[HN Gopher] Stars may form 10 times faster than thought
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Stars may form 10 times faster than thought
Author : rustoo
Score : 26 points
Date : 2022-01-05 20:41 UTC (2 hours ago)
(HTM) web link (www.science.org)
(TXT) w3m dump (www.science.org)
| 37 wrote:
| >But observations using the world's largest radio telescope are
| casting doubt on this long gestational period. Researchers have
| zoomed in on a prestellar core in a giant gas cloud--a nursery
| for hundreds of baby stars--and found the tiny embryo may be
| forming 10 times faster than thought, thanks to weak magnetic
| fields.
|
| I'm sure this has been taken into account already (by actual
| scientists much smarter than me) but, how do we know it isn't
| dark matter causing the collapse to happen faster than thought?
| Seems like a reasonable question to me. Lack of gravitational
| lensing?
|
| (edit:) Also
|
| >thanks to weak magnetic fields ... Zeeman effect etc
|
| This is a bit questionable to me. I understand the Zeeman effect,
| or thought I did, but I don't understand how it can be thanks to
| a "weak" magnetic field.
| pdonis wrote:
| _> how do we know it isn 't dark matter causing the collapse to
| happen faster than thought?_
|
| The average density of dark matter is way too small. It's
| significant on the scale of a galaxy because it doesn't clump,
| so its density is basically the average density everywhere
| (denser towards the center and less dense further out, but
| still of the same rough order of magnitude), instead of being
| isolated clumps surrounded by huge expanses of empty space, as
| with ordinary matter. But on the scale of a single stellar
| system the density of dark matter is so small that its effect
| on the dynamics is negligible.
| hsnewman wrote:
| Then again, they may not form 10 times faster than thought.
| 37 wrote:
| One order of magnitude off doesn't seem too bad of an original
| prediction
| literallyaduck wrote:
| It is still a long way away from 6,000 years.
| 37 wrote:
| This led me to thinking, how do we determine the age of the sun?
| I would have thought some radio spectrometry, but according to
| NASA[0]:
|
| >We look at the age of the whole solar system, because it all
| came together around the same time.
|
| >To get this number, we look for the oldest things we can find.
| Moon rocks work well for this. When astronauts brought them back
| for scientists to study them, they were able to find out how old
| they are.
|
| [0] https://spaceplace.nasa.gov/sun-age/en/
| politician wrote:
| Isn't it kind of weird to use the Moon to benchmark the age of
| the solar system when it's well known that the Moon formed
| after another body collided with the Earth? The Moon is younger
| than the Earth.
| tshaddox wrote:
| I assume it's because the Moon is geologically inactive and
| thus the rocks we got from the surface are expected to be
| essentially as old as the Moon itself.
| pdonis wrote:
| Not to benchmark, precisely, but to give a lower limit on the
| age that will likely be longer than any other lower limit we
| could obtain at our current or near future level of
| technology.
| sokoloff wrote:
| That led me down a "how did they date the moon rocks?" thread,
| which led me to this explanation:
| https://www.sciencealert.com/we-finally-know-the-precise-age...
| 37 wrote:
| >researchers say they've finally pinpointed the exact age of
| the Moon
|
| Hmm, sounds dubious, but I will read on. A short while later
| it leads me to the paper[0] and I spend a few more minutes on
| that, finding myself asking: how do we know the zircon
| fragments aren't from a meteor that is much older? Surely all
| the fragments came from approximately the same area, yes? Or
| maybe not?
|
| But nah, these knowledgeable astronomers must have already
| thought of all this stuff.
|
| Astronomy is just filled with rabbit holes I guess.
|
| [0] https://www.science.org/doi/10.1126/sciadv.1602365
| kfarr wrote:
| Just wait until you hear how astronomers date the
| approximate age of rabbit holes...
| pdonis wrote:
| _> how do we know the zircon fragments aren 't from a
| meteor that is much older?_
|
| Radiometric dating tells you _when the sample you are
| dating last solidified_. Of course the atoms in the sample
| themselves existed before that, but that doesn 't matter
| for radiometric dating since what is being measured is not
| the age of the atoms but the time the sample, the piece of
| rock you're analyzing, last solidified.
|
| _> Surely all the fragments came from approximately the
| same area, yes?_
|
| Um, yes, since the Apollo 14 astronauts only collected
| samples from a very small area.
|
| _> nah, these knowledgeable astronomers must have already
| thought of all this stuff._
|
| Yes, in fact, they have, plus a lot more things that
| haven't even occurred to you.
| smm11 wrote:
| So I might be able to notice a .00000001 percent change in my
| lifetime. Cool.
| glennonymous wrote:
| Not a scientist. But if this is true, would it imply that A) the
| universe is younger than we thought, or B) there was a much
| longer time between the Big Bang and the formation of the first
| stars? Seems to have very major cosmological implications.
| glennonymous wrote:
| Upon five more minutes' consideration, I thought of several
| reasons why this would probably not imply either of the things
| I suggested it might imply. But my larger question is: What, if
| any, would be the larger cosmological implications of this
| discovery?
| tuatoru wrote:
| Yes, according to this StackExchange answer[1] star formation
| _was_ thought to take around 10 million years (for low-mass
| stars - less for big stars).
|
| That would be a rounding error on a reasonably precise and
| accurate estimate of the age of the universe (which I don't
| think we have yet.)
|
| As for cosmological/other physical implications, it's a
| "well, now we know more" result.
|
| 1. https://astronomy.stackexchange.com/questions/156/how-
| long-d...
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