4 ms·

Astronomers uncover largest group of rogue planets yet

88 points by LinuxBender 5y ago

addaon 5y ago
Do these form like stars (as the primary mass in a cloud collapse?), or do they form like solar planets (secondary masses around a star) and get ejected? If the former, is there any mechanism for ejecting light elements to produce something like a terrestrial planet or are these inherently gas planets?
- stevenpetryk 5y ago
  From the article: > Some scientists believe rogue planets can form from the collapse of a gas cloud that is too small to lead to the formation of a star, or that they could have been kicked out from their parent system. But which mechanism is more likely remains unknown.
  - addaon 5y ago
    Not sure how I missed this, thanks! Am I correct that the latter mechanism can lead to a wider variety of planet compositions, since you have the wind off the forming star to blow off lightweight layers depending on how close to the star formation happens?
akiselev 5y ago
I'm kind of burned out on exoplanet discoveries since they're a dime a dozen nowadays but this title caught my eye because I've been rewatching Star Trek DS9 recently. The antagonist in the latter half of the series is the Dominion empire which is unilaterally controlled by a race of hivemind-y shapeshifters called the Changelings. The only time we get to see most of their species is on their home world, a rogue planet somewhere in the gamma quadrant. I've been fascinated by the idea of detecting rogue planets ever since and it's incredible they found so many. Unfortunately, it looks like their detection method might not be useful for older (billion+) or rocky planets (from the footnote): > The exact number of rogue planets found by the team is hard to pin down because the observations don't allow the researchers to measure the masses of the probed objects. Objects with masses higher than about 13 times the mass of Jupiter are most likely not planets, so they cannot be included in the count. However, since the team didn't have values for the mass, they had to rely on studying the planets' brightness to provide an upper limit to the number of rogue planets observed. The brightness is, in turn, related to the age of the planets themselves, as the older the planet, the longer it has been cooling down and reducing in brightness. If the studied region is old, then the brightest objects in the sample are likely above 13 Jupiter masses, and below if the region is on the younger side. Given the uncertainty in the age of the study region, this method gives a rogue planet count of between 70 and 170. That said, this is exciting news! > The study suggests there could be many more of these elusive, starless planets that we have yet to discover. "There could be several billions of these free-floating giant planets roaming freely in the Milky Way without a host star," Bouy explains.
- Jeff_Brown 5y ago
  Above 13 Jupiter masses would it have to be a burned out star?
  - TheOtherHobbes 5y ago
    Brown dwarf? Some sputtering early attempts at fusion, but not enough to become self-sustaining. 13 Mj is on the low side of the definition. It's not a definitive number and goes as high as 80 Mj, depending who you ask.
    - wumpus 5y ago
      13 Mj is the current mass at which people think deuterium fusion can start. Above 80 Mj, hydrogen fusion will start. These numbers depend on a lot of details of stellar atmospheres. I took a graduate-level Stellar Atmospheres class from S. Kumar, who first theorized about this class of not-quite-star.
TaylorAlexander 5y ago
I’m imagining at least one rogue planet out there (they said they could be billions) was happily orbiting a star for billions of years, life formed, even relatively intelligent life, and then another rogue planet fell in to the solar system and passed right by the first planet in such a way as to eject it from the solar system without hitting it, and all this life on the planet suddenly loses daylight as their planet flies off in to deep space. And now their ancient civilization is frozen in time, adrift in deep space.
- rd07 5y ago
  This could be a scenario for a doomsday movie. On another note, I wonder if our solar system has been visited by such rogue planet in the past.
  - LargoLasskhyfv 5y ago
    Not exactly the same, but similar: https://en.wikipedia.org/wiki/The_Wandering_Earth https://en.wikipedia.org/wiki/The_Wandering_Earth
- wumpus 5y ago
  https://en.wikipedia.org/wiki/A_Pail_of_Air https://en.wikipedia.org/wiki/A_Pail_of_Air full text: https://www.gutenberg.org/ebooks/51461 https://www.gutenberg.org/ebooks/51461
  - TaylorAlexander 5y ago
    wow very cool thank you!
  - deleted 5y ago
    [deleted]
  - perl4ever 5y ago
    Since you mentioned that before me, I'm going to link: https://en.wikipedia.org/wiki/Worlds_in_Collision https://en.wikipedia.org/wiki/Worlds_in_Collision It may not be very good as science fiction, but it's an interesting historical/social phenomenon.
JoeAltmaier 5y ago
I imagine most planets might be rogue. Stellar formation is incredibly energetic and violent. That any planets remain in stable arrangements is amazing.
fernly 5y ago
Would not a "group of rogue planets" more properly be called a "gang"?
- soneca 5y ago
  I thought it would be a guild of planets
- robbedpeter 5y ago
  Rogues Gallery, maybe? https://en.wikipedia.org/wiki/Rogues%27_gallery https://en.wikipedia.org/wiki/Rogues%27_gallery
almostdeadguy 5y ago
Only tangentially related, but Melancholia is a beautiful (and uh melancholic) movie about a rogue planet that perfectly captures a prevailing mood about our present moment: https://en.wikipedia.org/wiki/Melancholia_(2011_film) https://en.wikipedia.org/wiki/Melancholia_(2011_film) Not that we ever actually have to worry about a collision with a rogue planet.
hffft 5y ago
Does that mean the universe is still considered "new"?
ineedasername 5y ago
I wasn't aware that planets could have traditional RPG roles. Whatever class Earth chose, it really needs to roll a 20 right now. More in topic, I really like the idea of random planets floating the void on their own. I'd be really curious about they have a unique composition. Although the lack of an external energy source probably means there wouldn't be much potential for activity.

88 points by LinuxBender 5y ago

Do these form like stars (as the primary mass in a cloud collapse?), or do they form like solar planets (secondary masses around a star) and get ejected? If the former, is there any mechanism for ejecting light elements to produce something like a terrestrial planet or are these inherently gas planets?

stevenpetryk 5y ago
From the article: > Some scientists believe rogue planets can form from the collapse of a gas cloud that is too small to lead to the formation of a star, or that they could have been kicked out from their parent system. But which mechanism is more likely remains unknown.
- addaon 5y ago
  Not sure how I missed this, thanks! Am I correct that the latter mechanism can lead to a wider variety of planet compositions, since you have the wind off the forming star to blow off lightweight layers depending on how close to the star formation happens?

akiselev 5y ago

I'm kind of burned out on exoplanet discoveries since they're a dime a dozen nowadays but this title caught my eye because I've been rewatching Star Trek DS9 recently. The antagonist in the latter half of the series is the Dominion empire which is unilaterally controlled by a race of hivemind-y shapeshifters called the Changelings. The only time we get to see most of their species is on their home world, a rogue planet somewhere in the gamma quadrant. I've been fascinated by the idea of detecting rogue planets ever since and it's incredible they found so many. Unfortunately, it looks like their detection method might not be useful for older (billion+) or rocky planets (from the footnote): > The exact number of rogue planets found by the team is hard to pin down because the observations don't allow the researchers to measure the masses of the probed objects. Objects with masses higher than about 13 times the mass of Jupiter are most likely not planets, so they cannot be included in the count. However, since the team didn't have values for the mass, they had to rely on studying the planets' brightness to provide an upper limit to the number of rogue planets observed. The brightness is, in turn, related to the age of the planets themselves, as the older the planet, the longer it has been cooling down and reducing in brightness. If the studied region is old, then the brightest objects in the sample are likely above 13 Jupiter masses, and below if the region is on the younger side. Given the uncertainty in the age of the study region, this method gives a rogue planet count of between 70 and 170. That said, this is exciting news! > The study suggests there could be many more of these elusive, starless planets that we have yet to discover. "There could be several billions of these free-floating giant planets roaming freely in the Milky Way without a host star," Bouy explains.

Jeff_Brown 5y ago
Above 13 Jupiter masses would it have to be a burned out star?
- TheOtherHobbes 5y ago
  Brown dwarf? Some sputtering early attempts at fusion, but not enough to become self-sustaining. 13 Mj is on the low side of the definition. It's not a definitive number and goes as high as 80 Mj, depending who you ask.
  - wumpus 5y ago
    13 Mj is the current mass at which people think deuterium fusion can start. Above 80 Mj, hydrogen fusion will start. These numbers depend on a lot of details of stellar atmospheres. I took a graduate-level Stellar Atmospheres class from S. Kumar, who first theorized about this class of not-quite-star.

TaylorAlexander 5y ago

I’m imagining at least one rogue planet out there (they said they could be billions) was happily orbiting a star for billions of years, life formed, even relatively intelligent life, and then another rogue planet fell in to the solar system and passed right by the first planet in such a way as to eject it from the solar system without hitting it, and all this life on the planet suddenly loses daylight as their planet flies off in to deep space. And now their ancient civilization is frozen in time, adrift in deep space.

rd07 5y ago
This could be a scenario for a doomsday movie. On another note, I wonder if our solar system has been visited by such rogue planet in the past.
- LargoLasskhyfv 5y ago
  Not exactly the same, but similar: https://en.wikipedia.org/wiki/The_Wandering_Earth https://en.wikipedia.org/wiki/The_Wandering_Earth
wumpus 5y ago
https://en.wikipedia.org/wiki/A_Pail_of_Air https://en.wikipedia.org/wiki/A_Pail_of_Air full text: https://www.gutenberg.org/ebooks/51461 https://www.gutenberg.org/ebooks/51461
- TaylorAlexander 5y ago
  wow very cool thank you!
- deleted 5y ago
  [deleted]
- perl4ever 5y ago
  Since you mentioned that before me, I'm going to link: https://en.wikipedia.org/wiki/Worlds_in_Collision https://en.wikipedia.org/wiki/Worlds_in_Collision It may not be very good as science fiction, but it's an interesting historical/social phenomenon.

JoeAltmaier 5y ago

I imagine most planets might be rogue. Stellar formation is incredibly energetic and violent. That any planets remain in stable arrangements is amazing.

fernly 5y ago

Would not a "group of rogue planets" more properly be called a "gang"?

soneca 5y ago
I thought it would be a guild of planets
robbedpeter 5y ago
Rogues Gallery, maybe? https://en.wikipedia.org/wiki/Rogues%27_gallery https://en.wikipedia.org/wiki/Rogues%27_gallery

almostdeadguy 5y ago

Only tangentially related, but Melancholia is a beautiful (and uh melancholic) movie about a rogue planet that perfectly captures a prevailing mood about our present moment: https://en.wikipedia.org/wiki/Melancholia_(2011_film) https://en.wikipedia.org/wiki/Melancholia_(2011_film) Not that we ever actually have to worry about a collision with a rogue planet.

hffft 5y ago

Does that mean the universe is still considered "new"?

ineedasername 5y ago

I wasn't aware that planets could have traditional RPG roles. Whatever class Earth chose, it really needs to roll a 20 right now. More in topic, I really like the idea of random planets floating the void on their own. I'd be really curious about they have a unique composition. Although the lack of an external energy source probably means there wouldn't be much potential for activity.