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Astronomers may have spotted the smallest possible stars

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Re: Astronomers may have spotted the smallest possible stars

#11

Post by jessriedel »

JSteph22 wrote: post #5
jessriedel wrote: post #3

> But distinguishing between smaller brown dwarfs and planets requires looking at how they form. Even though they can end up about as massive as 10 Jupiters, planets always arise around a star, from its surrounding disk of gas and dust. > In contrast, stars, including brown dwarfs, form on their own within giant collapsing clouds of gas. Is this really the standard terminology? It’s not how I remember it, and it does…

As the article clearly points out several times by referencing the potential "upending of star formation theory" and the list of "brown dwarfs that shouldn't exist", current star and planetary formation theories are severely lacking, so you're right to question definitive statements such as stars forming "on their own".

I am questioning whether the article is accurately describing the scientific nomenclature. The author of course wants to say things are being “upended”, but I suspect the author just didn’t understand, or is inaccurately describing, the previous state of affairs.

Re: Astronomers may have spotted the smallest possible stars

#12

Post by jmclnx »

veunes wrote: post #2

Saturn-size brown dwarfs? Who would’ve thought!

Not sure what is meant by size ? IIRC, Saturn is kind of "fluffy" and could float on liquid water.

So a Brown Dwarf with the radius of Saturn, why not ? But its mass would probably be much greater than Saturn, but compressed down to Saturn's size :)

I thought I read somewhere a Brown Dwarf with 13x the mass of Jupiter would be about the same size as Jupiter.

Re: Astronomers may have spotted the smallest possible stars

#13

Post by aurelien »

Science.org is made without counsciouness in the way they force the reader to use javascript. But if you have really something to say, I would like to read it in Text WebBrowser only, I do not want to use crap web browser that are made to make you think you read something interesting. Pseudo journalism kill science.

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Re: Astronomers may have spotted the smallest possible stars

#14

Post by dylan604 »

munk-a wrote: post #10
goodcanadian wrote: post #7

Earlier quoted context omitted.

Is this really the standard terminology? Well, it is close enough. The definition is that a brown dwarf forms like a star through gravitational collapse within a protostellar nebula, but it just wasn't massive enough to ignite. However, a planet forms in an accretion disk around a star that is forming out of the larger cloud. Of course, nature does not always perfectly align itself within our neat categories, and it…

Does this also hold for rogue planets? I was under the impression that some rogue planets could form outside of any star's accretion disk.

But they did form in some star's accretion disc, just not the one they are roguing their way through. In theory, Jupiter could have caused a planet to go rogue when it made it's way to the inner solar system.

Re: Astronomers may have spotted the smallest possible stars

#15

Post by astrobe_ »

jmclnx wrote: post #12
veunes wrote: post #2

Saturn-size brown dwarfs? Who would’ve thought!

Not sure what is meant by size ? IIRC, Saturn is kind of "fluffy" and could float on liquid water. So a Brown Dwarf with the radius of Saturn, why not ? But its mass would probably be much greater than Saturn, but compressed down to Saturn's size :) I thought I read somewhere a Brown Dwarf with 13x the mass of Jupiter would be about the same size as Jupiter.

I remember that before the Shoemaker-Jupiter collision [1] of '95 there were rumors that it could "ignite" Jupiter giving birth to a star. It was probably on the same level as the rumors that the CERN accelerator could create a black hole, though.

[1] https://en.wikipedia.org/wiki/Comet_Shoemaker-Levy_9

Re: Astronomers may have spotted the smallest possible stars

#16

Post by s1artibartfast »

munk-a wrote: post #10
goodcanadian wrote: post #7

Earlier quoted context omitted.

Is this really the standard terminology? Well, it is close enough. The definition is that a brown dwarf forms like a star through gravitational collapse within a protostellar nebula, but it just wasn't massive enough to ignite. However, a planet forms in an accretion disk around a star that is forming out of the larger cloud. Of course, nature does not always perfectly align itself within our neat categories, and it…

Does this also hold for rogue planets? I was under the impression that some rogue planets could form outside of any star's accretion disk.

My understanding is that smaller rouge plants do not form in isolation and are always the product of ejection.

However, the categorization again is fuzzy, with definitional overlap between "planet", "sub-brown-dwarf", and "brown dwarfs"

Planets cover spherical objects ranging from 0.001 Jupiter masses to stars at ~80 Jupiter masses. Brown dwarfs range from 3-80 Jupiter masses.

Brown Dwarfs are planets and can form outside of an accretion disk. Planets smaller than brown dwarfs are not thought to be able to form outside of accretion disks.

Re: Astronomers may have spotted the smallest possible stars

#17

Post by Jerrrrrrry »

jessriedel wrote: post #11
JSteph22 wrote: post #5

Earlier quoted context omitted.

As the article clearly points out several times by referencing the potential "upending of star formation theory" and the list of "brown dwarfs that shouldn't exist", current star and planetary formation theories are severely lacking, so you're right to question definitive statements such as stars forming "on their own".

I am questioning whether the article is accurately describing the scientific nomenclature. The author of course wants to say things are being “upended”, but I suspect the author just didn’t understand, or is inaccurately describing, the previous state of affairs.

The nomenclature has shifted as we have found stars are make our "average white star," less average, less white, and less of a star.

The classification nomenclature is definitely in need of a refactoring.

Re: Astronomers may have spotted the smallest possible stars

#18

Post by numbol »

Just for pedantic remark, brown dwarfs is not stars, but they are substellar objects and formed in the similar fation (and this is why question about edge case of very large exoplanted vs very small brown dwarf is interestring)https://en.wikipedia.org/wiki/Substellar_object definition relies on sustained hydrogen fusion

Re: Astronomers may have spotted the smallest possible stars

#19

Post by veunes »

jmclnx wrote: post #12
veunes wrote: post #2

Saturn-size brown dwarfs? Who would’ve thought!

Not sure what is meant by size ? IIRC, Saturn is kind of "fluffy" and could float on liquid water. So a Brown Dwarf with the radius of Saturn, why not ? But its mass would probably be much greater than Saturn, but compressed down to Saturn's size :) I thought I read somewhere a Brown Dwarf with 13x the mass of Jupiter would be about the same size as Jupiter.

Yep, a 'Saturn-sized' brown dwarf would have Saturn's radius but vastly more mass

Re: Astronomers may have spotted the smallest possible stars

#20

Post by jessriedel »

goodcanadian wrote: post #7
jessriedel wrote: post #3

> But distinguishing between smaller brown dwarfs and planets requires looking at how they form. Even though they can end up about as massive as 10 Jupiters, planets always arise around a star, from its surrounding disk of gas and dust. > In contrast, stars, including brown dwarfs, form on their own within giant collapsing clouds of gas. Is this really the standard terminology? It’s not how I remember it, and it does…

Is this really the standard terminology? Well, it is close enough. The definition is that a brown dwarf forms like a star through gravitational collapse within a protostellar nebula, but it just wasn't massive enough to ignite. However, a planet forms in an accretion disk around a star that is forming out of the larger cloud. Of course, nature does not always perfectly align itself within our neat categories, and it…

> The definition is that a brown dwarf forms like a star through gravitational collapse within a protostellar nebula

Do you have a cite on that? (It conflicts with Wikipedia, for example.) In particular, I suspect that many people read something that describes how a certain type of star is thought to typically form and then interpret that as a definition.

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