Two Suns

[PlutonianEmpire]

In the new versions of the old star wars movies, Tatooine is depicted as having two suns. For this topic, assume having two suns will mean two Sol-like stars orbiting 6.6 million miles from each other (0.071 AU).

Why do we not have two suns? How would having two suns affect the the solar system? How would having two suns affect Earth? Would there be enough dust leftover to create planets assuming there was enough dust for two suns?

[MKruer]

I seem to recall this being discussed once before but I can seem to find the thread.

In the new versions of the old star wars movies, Tatooine is depicted as having two suns. For this topic, assume having two suns will mean two Sol-like stars orbiting 6.6 million miles from each other (0.071 AU).

Why do we not have two suns? How would having two suns affect the the solar system? How would having two suns affect Earth? Would there be enough dust leftover to create planets assuming there was enough dust for two suns? ?

While it true that most stars of Sol mass seem to be born in pairs, Sol being more the exception. The paring of most is on the distance of 100s of AU’s to light years.

As for the physics of it, there is nothing really preventing the paring of Stars with a habitable planet, so long as the orbits are stable. The habitable planet needs to be moved out in accordance to the radiation heat give off by the combined solar output.

Really the question is that needs to be asked is for how long that type of a close solar pair going to be stable?

As for the dust question let me put it this way. If there was enough dust to create to stars then there should be more then enough dust to create at least one planet.

[ajtribick]

Sol being one of the exceptions... the binary fraction for G-type stars seems to be roughly 2/3. For lower mass stars, the binary frequency appears to decrease.

As for whether planets can form in binary systems, the answer is yes: several such worlds are known, mostly in wide binaries (e.g. 55 Cancri, Upsilon Andromedae), though a handful of planets have been found in systems with separations around 20 AU between the stars (e.g. Gamma Cephei, HD 41004) and some circumbinary planets are known (orbiting PSR B1620-26 and HW Virginis). There are also some planets found to be in triple star systems (e.g. 16 Cygni, HD 40979), but the one that was hyped in the media (HD 188753) has not been detected by subsequent studies. The nondetection got hardly any media coverage, if any...

[Hungry4info]

but the one that was hyped in the media (HD 196885) has not been detected by subsequent studies. The nondetection got hardly any media coverage, if any...

I thought it was HD 188753?

[AVBursch]

Actually, we already know of such a system. HD 98800 is a quadruple system of 4 solar type stars (spectral type K, most astronomers consider K dwarfs to be solar-type) arranged as a pair of doubles. The binary, 'HD 98800B', is surrounded by two debris disks. Although no planets have been found in the HD 98800 system so far, the presence of a gap between the two disks indicate that an extrasolar planet may be present. The two stars that make up the HD 98800B binary are very close to each other, and the debris disks surround both stars.

[ajtribick]

Yeah my bad 188753. 196885 was brought up as a counterexample for the impossibility of alpha Centauri planets.

[ajtribick]

HD 98800 is another example of a system that is probably very different to the portrayal in the media. The reported gap is in a region which would in any case get swept out by the highly eccentric orbit of the HD 98800B binary, and the structure of the dust system is highly complex due to high eccentricities and mutual inclinations in the system. Not a convincing case of planet formation.

[Fenerit]

In the new versions of the old star wars movies, Tatooine is depicted as having two suns.

Even in the "old" Star Wars movie Tatooine had two suns...

[berg]

my question is this:

"can we hypothetically take the Tatooine from the star wars extras folder and put it into a star system like Sirius or 94 Cet? both are 2 suns orbiting a barycenter. which star would have to have the planet and at what angle would its orbit be for 2 suns to be in the sky together at once?"


any thoughts?

[AVBursch]

Sirius is one of the worst candidates for having an Earth-like world. An orbit in the HZ of Sirius A would be dynamically unstable due to gravitational perturbations from the degenerate dwarf Sirius B. Such a planet would be catapulted out of the system by Sirius B in less than 1000 years. Also keep in mind that Sirius B was once a blue dwarf of type B4V when it was much younger. An Earth-like planet in orbit around the barycenter of the 2 stars when Sirius B was still a blue dwarf would have been unstable as well. The 2 stars were alleged to be 9.1 au apoart at that time. Even at the outermost region of the HZ of that time (which would be roughly 45 au), the orbit would only be stable if it is eccentric like Pluto's -- which isn't too friendly for life.

94 Ceti is a much better candidate. It's basically a lot like 55 Cancri -- solar type star coupled to a red dwarf with a large seperation. Even though 94 Ceti is already known to have a Jupiter-mass planet within its HZ, the system, much like HD 28185, could have an Earth-like planet (low end, around 60 times the mass of Pluto) in orbit around the planet. The red dwarf would be reasonably bright in the moon's sky, around visual magnitude -10.

[Hungry4info]

AVBursch,

The new revisions to the parallax measurements suggest that HD 28185 is a tad farther, and brighter than assumed, and thus HD 28185 b may be just a little too hot.


Berg,

HW Virginis is the closest system known to Tatooine. A tight binary star orbited by two super-Jovian planets. The two stars at HW Vir are, however, much different than those at Tatooine.