Thursday, February 9, 2023

3868 - WHITE DWARF - mass is measured?

 

-  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.

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-    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.

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-   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.

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-    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.

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-    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.

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-    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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