David Parker’s Reviews > Lonely Hearts of the Cosmos: The Scientific Quest for the Secret of the Universe > Status Update

Quantum entanglement: we are all brothers, we all come from the same nebula elements from Super Novas.

H-R diagram, giants, dwarf, and main sequence.
The galactic bulges and global clusters what Baade calls “Population II”, lacked the massive blue stars because the bulges were older than other parts of the galaxy.

How long is the main sequence phase?

Our Sun has already been in its main sequence for 4.5 billion years, and will probably last another 7.5 billion years before it runs out of fuel. The smallest red dwarf stars can smolder in the main sequence phase for an estimated 10 trillion years

Why is it called the main sequence?

The 'main sequence' part of the name refers to the fact that the Sun is at a stage in its life when the primary fuel source is the conversion of hydrogen to helium. Stars in this phase lie on what we call the main sequence of the Hertzsprung-Russell (HR) diagram.

Why does the main sequence phase end?

At some point, the star will run out of material in its core for those nuclear reactions. When the star runs out of nuclear fuel, it comes to the end of its time on the main sequence.

Are there main sequence stars in globular clusters?
As globular clusters are generally much older than open clusters their colour-magnitude diagrams show more evolved stars. They also have no high-mass stars left on the main sequence.

The turn-off point is a sign of the age of the cluster: assuming all the cluster's stars began their life at roughly the same time, then it is expected that the hot and bright stars, which have short lives, are all past their main sequence, and the age of the cluster should be just shorter than the longest expected ...

The main sequence turn off age tells us how old the cluster is. The mass of a star sets the luminosity, the temperature, the size, and how fast it will evolve off of the main sequence. This is fortunate because stars of the same mass will evolve at the same time.

Jesse Greenstein, “stellar mortician”, from YerkesObservatory in. Chicago hired to set up the astronomy program. His specialty was old stars whose fire had or about to fail.

Fritz Zwickau, Swiss, trained as a solid state physicist; one of his major discoveries — that 90% of the matter in the universe is invisible and would not be taken seriously for 40 years.

Hubble and Humason macroscopically
Baade and Shapley microscopically
Sandage the disciple