As you can see there, the type of exoplanet humanity has detected the most are Jupiter-sized exoplanets orbiting close to their stars.
For two reasons:
High masses aid the radial velocity method because they make their host stars wobble more compared to lower mass exoplanets. Lower mass wobbles are just outside the sensitivity range of our best spectrometers.
Also aiding in the transit method, they have a short "year" - typically just a few days, making them pass in front of their star more often. The likelihood of detecting these is therefore a lot higher during a given observation time. In addition, exoplanets that orbit more distantly from their star have a lower chance of having an aligned orbital plane, that makes them transit the star through our line of sight to it. The necessary angle of alignment is much tighter compared to closer orbiting exoplanets.
Earth-like exoplanets (~0.003 Jupiter masses, period= ~365 days) are currently outside the sensitivity range of most instruments. Jupiter-like exoplanets tend to reduce the brightness of their host star by at most a few % when they occlude it - Earth has about a tenth of the diameter of Jupiter, so less than 1/100th of its disk area, so when an exoplanet like it passes in front of a star, it only reduces its brightness by a one hundredth of these few percent.
This is where even 16-bit cameras cease to be useful because even if the exposure times are optimized to be as close as possible to filling their "photon count buckets" in a single exposure, Earth and exoplanets like it would only reduce the brightness by 6 instead of 655 (of 2^16=65536) counts, which isn't that statistically meaningful anymore with all the additional uncertainty that is involved when taking images.
> The MEarth Project is a United States NSF-funded, robotic observatory that is part of Fred Lawrence Whipple Observatory on Mt. Hopkins, Arizona, US. The project monitors the brightness of thousands of red dwarf stars with the goal of finding transiting planets. As red dwarf stars are small, any transiting planet blocks a larger proportion of starlight than transits around a Sun-like star would. This allows smaller planets to be detected through ground-based observations.
So I guess the summary is: finding and detecting earth-like planets around dwarf stars is possible, however around sun-like stars not quite yet using these two methods
Yeah, I was going to say it's probably to do with "sun-like" and angular size ratios. (I'm not religious, but the sun and the moon being the same angular size has always felt like an easter egg that a creator might leave as a bit of fun).
Sun-like is important in the search for life because despite putting out lots more energy, the suspicion is that yellow stars tend to be less temperamental in their flare behavior (so they don't scour the surface of any potential planets with large amounts of radiation every once in awhile). And there is evidence that our sun is even a particularly calm yellow star. The habitable zone is also in a region that doesn't tidally lock the planet; a day-night cycle seems important though not neccesarily a requirement for habitability. And yellow stars' lifecycle seems to be long enough to allow for life to form and evolve. Essentially they seem most likely to produce habitable planets - it's probably not mere happenstance that we live around one.
How often is the bucket filled during the transit? Noise in each emptying will average out, so a dip could be detected even if the dip in a single reading of the bucket could not be.
Typical transits last a few hours, and exposures times are typically a few minutes. So you have up to hundreds of exposures per transit. I guess how "statistically recoverable" this data is depends beside the resolution also on the noise level. The atmosphere introduces a lot of variability in ground-based observations, and a star's brightness is not constant either.
I suppose it depends how regular the signal is otherwise. If a dip happens super-regularly (which I guess it would with single star planet orbits), it might be small relative to pointwise noise of the detector, but large enough to be detected over time (if you have the observations).
Your point on period length stands. And anyway I'm just waxing lyrical, I'm a statistician and amateur stargazer not a pro :)
In the case of an earth-like planet (considering not just composition and size, but also orbit + host star similarity) that's difficult to do when the transit only occurs every 365 days
Even finding just one such planet will require a lot of observation:
The "geometric probability" of the orbital plane being aligned for an earth-like orbit seems to be around 0.5% [0]. Assuming every star has an earthlike planet [1], only 1 in 200 observed stars will be correctly aligned.
So observing 365*200=73,000 stars over an entire day (also not possible for ground-based telescopes due to the day/night cycle) should statistically result in one transit observation. The transit duration is also a problem, for an earth-like exoplanet it is 13 hours, so if the observation time is too short, one would only catch the beginning or end of the transit
[1] The current hypothesis seems to be that every star has at least one planet https://en.wikipedia.org/wiki/Planet-hosting_star), but it's all a bit up in the air as not many exoplanets (and especially earth-like ones) have been observed yet. The sample size is too low.
> The current hypothesis seems to be that every star has at least one planet
I think you mean, that stars have at least one planet on average. E.g. in the unlikely event that only one third of stars had planets, but each one of those stars had on average 3 stars, then it would fit the hypothesis of averaging at least one planet per star. It's not a stretch at all since our rather boring star has at least 8 planets, and of the 4,051 stars we can currently detect with exoplanets, they have a total of 5,438 planets, meaning over 1.34 planets per star not including the unknown but unquestionably vast number of planets we currently don't have the capability of detecting.
Still, just as we suspect large numbers of rogue planets that have lost their stars, there must be at least some stars out there that have lost their planets, whether to passing neutron stars or perhaps indigestion.
Just like some of your telemetry at work. Over the course of the day the amount of jitter in the signal can be very high, but at some point the mins, maxes and mean start to resolve into the fact that the previous deployment increased or decreased system load or response times.
Unlike work charts though, I suspect they’re using FFT analysis to break down periodic signals.
What I like the most in finding gas giants is that each of them must come with a full compliment of rocky or icy moons, which is wonderful news for anyone looking for life similar to ours.
Must they? Depending on where the original atoms of the start system in question are in their journey through the eons, there might not be a lot of rocky material at all in a given system.
My somewhat limited understanding of astrophysics is that the source material for the solar system dictates what class of star can form. Supernovas create a certain range of star types and also produce heavy atomic weights.
but it wouldn't? US astrophysicists and others use units like AU. and if they were using football fields, its to make it so people understand it better. AU is pretty hard to grasp for most people I'd imagine. the writer is American anyway.
Equally, we never say "50% of a m/s" instead of "0.5m/s"
And notations like 0.9c are also quite commonly used for velocities close to the speed of light
(the LHC tends to use TeV more often as a unit, which corresponds to a certain velocity for protons, but they mainly care about the energy)
But using percentages with the speed of light makes some sense because it marks one end of an absolute scale, there is no way to go 1.1c or 2.5c. So using a percentage emphasises how close we are to the maximum value.
I find it hard to believe somebody would know what exactly is AU, yet at the same time struggle with fractions (or whatever is the proper name for it), while being OK with percentages representation of same numbers.
The whole point on an AU is we don't need to know an exact number. Using human relatable measurements means the numbers get mind numbingly big, fast. Even though the average human doesn't know the exact distance from the earth to the sun in meters and/or feet, they can get a rough sense of "the distance from the earth to the sun". also, at what exact moment are you taking that exact distance in meters/feet? the orbit is not exactly circular, so that radius measurement isn't the same all the time.
nor does the average person know the exact radius/diameter of the earth, jupiter, or the sun, but we often see references to the earth is a fraction of jupiter and that the sun is some large number of jupiters.
to be clear, I was referring to use of percentages rather than "Astronomical Unit" vs AU
I could understand wanting to explain what AU stands for, and what an Astronomical Unit represents, it just seemed weird to then convert everything into percentages as well
i agree, it's a bit weird. personally I'd use 0.5 rather than 50% to record the facts, and 50% to make a salient point/summary, since the latter is a higher level of abstraction (perhaps even anthropocentric)
I thoroughly enjoyed that and read the book afterwards. The series is quite close to the book with a lot of the dialogue being almost identical.
I hear that Netflix is going to release a Three Body series this year, but it's going to be set in the U.S. which seems strange to me as the Chinese setting was an important part of the plot. Apparently Liu Cixin is on board with it, so I'm sure I'll give it a watch.
Edit: I thought Hewei Yu was great as Da Shi - very entertaining.
There is a ton of discussion on here about it, which is why I am not getting into the details in this post. You can find it by putting "three body problem ycombinator" into a search engine.
In short, you are far from alone - it's vastly overrated by one group and always advertised (more than ANY other book on here), and another group (including myself) thinks the characters are flat, the science is weak, and the overall "solution" in the book is far too contrived.
TBP itself is bad, agreed, but the other books in the trilogy are some of the best ever. Dark Forest in particular is amazing —- for me the actual moment the series takes flight is when the Wallfacer Project is introduced in DF.
The moon has a much larger effect but the effect of the sun is also significant: the variation in the strength of the tides over the course of a month is due to the effects of the sun and moon coming in and out of phase.
>It is estimated that approximately one third of the star systems in the Milky Way are binary or multiple, with the remaining two thirds being single stars.[62] The overall multiplicity frequency of ordinary stars is a monotonically increasing function of stellar mass. That is, the likelihood of being in a binary or a multi-star system steadily increases as the masses of the components increase.[61]
(later)
>While a number of binary star systems have been found to harbor extrasolar planets, such systems are comparatively rare compared to single star systems. Observations by the Kepler space telescope have shown that most single stars of the same type as the Sun have plenty of planets, but only one-third of binary stars do. According to theoretical simulations,[66] even widely separated binary stars often disrupt the discs of rocky grains from which protoplanets form.
What do seasons look like on a circumbinary planet?
I know that it's still going to be orbiting a center of mass somewhere between the two stars, but is that orbital ellipse significantly different from a planet orbiting one star?
And as the stars themselves are farther from the center of mass and relatively closer to the orbital ellipse, how does that change the behaviors at the equinox? It seems like there will be points on the long axis of the ellipse which are not the equinox but where one sun or another will be closer to the planet than at the equinox.
In molecular biology, it's generally considered good practice to avoid giving things stupid names, principally because telling someone "your child has a mutation in their Sonic Hedgehog gene, and will suffer intellectual disability" isn't the greatest thing in the world.
I don't see why this shouldn't hold for these sorts of discoveries ("BEBOP" in this case) - it's just a sort of weird namespace pollution for the language. Or perhaps I'm just an old curmudgeon.
I can’t see where the name for an exoplanet being silly affects humans directly though, unlike your molecular biology example. We’re never visiting there, sadly, so why not add some whimsy to what are otherwise staid research outcomes?
But what happens when they visit here, and then while they're on the fence of us being friendly discover what name we refer to them as and then just decide the universe is better off without us?
In molecular biology, you are doing research that will affect people's health. Out of respect for people who will be diagnosed with illness, you choose nomenclature carefully.
We are unlikely to ever visit BEBOP. In short, it doesn't matter. But if we identified a very large impactor heading towards Earth, I suspect we might have a care in the naming instead of calling the asteroid something silly, such as "Butthead".[1]
[1] _ This is not intended to be a possible name for future very large impactors.
You mostly can't shame all of humanity at the same time (shame doesn't work like that). So even something like "The Big Bunny Ass asteroid is predicted to collide with Earth in 12 years and kill 5 billion people" doesn't get the same reaction as the Sonic gene from the example.
But the tradition from physics (and the closest areas, like astronomy) of using silly names does make it sound a lot like witchcraft. What is very funny for some people, and enraging for others.
I agree that a "Sonic Hedgehog" gene would sound silly but honestly I don't see how "BEBOP" qualifies as silly. What would be the better alternative? Cultural references are a good way to name things. A style of jazz is not a bad choice.
Additionally:
The newfound world is called BEBOP-1c, after the name of the project that collected the data, BEBOP, which stands for Binaries Escorted By Orbiting Planets. (BEBOP-1 is another name for the binary system TOI-1338.)
How is this any worse than, say, how we've named our local planets? Those are also cultural references - they're just ones that you're already used to.
I often see tangentially related things like this brought up in astronomy related posts.
I think it's because people don't know very much about astronomy but they want to sound smart so they pivot to an opinion on a subjective but related subject.
Lem's "Solaris" also described a planet near double star. Don't want to argue much about imaginary worlds but how Tatooine and Solaris systems differ from each other?
With regards to the planets themselves, Solaris is covered in an ocean (spoiler rot13: na bprna bs try gung vf erirnyrq gb or n fvatyr, cynarg-rapbzcnffvat ragvgl), whereas Tatooine is a desert planet.
The systems are different in that Tatooine (as far as I remember) orbits around a pair of stars. Solaris is orbiting between the two stars in an orbit that should be highly unstable but for reasons unknown the planet appears to be stabilizing itself.
With the radial velocity method they used, anytime - it's a telescope with a spectrometer that only relies on the planets wobbling the stars around a bit to produce a doppler shift.
> A visual inspection of TESS lightcurves shows no transit of TOI-1338/BEBOP-1c, however, thanks to orbital circulation, transits are expected to occur in due time. Circumbinary orbits exhibit nodal precession. This changes the orientation of a circumbinary planet’s orbital plane with respect to both the binary and the observer. This makes a planet change from a transiting to a non-transiting configuration (15, 30) as has been seen in a few systems (31, 32). Using an analytic criterion (33,34), we find that TOI-1338/BEBOP-1c is guaranteed to eventually transit mainly because the binary is so well-aligned with our line of sight (Ibin = 89.658◦) combined with the rather large size of the primary star (RA = 1.299R⊙). Whilst TOI-1338/BEBOP-1c will eventually transit, we are unable to predict when and how frequently. Its precession period is of order 119 years, during which time there will be two periods of transitability of a duration depending on TOI-1338/BEBOP-1c’s orbital inclination.
Yes, absolutely. It's a close binary, where you can get 90% or more the way to the truth by modelling the stars as a single object at their barycenter. TOI-1338 A is a star slightly larger than the sun, and TOI-1338 B, which is a star with ~a third of Sun's mass orbits it in 14 days. This is basically touching as far as stars go.
Orbital period vs mass distribution of known exoplanets:
https://exoplanetarchive.ipac.caltech.edu/exoplanetplots/
As you can see there, the type of exoplanet humanity has detected the most are Jupiter-sized exoplanets orbiting close to their stars.
For two reasons:
High masses aid the radial velocity method because they make their host stars wobble more compared to lower mass exoplanets. Lower mass wobbles are just outside the sensitivity range of our best spectrometers.
Also aiding in the transit method, they have a short "year" - typically just a few days, making them pass in front of their star more often. The likelihood of detecting these is therefore a lot higher during a given observation time. In addition, exoplanets that orbit more distantly from their star have a lower chance of having an aligned orbital plane, that makes them transit the star through our line of sight to it. The necessary angle of alignment is much tighter compared to closer orbiting exoplanets.
Earth-like exoplanets (~0.003 Jupiter masses, period= ~365 days) are currently outside the sensitivity range of most instruments. Jupiter-like exoplanets tend to reduce the brightness of their host star by at most a few % when they occlude it - Earth has about a tenth of the diameter of Jupiter, so less than 1/100th of its disk area, so when an exoplanet like it passes in front of a star, it only reduces its brightness by a one hundredth of these few percent.
This is where even 16-bit cameras cease to be useful because even if the exposure times are optimized to be as close as possible to filling their "photon count buckets" in a single exposure, Earth and exoplanets like it would only reduce the brightness by 6 instead of 655 (of 2^16=65536) counts, which isn't that statistically meaningful anymore with all the additional uncertainty that is involved when taking images.