Van Maanen's Star -- White Dwarf in Pisces
A White Dwarf is a remnant of a stellar core. It is formed when stars of about our sun’s mass
run out of fusion material. Once the star no longer has an energy source, it cannot support itself
against gravity and collapses. As the core collapses the outer-shell of the star is expelled into
space. The core continues to collapse until the repellent force of the electrons (electron
degeneracy pressure) stops the stellar core from collapsing further. What results is a very dense
stellar core – a teaspoon of it would weigh several tons if transferred to Earth. Van Maanen’s
Star is one of the easiest White Dwarfs to find in the night sky from the light polluted suburbs
where I live.
Bob Prokop’s webpage, (theobserverschair). goes into more detail on Van Maanen’s Star.
He states, “Like all white dwarfs, Van Maanen's Star packs a lot of mass into a very tiny place.
With a diameter only slightly larger than the Earth's, it nevertheless has nearly two thirds of
the sun's mass crammed into that tiny volume. It is believed that Van Maanen's Star began
its life a little over 4 billion years ago as a main sequence star with approximately 2.6 solar
masses. After a relatively brief time (less than a billion years), it swelled up into a red
supergiant with a circumference roughly equivalent to Jupiter's orbit in our own Solar System,
before collapsing upon itself into a white dwarf about 3 billion years ago. Most intriguing is the
star's abnormally high metallicity for a white dwarf. Astronomers speculate that perhaps a
rocky, Earthlike companion to the star crashed onto its surface in the (astronomically) recent
past, thus "polluting" its spectrum with the anomalous heavy elements.”