🪐 Astronomers Found Two Giant Planets Less Dense Than Cotton Candy
Astronomers have confirmed the existence of two of the puffiest planets ever discovered — gas giants roughly the size of Jupiter, but with densities so low they are less dense than cotton candy.
The pair, named TOI-791 b and TOI-791 c, orbit an F7-type star about 1,110 light-years from Earth in the southern constellation Volans. Their numbers are almost hard to believe: TOI-791 b has an average density of just 0.038 g/cm³, while TOI-791 c comes in at 0.047 g/cm³.
For comparison, Jupiter’s average density is about 1.33 g/cm³. Cotton candy is roughly 0.05 g/cm³. Earth is around 5.5 g/cm³.
That makes these planets not just “fluffy” by astronomical standards — they are among the lowest-density giant planets ever detected.
The discovery, published in Monthly Notices of the Royal Astronomical Society, is especially valuable because the two planets appear to be locked in a rare 5:3 orbital resonance: for every five orbits of the inner planet, the outer one completes almost exactly three. This gravitational interaction slightly shifts the timing of their transits across the star, allowing astronomers to estimate their masses.
🔹 The planets were first spotted by volunteers in the Planet Hunters TESS citizen-science project
🔹 Confirmation required eight years of observations
🔹 Data from the ASTEP telescope at Antarctica’s Concordia Station were crucial
🔹 Each transit lasts more than 11 hours — unusually long for ground-based observations
🔹 Only a handful of systems are known to contain multiple super-puff planets
The leading idea is that these worlds may have relatively small cores surrounded by enormous hydrogen- and helium-rich atmospheres. But exactly how such diffuse planets form — and how they keep their atmospheres for so long — remains an open question.
Important caveat: these measurements come from transits and orbital timing effects, not from direct imaging. The densities are robust within the current model, but the planets’ true atmospheric composition will require follow-up observations — potentially with the James Webb Space Telescope.
Super-puff planets are strange because they sit at the edge of what our planet-formation models can comfortably explain.
If a giant planet can be less dense than cotton candy and still hold itself together, what else is out there that our theories have not yet learned to expect?
📄 Source: https://academic.oup.com/mnras/article-lookup/doi/10.1093/mnras/stag864
#exoplanets #astronomy #space #TESS #superpuffs
Astronomers have confirmed the existence of two of the puffiest planets ever discovered — gas giants roughly the size of Jupiter, but with densities so low they are less dense than cotton candy.
The pair, named TOI-791 b and TOI-791 c, orbit an F7-type star about 1,110 light-years from Earth in the southern constellation Volans. Their numbers are almost hard to believe: TOI-791 b has an average density of just 0.038 g/cm³, while TOI-791 c comes in at 0.047 g/cm³.
For comparison, Jupiter’s average density is about 1.33 g/cm³. Cotton candy is roughly 0.05 g/cm³. Earth is around 5.5 g/cm³.
That makes these planets not just “fluffy” by astronomical standards — they are among the lowest-density giant planets ever detected.
The discovery, published in Monthly Notices of the Royal Astronomical Society, is especially valuable because the two planets appear to be locked in a rare 5:3 orbital resonance: for every five orbits of the inner planet, the outer one completes almost exactly three. This gravitational interaction slightly shifts the timing of their transits across the star, allowing astronomers to estimate their masses.
🔹 The planets were first spotted by volunteers in the Planet Hunters TESS citizen-science project
🔹 Confirmation required eight years of observations
🔹 Data from the ASTEP telescope at Antarctica’s Concordia Station were crucial
🔹 Each transit lasts more than 11 hours — unusually long for ground-based observations
🔹 Only a handful of systems are known to contain multiple super-puff planets
The leading idea is that these worlds may have relatively small cores surrounded by enormous hydrogen- and helium-rich atmospheres. But exactly how such diffuse planets form — and how they keep their atmospheres for so long — remains an open question.
Important caveat: these measurements come from transits and orbital timing effects, not from direct imaging. The densities are robust within the current model, but the planets’ true atmospheric composition will require follow-up observations — potentially with the James Webb Space Telescope.
Super-puff planets are strange because they sit at the edge of what our planet-formation models can comfortably explain.
If a giant planet can be less dense than cotton candy and still hold itself together, what else is out there that our theories have not yet learned to expect?
📄 Source: https://academic.oup.com/mnras/article-lookup/doi/10.1093/mnras/stag864
#exoplanets #astronomy #space #TESS #superpuffs
OUP Academic
ASTEP confirmation of a pair of long-period Jupiter-sized planets with extremely low densities transiting TOI-791
ABSTRACT. Gas giant planets with periods $20~\lt ~P~\lt ~300~\rm d$ orbiting Sun-like stars are a relatively uncommon outcome of planetary formation, and k
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🔭 The Largest Eye on Earth Is Rising Above the Atacama
At an altitude of 3,046 metres on Cerro Armazones in Chile’s Atacama Desert, engineers are building the most powerful optical telescope ever attempted: ESO’s Extremely Large Telescope, or ELT.
Its primary mirror will span an astonishing 39 metres — far too large to manufacture as a single piece. Instead, it will function as one perfectly synchronised surface made from 798 hexagonal segments, each about 1.45 metres across. The ELT will collect roughly 100 million times more light than the human eye and more than all existing 8–10-metre-class telescopes combined, observing the Universe in visible and infrared light.
But size is only part of the story.
Earth’s turbulent atmosphere makes stars twinkle — beautiful to us, disastrous for precision astronomy. The ELT’s 2.4-metre adaptive mirror, M4, will be controlled by more than 5,000 actuators, reshaping its surface as often as 1,000 times per second to cancel atmospheric distortion and vibrations almost in real time.
The result could transform the search for life beyond Earth. The ELT will directly image some exoplanets, including potentially rocky worlds in nearby habitable zones, and examine their atmospheres for molecules such as water, methane, carbon dioxide and even oxygen.
First test observations are currently planned for March 2029, followed by the first scientific observations in December 2030.
What will it see first: an Earth-like world, the earliest galaxies — or something astronomers have not yet imagined?
#Astronomy #Space #ELT #Exoplanets #Science #Atacama
At an altitude of 3,046 metres on Cerro Armazones in Chile’s Atacama Desert, engineers are building the most powerful optical telescope ever attempted: ESO’s Extremely Large Telescope, or ELT.
Its primary mirror will span an astonishing 39 metres — far too large to manufacture as a single piece. Instead, it will function as one perfectly synchronised surface made from 798 hexagonal segments, each about 1.45 metres across. The ELT will collect roughly 100 million times more light than the human eye and more than all existing 8–10-metre-class telescopes combined, observing the Universe in visible and infrared light.
But size is only part of the story.
Earth’s turbulent atmosphere makes stars twinkle — beautiful to us, disastrous for precision astronomy. The ELT’s 2.4-metre adaptive mirror, M4, will be controlled by more than 5,000 actuators, reshaping its surface as often as 1,000 times per second to cancel atmospheric distortion and vibrations almost in real time.
The result could transform the search for life beyond Earth. The ELT will directly image some exoplanets, including potentially rocky worlds in nearby habitable zones, and examine their atmospheres for molecules such as water, methane, carbon dioxide and even oxygen.
First test observations are currently planned for March 2029, followed by the first scientific observations in December 2030.
What will it see first: an Earth-like world, the earliest galaxies — or something astronomers have not yet imagined?
#Astronomy #Space #ELT #Exoplanets #Science #Atacama
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Max-Planck-Gesellschaft
Astronomers produce the first complete picture of (gas) planet formation in action
We present new deep, very high angular resolution observations of the sub-mm continuum (19x13 mas) and 12CO (67x52 mas) emission from the disk surrounding the planet host WISPIT2. Our analysis reveals a clear gas gap carved by WISPIT 2b and an empty cavity…
🪐 Astronomers Just Watched a Planet Being Built
We know surprisingly well how planets should form.
The problem is that the crucial parts of the process happen hundreds of light-years away, on scales so tiny that astronomers have mostly had to reconstruct them from simulations and indirect clues.
Now they have caught the process in action.
Using Atacama Large Millimeter/submillimeter Array, astronomers imaged gas moving around WISPIT 2b, a newborn planet about 430 light-years from Earth.
It is a monster in the making: roughly five times the mass of Jupiter, orbiting inside the disk of gas and dust from which its planetary system is still emerging.
And around the planet, the gas is doing something remarkable.
On one side of WISPIT 2b it is moving toward us; on the other, away from us.
Together, those motions reveal a swirl of gas around the growing planet — exactly the kind of interaction predicted by simulations of planet formation, but never directly observed around a known protoplanet before.
The system is unusually valuable because astronomers can now see essentially every major piece of the process at once:
the enormous protoplanetary disk, the planet itself, hydrogen emission showing that WISPIT 2b is still accreting material, the gap it has carved through the disk — and now the surrounding gas responding directly to the planet.
A second young planet, WISPIT 2c, is also reshaping the system by carving out a larger cavity. And at the center, astronomers recently discovered that there isn’t even one star.
There are two.
The scale of the observation is extraordinary.
At WISPIT 2’s distance, resolving a structure the size of Earth’s orbit around the Sun is roughly equivalent to reading a normal book from five kilometers away.
For decades, simulations have shown us beautiful animations of planets growing inside swirling disks.
Now nature has finally provided the footage.
We are beginning to watch solar systems assemble in real time.
#Space #Astronomy #Exoplanets #PlanetFormation #ALMA #WISPIT2 #Science
https://www.mpg.de/26990768/astronomers-produce-the-first-complete-picture-of-gas-planet-formation-in-action
We know surprisingly well how planets should form.
The problem is that the crucial parts of the process happen hundreds of light-years away, on scales so tiny that astronomers have mostly had to reconstruct them from simulations and indirect clues.
Now they have caught the process in action.
Using Atacama Large Millimeter/submillimeter Array, astronomers imaged gas moving around WISPIT 2b, a newborn planet about 430 light-years from Earth.
It is a monster in the making: roughly five times the mass of Jupiter, orbiting inside the disk of gas and dust from which its planetary system is still emerging.
And around the planet, the gas is doing something remarkable.
On one side of WISPIT 2b it is moving toward us; on the other, away from us.
Together, those motions reveal a swirl of gas around the growing planet — exactly the kind of interaction predicted by simulations of planet formation, but never directly observed around a known protoplanet before.
The system is unusually valuable because astronomers can now see essentially every major piece of the process at once:
the enormous protoplanetary disk, the planet itself, hydrogen emission showing that WISPIT 2b is still accreting material, the gap it has carved through the disk — and now the surrounding gas responding directly to the planet.
A second young planet, WISPIT 2c, is also reshaping the system by carving out a larger cavity. And at the center, astronomers recently discovered that there isn’t even one star.
There are two.
The scale of the observation is extraordinary.
At WISPIT 2’s distance, resolving a structure the size of Earth’s orbit around the Sun is roughly equivalent to reading a normal book from five kilometers away.
For decades, simulations have shown us beautiful animations of planets growing inside swirling disks.
Now nature has finally provided the footage.
We are beginning to watch solar systems assemble in real time.
#Space #Astronomy #Exoplanets #PlanetFormation #ALMA #WISPIT2 #Science
https://www.mpg.de/26990768/astronomers-produce-the-first-complete-picture-of-gas-planet-formation-in-action
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