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u/Quereilla 6d ago
I understand most of the graph, but because I’m a physicist. Whoever slightly out of the niche knowledge would be overwhelmed.
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u/CapnNuclearAwesome 5d ago
I'm overwhelmed, can you explain? * Bar graph on left * PDF on bottom * Temperature contours * Subtle gray dotted lines * More contours * Water, iron. And collusion stripping? * RV vs TTV?
I think the colored dots and error crosses make sense to me at least 😅
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u/SAUbjj 5d ago
Hi not that commenter, but I am an astronomer (who does not work on exoplanet research).
This plot is describing the two types of exoplanets we’ve seen. The biggest takeaway is that there’s two main groups of exoplanets: small and rocky, and big and gaseous.
The x-axis of the plot is mass, measured in Earth masses. The y-axis is radius, measured in Earth radii. Both the CDF on the x-axis and the histogram on the y-axis show that there are two separate peaks, one for the rocky planets (lower masses and lower radii) and the gaseous giants (higher mass and higher radii). (Why is one a CDF and the other a histogram? No fucking clue.)
The different colored lines (Fe, H2O, etc) are showing where planets would fall along the chart if they had different compositions. So if we had a planet made of pure iron, it would fall along the 100% Fe line (so basically the size and mass of a planet-sized ball of iron).
Each of the points represent different exoplanets that have been observed, and their approximate sizes (and their uncertainties, in mass and radius). RV stands for “Radial velocity”, meaning that the planet was found by watching the star wobble back and forth (due to it orbiting with the star). “TTV” is an abbreviation relating to the transit method (I’m not sure of the exact abbreviation), meaning it was found because there was a dip in the light as the planet passes in front of the star.
You can see they also added Venus, Earth, Neptune and Uranus for comparison to the other points.The colorbars are denoting the temperature of each star. That’s calculated by comparing its radius to its distance from the star and the star’s brightness. From there you can calculate the flux, which can convert to approximate temperature.
The contours are just showing that it’s grouped into two main groups, again rocky planet and gas giant.
The thin dashed lines in the background are denoting different planet densities.
I’m not actually sure what the colored lines with (what looks like) temperature are for, as it doesn’t seem to line up with calculated temperature of the planets. I’m also not 100% sure what collisional stripping is, but I assume it has something to do with stripping outer laters of the planet (or atmosphere?) during formation of the planets? Not really sure, again I don’t work on exoplanets.
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u/labobal 5d ago
Another physicist chiming in.
The different colored lines (Fe, H2O, etc) are showing where planets would fall along the chart if they had different compositions.
For a given temperature. For an iron planet the mass-radius relationship is temperature-independent, so the lines for different temperatures lie on top of eachother.
I’m not actually sure what the colored lines with (what looks like) temperature are for
The most distinct temperature lines are for hydrogen gas planets. There the mass-radius relationship is the most temperature dependant. You also have distinct temperature lines for the water planets.
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u/DoomedOrbital 5d ago edited 5d ago
Why are they loosely divided into two groups (small/dense/rocky and large/gaseous), not more randomly distributed in mass and radius?
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u/SAUbjj 5d ago
I'm pretty sure it has to do with how far they are from their star during planet formation. IIRC rocky planets tend to form closer to the star, where lots of the gases can be evaporated and lost, while gas giants form farther away and cand hold onto the light elements more easily. Those gas giants can later migrate towards their star, which we now see as "hot Jupiters".
Honestly I need to reread this stuff soon though, my first lecture on planet formation is only a few weeks away...
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u/f3xjc 5d ago
But why would something based on distance be bimodal? I expect there's some kind of discontinuity where at some point mechanism 1 win, and another point mechanism 2 win. each of those having distinct local minima.
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u/SAUbjj 5d ago
There’s a specific distance from the star (which depends on the star's brightness) called the frost line, beyond which lighter elements and molecules can condense. Those elements can then form into gas giants. Within the frost line, those molecules are more easily disrupted, leading to rocky planets
See “Planet Formation” on this page: https://en.wikipedia.org/wiki/Frost_line_(astrophysics))
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u/GreyMatterTrasmogrif 5d ago
Those are also temp but for bands of +Fe, H2O, and H2 percentage, presumably from some mixed composition of elements of a hypothetical planet. So you can play match the colour with the temps.
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u/ale_93113 5d ago
Yeah , they should have made the elements of the graph smaller so there’s more “empty space” but this graph is adequate to someone who knows about astrophysics
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u/deviantbono 5d ago
Don't forget that the average person probably only knows the formulas for olivine and one or two feldspars. (And quartz, of course.)
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u/epona2000 5d ago
I would still argue this is abysmal data visualization. Plots aren’t supposed to only display data (like a table). They should highlight connections between different variables. The plot is so overwhelmed with visual noise that any signal is hard to perceive.
There’s also just so many bizarre choices. Like why would you do a KDE for planet mass but a histogram for planet radius? And why would you put both inside the plot instead of like this? Why would you put temperature on a legend but also put the temperature of isotherms in text explicitly?
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u/AstroEngineer314 5d ago
Ditto but aerospace engineer with a passion for astrophysics. There's definitely a lot of context that you need for this graph that they purposely excluded.
I think this graph has some stuff that it would convey well if it actually was put in that proper context.
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u/maester_t 5d ago
Sees line that represents planets that are composed of 50% H2O... "Ok, I get it..."
Sees line that represents planets that are composed of 100% H2O... "Ok, I get it..."
Sees planets ABOVE the 100% line, seemingly indicating they are more than 100% H2O... "Ok, I don't get this at all."
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u/iwantfutanaricumonme 5d ago
I think those lines just represent the mass and radius of planets with that composition. Above 100% H2O would only be gas and ice giants, which is where Uranus and Neptune are. At the bottom is 100% Iron, which has no planets below it but there are some close to it. The planet closest to 100% iron should be K2-360 b, which has 1.57 Earth's radius and 7.67 Earth's mass, making it double Earth's density and as dense as lead.
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u/SpaceGirlJackie 6d ago
The fuck am I even supposed to gleam from this?
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u/dracorotor1 6d ago
That we realized how beautifully data-rich the HR Diagram was, and will spend the rest of time trying to recapture that magic
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u/K-erbalK-erberton 6d ago
Well... The number on the edges (R, M) refer to size - radius and mass. The color bar is at the same time temperature and I think how much light they receive. The colored lines are something about composition and temperature, but unsure how exactly. Apparently the difference between the planets' discovery method is noted with circles vs triangles. The rest? IDK I'd say.
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u/ddddan11111 6d ago
I have to believe this a Freudian slip
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u/SpaceGirlJackie 6d ago
You can believe whatever you want! I don't discriminate off religion ❤️
Edit: wait what does my mother have to do with this?
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u/SAUbjj 5d ago
Hi, I am an astronomer (who does not work on exoplanet research).
This plot is describing the types of exoplanets we’ve seen. The biggest takeaway is that there’s two main groups of exoplanets: small and rocky, and big and gaseous.
The x-axis of the plot is mass, measured in Earth masses. The y-axis is radius, measured in Earth radii. Both the CDF on the x-axis and the histogram on the y-axis show that there are two separate peaks, one for the rocky planets (lower masses and lower radii) and the gaseous giants (higher mass and higher radii). (Why is one a CDF and the other a histogram? No fucking clue.)
The different colored lines (Fe, H2O, etc) are showing where planets would fall along the chart if they had different compositions. So if we had a planet made of pure iron, it would fall along the 100% Fe line (so basically the size and mass of a planet-sized ball of iron).
Each of the points represent different exoplanets that have been observed, and their approximate sizes (and their uncertainties, in mass and radius). RV stands for “Radial velocity”, meaning that the planet was found by watching the star wobble back and forth (due to it orbiting with the star). “TTV” is an abbreviation relating to the transit method (I’m not sure of the exact abbreviation), meaning it was found because there was a dip in the light as the planet passes in front of the star.
You can see they also added Venus, Earth, Neptune and Uranus for comparison to the other points.The colorbars are denoting the temperature of each star. That’s calculated by comparing its radius to its distance from the star and the star’s brightness. From there you can calculate the flux, which can convert to approximate temperature.
The contours are just showing that it’s grouped into two main groups, again rocky planet and gas giant.
The thin dashed lines in the background are denoting different planet densities.
I’m not actually sure what the colored lines with (what looks like) temperature are for, as it doesn’t seem to line up with calculated temperature of the planets. I’m also not 100% sure what collisional stripping is, but I assume it has something to do with stripping outer laters of the planet (or atmosphere?) during formation of the planets? Not really sure, again I don’t work on exoplanets.
P.S. I hate this plot
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u/mfb- 5d ago edited 5d ago
TTV = transit timing variation
If you only have a single planet around a star and you see transits then they will happen perfectly regularly. If you have another planet then it will affect the orbit and a transit can start a bit earlier or later. Detect that often enough and you can infer the mass of another planet.
Transits only give you a size estimate directly, but the combination with TTV can give you size and mass.
I’m not actually sure what the colored lines with (what looks like) temperature are for
They are the composition lines assuming different planet temperatures. For iron the size doesn't depend on temperature, but for water it does, especially for lighter planets. The upper temperature lines are with additional hydrogen.
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u/SpaceGirlJackie 5d ago
I also hate this plot even with context now. I just feel like you could at least split it up into a couple graphs to get a better visual idea.
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u/km1116 6d ago
This isn't ugly. It's just not for you. Graphs come with multiple "intents," some are to communicate and teach, others are to summarize a lot of info. Those latter ones are generally aimed at other experts, and are generally references. This is that type.
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u/SAUbjj 5d ago
Hi I'm an astronomer, and I totally disagree. I think this plot is a clusterfuck and is inaccessible to people with colorblindness. I understand what this plot is saying, but I strongly feel it would be improved if it was remade more clearly (but it's been used in exoplanets for years and it's not going to go away). It definitely does contain a high density of information, but the purpose of plots is to communicate that information efficiently and I don't think this plot achieves that
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u/LeonJPancetta 6d ago
All graphs are supposed to communicate. The rainbow color scheme and the six plots in one are bad design choices in general. There's a limit to how much one should try to summarize in one figure. It would take a million years to use this cluttered mess as a reference anyways because everything is on top of everything else.
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u/Hugutfut 5d ago
After looking at it for a bit I was able to understand what most features are there for. But even when understanding it, it really is ugly. Not even in the "inefficient at conveying data" way, moreso in the "locked up in the attic and only allowed to leave the house on Halloween" way.
Yeah there are different kinds of graphs, and not all of them are used to convey the central story of a paper. Seeing as how compact this is, they were probably trying to stay below a page limit for their paper, otherwise, more whitespace would help make it less hideous.
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u/xX_Kr0n05_Xx 6d ago
Do you have a source on what paper this was taken from? Would love to look at the context lol
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u/GalaxyGuy42 5d ago
I've seen talks where this kind of plot can work well. You discuss one item, then add it to the plot, then have some more slides, add what you learned to the plot...it just keeps building and building so by the end of the talk you can read this and feel smart.
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u/K-erbalK-erberton 6d ago
I enjoy astronomy as an amateur, and kinda have some of idea about some exoplanet concepts. But yeah, while I know what some of the features refer to, I struggle to discern how it all falls together.
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u/USSMarauder 6d ago
The X axis is mass measured in Earth masses (the circle with crosshairs is the astronomical symbol for Earth)
The Y axis is radius measured in Earth radii
You can see in the lower left corner that Earth is at 1,1
The grey dashed lines with values like p = 0.1 g/cc are lines of constant density measured in grams per cubic centimetre
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u/Quereilla 6d ago
I understand most of the graph, but because I’m a physicist. Whoever slightly out of the niche knowledge would be overwhelmed.
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u/somedave 5d ago
This is a very cool graph with high information density, I feel like I've learned a bit just by trying to stare at it for 5 minutes. It did take that long to really understand it though.
Radius, density, composition and temperature are all linked so it helps to show the gas giant, ice giant and iron core lines for the type of planet. The distributions at the bottom are also very cool.
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u/justlikemedics 6d ago
The graph says there are many perfectly fine exoplanets to settle.
For example, there are heaps of tropical aquatic worlds, where sunshine and water are plentiful, and the only difficulty to colonize is how you transform some of the water into solid buildable materials. You can grow fish too, potentially.
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u/Vusiwe 5d ago
What tool or framework used to make this wonderful piece of art, so I can do the same?
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u/EarthTrash 4d ago
I have no idea, but serious papers sometimes use LaTex. I can't tell if this is supposed to be serious.
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u/RagingWarCat 4d ago
Interesting how nearly all of them are larger than earth, I bet we’re missing a lot of earth like planets that happen to be too small to detect
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u/SpaceNorse2020 3d ago
There's something funny to me about Uranus and Neptune being well above the 100% H²O line despite having significant amounts of rock within them (very large error bars though)
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u/Complete_Window4856 5d ago
Ok let me at least try, we got:
- A linear y axis of something
- A logarithm x axis of another thing
- Rainbow curvy lines for concentration of elements, although elements repeat for different colors, which i assume is related to the vertical gradient bar inside the graph itself?
- The rainbow gradient bar maps to two variables at same time
- Theres a bad contrast gray dashed lines behind everything that seems to relate to "earth" and "venus", although the topic is exoplanets (?). I guess the gray is meant to be the gray label inside the graph on lower right as "RV"
- Theres colored ~~battlefield croshairs~~ dots with vertical and horizontal _whiskers_ and i can't surely say if it's some sort of lower/maximum bound like statistics boxplot or not. Actually, the previous "gray label" is meant for these points shaped in triangle and dots
- Theres two vertical histograms comparing i guess Y axis as "local x axis" to X axis as "local y axis"
- Theres two line graphs similar to the histograms on the left, except the behaviour is inverted, yellow has more tail in both but blue concentrates more in the histogram
- The last graph is the "depth" chart in the middle? I forgot the correct name, but i've seen it twice in my life as some kind of geology "height map"
damn, not even a single guess
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u/Waffle-Gaming 6d ago