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Astronomers may have found the first exomoon

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Re: Astronomers may have found the first exomoon

#21

Post by catigula »

benabbott wrote: post #5

this would actually be a planet, based on my understanding of celestial bodies? moons are natural satellites orbiting planets. this "moon" is orbiting a brown dwarf.

>According to the IAU working definition (from August 2018) an exoplanet can orbit a brown dwarf. It requires a mass below 13 MJ and a mass ratio of M/Mcentral<2/(25+√{621}), or roughly 1/25. This means that an object with a mass up to 3.2 MJ around a brown dwarf with a mass of 80 MJ is considered a planet. It also means that an object with a mass up to 0.52 MJ around a brown dwarf with a mass of 13 MJ is considered a planet

Re: Astronomers may have found the first exomoon

#22

Post by delta_p_delta_x »

Worth noting that the artist's impression is... not accurate. Both CD-35 2722 b (the brown dwarf orbiting the primary star) and CD-35 2722 b I (the exomoon orbiting the secondary) should be much closer in size. It is estimated that Jupiter is essentially the largest any gas giant can get; adding more mass will simply increase density and interior temperature until deuterium and lithium fusion and brown dwarfdom, and then at around 80 Jupiter masses, protium fusion and stardom.

Look at Barnard's Star[1], which is actually a fusing red dwarf star: it is not much bigger than Jupiter.

[1]: https://en.wikipedia.org/wiki/Barnard%27s_Star

Re: Astronomers may have found the first exomoon

#24

Post by jayGlow »

bluGill wrote: post #19

I wonder if this thing in turn has something in orbit around it? At the size I wouldn't surprise me if it had satellites of its own in orbit, leaving open the question of what to call them. (I'm no astrophysicist, is this really possible I don't know, but it wouldn't surprise me. What would surprise me is if we could detect them)

I had to look it up and it is theoretically possible, they could be called sub moons or moonmoon. I'm partial to the name moonmoon personally.

Re: Astronomers may have found the first exomoon

#25

Post by _joel »

Brown dwarfs fascinate me, they can be at room temperature (range from about 2,800 K down to 250 K (roughly 2,500 °C to -23 °C / 4,500 °F to -10 °F)

You could basically have a bath in a brown dwarf, sure you might not last long, but still...

Re: Astronomers may have found the first exomoon

#26

Post by Someone »

bluGill wrote: post #19

I wonder if this thing in turn has something in orbit around it? At the size I wouldn't surprise me if it had satellites of its own in orbit, leaving open the question of what to call them. (I'm no astrophysicist, is this really possible I don't know, but it wouldn't surprise me. What would surprise me is if we could detect them)

https://en.wikipedia.org/wiki/Subsatellite:

“A subsatellite, also known as a submoon, moonlet or informally a moonmoon, is a "moon of a moon" or a hypothetical natural satellite that orbits the moon of a planet”

Re: Astronomers may have found the first exomoon

#27

Post by PaulHoule »

delta_p_delta_x wrote: post #22

Worth noting that the artist's impression is... not accurate. Both CD-35 2722 b (the brown dwarf orbiting the primary star) and CD-35 2722 b I (the exomoon orbiting the secondary) should be much closer in size. It is estimated that Jupiter is essentially the largest any gas giant can get; adding more mass will simply increase density and interior temperature until deuterium and lithium fusion and brown dwarfdom, and…

Nice charts in this paper that support this thesis

https://pmc.ncbi.nlm.nih.gov/articles/PMC6525489/

Re: Astronomers may have found the first exomoon

#28

Post by walrus01 »

delta_p_delta_x wrote: post #22

Worth noting that the artist's impression is... not accurate. Both CD-35 2722 b (the brown dwarf orbiting the primary star) and CD-35 2722 b I (the exomoon orbiting the secondary) should be much closer in size. It is estimated that Jupiter is essentially the largest any gas giant can get; adding more mass will simply increase density and interior temperature until deuterium and lithium fusion and brown dwarfdom, and…

> It is estimated that Jupiter is essentially the largest any gas giant can get

That does not appear to be the case if we mean mass, not diameter.

https://en.wikipedia.org/wiki/Super-Jupiter

https://en.wikipedia.org/wiki/CoRoT-3b

Re: Astronomers may have found the first exomoon

#29

Post by Foskya »

walrus01 wrote: post #28
delta_p_delta_x wrote: post #22

Worth noting that the artist's impression is... not accurate. Both CD-35 2722 b (the brown dwarf orbiting the primary star) and CD-35 2722 b I (the exomoon orbiting the secondary) should be much closer in size. It is estimated that Jupiter is essentially the largest any gas giant can get; adding more mass will simply increase density and interior temperature until deuterium and lithium fusion and brown dwarfdom, and…

> It is estimated that Jupiter is essentially the largest any gas giant can get That does not appear to be the case if we mean mass, not diameter. https://en.wikipedia.org/wiki/Super-Jupiter https://en.wikipedia.org/wiki/CoRoT-3b

But... he literally said in the following sentence that adding more mass does not change size, implying that he is talking about diameter, not mass.

Re: Astronomers may have found the first exomoon

#30

Post by astrolx »

molf wrote: post #7
pelagicAustral wrote: post #3

I know this is besides the article and all, but why would the Chilean flag be the only one to have 8px left margin? This is killing me...

I believe such organisations tend to do such things very intentionally :-) About ESO [1] > We are an intergovernmental organisation established in 1962 supported by 16 Member States (Austria, Belgium, Czechia, Denmark, Finland, France, Germany, Ireland, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom), our host country Chile and strategic partners. So Chile has a distinct s…

Exactly. Chile has a special status as host country of the observatory!
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