Super hot Jupiter - too close to parent star?

HRDiagram

HRDiagram
A few days ago, I came a cross a gas giant (class V) orbiting exremely close to its parent star.
I don't know how common it is, but I had never seen (or perhaps noticed?) such an extreme before (at least not with a main sequence star, M class, in this case).
I have seen plenty of metal rich bodies that orbit within scooping distance of the star, but never experienced a gas giant within the star's scooping range.
I noticed it because I could not scan the planet with the FSS, it was too close and kept giving me an error.
The orbit time was less than 4 hours, and a rough calculation (based on the data on the journal) showed that the shortest distance between star and planet is about 200,000km (0.67ls).

superhot1.jpg
 

HRDiagram

HRDiagram
Hot Jupiters are being discovered all the time, and it's nice to see the Stellar Forge accounting for them.
I remember, from the 90s, one of the first official confirmations of exoplanets, when a gas giant was discovered orbiting a main sequence star in 4-5 days, and I thought it was bonkers.

I wonder how close they can get in ED, though, this was the first time I see it in game.

One aspect I like of the stellar forge is that it takes into account the oblation of a planet, based on its rotational speed, and the planet I found is markedly oblated. 🥳
 

Kira Goto

Kira Goto
HRDiagram said:
One aspect I like of the stellar forge is that it takes into account the oblation of a planet, based on its rotational speed, and the planet I found is markedly oblated.
Click to expand...
Are you sure it’s not [also] tidal forces from being so close to an object as massive as a star stretching the whole thing a bit? I thought it was down to that, could be wrong though.

It is quite neat regardless of that.
 

HRDiagram

HRDiagram
Kira Goto said:
Are you sure it’s not [also] tidal forces from being so close to an object as massive as a star stretching the whole thing a bit? I thought it was down to that, could be wrong though.

It is quite neat regardless of that.
Click to expand...
Good point. The only gas giants we can observe in detail are far enough from the Sun for us to conclude that their shape is prevalently dictated by their rotation.
If the stellar forge takes into consideration the star's gravity as well, I wouldn't know
 

varonica

varonica
HRDiagram said:
Good point. The only gas giants we can observe in detail are far enough from the Sun for us to conclude that their shape is prevalently dictated by their rotation.
If the stellar forge takes into consideration the star's gravity as well, I wouldn't know
Click to expand...

We do get oblate spheroid gas giants just from spin speed, but you are looking at hours to do a rotation, if your gas giant was being stretched by the star I would expect it to be mainly happening to the side that was facing the star with less on the side away, although you will get some, it won't be as extreme. Sort of like the tides on earth, you get high tides, days when the moon is directly overhead, and low tides, days when the moon is on the other side of the planet, in both cases it causes an increase in water height, but it's not the same for both sides.

Just to clarify, it's more complicated than that, the water doesn't move, the earth rotates through the bulges of water and the highest bulge will always be facing the moon, so we pass through the high bulge once per day and the low bulge once per day, hence high and low tides.
 

Felix DiCestria

Felix DiCestria
varonica said:
We do get oblate spheroid gas giants just from spin speed, but you are looking at hours to do a rotation, if your gas giant was being stretched by the star I would expect it to be mainly happening to the side that was facing the star with less on the side away, although you will get some, it won't be as extreme. Sort of like the tides on earth, you get high tides, days when the moon is directly overhead, and low tides, days when the moon is on the other side of the planet, in both cases it causes an increase in water height, but it's not the same for both sides.

Just to clarify, it's more complicated than that, the water doesn't move, the earth rotates through the bulges of water and the highest bulge will always be facing the moon, so we pass through the high bulge once per day and the low bulge once per day, hence high and low tides.
Click to expand...
Plus Spring tides at New Moon when Earth, Moon and Sun line up.
 

GroG79

G

Newly named planets - Name an exoplanet - 2019

The International Astronomical Union (IUA) is celebrating their 100 year existence They will do so by naming 100 known exoplanets. You can read more about that here: https://www.iau.org/news/pressreleases/detail/iau1908/ The IAU is the authority responsible for assigning official...
forums.frontier.co.uk forums.frontier.co.uk

List: https://nameexoworlds.iau.org/2022exoworlds

I went out of my way to visit most of these systems.
Quite some had hot Jupiters (which I proceeded to map)
 

HRDiagram

HRDiagram
Greasetrap42 said:
Similar thread with gas giants crazy close to star: Planets Crazy Close To Star
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Brilliant! That's a relatively old post, so I didn't find it, but happy to see it!
Let's keep in mind that the UI rounds the numbers. In your post you say that the orbit period is 0.2 days, but it might as well be as low as 1.51 and rounded up, so it's even faster!
Same goes with the semiaxis.
It might be even more extreme than what it looks like!
I wasn't happy with was being shown on the UI, or on EDSM, so I checked the journal.

The semi major axis of the orbit appears as 0.00AU in ED, and from the journals it's around 570,000km (that is 0.0038AU).
I think I'll go back there one of these days to take more pictures 🤭
 
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GrandAdmiralThrawn

GrandAdmiralThrawn
And around a Neutron star, no less! Awesome. Let me contribute something too (I should really come back to ED already to continue my brown dwarf mission...), here's a class IV gas giant in close proximity to a brown dwarf:​

elite-254-CL4.jpg elite-255-CL4.jpg elite-256-CL4.jpg
(Click to enlarge)​

Should be relatively uncommon, I have only seen 1 class IV gas giant in about 8000 brown dwarf systems. No class V yet.​
 

Ozzie_J_Isaacs

Ozzie_J_Isaacs
This Class V Gas Giant found by Cmdr SleepyDelegate is also interesting.
The gas giant orbits the white dwarf once in 18.74 minutes.
The distance is only 0.45ls

I managed to map the planet. It was really tricky, I had to fly parallel to the planet. Otherwise I either flew out of the scan area or into the exclusion zone of the white dwarf.
42jlc3t.jpg


azrwkkp_460s226ndye.jpg


highresscreenshot_202j9dzd.jpg


highresscreenshot_202gyeu9.jpg



 

Markov Chaney

M
Spring and neap tides are to do with star and satellite (Sun and Moon if you're standing on Earth) being in alignment or not. Not to do with rotation or "tidal force" in the spaghettification / Roche / tearing things apart sense.

High tide is twice a day because "tidal force" ensures the water is pulled into a whole ellipse not just a big peak right opposite the moon. But the meaning of "tidal" in "tidal force" is quite different to the ocean meaning and I kinda wish it wasn't the same word for all these things.

The trick is when comparing forces you have to remember the whole Earth is falling towards the Moon. The water on the far side is in a slightly weaker field because it is farther away so whilst the force on it is like 1% less compared across the whole Earth-Moon system, it's quite a lot less when you're comparing only with the way the centre of the Earth is falling towards the moon.

The large proportion of the force is dealt with at the Earth-Moon level so the small difference between front and back of Earth actually becomes quite large when you frame it across Earth only. In short gravity squeezes bodies as well as attracting them and it works on relative differences across that body, not the much much bigger distances between the bodies, so it's a bit counter-intuitive.

on the other hand a 40ft tide on an 8,000 mile planet is not much anyway, it just seems big when you are in the beach cafe watching it.

Now imagine that water isn't free to move and everything is rock... eventually that rock cannot deal with that energy being pumped into it twice a day, and that's the Roche limit, which breaks up inelastic moons if they orbit too close.
 
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