As I was peeking into habitability prospects for star-systems, I had occasion to appeal to the age of the star. I'd based a lot of that on events here on Earth. Let's list up some milestones as this blog has been alerted.
Where stellar-age is marked for a given K or G type, this is calculated from the Main Sequence of hydrogen fusion. That's also whence luminosity; from the baseline of 67.7%, to the 100% of today.
That 2001 paper further implies that we entered the Sequence like 30 million years prior to those first rocks. However: this looks like rounding-error. Our "T Tauri era" when Sol roasted out all its interior soot is, therefore, a "B.C." to this exercise.
... which exercise must be general. We are excluding the "Boring Billion", the abrupt core transitions, the 19-hour Moon lock, Ediacara, Cambrian or Chicxulub. I figure them for ludus naturae specific to this system, or Acts Of God. For all I know, the Lord G-d unpurpled our planet too; so, that's where we'll leave this count to the 'alamûn.
Also excluded: "Late Heavy Bombardment". It's untestable for Luna and didn't hit Vesta. I did however divert to Mars as a proxy for the water-ocean here on Earth too; it's a prerequisite for stromatolites. UPDATE 6/6: The water seems sudden upon the Earth, amidst nonmagnetism. This seems bombardic.
So, we're focused on the unbreathable Archaean. In millions of years:
- 0 - Cooling of first asteroids [4.567 Gya]
- 107 - Theia crash [4.46 Gya]
- 550 - Nonoceanic hydro cycle [4 Gya]
- 867 - Magnetic field starts [3.7 Gya; 75% L] - end of Mars' Noachian
- 867-1600 - Mars' Hesperian ocean [3.7-3 Gya]
- 1090 - Oceanic stromatolites [3.48 Gya]
- 1600-2100 - Cratons [3-2.5 Gya; 80% L]
- 1900 - CO2 measurement [2.7 Gya]
- 2107-2141 - Oxidation [2.460–2.426 Gya]
- 2300 - Free atmo oxygen [2.2 Gya]
For other systems: M dwarfs take longer to enter the main sequence. Its oldest (roasted) rocks will precede the start of the star's clock. I don't know about K except that its "goldilocks" status has been overstated.
In our future: 4800 My will occasion that last desert continent when the Sun be 102%. 5 My, we're steamworld although the core will probably keep us a nice cloudy Sudarsky II from a distance. 6 My, tectonics stall and we're fully Venereal.
No comments:
Post a Comment