List members , our world is in so much turmoil these days due to the COVID-19 Pandemic that some fascinating , recent astronomial discoveries are not getting the right attention .
It is not just the biggest planets of our own Solar system , but also the tiny planetoids at the outer fringes , that have an egg shape . Jupiter itself has a 7% variation (quite a lot) between Polar and equatorial diameter , Saturn has 10% variation which we've already discussed in depth on this forum . I continue to be amazed how mainstream astronomy has been able to gloss over such a basic aspect of science , as the fundamental shape of all stars & planets . "Oh , that's just a trivial deviation from a spherical shape they may say" - OH REALLY ?? The Devil is in the details and if you got the shape itself wrong , what theories of physics can you make about stars & planets .
**Incidentally , both Newton and Einstein had assumed planets & stars to be of a perfect spherical shape...hmm if this was one of their baseline assumptions , how accurate can their theories truly be ? Think deeply about it , if stars do NOT have a perfect spherical shape , can the so called "runaway gravitational collapse" to form a Black Hole , hold true in any case ??
Later in the post I' ve also shared the most extreme case known of an egg shaped planet in our Universe :-
Astronomers have found a ring of particles surrounding a small, distant space rock at the edge of our Solar System. The ring encircles a strange world called Haumea, a dwarf planet that’s shaped a bit like a squashed egg. Haumea is one of just five officially recognized dwarf planets in the Solar System, but it’s the only one we know of to have its very own ring.
Although Haumea is unique among its peers, this isn’t the first time a ring has been found around a small body like this in our Solar System. In 2014, this same group of astronomers said that they had found two thin rings around a smaller, minor planet called Chariklo that orbits between Jupiter and Neptune. The discovery completely surprised the astronomy community. Up until that point, only the gas giants in our Solar System — Saturn, Jupiter, Neptune, and Uranus — were known to have rings.
The difference between a planet and a dwarf planet:
But now that rings have been found around another small, distant object, it’s possible that even more bodies far out in our Solar System have rings, too. That poses a puzzle for astronomers: how are these rings forming? Most explanations for ring formation have focused on the biggest planets in our cosmic neighborhood. But now, researchers are going to need to come up with ways to explain how rings are forming around these tiny objects — and how the rings are staying there. “I think that where the rings are coming from, how they’re forming essentially, is going to be a big topic of research,” Amanda Sickafoose, a planetary astronomer at MIT who wrote a Nature editorial on the discovery, tells The Verge .
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An artistic rendering of Haumea and its rings
Image: IAA-CSIC/UHU
Astronomers serendipitously found Haumea’s ring, described today in Nature , when they watched the dwarf planet briefly pass in front of a background star, blocking out the star’s light. Such a passing causes a momentary eclipse known as an occultation. The intention was to learn more about Haumea. By observing this quick dip in light, astronomers can gather quite a lot of information about the foreground object, such as its size, shape, and whether or not rings are present.
On January 21st, the astronomy team observed Haumea’s occultation of a distant star — eloquently named URAT1 533-182543 — with 12 different telescopes across Europe. The telescopes helped the astronomers constrain Haumea’s size, shape, and density. And they also observed the star’s light blink out on opposite sides of Haumea, indicating the existence of a ring. “Because they saw that from a number of different sites, they were able to trace that there has to be a ring of material going all the way around Haumea,” says Sickafoose.
Using the data from the 12 different telescopes, the astronomers determined that the ring was about 43.5 miles wide, with a radius of nearly 1,500 miles. It also seems to spin somewhat slowly around Haumea; in the time it takes the ring to do one complete revolution around the dwarf planet, Haumea spins around its own axis three times.
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The mechanisms that formed Saturn’s rings are probably very different than the ones that formed Haumea’s ring.
Image: NASA
As for how this ring got there, astronomers aren’t quite sure yet. Many of the mechanisms that are thought to have formed rings around the giant planets wouldn’t explain the rings around Haumea and Chariklo. Part of Saturn’s rings, for instance, are made of material spewing from one of the planet’s moons, Enceladus. While Haumea has two moons of its own, they’re too small and too far from the dwarf planet to contribute to the ring, says Sickafoose. Additionally, astronomers believe that the gas giants’ rings may be leftovers from asteroids or other objects from outside the Solar System that got drawn in by the planets and then got torn apart by gravity or collisions. But that explanation also doesn’t work for Haumea and Chariklo. “These small bodies wouldn’t be able to do that,” says Sickafoose.
The likeliest explanation for Haumea’s ring is a large collision of some kind
The likeliest explanation for Haumea’s ring is a large collision of some kind — and there’s some evidence that happened in the dwarf planet’s past. Haumea shares a unique water-ice signature with a handful of other objects in the outer Solar System. That’s a sign that Haumea and these other objects were actually one body in the past, and some collision with another rock broke them apart. It’s possible this same collision also caused a ring of debris. “Because we know there was a collision and we know there’s a ring, there’s a high likelihood those things are tied together,” says Sickafoose.
But even if astronomers come up with an explanation for the ring formation, there’s another riddle to solve: what is keeping the ring there? “Rings are thought to kind of dissipate fairly quickly,” says Sickafoose. Over time, rings are thought to lose energy and fall apart. Also highly energetic particles streaming from the Sun can push on the particles in a ring, causing the debris to fall inward. If Haumea’s ring was formed by a collision, it probably happened hundreds of millions — maybe even billions — of years ago. So something must be preventing the ring from going away.
Above all, this discovery opens up a lot of questions about rings, and Sickafoose thinks many researchers will be trying to answer them in the coming months and years. “How did this form, where did it come from in the first place, and why do some objects have [rings] and others don’t?”
Hubble reveals egg-shaped exoplanet so hot it's venting vaporized iron into space
August 02, 2019
WASP-121b is an exoplanet so broiling hot that it's venting vaporized iron into space, and being pulled into a football shape by the intense gravity of its host star
NASA, ESA, and J. Olmsted (STScI)
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Between exoplanets with ruby clouds and those that are actually just giant diamonds, science fiction has barely prepared us for just how weird alien worlds could be. Now, thanks to new Hubble observations we have another contender in WASP-121b, a planet that's so intensely hot it's vaporizing heavy metals and venting them into space. As if that wasn't enough, the poor planet is also being stretched into an egg shape thanks to the strong gravity of its host star.
WASP-121b was discovered back in 2015, and its searing temperatures have been a known feature since then. But this exoplanet is hot even among its class of so-called "Hot Jupiters," with temperatures in the upper atmosphere reaching a blistering 2,538° C (4,600° F). That's roughly 10 times hotter than that of any other known planet.
And now Hubble has looked a bit closer and spotted a strange new side effect of this incredible heat. Using its Space Telescope Imaging Spectrograph instrument, the team studied the planet's atmosphere. As WASP-121b passes in front of the star, astronomers can measure the wavelengths of light that filter through the atmosphere, giving them an indication of what kinds of gases are present and in what amounts. By focusing in on the ultraviolet light, the team could make out the signatures of heavy metals like magnesium and iron.
This isn't particularly surprising news on its own, but the unexpected thing was just how high up those metals were. In fact, they were escaping from the exoplanet's atmosphere entirely, venting into space.
"Heavy metals have been seen in other hot Jupiters before, but only in the lower atmosphere," says David Sing, lead researcher on the study. "So you don't know if they are escaping or not. With WASP-121b, we see magnesium and iron gas so far away from the planet that they're not gravitationally bound.
"We were mainly looking for magnesium, but there have been hints of iron in the atmospheres of other exoplanets. It was a surprise, though, to see it so clearly in the data and at such great altitudes so far away from the planet. The heavy metals are escaping partly because the planet is so big and puffy that its gravity is relatively weak. This is a planet being actively stripped of its atmosphere."
WASP-121b is under so much stress because it's orbiting extremely close to its host star, completing a "year" every 1.27 days. That would make for a toasty planet in our solar system, but it just so happens this star is far hotter and brighter than our Sun. To cap it all off, the intense gravity of this tight orbit is pulling the planet into a football shape.
The weird world of WASP-121b is one to watch, and the team says that the soon-to-be-launched James Webb Space Telescope could help with that. Since it focuses on infrared light, this could search for water and carbon dioxide in the atmosphere. After all, Hubble has previously found the glowing evidence of water in this incredibly hot atmosphere.
The research was published in the Astronomical Journal .
Source: Hubble
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