Exoplanets – worlds of other suns

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Webb findings support long-proposed process of planet formation
https://phys.org/news/2023-11-webb-long ... ation.html
by Ann Jenkins, Space Telescope Science Institute

Scientists using James Webb Space Telescope just made a breakthrough discovery in revealing how planets are made. By observing water vapor in protoplanetary disks, Webb confirmed a physical process involving the drifting of ice-coated solids from the outer regions of the disk into the rocky-planet zone.

Theories have long proposed that icy pebbles forming in the cold, outer regions of protoplanetary disks—the same area where comets originate in our solar system—should be the fundamental seeds of planet formation. The main requirement of these theories is that pebbles should drift inward toward the star due to friction in the gaseous disk, delivering both solids and water to planets.

A fundamental prediction of this theory is that as icy pebbles enter into the warmer region within the "snowline"—where ice transitions to vapor—they should release large amounts of cold water vapor. This is exactly what Webb observed.

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TESS Giants Transiting Giants V -- Two hot Jupiters orbiting red-giant hosts
https://arxiv.org/abs/2311.06678

TOI-1736 and TOI-2141: two systems including sub-Neptunes around solar analogs revealed by TESS and SOPHIE
https://arxiv.org/abs/2311.07011

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NASA's Hubble measures the size of the nearest transiting Earth-sized planet
https://phys.org/news/2023-11-nasa-hubb ... iting.html
by Harvard-Smithsonian Center for Astrophysics

NASA's Hubble Space Telescope has measured the size of the nearest Earth-sized exoplanet that passes across the face of a neighboring star. This alignment, called a transit, opens the door to follow-on studies to see what kind of atmosphere, if any, the rocky world might have.

The diminutive planet, LTT 1445Ac, was first discovered by NASA's Transiting Exoplanet Survey Satellite (TESS) in 2022. But the geometry of the planet's orbital plane relative to its star as seen from Earth was uncertain because TESS does not have the required optical resolution. This means the detection could have been a so-called grazing transit, where a planet only skims across a small portion of the parent star's disk. This would yield an inaccurate lower limit of the planet's diameter.

"There was a chance that this system has an unlucky geometry and if that's the case, we wouldn't measure the right size. But with Hubble's capabilities we nailed its diameter," said Emily Pass of the Center for Astrophysics | Harvard & Smithsonian in Cambridge, Massachusetts. Pass is the first author of a paper recently published in The Astronomical Journal that describes this work.

Hubble observations show that the planet makes a normal transit fully across the star's disk, yielding a true size of only 1.07 times Earth's diameter. This means the planet is a rocky world, like Earth, with approximately the same surface gravity. But at a surface temperature of roughly 500 degrees Fahrenheit, it is too hot for life as we know it.

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Nasa's James Webb telescope spots collection of shocking materials on distant planet

Story by Andrew Griffin •
3d

Nasa’s James Webb Space Telescope has spotted a “fluffy” planet with an atmosphere made up of a collection of intriguing materials.

The planet has a similar water and cloud cycle to that of our own Earth. But the clouds are made of sand and the clouds are made of silicate.

Other parts of the atmosphere are more like our own and could be an intriguing hint of the telescope’s ability to investigate planets that might be home to distant alien life.

Data gathered using the telescope revealed that WASP-107b - a planet 200 lightyears away that orbits a star in the constellation of Virgo - has a dynamic atmosphere made up of water vapour, sulphur dioxide, and sand clouds.

More:
https://www.msn.com/en-us/news/technolo ... r-AA1jYzwh

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Characterising TOI-732 b and c: new insights on the M-dwarf radius and density valley
https://arxiv.org/abs/2311.12577

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Astronomers discover two 'hot Jupiters' orbiting red-giant stars

https://phys.org/news/2023-11-astronome ... giant.html

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Where are All the Double Planets?
by Laurence Tognetti
November 25, 2023

Introduction:

(Universe Today) A recent study published in the Monthly Notices of the Royal Astronomical Society examines formation mechanisms for how binary planets—two large planetary bodies orbiting each other—can be produced from a type of tidal heating known as tidal dissipation, or the energy that is shared between two planetary bodies as the orbit close to each other, which the Earth and our Moon experiences. This study comes as the hunt for exomoons and other satellites orbiting exoplanets continues to expand and holds the potential to help astronomers better understand the formation and evolution of exoplanets and their systems. So, why is studying binary planets specifically important?

“Binary planets are not present in our Solar System, at least nominally, given the similarities with the Pluto-Charon system which, however, is a dwarf planetary analog,” Dr. Cecilia Lazzoni, who is a Postdoctoral Research Fellow at the University of Exeter and lead author of the study, tells Universe Today. “Proving new formation mechanisms that enable the formation of such pairs would justify the existence of a complete new type of worlds. For example, if a Jupiter-like planet could host an Earth-like satellite, that satellite could be in principle habitable though far from its star, using the energy coming from the giant planet.”

The Pluto-Charon duo is currently hypothesized to have likely formed from Like the Earth’s Moon, which was from a collision of another planetary body into Earth. Additionally, Charon is also more tidally locked with Pluto that our Moon is with the Earth, as Charon orbits over the same spot above Pluto, whereas our Moon’s freely orbits around the Earth. However, what makes the Pluto-Charton system unique is Charon’s size compared to Pluto, as its diameter and mass are half and one-eighth of Pluto, respectively, making it the largest moon compared to its parent body in the entire solar system, and the center of gravity between the two bodies is more centered than the Earth-Moon system. It is for these reasons that the Pluto-Charon system is often referred to as a dwarf planet binary system.

Read more here: https://www.universetoday.com/164456/w ... e-164456

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Scientists Discover Six Alien Worlds Perfectly Synchronized
Michele Starr
November 30, 2023

Introduction:

(Science Alert) A planetary system not so far from the Solar System has six worlds orbiting their star in beautiful, perfect harmony.

Each of the six exoplanets orbiting the bright star HD 110067 has an orbit in lockstep with the adjacent exoplanets, resulting in a rare phenomenon known as a chain of resonance. This suggests that the system has existed relatively undisturbed since its formation over a billion years ago – an exceptional hidden jewel in the Milky Way.

"We think only about one percent of all systems stay in resonance," says astrophysicist Rafael Luque of the University of Chicago. "It shows us the pristine configuration of a planetary system that has survived untouched."

Orbital resonances are neither uncommon, nor unexpected. They occur when two bodies orbiting a third body exert a gravitational influence on each other, in such a way that their orbital periods line up. Not exactly 1:1 – that appears to be super uncommon – but it can be expressed as a ratio.

For example, Pluto and Neptune are in resonance with each other: Pluto completes 2 orbits around the Sun for every 3 of Neptune's; that's a resonance of 2:3. And some of Jupiter's moons are in a resonance chain. For every 1 of Ganymede's orbits, Europa completes 2 and Io 4 orbits, for a chain of 1:2:4, also known as a Laplace resonance.

Read more here: https://www.sciencealert.com/scientist ... ronized

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Scientists just found a planet-forming disk beyond our Milky Way for the 1st time -- yes, they're thrilled

By Robert Lea published about 8 hours ago

"We know discs are vital to forming stars and planets in our galaxy, and here, for the first time, we're seeing direct evidence for this in another galaxy."


Astronomers have discovered the first example of a swirling disk of material feeding a young star located in a galaxy outside the Milky Way. The disk is near-identical to those found around infant stars in the Milky Way and suggests that stars and planets form in other galaxies just as they do in our own.

The young star in question is located in the Large Magellanic Cloud  —  a neighboring galaxy to the Milky Way located 160,000 light-years away  —  and its system, designated HH 1177, is embedded in a massive cloud of gas.

The team behind this discovery observed the system with the Atacama Large Millimeter/submillimeter Array (ALMA), the largest astronomical project on Earth consisting of 66 antennas in Northern Chile that make up a single radio telescope.

"When I first saw evidence for a rotating structure in the ALMA data, I could not believe that we had detected the first extragalactic accretion disc. It was a special moment," researcher lead author and Durham University scientist Anna McLeod said in a statement. "We know discs are vital to forming stars and planets in our galaxy, and here, for the first time, we're seeing direct evidence for this in another galaxy."

More:
https://www.space.com/planet-forming-di ... way-galaxy