Researchers map the movement of white dwarfs of the Milky Way

Date:
March 23, 2022
Source:
Lund University
Summary:
White dwarfs were once normal stars similar to the Sun but then
collapsed after exhausting all their fuel. These interstellar
remnants have historically been difficult to study. However, a
recent study reveals new information about the movement patterns
of these puzzling stars.



FULL STORY ========================================================================== White dwarfs were once normal stars similar to the Sun but then
collapsed after exhausting all their fuel. These interstellar remnants
have historically been difficult to study. However, a recent study from
Lund University in Sweden reveals new information about the movement
patterns of these puzzling stars.


========================================================================== White dwarfs have a radius of about 1 percent of the Sun's. They have
about the same mass, which means they have an astonishing density
of about 1 tonne per cubic centimeter. After billions of years, white
dwarfs will cool down to a point where they stop emitting visible light,
and turn into so-called black dwarfs.

The first white dwarf that was discovered was 40 Eridani A. It is a bright celestial body 16.2 light-years from Earth, surrounded by a binary system consisting of the white dwarf 40 Eridani B and the red dwarf 40 Eridani
C. Ever since it was discovered in 1783, astronomers have tried to learn
more about white dwarfs in order to gain a deeper understanding of the evolutionary history of our home galaxy.

In a study published in Monthly Notices of the Royal Astronomical Society,
a research team can present new findings about how the collapsed stars
move.

"Thanks to observations from the Gaia space telescope, we have for the
first time managed to reveal the three-dimensional velocity distribution
for the largest catalogue of white dwarfs to date. This gives us a detailedpicture of their velocity structurewith unparalleled detail,"
says Daniel Mikkola, doctoral student in astronomy at Lund University.

Thanks to Gaia, researchers have measured positions and velocities
for about 1.5 billion stars. But only recently have they been able to completely focus on the white dwarfs in the Solar neighbourhood.

"We have managed to map the white dwarfs' velocities and movement
patterns.

Gaia revealed that there are two parallel sequences of white dwarfs when looking at their temperature and brightness. If we study these separately,
we can see that they move in different ways, probably as a consequence
of them having different masses and lifetimes," says Daniel Mikkola.

The results can be used to develop new simulations and models to
continue to map the history and development of the Milky Way. Through
an increased knowledge of the white dwarfs, the researchers hope to be
able to straighten out a number of question marks surrounding the birth
of the Milky Way.

"This study is important because we learned more about the closest regions
in our galaxy. The results are also interesting because our own star,
the Sun, will one day turn into a white dwarf just like 97 percent of
all stars in the Milky Way," concludes Daniel Mikkola.


========================================================================== Story Source: Materials provided by Lund_University. Note: Content may
be edited for style and length.


========================================================================== Journal Reference:
1. Daniel Mikkola, Paul J. McMillan, David Hobbs, John Wimarsson. The
velocity distribution of white dwarfs in Gaia EDR3. Monthly Notices
of the Royal Astronomical Society, 2022 [abstract] ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/03/220323101234.htm

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