# Tag Info

10

Yes. An example would be the Cataclysmic Variable stars (CVs), where the donor star (often in the main sequence), loses material via Roche Love overflow onto a compact white dwarf companion. The other obvious example (though less common) are the Low Mass X-ray Binaries (LMXBs), where the Roche Love overflow is onto a neutron star or black hole. Nelson & ...

9

"Satellite type" and "Planet type". The terms seem to have been coined by Rudolf Dvorak in 1982 paper "Planetenbahnen in Doppelsternsystemen" Due to the fact that quasiperiodic orbits exist around stable orbits 3 different types of possible planetary orbits are found: S-types (satellite type orbit around one primary), P-types (...

7

No. Such an arrangement is at best "metastable". That is, although there are periodic solutions to the three body problem (stable orbits) an infintesimal perturbation (eg the proverbial butterfly flapping its wings) will push the system off the stable orbit and into chaos. Getting a planet to remain at the barycentre is like trying to balance a ...

7

You will always get a "stable" orbit if the stars have less than escape velocity relative to each other. (unless you are modelling the stars as having non-zero radii so they can collide) The stars will enter into elliptical orbits around a barycentre. But I guess you want a circular orbit. For a circular orbit the speed $v$ is given by $$v^2=GM/r$$...

6

It just means that in a star that is an unresolved binary system (i.e. the light you receive comes from both stars), the secondary contributes a fraction of that light. This fraction could be expressed as a fraction of the total luminosity or a fraction of the flux at a particular wavelength or in a particular waveband. How do you work it out theoretically? ...

6

The stability of this system depends the ratio of masses of the two stars. If the larger star is more than 25 times more massive than the smaller star, then L5 is potentially stable, and this remains the case even if the planet does not have negligible mass The calculation of the value is done in detail on physics.stackexchange and there you can establish ...

6

Wide binary stars it turns out is an active research topic, with groups using statistical searches of catalogs (Tycho Gaia ...) to find in 3D space pairs of stars that are moving together taking into account possible orbital motion. Here people are looking at the physical separation not the angular separation. On the theory side it is suggested that nearly ...

5

Short Answer: Star sytem HD 188753 seems to be an example of the type of star system asked for. Long Answer: Part One of Two: The orbital characteristics. In any multiple star system, all of the stars will orbit the combined barycenter of the system. Any pairs will orbit around the barycenter of the pair, and the barycenter of each pair will orbit around ...

5

I assume that the diagram indicates what the observer sees (if they had a big enough telescope!). i.e. The viewpoint is nearly in the orbital plane but not quite. Why then are the eclipses asymmetric, with the secondary eclipse being shallower than the primary? Well probably because the surface brightness of the two stars is different - i.e. they have ...

5

It seems that the authors are just referring to the accepted model of a pulsar, i.e. a neutron star spinning and emitting beams of radiation at its poles. In that sense, the term is used here no differently than it would be in the context of an isolated pulsar. It's just a very simple way of visualizing why an observer far away appears to see periodic pulses ...

4

There is no average value. The large scale magnetic fields of main sequence stars are both a function of spectral type and rotation. In turn, rotation is age-dependent. In addition, the gas pressure at a distance from the star depends on conditions in the stellar wind and this too will depend on spectral type, rotation and age. There are no universally ...

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 ...

4

There are only about a dozen circumbinary exoplanetary systems known - the first discovered was Kepler 16b. The statistics of circumbinary planets is a relatively unstudied area. One of the major uncertainties is the inclination distribution of the exoplanets. If they are confined to the orbital plane of the binary system, then transiting circumbinary ...

3

The question is one which could have been asked a generation ago by someone who kept up with astronomical discoveries, but not more recently by someone familiar with the search for exoplanets. In short, the answer is yes, binary systems can have planets and some have been discovered. I don't know much about theoretical calculations about how probable it is ...

3

Systems like this are known as colliding-wind binaries (CWBs), and they do produce some interesting effects. When winds collide, they create shocks, which in turn heats up gas. The most notable result is x-ray emission, which tends to happen whenever you have non-negligible shock heating in stellar winds; there is certainly additional thermal and non-thermal ...

3

Could there be a planet at the barycenter between two or more stars revolving around each other? No. The best case two star scenario is two stars of equal mass. In that case, the barycenter is midway between the two stars and coincides with the L1 Lagrange point. The L1 Lagrange point is metastable. Another name for metastable is unstable. Think of it as a ...

2

I solved the issue. Everything I posted in the OP was correct; I made a simple, stupid sign error when transcribing the expressions into code. It should also be noted that in the OP, the expression for Pk is wrong. The correct expression is Pk = sin (inc) sin (aop) Just in case anybody is trying to pull this off themselves! Thanks for the ideas everyone! ...

2

$\eta$ Cassiopeiae A has an estimated mass of 0.972 M$_\odot$, an estimated temperature of 5973 K, and a B-V color index of ~0.58[1]. In addition to the spectrum of the star, we look at these and other properties when attempting to classify main sequence stars. You can see a table [here] which shows the bulk properties of each spectral type that we can use ...

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.

2

I am not an expert on the topic but probably you have to specify in your search which mass regime are you looking for (low or high mass x-ray binaries). Accretion time must be important and depends on the mass. High-mass stars are young (very short life) < $10^7$ years. This reference is quite old but probably helps a bit: The Average X-Ray Lifetime of ...

2

Usually, how is phase=0 defined? It is relative to the line of apses perhaps with phase=0 at periastron? The true anomaly, $\theta$, is the angle between the current location of the orbiting particle and its location in the orbit at which it is closest to the central body (called the periapsis/periastron). The word "phase" is used variously in ...

2

Moreno et al. in their paper Eccentric binaries: Tidal flows and periastron events [2011] define the orbital phase as from -0.5 to 0.5, where periastron is at phase 0, and apastron is at -0.5 and 0.5. Orbital phase here is $\phi = \dfrac{t}{P}$, where time $t=0$ at periastron and $P$ is the orbital period. This definition allows them to plot the behavior ...

2

Here is a picture from the most recent review I could find - Horvath et al. (2020). The companion of J0453+1559 is still the least massive of the double neutron stars with very precisely measured masses. I cannot find any citations to the Martinez et al. paper (here is a list) that either update the mass or shed any further light on its true identity. It ...

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

The lifetime of an X-ray binary is pretty broad and it depends on the type of X-ray binary you are talking about. There are 3 main types of X-ray binaries: Low Mass X-ray Binaries Intermediate Mass X-ray Binaries High Mass X-ray Binaries The accretion process is drastically different for each of these types, which means that there is no broad lifetime of ...

1

The spectral type of a star is determined by looking at its spectrum. Sometimes authors will use other, approximate, relationships between spectral type and colour or mass, or they will look at the spectrum compared with standard templates in different wavelength regions. These are all possible reasons why different sources might suggest slightly different ...

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