It's posited that this planet kept its atmosphere despite intense solar radiation pressure because it either moved into this orbit recently from a safer place, or it had much more atmosphere to begin with. I wonder if maybe it just has a very powerful magnetic field that protects it, just like Earth's does.
That's the reason Earth has kept its atmosphere while Mars did not, despite the fact that Mars is twice as far from the sun.
Mars is also much lighter than Earth. Venus is less massive than Earth, but not by much.
Even so, Venus has had most of its hydrogen stripped away over time. Thanks to its high temperature, that also includes hydrogens formerly bound in heavier molecules, like water. The process continues, very slowly. Venus is still losing its hydrogen and helium, more quickly than Earth.
One terraforming plan for Venus involves shipping magnesium hydride there, decomposing it, and using both the H2 and the Mg to react with all the CO2 in the atmosphere to make soot, chalk, and water, reducing the surface pressure to about 3 atm of mostly N2. Nothing works without shipping hydrogen to Venus. But once it's there, it will take many millions of years to get stripped away again, because that happens so slowly, over geologic time scales.
Venus has a very thick, hot and high pressure atmosphere. This both makes it hard to blow off and gives it a strong ionosphere which acts as a stand in for a magnetosphere.
More intuitively, solar radiation would be radiation from the planet's local star, its sun. Radiation from our star would be stellar radiation. We're here; it isn't.
Estimates I've seen are that Earth's core temps are attributably roughly 50-50 to latent gravitational heat of formation, and to radioactive decay of heavy elements (incidentally producing virtually all helium found on the planet).
Any sufficiently large rocky planet or gas giant is likely to have a similarly molten core, the latter likely within a metallic hydrogen core.
The HN headline is incomplete and therefore confusing. I realize it is an attempt to avoid the sadly clickbaity phys.org headline, but the fact the planet is smaller than Neptune and has its own atmosphere is not the interesting thing. The interesting thing is that the planet is smaller than Neptune with its own atmosphere in the region close to stars where Neptune-sized planets have not previously been found.
OK, we've updated it from “An exoplanet smaller than Neptune with its own atmosphere has been discovered”. In either case I think users will be able to decide whether or not their Neptune-related exoplanet curiosity is aroused enough to click through to the article.
I mean, I think everything you just laid out is effectively encapsulated by the fact that "neptunian desert" is in quotes, encouraging the reader to click through to see the exact scope/scale of said desert.
Or at least, that's what went through my mind when I opened the article. I made an assumption that there was either/both:
1. a lack of exoplanets identified at around the size of Neptune, or
2. a lack of planets in the rough orbital region around a given star analogous to the region occupied by Neptune in orbit around the Sun.
and in order to clarify which of the two it was, I clicked on.
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tl;dr: still clickbait, but I wouldn't call it confusing and I would call it an effective summary for those in the field.
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edit: sctb evidently edited the title from the original to the neptunian desert title, which makes my comment seem largely out of place as I believed OP was commenting on the 'neptunian desert' title and had not seen the original title which was the subject of OP's comment.
My comment can be disregarded, but I'm leaving it up for historical purposes.
What the hell is the Neptunian Desert? All I can find on google is articles about this, none of which actually explain what it is. Is it an actual location in space or just a space in the distribution of planets?
The Neptunian Desert is the region close to stars where no Neptune-sized planets are found. This area receives strong irradiation from the star, meaning the planets do not retain their gaseous atmosphere as they evaporate leaving just a rocky core. However NGTS-4b still has its atmosphere of gas.
Not sure why GP's downvoted, the definition sucks. What's "close to stars"? 1AU? Here to Pluto? Here to the Oort cloud? 1LY? In the orbital plane? Localized to an arc or surround
ing the Sun?
Then the link to desert goes to nothing but Earth deserts and the wikipedia article was literally made today. It's like the author has no clue what the Neptunian Desert is.
I decided to declare a jihad on downvotes. In some ways, this site is as bad as reddit with the children and their 'vote' concept. Every downvoted comment gets an upvote from me, it doesn't matter what they say.
Readit News
That's the reason Earth has kept its atmosphere while Mars did not, despite the fact that Mars is twice as far from the sun.
With an orbit of 1.3 days, I would guess that it is tidally locked, which I think would make it unlikely to have a strong magnetic field.
How would you explain Venus having an atmosphere while not generating a magnetic field?
Even so, Venus has had most of its hydrogen stripped away over time. Thanks to its high temperature, that also includes hydrogens formerly bound in heavier molecules, like water. The process continues, very slowly. Venus is still losing its hydrogen and helium, more quickly than Earth.
One terraforming plan for Venus involves shipping magnesium hydride there, decomposing it, and using both the H2 and the Mg to react with all the CO2 in the atmosphere to make soot, chalk, and water, reducing the surface pressure to about 3 atm of mostly N2. Nothing works without shipping hydrogen to Venus. But once it's there, it will take many millions of years to get stripped away again, because that happens so slowly, over geologic time scales.
Stellar radiation. Solar implies our own local star, Sol.
Is an exoplanet that far out likely to have a molten core / maintain a magnetic field in some other way?
Any sufficiently large rocky planet or gas giant is likely to have a similarly molten core, the latter likely within a metallic hydrogen core.
(Highly speculative, see e.g., https://www.universetoday.com/47966/jupiters-core/)
Asteroids and ice planetoids probably not: insufficient initial heat, radiative heat losses.
Original paper, I believe: https://arxiv.org/abs/1809.00678
Or at least, that's what went through my mind when I opened the article. I made an assumption that there was either/both:
1. a lack of exoplanets identified at around the size of Neptune, or
2. a lack of planets in the rough orbital region around a given star analogous to the region occupied by Neptune in orbit around the Sun.
and in order to clarify which of the two it was, I clicked on.
---
tl;dr: still clickbait, but I wouldn't call it confusing and I would call it an effective summary for those in the field.
---
edit: sctb evidently edited the title from the original to the neptunian desert title, which makes my comment seem largely out of place as I believed OP was commenting on the 'neptunian desert' title and had not seen the original title which was the subject of OP's comment.
My comment can be disregarded, but I'm leaving it up for historical purposes.
The Neptunian Desert is the region close to stars where no Neptune-sized planets are found. This area receives strong irradiation from the star, meaning the planets do not retain their gaseous atmosphere as they evaporate leaving just a rocky core. However NGTS-4b still has its atmosphere of gas.
Then the link to desert goes to nothing but Earth deserts and the wikipedia article was literally made today. It's like the author has no clue what the Neptunian Desert is.
https://en.wikipedia.org/wiki/Neptunian_Desert
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