# Tag Info

36

Stars are not actually gaseous, they are plasmas, i.e., highly ionized. Hence, the entire star is highly conductive and does not easily develop the voltage difference via friction needed for lightning like that in our atmosphere. On the other hand, stellar atmospheres have strong magnetic fields which reconnect, and that causes strong voltage spikes that ...

10

The luminosity mass relation is inexact. The luminosity also depends on the composition of the star, particularly in and around the nuclear burning regions. The composition changes during the main sequence lifetime as hydrogen gets turned into helium. The average mass per particle goes up and the number of electrons per mass unit goes down. The former means ...

8

There are two phases to this problem. In order to accrete into stars, a huge amount of angular momentum must be lost to allow so much mass to gather into a small volume. A second problem is how stars like the Sun end up rotating so slowly, when younger versions of stars similar to the Sun rotate much faster. The solution to the first problem may be solved by ...

8

An essential feature of the lightning is the electrical breakdown - an insulator (air) becomes a conductor for a while, relatively high current flows in the conducting channel for a short while, then stops. The conducting channel is an insulator again. This requires insulating (dielectric) medium and a means of creating an intense electric fields. Given ...

3

Black holes do not suck in matter any more than stars and planets do: an object in orbit would remain in stable orbit if nothing perturbed it. However, in the long run ($10^{19}$ years and more) interactions between stars will perturb their orbits, making many of them end up in the central black hole. An easy way of seeing this is to consider a random close ...

2

To find the distance from one star to another, we need three things for both of the stars: their right ascensions, declinations, and the distance from Earth to those stars. So, let's get those things: From the Wikipedia page on Alpha Centauri: $RA = 14^h\:39^m\:36.49400^s$ $DEC = -60^{\circ}\:50'\:0.23737''$ $R = 4.37\:\rm{ly}$ (you gave 4.366, some other ...

2

The online version of the digitised sky survey will give you as many images of the sky as you want. Be aware that these are based on photographic plates. Also be aware that every imaging system has its own peculiarities in terms of the shape of the point spread function (i.e. the shape of a star in the image) and features such as diffraction spikes. https://...

1

According to the associated paper (to get to this, click on the Bibcode link near the top right in VizieR), this refers to the source of the UBV photometry. I believe the relevant references are the ones in the V/19/clusters table, e.g. for the second cluster (NGC 188) the reference is to Upgren, Mesrobian & Kerridge (1972). This does provide cross-...

1

As others have pointed out, the reason why we don't see non-stellar neutron stars is that the pressures needed to form them are usually only found in stars. Lower pressures don't form neutron degenerate matter and higher pressures form black holes. I think part of your question may be whether or not smaller quantities of neutron-degenerate matter, which ...

Only top voted, non community-wiki answers of a minimum length are eligible