11

(Ignoring that all orbits are technically unstable due to the emission of gravitational waves.) There are known solutions to the gravitational three body problem that can be shown to be stable. Lagrange found a three body solution for general masses where all three orbit the common center of mass in an equilateral triangular formation. Gascheau proved in ...


5

The absolute minimum mass of the unseen companion is $4.2 M_{\odot}$ (and my reading is that this really is an unlikely minimum, requiring an abnormally faint primary for its spectral type and an orbital inclination of 90 degrees, but let's go with it) and the argument is that a main sequence star of this mass would make its presence known in the spectrum. ...


4

Yes, you are correct. The luminosities can be added. Luminosity is the amount of electromagnetic energy emitted per unit of time (measured in $ \textrm{J} \cdot \textrm{s}^{-1} $ or $\textrm{W}$). So if you have a multiple star system, the total amount of energy emitted (i.e. the total luminosity) is simply the sum of the energy emitted by each of its ...


2

Many hot stars are born in multiple star systems because the cores of these stars tend to split (see Jeans instability). With lower mass stars this still can happen. However, there are other ways. For example, in a young star cluster, close encounters with other stars can cause a star to be captured by another one.


1

It is quite possible that binary stars average less stable than single stars, that trinary stars average less stable than binary stars, that quarternary stars average less stable than trinary stars, and so on. But unless that prevents trinary or higher star system from remaining stable long enough to possibly have planets that become interesting from a ...


1

No. It isn't proven that any real orbital systems are stable on sufficiently long time scales. Even our (single star) Solar System is not stable. In their paper: On the Dynamical Stability of the Solar System, Batygin and Laughlin, use the numerical techniques pioneered by Laskar to show scenarios in which various planets fall into the Sun or are ejected ...


1

As far as I know, all known old multiple star systems with stable orbits have highly hierarchical structures. Binary star pairs in those systems orbit much closer to each other than they do to other binary pairs or single stars within the system. In such a system it would be very unlikely for a star which is part of one binary to be temporarily captured by ...


1

You can definitely scratch out any planets, as their gravitational field will not be strong enough. Even a very dense neutron star wouldn’t give much effect, as far as I know. As for black holes, well, basically any black hole will give this effect. However, those are too far to reach with our current means. Safe travels!


1

I suppose that the International Astronomical Union has rules for naming stars in multiple systems. I believe the usual rule is to describe the brighter star as A and the dimmer star as B, which works well as long as neighter star is very variable. Thus the brighter star in Alpha Centauri is Alpha Centauri A and the less bright star is Alpha Centauri B. ...


1

The purpose of the notation is to indicate how the system is physically constructed, to indicate which stars orbit which - especially useful in hirachically organized stellar systems. So both ways are correct as their meaning is understood. The notation I encounter most often is the first one you indicate: indicating with capital letters the systems which ...


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