Movies page 15
Edward Pickering discovered the first spectroscopic binary in 1899 when he observed the periodic splitting of the spectral lines of the star Miser in a 104 day period. Detailed observations of many binary star systems were collected by astronomers such as William Struve and S. W. Burnham, allowing the masses of stars to be determined from computation of the orbital elements. The first solution to the problem of deriving an orbit of binary stars from telescope observations was made by Felix Savary in 1827.
The twentieth century saw increasingly
rapid advances in the scientific study of stars. The photograph became a valuable astronomical tool. Karl Schwarzschild discovered that the color of a star,
and hence its temperature, could be determined by comparing the visual magnitudeagainst the photographic magnitude. The
development of the photoelectric photometer allowed very precise measurements of
magnitude at multiple wavelength intervals. In 1921 Albert A. Michelson made the first measurements of a
stellar diameter using an interferometer on the Hooker telescope.
Important conceptual work on the
physical basis of stars occurred during the first decades of the twentieth
century. In 1913, the Hertz
sprung-Russell diagram was
developed, propelling the astrophysical study of stars. Successful models were
developed to explain the interiors of stars and stellar evolution.
The spectra
of stars were also successfully explained through advances in quantum physics. This allowed the
chemical composition of the stellar atmosphere to be determined.
With the exception of supernovae, individual stars have
primarily been observed in our Local
Group of galaxies, and especially in the visible part of
the Milky Way(as demonstrated by
the detailed star catalogues available for our galaxy). But some stars have been observed in
the M100 galaxy of the Virgo
Cluster, about 100 million light years from the Earth.
In the Local Super cluster it is possible to see star clusters,
and current telescopes could in principle observe faint individual stars in the Local Cluster—the most distant stars
resolved have up to hundred million light years away (see Cepheid’s).
However, outside the Local Super
cluster of galaxies, neither
individual stars nor clusters of stars have been observed.
The only exception
is a faint image of a large star cluster containing hundreds of thousands of
stars located one billion light years away. Times the distance of the most
distant star cluster previously observed.
