Discover Top Posts Tagged with #white dwarfs

Friedrich Wilhelm Bessel – Scientist of the Day

Friedrich Wilhelm Bessel, a German astronomer, was born July 22, 1784, in Minden, Westphalia.

Exoplanets Around White Dwarfs

Spotting a planet orbiting a white dwarf has not been an easy task, all the traditional methods tend not to work, especially if that planet is a good few AU away from the tiny remnants of a star.

That was until JWST started looking, using it's IR capabilities it's been able to directly image Jupiter sized planets orbiting these dead stars.

Finding Jupiter sized planets around WD's is a leap in our understanding of what happens to the planets after our Sun becomes a white dwarf, and it seems at least, the outer planets do continue on, although with the reduced mass, they may slowly move outwards in orbit, while throwing a whole lot of debris inwards.

And that may solve a second puzzle, why some white dwarfs seem to have higher % of metals in their atmosphere than others. Planets consumed during the red giant phase (likely Mercury, Venus and Earth in our stars case) will be blown out as the atmosphere is released before the white dwarf, but asteroids and comets may be pushed inwards by Jupiter and Saturn, adding more metals to the now dead stars surface.

The original study can be found here

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And the source of the artists impressions were found here

https://www.universetoday.com/165502/webb-directly-images-two-planets-orbiting-white-dwarfs/#google_vignette

#astronomy #stars #exoplanets #white dwarfs #star death #asteroids

space splurge

what absolutely fascinates me is that one day, far beyond our existence as humans and most likely anything related to the mere idea of intelligence that we have today, there won't be a single star in the sky because they'll have all run out of fuel. red dwarfs and blue dwarfs will hardly even be an idea, the only illumination (degenerate era of the universe) will be from the white dwarfs, but even those will collapse into black holes. it'll be a ghost universe, just the "shells" of what used to be stars

#PLEASE SOMEONE ASK ME ABOUT SPACE I WANT TO TALK ABOUT SPACE #blnkrambles #space #white dwarfs

This is the Dumbbell Nebula! 🏋️‍♂️🏋️‍♂️🏋️‍♂️

This planetary nebula is the remnant of a dead star that used to be a lot like the Sun and there is a white dwarf at its center! This nebula is easily viewable in the night sky with just binoculars in the constellation Vulpecula! 🔭🔭🔭

Taken by me (Michelle Park) using the Slooh Canary Two telescope on September 13th, 2020 at 22:17 UTC.

What is your favorite type of star?

Probably white dwarfs. Those little guys are kind of cute, and my first first-author paper had to do with Type Ia SNe, so I have a bit of a soft spot for them

#asks #thanks for asking :)#alma night #stars #white dwarfs #astronomy #supernovae #quasarlasar

Pure Oxygen

Here is an interesting little oddity: a white dwarf star whose outer atmosphere is composed of almost pure oxygen:

http://science.sciencemag.org/content/352/6281/37

And a non-paywalled article: http://www.popularmechanics.com/space/deep-space/a20213/newly-discovered-star-has-an-almost-pure-oxygen-atmosphere/

White dwarfs are noted for having unusual chemical compositions. A white dwarf is essentially the exposed core of a normal star, after hydrogen burning has stopped, the red giant phase has concluded and the outer layers have been shrugged off. Basically the WD is the ball of very hot stellar “ash” left over once the fire goes out - and, like a pile of ash, it retains heat for a while, so it carries on glowing.

(Also, white dwarfs are arguably misnamed. New white dwarfs are white in colour, or even bluish, as they're still extremely hot. But they cool and fade as they age. The ‘coldest’ white could have a temperature as low as about 3,000 Kelvins - see for instance https://public.nrao.edu/news/cold-white-dwarf/ )

Helium white dwarfs are fairly normal, as these things go. Carbon white dwarfs aren’t particularly unusual either - both of those elements are common by-products of nuclear reactions.

But ending up with a ball of almost pure oxygen is rather weird. Well, the WD may not be entirely oxygen - due to their extreme surface gravities (hundreds of millions of Gs), WDs actually stratify their elemental composition. Heavier atoms actually sink deeper into the star. So there may be other stuff, deep down. But, this makes things even weirder, because it means that oxygen is the *lowest* atomic mass of the constituents of this WD.

Something very odd has happened in this star’s history.

#Astronomy #astrophysics #white dwarfs #interesting research

IC 405 - Flaming Star Nebula

1,500 light years from Earth in the Northern constellation of Auriga, this reflective (blue) and emissions (red) nebula holds some interesting secrets.

The proper motion (the direction of travel of the star) of the central star appears to lead back to the Orion Nebula.

More so, recent research on a white dwarf named J0927 has suggested it may be the fastest moving known star in our galaxy, moving at over 5 million miles per hour, enough to actually break through the galaxy gravity and spin off into intergalactic space.

For a while dwarf to have reached these speeds, it must have been ejected from a type 1a supernova, and a very special type at that.

Type 1a supernova's occur when a white dwarf gains mass, exceeds the Chandrashekar limit and goes supernova, normally from a close partner. In this instance it is thought two white dwarfs that had significant left overs of helium from their former red giant stars got too close and the helium accreted to one and cause the white dwarf to re-animate itself, in what is known as a dynamically driven double-degenerate double-detonation (D6) supernova.

Many stars in our night sky have high proper-motions, although most is because their orbit around our galaxy differs significantly from ours, but these few examples of stars with hypervelocity make you understand that intergalactic space is probably full of stars, many speeding away from their galaxy of origin, some that may even get captured by our Milky Way, even if they are white dwarfs.

Source :

Astronomers discovered a new population of ultra-fast-moving stars, including the fastest 'runaway' star ever seen in our galaxy.

#white dwarfs #d6 supernova #astronomy #high proper motion #stars #nebula

There's Something "Strange" about XMMU J173203.3-344518

To call upon the inner VSauce, Dead stars come in three flavours, White Dwarf, Neutron Star and Black Hole .... "Or do they ?"

Well, they certain do come in those types, and the outcome is based on the final mass of the object as gravity wins the fusion battle, and collapses the once glorious star into it's death mask.

Stars like our Sun end up as white dwarfs, the remaining fused atoms crushed together into a moon sized ball of mostly carbon and oxygen atoms.

If the mass is beyond the Chandrasekhar limit (around 1.4 times the mass of our Sun) then gravity can crush those atoms further creating a city sized blob of neutrons, otherwise known as a Neutron Star, or if the energy pushed from it's poles are visible from Earth, a Pulsar (as they appear to pulse as the object rotates).

Finally, if the mass exceeds around 2.2 solar masses, even that collapses into breaking our understanding of physics and creating a Black Hole.

However, some theorize that it could be possible to have a mass that went beyond the neutron, but instead created an even smaller sized object of quarks, a Quark Star, or given the type of Quark.. A "Strange" star.

XMMU J173203.3-344518 is a tiny star 8,150 light years from Earth and initial measurements seem to point to a very low mass tiny object that's odd behavior looks like that of a Quark star, or at least how we'd theorise such an object to behave.

At this point, and as it should be with almost everything we do in Science, the initial results could be because of errors in observation, measurement etc .. so this is yet to be ruled out, and there may be a much more mundane explanation for this object's odd behavior, however the initial data certainly points to a very fascinating possibility, and one I am sure will be followed up.

With a mass of around three-quarters of our Sun crammed into a ball that could sit comfortably inside Manhattan, the compact object XMMU J17

#quark stars #neutron stars #white dwarfs #stars #astronomy #vsauce