# Tagged Questions

Luminosity is the energy radiated from a body per second.

3answers
5k views

### Why is moonlight less colourful than yellow light?

Just what the title states; and this isn't an original question: On full-moon, moonlight is almost as bright as mid-dawn; yet there is hardly any colour visible. This is not the case with sunlight. ...
4answers
214 views

### What objects/states of objects with absolute magnitude do we know of?

For measuring distances the knowledge of absolute magnitude or luminosity is often crucial, especially for very big distances. Unfortunately we can't measure the diameter of far distant objects and ...
3answers
582 views

### Are there formulae for calculating stellar luminosity and effective temperature as a function of age?

Is there a manageable formula or set of formulas or simple algorithms that approximate stellar luminosity and effective temperature (or radius) as a function of stellar age? I'm aware that accurate ...
2answers
113 views

### how to model the exponential growth of luminosity when you flick a light on

My original thought was: $$L = L_0 \left( 1 - e^{-t/\tau} \right)$$ where $L$ = luminosity and $L_0$ = initial luminosity. But when I tested this I found that the time constant $\tau$ was higher ...
0answers
34 views

### Lorentz factor correction for luminosity

I am looking at the physics behind gamma ray bursts, working through a comprehensive review Kumar & Zhang (2014) (arXiv link). On page 92, Eq (111) the luminosity or a relativistically expanding ...
0answers
30 views

### Observed flux from distant galaxies

If anyone is able to shed some light on this (pun intended). For an observed distant galaxy with known luminosity: L = 10^10 L(sun), the light is emitted at redshift z = 2 The Flux equation is F = ...