14 ms·
Stars may form 10 times faster than thought
- hsnewman 5y agoThen again, they may not form 10 times faster than thought.
- dr_dshiv 5y agoI think I think faster than stars form, right?
- 37 5y agoOne order of magnitude off doesn't seem too bad of an original prediction
- 37 5y agoThis 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/ https://spaceplace.nasa.gov/sun-age/en/
- politician 5y agoIsn'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 5y agoI 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 5y agoNot 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.
- vlovich123 5y agoIf Theia is older than the Earth, then wouldn't the Moon also be older?
- politician 5y agoAIUI, the heat of the collision would've melted everything that wasn't already molten. Any "age" information would be lost as the system cooled. At least, that's my understanding from playing with Universe Sandbox.
- vlovich123 5y agoThat would only be the case for the piece that collided though right? The side that wasn’t part of the collision should have retained its age information. Also, presumably Theia didn’t bounce off but just merged with the moon being formed from the piece of Earth on the opposite side from the collision that got ejected, right? So at most half the moon surface should be from the collision and half of it should have the age of the Earth?
- treeman79 5y agoMoon is a mix of earth and theia. So is Earth. So sort of like a strawberry banana smoothie in two cups. Core of Theia sunk into Earth and there is some recent imaging showing what may be the second core. https://www.iflscience.com/environment/fragments-of-the-planet-that-formed-the-moon-may-be-buried-by-the-earths-core/ https://www.iflscience.com/environment/fragments-of-the-plan...
- jacquesm 5y agoTheia is - for now - a hypothesis, not an established fact.
- sokoloff 5y agoThat 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-of-the-moon-thanks-to-apollo-14-moon-rocks https://www.sciencealert.com/we-finally-know-the-precise-age...
- 37 5y ago>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 https://www.science.org/doi/10.1126/sciadv.1602365
- kfarr 5y agoJust wait until you hear how astronomers date the approximate age of rabbit holes…
- pdonis 5y ago> 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.
- jacquesm 5y ago> Yes, in fact, they have, plus a lot more things that haven't even occurred to you. Exactly. Like that comment about the JWST last week that was wondering why they didn't bring down the number of single-points-of-failure. Backseat driving at its best.
- 37 5y ago>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 5y ago> 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.
- dtgriscom 5y agoThe observations didn't measure the speed of the collapse; they measured the strength of the magnetic field which guides models of the collapse. Magnetic fields tend to slow the gas collapsing, so finding that the fields were lower than expected decreases the expected time of collapse.
- glennonymous 5y agoNot 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 5y agoUpon 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 5y agoYes, 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-does-it-take-to-produce-a-star-why-does-it-take-that-long https://astronomy.stackexchange.com/questions/156/how-long-d...
- omegalulw 5y ago> the universe is younger than we thought, Not really. Don't we estimate the age of the universe by estimating how redshifted the CMB is compared to what we would expect given initial conditions?
- literallyaduck 5y agoIt is still a long way away from 6,000 years.
- UncleOxidant 5y ago^ found Ken Ham.
- smm11 5y agoSo I might be able to notice a .00000001 percent change in my lifetime. Cool.
- peter303 5y agoThere was a hardcore "Revive Arecibo" workgroup at two recent astronomy conferences. That telescope made important data contributions up to the end, despite its age. Alas, probably a pipe dream, since NASA/NSF has limited funding for all the fantastic stuff in the pipeline already.
- UncleOxidant 5y agoMaybe there's also a realization that the location isn't ideal in a time of increasing hurricane activity due to climate change?
- bryanrasmussen 5y agoThe ambiguity of the English language can often be lessened via simple changes, such as: Stars may form 10 times faster than generally thought.