Tag: Rogue Planets

Astronomy News for June 2024: New Discoveries by the James Webb and Euclid Space Telescopes.

We’ve gotten used to big discoveries about the Universe being made by space telescopes. Hubble, the Chandra X-ray and the Kepler planet hunting telescopes have all revolutionized our picture of Universe, both near and far, big and small. Now it’s NASA’s James Webb Space Telescope (JWST) along with the European Space Agency’s (ESA) Euclid space telescope that are making the discoveries so in this post I’ll be discussing one from each. I’ll start with JWST.

Orbiting more than a million kilometers from Earth the new James Webb Space Telescope is making observations that are revolutionizing Our understanding of the Universe. (Credit: NASA)

Although it will be making other observations the JWST was primarily designed to peer back further in time than Hubble or any ground-based telescope can. How does JWST look backward in time? Well since the speed of light is a finite 3×108 m/s you’re actually always doing that. You see if you look at the Moon you’re actually not seeing the Moon as it is but the Moon as it was about a second and a half ago because that’s how long it took the light that’s entering your eyes to get from the Moon to you!

At the speed of light our solar system is no more than a few light hours away. The universe however is more than 13 billion light years across. The farther away something is, the farther back in time you’re seeing it! (Credit: Amazon.com)

Similarly if you look at the planet Jupiter you’re really seeing it as it was about 35 minutes ago, because Jupiter is so far away that it takes light about 50 minutes to get from the planet to your eyes. The brightest true star in the sky is Sirius at a distance of about 10 light years so that means when you look at Sirius you’re really looking 10 years into the past. Finally, if you manage to find the Andromeda galaxy, the furthest object you can see with your unaided eye, you’ll be looking about two and a half million years into the past!

The Andromeda galaxy is so distant that it takes light 2.5 million years to get from there to Earth. So when we look at Andromeda what we see is the galaxy as it was 2.5 million years ago. (Credit: BBC Sky at Night Magazine)

So, when astronomers want to see what conditions were like in the early Universe, less than a billion years after the Big Bang let’s say, all they have to do is look far enough away. About 13.5 billion light years away if our calculations are right about the Big Bang. There are a couple of problems with that however, first of all the further away something is the smaller and dimmer it will appear to be, so you’ll need a bigger telescope. Oh, and you’d better put your telescope in space because the gas molecules moving around in Earth’s atmosphere will just smear whatever images you try to take.

The gas molecules in our atmosphere are moving rapidly all the time. As light tries to pass through them it gets knocked about, something called dispersion. That’s why photographs of distant objects look fuzzy when compared to images of close objects. This effects the images astronomers take of celestial objects as well. (Credit: Makodeny.org)

There’s a second more subtle problem as well caused by the expansion of the Universe that’s called the Doppler effect. Now the Doppler effect is familiar enough to everyone. Picture yourself standing on a sidewalk and a police car or ambulance is coming toward you with its siren blaring. As the vehicle is coming toward you the siren’s pitch is quite high but as it goes past the tone drops noticeably. What is happening is that the sound waves are squeezed together as the car approaches you but then are pulled apart as it recedes. That’s the Doppler effect and it happens to light waves as well as sound.

We’re all familiar with the Doppler effect. It the reason that sirens have a higher pitch as they’re approaching, and a lower pitch as then are moving away. (Credit: The Physics Classroom)

Since the Universe itself is expanding that causes all but a very few nearby galaxies to move away from us and that causes the light from those receding galaxies to get shifted to the red. For a galaxy that’s more than 10 billion light years away it’s visible light, the light we’d like to observe it by, gets shifted all the way into the Infrared requiring much more complicated equipment to make observations. That’s why the JWST was built the way it was and placed into an orbit that’s over a million kilometers from Earth.

Astronomers can measure the redshift of distant galaxies by looking for the shift of the spectral lines of the elements in the light coming from those galaxies. This gives them a very precise measurement of the velocity of that galaxy away from us. (Credit: Wikipedia)

It’s been almost two years now since JWST began its task of studying the early Universe and the first results are starting to get published. In particular it was announced on the 30th of May that JWST had broken its own record for discovering the farthest, and hence youngest galaxy ever observed. The galaxy has been given the designation of JADES-GS-z14-0 and it is estimated to have existed a mere 290 million years after the Big Bang.

The most distant galaxy observed so far, JADES-GS-z14-0 formed less than 290 million years after the Big Bang. (Credit: X.com)

Now JADES-GS-z14-0 is a small galaxy compared to modern galaxies like the Milky Way or Andromeda, being measured at about 1,600 light years across and only having a mass of a couple of million stars. Unlike other early galaxies, which appear to get most of their light from gas falling into the supermassive black hole in their center, JADES-GS-z14-0 seems to get its light from millions of very bright, young stars.

Bright, young stars being formed inside a gaseous nebula. (Credit: SciTechDaily)

The fact that such a well developed galaxy could have formed in such a short time after the Big Bang has a lot of early Universe theorists scratching their heads but there it is, and it appears certain that JWST will discover more of them in the days to come. So our models of how the first galaxies came into being are just going to have to change to account for the observable facts.

Theories are generated from facts, observations, not the other way around! (Credit: Quora)

In the same way new observations by the ESA’s Euclid space telescope are upending some of our ideas about how stars form in the present Universe. You see fifty years ago our models of star formation basically started with a gas cloud in the Milky Way collapsing due to gravity. As the cloud condensed it split into smaller clouds each of which was just big enough to then condense further into a star and maybe some planets. At that time we weren’t even certain how many stars had planets.

Forty years ago we weren’t certain any other stars had planets but now we know of thousands of exoplanets, these are just some that we think might have life on them. (Credit: SETI Institute)

Back then some astronomers suggested that there might be objects smaller than stars roaming interstellar space, objects too small to ignite the nuclear fire that makes stars shine so they would be dark. These proposed objects were given the name Brown Dwarf stars, but nobody knew how to find them. Well over the last decade or so we’ve found a couple of dozen and so brown dwarfs are now a recognized part of the celestial zoo. (See my posts of 22September 2021 and 19August 2023 for more about Brown Dwarf stars)

Too big to be a planet, yet too small to be a star Brown Dwarfs are a hot topic of research because we aren’t certain just how many of these objects there are roaming around our galaxy! (Jet Propulsion Labouratory)

So if brown dwarfs are real that begs the question, are there even smaller objects floating through space, planet sized objects that either never belonged to a star or that somehow got kicked out of their solar system. These objects have been named rogue planets and the Euclid space Telescope has discovered seven of them, so far!

Rogue Planets, planets roaming the Galaxy but not orbiting any star are the latest addition to the Celestial Zoo. (Credit: Wikipedia)

Just imagine an object, just about the size of our Earth that for billions of years has been traveling through the galaxy without the warmth of any star, cold and alone. Some astronomers are already suggesting that our galaxy may contain more than a trillion such rogue planets. After all with the mass of a single star you could make hundreds of thousands of planets so if the stellar nurseries that produce the stars also make rogue planets there probably are more of them out there than the stars.

Our Milky way galaxy contains over 200 billion stars that we can see. The question is, how many other objects does it also contain that we can’t see? (Credit: EarthSky)

Every time we look at the Universe with newer, better instruments we find new and unexpected objects out there to understand.

For Decades Astronomers and Physicists have been thinking that Dark Matter is made up some kind of exotic sub-atomic particle. Maybe they’re wrong, maybe Dark Matter is made up of ordinary matter but in objects that don’t shine.

Let me begin today but reminding everyone of the problem of Dark Matter. Over the last 70-80 years as astronomers studied the dynamic behavior of the galaxies they found that the gravity of the objects that they could see, i.e. the stars that shined, was not sufficient to account for the way galaxies moved. There had to be some form of missing mass, some kind of dark matter in galaxies in order to explain their dynamics.

The Rotation speeds of stars in the spiral arms of galaxies, top curve, do not fit the expected speeds based on the matter that we can see, bottom curve. Dark Matter is the generic term for whatever was causing the difference. (Credit: Wikipedia)


Back in the 1980s when I was an undergraduate the ideas about Dark Matter had basically coalesced into two types of matter. These two classes of matter were given the corny names of Machos, meaning Mass Concentrations, and WIMPS meaning Weakly Interacting Massive Particles. Mass Concentrations were thought to be composed of ordinary particles like protons, neutrons and electrons and could be anything from small black holes to dark stars, given the name brown dwarfs, or even smaller objects like planets.

Too small to be a star yet too big to be a planet the question is, just how many Brown Dwarfs are there in the spaces between the stars? (Credit: Space News)


Now astronomers didn’t like the idea of having to look between the stars for small objects that didn’t shine by their own light, so they didn’t like Machos. Let’s face it telescopes are the main tool of astronomers and telescopes gather light from objects that shine like stars.

Telescopes gather a large amount of light, more than our eyes do, as well as magnifying an image. But objects that don’t emit or reflect light can’t be seen in a telescope no matter how powerful it is! (Credit: Meade)


On the other hand physicists loved the idea of WIMPs because at the time they were coming up theories of ‘Supersymmetry’ that predicted the existence of a large number of massive particles some of which could be WIMPs. So starting in the 1990s Machos were largely ignored while everybody went looking for WIMPs either in outer space or at the big atom smashers like the Tevatron at Fermilab or the new Large Hadron Collider at CERN.

Physicists are searching for ‘Physics beyond the Standard Model’. Some of that physics could be Dark Matter. (Credit: Phys.org)


Problem is that after thirty years of searching no particles that could be WIMPs have been found. And now it seems that the wind has shifted and maybe it’s time to take another look at Machos.

The James Webb Space Telescope is designed to observe the Universe in the infrared portion of the EM spectrum. This will enable it to search for both Brown Dwarfs and Rogue Planets helping astronomers get a better idea of their numbers. (Credit: Space.com)


For one thing astronomers have new, bigger, better instruments that are more capable of looking for objects that don’t shine at visible wavelengths. Just a few months ago I published a post about how astronomers are beginning to discover large numbers of Brown Dwarf stars, objects too big to be called planets but too small to ignite nuclear fusion in their cores so they do not shine like a star. See my post of 22 September 2021.

Just a few of the observatory domes that make up the European Southern Observatory high in the mountains of Chile. (Credit: Physics World)


Now a new study from the European Southern Observatory in Chile and Bordeaux University has announced the discovery of as many as 170 rouge planets, that is planets that do not orbit any star but rather move through the Milky Way all on their own. The rogue planets were discovered in a star forming region of the galaxy relativity close to our solar system in the constellations of Scorpius and Ophiuchus.

As one of the zodiacal signs Scorpius is a well known constellation but nearby Ophiuchus is also a very interesting part of the sky. The stellar nursery where the Rogue Planets were discovered lays between these two constellations. (Credit: International Astronomical Union)


It was the fact that the rogue planets were very young, and therefore still warm that enabled the astronomers to find them in the infrared region of the electromagnetic spectrum. Even so the astronomers at Bordeaux had to shift through observations accumulated over 20 years and still aren’t certain how many rogue planets they’ve found, the best estimate being 70 to 170 Jupiter sized worlds.

How many Rogue Planets are out there? It’s difficult to say because, once they’ve cooled down from their formation they are nearly impossible to find! (Credit: The Verge)


Still if the star forming regions in space are also producing large numbers of solitary planets who knows how many older rogue planets there could be between the stars. Could there be as many rogue planets as there are stars? Or maybe even more? Finding out just how many rogue planets there really are could be a difficult task, remember once the planet cools down like our earth did after a few million years they’ll be almost impossible to find.

Actual image of a Rogue Planet that is so young that it is still warm enough to be visible. (Credit: Colorado College Sites)


And there’s one more candidate for a Macho because the possibility that there could be large numbers of small, ‘primordial’ black holes in the Universe is once again being seriously discussed. These would be black holes with a mass that of a planet that formed in the first seconds after the big bang and have just been floating around ever since then. Such black holes would also be very difficult to find, unless of course one of them came inside our solar system.

Primordial Black Holes could have been formed a millionth of a second after the Big Bang. How many are out there? Your guess is as good as mine. (Credit: Owlcation)


So maybe we don’t need physics beyond the standard model in order to explain Dark Matter. If there are a lot more Brown Dwarfs than we ever imagined, more Rogue Planets and more primordial Black Holes maybe Dark Matter is just protons, neutrons and electrons in objects that don’t shine by their own light.
Machos may not be as exciting as WIMPs, but reality is what it is and after thirty years of failing to find any exotic elementary particles maybe we need to give Machos a rethink!