# Tag Info

### Why haven’t we observed supernova events of the hypothetical population III stars?

Massive Population III stars are thought to predominantly exist for a short period of time during the initial stages of galaxy formation and prior to the epoch of reionisation at $z \sim 6-20$ (though ...
• 114k
Accepted

### Why haven’t we observed supernova events of the hypothetical population III stars?

The problem is really the distance here. I believe the most distant supernova ever observed is SN 1000+0216 at redshift 3.9. This observation was possible only because of the extremely high and ...
• 2,676
1 vote

### Where can I find a list of galactic Long/Lat for stars?

I found an online program which calcauates galacitic logitude and latitude from equatorial coordinates of right ascension and declination. https://ned.ipac.caltech.edu/coordinate_calculator?in_csys=...
• 4,600
1 vote

### Where can I find a list of galactic Long/Lat for stars?

The Yale bright star catalogue has glon and glat data right in the table It looks like this: bsn name hd ... glon glat vmag spectype 1 3 114.44 -16.88 6.7 A1Vn 2 6 98.33 -61.14 6.29 gG9 3 33 ...
• 87.6k
1 vote

### Formation of the First Stars

Metallicity impacts star formation and stellar evolution in many different ways. Star formation A dense core of a molecular cloud becomes unstable and starts collapsing under its own gravity. During ...
• 2,676

### How can pre-main sequence stars radiate more energy than main-sequence stars?

The luminosity of a PMS star is provided by the rate of change of gravitational potential energy as it contracts. Since PMS stars contract along Hayashi tracks at almost constant effective temperature,...
• 114k
Accepted

### Rotation direction of Pulsars

Does the Earth rotate clockwise or anticlockwise? If you are floating above the north pole of Earth you would see the Earth rotating anticlockwise(*) if you were floating above the south pole, you ...
• 87.6k
Accepted

### When was/will Polaris's declination be maximised?

Soon after 2100: In 2018 Polaris was 0.66° away from the pole of rotation (1.4 times the Moon disc) and so revolves around the pole in a small circle 1.3° in diameter. It will be closest to the pole (...
• 87.6k
The Sun's magnetic activity cycle of $\sim 22$ years involves a large-scale reversal of the polarity of the magnetic field every $\sim 11$ years. There are very many observations of other solar-type ...