A white dwarf eats an ice giant, the Sun attacks the Parker Solar Probe, and an ultra-massive black hole

There is so much news today, it’s hard to know where to start. From the discovery of a Neptune-like world being consumed by its now-dead parent star, to our Sun’s violent corona, to the a galaxy with 2 trillion solar masses of stars and a 40 billion solar mass black hole, we dance across size, energy, and space. Join in and learn it all with us.

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This week, a new research paper based on Sloan Digital Sky Survey Data, had the kind of result that left me proclaiming “FINALLY.” This was one of those results that actually confirmed that one of the stories we’ve been telling about how our Solar System may evolve has FINALLY been seen to be true in another Solar System. The result I’m talking about is the discovery of a partially destroyed Ice Giant orbiting a white dwarf star, demonstrating that solar systems can keep their planets when their stars die as white dwarfs and planetary nebula.

In a new paper in Nature, a team led by Boris Gansicke found that the white dwarf star G29-38 is surrounded by a disk of hydrogen, oxygen, and sulfur that is consistent with a massive Neptune-like planet losing its atmosphere at a rate of 3000 tons a second.

With our own solar system, one of the most common questions astronomers get is “Will the Earth survive the death of the Sun?” We think the answer is, sure, our world will survive but life as we know it will get toasted while the sun is a red giant star. But… our world should still be here. Should isn’t the most comfortable of words, however, and it’s always nice when we can see examples that what we think will be true here is true elsewhere.

Now, this discovery isn’t entirely promising when it comes to the fate of our world. One of our planet’s great hopes is that our planet will migrate away from the Sun as it loses mass, and the gravitational attraction between our world and the Sun is lessened and angular momentum is lost. In G29-38, we find this Neptune-like world in a small orbit that places it in a location that would have once been occupied by the outer atmosphere of the star. Somehow, this world migrated inwards, and this kind of implies other worlds – inner worlds like our own – may have just fallen into the star at some point in the past.

This may not be as bad as you might think – it depends on if you’re a fan of a quick planetary death or slow death. This white dwarf is radiating extremely high energy photons from its 28,000 C surface, and this energy is blasting off the atmosphere of the planet, over time digging deeper and deeper into its atmosphere. This is a death by a myriad of ionizing particles.

This research points to a new way to look for planets around white dwarfs. This destroyed ice giant was rich in elements like hydrogen, oxygen, and sulfur that appear in the spectra of the star embedded in the gas. By looking for this kind of chemical signature in the light of other white dwarfs, we may be able to find more planetary systems in the process of being destroyed.

Smaller stars, like our sun and the white dwarfs they will form, are often paid less attention than their showier, higher mass siblings which form high density neutron star and black hole remnants. This may be a mistake, because the Parker Solar probe is finding that our Sun is way more complicated and weird than expected. This rugged spacecraft is diving through the Sun’s Atmosphere on a highly elliptical orbit. While in the Sun’s corona, it is capturing data on the sun’s magnetic fields, and it is finding things are way weirder than expected.

In a suite of 4 papers in the journal Nature, scientists present the Parker Solar Probe’s first round of science results. They find the solar wind is carrying far more rotation than planned. This means that as the wind comes off the Sun, it is continuing to move in a rotating way, carried by the Sun’s magnetic field. As a result, this wind has a different trajectory than expected and also carries away far more rotational momentum than expected. An immediate consequence of this finding is that we need to change how we calculate the likelihood a coronal mass ejection will hit the Earth. In the long term, this means the Sun’s rotation will change in ways we hadn’t anticipated.

They also found that waves in the magnetic field – Alfven waves – generally behave as expected from observations, but there are periodic rogue waves that have 4 times the normal energy, flip the regional polarity, and have velocities of 300,000 miles per hour.

And this is just the start. The Parker Solar Probe will complete 24 orbits around the sun before the end of 2025, catching observations of deeper and deeper layers of the Sun as it goes. Each of these orbits represents new possible science, and new insights into our nearest star.

Heavyweight in the heart of the Abell 85 central galaxy (MaxPlanck)

From stellar astronomy we now jump to galaxies and galaxy clusters. Since the late 1990s, astronomers have been working to directly measure the masses of supermassive black holes in the centers of galaxies from the rate stars orbit around them. While generally only useful for nearby galaxies, astronomers are pushing the limits of what is possible to gain insights into the evolution of the rare and massive galaxies in the heart of galaxy clusters. In new research looking that the central galaxy in Abell 85, a team from the Max Planck Institute for Extraterrestrial Physics finds that this system has 2 trillion solar masses of stars orbiting a 40 billion solar mass ultra-massive black hole. This particular system was targeted because the core of the galaxy has a low surface brightness. Unlike other systems, it’s brightness is flat across the entire inner several thousand light years. This makes sense if during some violent past, in-falling material had created a massive accretion disk that was able to blast clear the inner part of the galaxy with light pressure. This is theorized to happen, and to limit just how large supermassive black holes can get from material falling onto them.

While this galaxy is far larger than had previously been expected, new computer models are able to reproduce this system by considering galaxy merger events that drove matter onto the black hole, while also flinging massive stars out of the galaxy’s core. This explains both the size of the black hole, and the low surface brightness of the galaxy core.

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And that rounds out our show for today.

Thank you all for listening. The Daily Space is produced by Susie Murph, and is a product of the Planetary Science Institute, a 501(c)3 non profit dedicated to exploring our Solar System and beyond. We are here thanks to the generous contributions of people like you. Want to become a supporter of the show? Check us out at Patreon.com/cosmoquestx

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