Pardon my pedantry but that's another way to say "we used regular light to find it".
If I remember my physics right, stars, like a candle or an incandescent light bulb emit light as blackbody radiation.
Just for the record: I'm an English professor. I know less about blackbody radition than the person who created the picture. I just read someone saying that in the thread and decided to make a joke out of it.
Light bulbs don't emit black body radiation. They don't nearly have enough black body temperature for bright yellow light. I guess tungsten has different emission pattern.
I measured the emission spectrum of a tungsten lamp in the laboratory a few years ago. I don’t remember all the details, but in the visible spectrum the tungsten the amount or radiation that the tungsten lamp emits is roughly 0.3-0.4 times the radiation that a black body would emit.
* In page 151 it has a graph of the emissivity of tungsten for different colors and temperatures. More emissivity for blue (A) than for red (C).
* In page 156 it has a greph of the difference between the color temperature and the true temperature. For 3000K, the difference is only ~100K. I think that it’s changes the color only slightly.
* More friendly version, with an experiments with actual lamps.
* In page 525 it explains that the emissivity if tungsten at that temperature in ~0.42 but you must introduce a correction because the glass of the lamp absorbs a 8% of the light.
Isn't "black body" in physics just something that absorb all incoming radiation meaning that the radiation coming out from it is all originating from said object?
The radiation from a black perfectly body is then a function of its temperature.
You're wrong. The very word "incandescent" means "glowing because it's hot". The fillamant and the gas inside the bulb reach temperatures of up to around 3000 K.
The surface of the sun might be about 6000 K, but it glows white-hot, not yellow as many believe.
Apparently, the estimated number of orphan planets is "100,000 per star in the galaxy!" [1].
The star equivalent to these orphan planets are called, well, orphan stars. They are not bound to a particular galaxy and roam about freely in the space between galaxies [2].
"The Milky Way may be teeming with more than 100,000 free-flying planets for every star[...]."
"This is the finding from a study that extrapolates from observations of a dozen so-called “nomad” planets, which were detected when their gravity briefly contorted light of passing stars[...]."
Guess that very much depends on which angle, relative speed and path it comes in.
Based on my very limited astrophysics I'd guess it wouldn't have much of an impact and in most cases would just cruise through the system with a slight gravitational course correction arc and be on it's way again to interplanetary space.
This concept was considered as early as 1933 in the excellent and influential novel When Worlds Collide (https://en.wikipedia.org/wiki/When_Worlds_Collide), which I highly recommend as well as the sequel After Worlds Collide where they have all sorts of fun on Bronson Beta. Skip the movie, the books are of course more dated but much better.
If there are 100,000 free floating planets per star, and it's still an incredibly small chance that one wanders into a solar system it gives you some slight sense of proportion.
A rogue, an aimless wanderer, creation’s castaway; this world was all those things.
For uncounted centuries it had been falling, alone, without purpose, falling through the cold lonely places between the suns. Generations of stars had succeeded each other in stately sweeps across its barren skies. It belonged to none of them. It was a world in and of itself; entire. In a sense it was not even part of the galaxy; its tumbling path cut through the galactic plane like a nail driven through a round wooden tabletop. It was part of nothing.
The colors are "real" in the sense that they correspond to different wavelengths of light, but they have almost assuredly been adjusted so they match the range the human eye can see.
This really interests me as well - how do they know that it's a 12 million years old planet?
I suppose a big reason would be that it does give off a heat significant (if not AS significant) signature to begin with - a large spaceship would very likely try to conserve as close to 100% of its energy.
Then again - what about a dyson sphere that is still under construction?
So what happens to planets who orbit a star that dies? It seems like they would be come orphans. That was my first thought. I know next to nothing about the Universe.
When a star "dies", it goes through some phases, there one of them is that is grows really big. Planets would presumably be consumed in this process. In any case, a star doesn't disappear when it dies. It just ceases burning.
Some stars explode with such energy that they evaporate. The thermal motion of the gas exceeds the gravitational binding energy. Any outer planets simply drift off into the cosmos.
Some mass is sloughed off late in a star's life, but the star's core remains behind and this can still be quite massive. If a planet is not consumed by the star in the giant (or supernova) stages, it's orbit would be altered because of the decreased mass of the star.
Pluto is tiny and cold. Big planets emit lots of infrared from internal heat. Jupiter still radiates more heat than it receives from the Sun (source: wikipedia)
I'm pretty sure they're just measuring the blackbody radiation it's giving off in the infrared spectrum. This thing is about half the mass necessary to ignite fusion and become a brown dwarf, and it's very young, so it's still got a lot of heat.
As I understand, a nearby star will strip off most of the gas and make it more akin to a comet, so pretty much opposite of fusion will happen if it were to get close to a star.
Astronomer: We want something sort of like Jupiter, but purple.
Artist: Can I do that big red storm thing?
Astronomer: No, no. Don't do that. We don't know if there's a storm. We used blackbody radiation to find it.
Artist: So wait, it's supposed to be black?
Astronomer: No! It's gotta be PURPLE.
Artist: But you said . . .
Astronomer: Never mind. Just make it look lonely. And don't put any stars around it.