4 ms·

'Metallicity' in that sense is used to describe stars and the Sun, being a relatively young star is metal rich. Edit: 'young' is confusing here as pointed out

by pvg 3y ago

'Metallicity' in that sense is used to describe stars and the Sun, being a relatively young star is metal rich. Edit: 'young' is confusing here as pointed out in sibling comments - young compared to the age of the universe rather than young in terms of stage of stellar evolution. To make this even more confusing, this is 'population I' - younger and more metal rich unlike older, metal-poor 'population II' stars. https://en.wikipedia.org/wiki/Stellar_population#Chemical_classification_by_Baade https://en.wikipedia.org/wiki/Stellar_population#Chemical_cl...

vlovich123 3y ago
Ah ok. So this is about the composition of just the star and not anything about the broader system.
- pvg 3y ago
  Yeah although like most things in exoplanetary astronomy, the relationship between metallicity and planetary systems is an area of active research with various not-totally-intuitive findings: https://www.space.com/31456-rocky-planet-found-unlikely-star.html https://www.space.com/31456-rocky-planet-found-unlikely-star... https://www.nature.com/articles/s41467-023-37195-4 https://www.nature.com/articles/s41467-023-37195-4
  - spookie 3y ago
    That Neptune sized planet sure is close to its star. Interesting
    - pvg 3y ago
      Oh they get even bigger and closer and we've seen a bunch of those because they're more readily detectable: https://en.wikipedia.org/wiki/Hot_Jupiter https://en.wikipedia.org/wiki/Hot_Jupiter
- defrost 3y ago
  Almost pretty much the same thing really. Consider that our sun contains 99.86% of the mass of our Solar System. Bear in mind the headline is about total spectrum of elements in entire galaxies ... eg: as in looking at our galaxy, the entire milky way, from a distance that makes it dwindle to a near point and difficult to estimate how many stars make it up. Of all the many galaxies that we can see, this is a story about a handful that are mostly hydrogen and helium .. more so than what we see as typical for galaxies.
  - pvg 3y ago
    Almost pretty much the same thing really. Consider that our sun contains 99.86% of the mass of our Solar System. If you dumped that into a Sun-sized metal-poor star, it would probably pass for metal-rich.
    - defrost 3y ago
      Given our sun is a population I or heavy-element-rich star that'd almost certainly be the case ... the elements that didn't fall into our sun to make it so remained in orbit and are also heavy element rich (obviously relatively more so that the mostly H-He sun). A Sun sized metal poor star wouldn't be surrounded by large amounts of orbiting heavy elements .. that would suggest even larger amounts failed to orbit and fell into that star. ( I'll freely confess to being decades out of date on the conjectured life of stars though, these days I mainly do geophysics related to astrophysics (cancelling out ground effects from SKA type projects) )
      - pvg 3y ago
        Oh I just meant that amount of metal for some (entirely made up) stars would already be pretty metal. The sort of astro out of an Asimov joke story. But as the black hole approached, Hieronymus noted there was no gravitational effect. He studied it more closely and announced, with a chuckle, that it was not a black hole after all. “It’s nothing,” he said. “Just an ordinary asteroid someone has painted black.”
        3y ago

by pvg 3y ago

vlovich123 3y ago

Ah ok. So this is about the composition of just the star and not anything about the broader system.

pvg 3y ago
Yeah although like most things in exoplanetary astronomy, the relationship between metallicity and planetary systems is an area of active research with various not-totally-intuitive findings: https://www.space.com/31456-rocky-planet-found-unlikely-star.html https://www.space.com/31456-rocky-planet-found-unlikely-star... https://www.nature.com/articles/s41467-023-37195-4 https://www.nature.com/articles/s41467-023-37195-4
- spookie 3y ago
  That Neptune sized planet sure is close to its star. Interesting
  - pvg 3y ago
    Oh they get even bigger and closer and we've seen a bunch of those because they're more readily detectable: https://en.wikipedia.org/wiki/Hot_Jupiter https://en.wikipedia.org/wiki/Hot_Jupiter
defrost 3y ago
Almost pretty much the same thing really. Consider that our sun contains 99.86% of the mass of our Solar System. Bear in mind the headline is about total spectrum of elements in entire galaxies ... eg: as in looking at our galaxy, the entire milky way, from a distance that makes it dwindle to a near point and difficult to estimate how many stars make it up. Of all the many galaxies that we can see, this is a story about a handful that are mostly hydrogen and helium .. more so than what we see as typical for galaxies.
- pvg 3y ago
  Almost pretty much the same thing really. Consider that our sun contains 99.86% of the mass of our Solar System. If you dumped that into a Sun-sized metal-poor star, it would probably pass for metal-rich.
  - defrost 3y ago
    Given our sun is a population I or heavy-element-rich star that'd almost certainly be the case ... the elements that didn't fall into our sun to make it so remained in orbit and are also heavy element rich (obviously relatively more so that the mostly H-He sun). A Sun sized metal poor star wouldn't be surrounded by large amounts of orbiting heavy elements .. that would suggest even larger amounts failed to orbit and fell into that star. ( I'll freely confess to being decades out of date on the conjectured life of stars though, these days I mainly do geophysics related to astrophysics (cancelling out ground effects from SKA type projects) )
    - pvg 3y ago
      Oh I just meant that amount of metal for some (entirely made up) stars would already be pretty metal. The sort of astro out of an Asimov joke story. But as the black hole approached, Hieronymus noted there was no gravitational effect. He studied it more closely and announced, with a chuckle, that it was not a black hole after all. “It’s nothing,” he said. “Just an ordinary asteroid someone has painted black.”
      - 3y ago