A few astronomy questions.?

Question

Are planetary nebulae the most important source for elements heavier that iron due to them being the end point of the evolution of the most common types of stars, or are supernovae of very large stars more important for pumping heavier elements out into the cosmos ?

and will a star of 2 solar masses always have a higher luminosit than a star of 1 solar mass, i'd imagine it would do, but then again i'm not too sure whether the composition of the star is more important to the luminosity ?

Thanks.

Answer 1

A planetary nebula is an astronomical object consisting of a glowing shell of gas and plasma formed by certain types of stars at the end of their lives. The name originates from a similarity in appearance to giant planets when viewed through a small optical telescope and is unrelated to planets of the solar system. They are a relatively short-lived phenomenon, lasting a few tens of thousands of years, compared to a typical stellar lifetime of several billion years.

At the end of the star's life, during the red giant phase, the outer layers of the star are expelled via pulsations and strong stellar winds. Without these opaque layers, the remaining core of the star shines brightly and is very hot. The ultraviolet radiation emitted by this core ionises the ejected outer layers of the star which radiate as a planetary nebula.

Planetary nebulae are important objects in astronomy because they play a crucial role in the chemical evolution of the galaxy, returning material to the interstellar medium which has been enriched in heavy elements and other products of nucleosynthesis (such as carbon, nitrogen, oxygen and calcium). In other galaxies, planetary nebulae may be the only objects observable enough to yield useful information about chemical abundances.

In recent years, Hubble Space Telescope images have revealed many planetary nebulae to have extremely complex and varied morphologies. About a fifth are roughly spherical, but the majority are not spherically symmetric. The mechanisms which produce such a wide variety of shapes and features are not yet well understood, but binary central stars, stellar winds and magnetic fields may all play a role.

a 2 solar mass star would be alot brighter than 1 solar mass star this is because of the simple process of nuclear fusion (lol)

Answer 2

Iron and heavier elements come from supernovae. The type of star that produces a planetary nebula doesn't get that far in the fusion sequence before it dies.

A 1 solar mass red giant will outshine a 2 solar mass main sequence star. Metallicity has a slight effect on luminosity, but not that much; a 2 solar mass star is about 10 times as bright as the Sun.

Answer 3

Supernovae can dump more mass into the interstellar medium than the process that produces planetary nebulae.  Some supernovae leave nothing behind.

A 2 solar mass star will have higher luminosity than a 1 solar mass star until it stops creating energy through fusion.  Even high metalicity stars are mostly hydrogen.