- 3868 - WHITE DWARF - mass is measured? A bright white dwarf star shining in front of a vast sea of distant stars and galaxies becomes the first time that the mass of an isolated white dwarf star has been directly measured.
-------------- 3868 - WHITE DWARF - mass is measured?
- Astronomers
have finally weighed an isolated white dwarf, or the shriveled husk of a dead
star, using a strange phenomenon predicted by Einstein's theory of relativity.
-
- Massive
white dwarfs help explain the strange, ultra-dense matter that makes up these
stellar leftovers. Astronomers used the
legendary Hubble Space Telescope to measure the mass of a standalone white
dwarf “LAWD 37”. Although astronomers
have weighed white dwarfs in binary star systems LAWD 37 is the first white
dwarf to be measured in isolation.
-
- The research
team used a quirky property of the universe to make this pioneering
measurement: the fact that gravity warps space-time. As LAWD 37 passed in front
of a distant bright star, the light from the background star bent around the
nearby white dwarf in a process known as gravitational microlensing, originally
predicted by Albert Einstein.
-
- When LAWD
37 warped the star’s light, the star appeared to shift ever so slightly in the
sky, an effect Hubble can detect with incredible precision. These events are
rare, and the effects are tiny. The size
of the measured offset is like measuring the length of a car on the Moon as
seen from Earth. This extremely precise measurement took years of observations
with Hubble to acquire.
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- Many stars,
like our sun, don’t end with a bang. Instead, they slowly expand and fade out,
losing their outer layers and leaving behind their dead cores. These remnants,
known as white dwarfs, are made of degenerate matter, a strange type of
ultra-compressed gas scientists are still working to understand.
-
- Located
only 15 light-years from Earth, LAWD 37 has been a popular subject of study for
many years. The study used positioning
data from the European Space Agency’s Gaia mission to predict precisely when
LAWD 37 would pass in front of the distant star, allowing the team to prepare
for the gravitational lensing event accordingly.
-
- Based on
the distant star’s slight movement in the sky, the team calculated that the
white dwarf is approximately 56% as massive as the sun. The team is already observing another white
dwarf, LAWD 66, and will continue to watch it until they have enough
information to measure its mass in 2024.
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February 9, 2023 WHITE DWARF
- mass is measured? 3868
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--- Thursday, February 9, 2023 ---------------------------
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