Asteroids: Fun facts and information about asteroids

rod

Oct 22, 2019
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Good reporting and information summaries here. Modeling asteroid orbits for NEA/NEOs, main belt, and Centaurs for example is challenging. Main belt asteroids could orbit with a period near 4.4 years so in one billion years, could complete more than 227 million revolutions around the Sun. Now another new report indicates the early solar system protoplanetary disk likely had a gap in it based upon meteorite studies.

Scientists find evidence the early solar system harbored a gap between its inner and outer regions, https://phys.org/news/2021-10-scientists-evidence-early-solar-harbored.html
Reference paper, Paleomagnetic evidence for a disk substructure in the early solar system, https://www.science.org/doi/10.1126/sciadv.abj6928, 15-Oct-2021. My observation. The paper discusses the model developed, it is interesting and detailed. Different model rates of accretion are presented too showing different accretion rates in different parts of the postulated, solar system protoplanetary disk. Different areas in the early solar system accretion disk or protoplanetary disk could have accretion rates 1 x 10^-5 Msun yr^-1, 4 x 10^-9 Msun yr^-1 and 1 x 10^-7 Msun yr^-1. If a proto-Jupiter is used in the model, Jupiter could form in 10,000 years but this is not desired 😊 Using an accretion rate of 1 x 10^-5 Msun yr^-1, 3.33 earth mass per year could accrete in the early protoplanetary disk in our solar system. Using a minimum solar disk mass of 3300 earth masses, the early solar system accretion disk can disappear <= 1,000 years. So explaining the present population of asteroids documented today is no easy job, especially when considering protoplanetary disk models in use. Even the Moon forming giant impact scenario now seems to need at least two impacts to explain but this also opens the door to other challenging issues in the spinning, protoplanetary disk model used to show how our solar system evolved from a gas cloud. TWO IMPACTS, NOT JUST ONE, MAY HAVE FORMED THE MOON, https://skyandtelescope.org/astronomy-news/two-impacts-not-just-one-may-have-formed-the-moon/

There is plenty of juggling going on in the models developed to explain how we evolved from a gas cloud today :)
 
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Jun 1, 2020
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There is plenty of juggling going on in the models developed to explain how we evolved from a gas cloud today :)
Yes, an accurate model must explain all orbits for all the objects. Two models come close, including the NICE model.

However, the evidence that clouds contract to form stars and planets is abundant, both in theory and observation. It took radio and IR astronomy to have any real observational evidence, but we now have that.
 
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rod

Oct 22, 2019
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Helio, in reference to your post #3. When it comes to observations of gas clouds evolving into stars and planets (and later people), as I understand astronomy, no one has watched a gas cloud form a ZAMS and planet(s) appear from them, such evolution takes much too long apparently :). Computer simulations do not start with the dust grains and show all the steps how it grows into the planets we see today (current masses) in our solar system and their present orbits as well as any moons documented (set aside the asteroids). This is becoming very apparent now in the detailed, reports on the simulations released that I read and keep track of in my home database. What we have is a long chain of postulated events in the past with little or no repeatable science in the present in my view. A good example is observing Theia form some place in the protoplanetary disk away from the proto-earth, and migrate around only later to hit the proto-earth without destroying everything creating a lunar disk (that can quickly disappear too) and now, perhaps a return giant impact is needed, otherwise more problems arise in the giant impact scenario. We can look at exoplanets and *observe* about 45% are hot jupiters and planets like super-earths orbiting their parent stars near or closer than where Mercury orbits in our solar system. We do not see any configuration like this in our solar system and these other exoplanet types orbiting close in are found around stars ranging from 0.2 solar mass up to 2 solar mass or a bit more. While radio and IR astronomy have done much, it is clear the gas cloud paradigm with spinning accretion disk has holes in it, especially when evaluated using our solar system or hot jupiters that could complete more than 100 billion revolutions around their parent star in a one billion year period, and perhaps hundreds of billions of revolutions may be needed too for some hot jupiters. Holes and anomalies should be documented and disclosed if we are practicing the scientific method and not some philosophy of origins tossed around today.
 
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