Planetary systems around w ursae majoris type stars.

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Planetary systems around w ursae majoris type stars.

Post by Darkness nova on 16th August 2009, 6:14 pm

Would the formation of such a system disrupt the planet forming process and would the two stars make the HZ of the system expand outward due to the heat of two stars instead of one? Finally since there are two stars wouldn't that mean that the planets in such a system would be larger and more massive since two stars formed and would have at least twice the amount of mass around them as a regular star of similar spectral type and mass? I ask this because I found the W ursae majoris add-on for celestia here I beleive and of course the first thing I thought of after exploring with it was "I wonder what kind of planetary system I could make around one of these."

How would the mechanics of such a system work?

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Re: Planetary systems around w ursae majoris type stars.

Post by Sirius_Alpha on 16th August 2009, 11:41 pm

Having no W UMa type planetary systems to study, it's really hard to base a supposition on anything other than speculation and theoretical work. I would assume that a planetary system could form, but not short-period planets (due to tides).

Any planets in orbit would do so around the star's barycentre.

I would guess that the temperature conditions of the planet would depend heavily on the types of stars its orbiting. If a cool star eclipses a smaller, hotter star, then there may be several-day-long drops in temperature for any planets in the hotter star's shadow.

Though I don't know if the components of W UMa type stars can have radically different spectral types. I don't see why not.

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Re: Planetary systems around w ursae majoris type stars.

Post by Edasich on 17th August 2009, 8:08 am

Curiously if you try making a planet orbiting system barycenter of a W-UMa-type system, you get planet's average temperature zero K.
Because it's just like it were orbiting around nothing.

However it's also curious that W-UMa type binaries (as well as some Algol, RS CVn and cataclysmic variables too) often show indications of additional third (or even fourth) bodies in outer orbits, hinted by small orbital period variations.

The additional bodies are usually low mass stellar objects (mass ranging between 1-0.2 Solar masses, sometimes even >2 Mso in massive systems). Nevertheless, and according to assumed orbital inclination of the object, even VLMO and brown dwarfs are inferred to orbit eclipsing binaries.

Here some examples:

- 44 Bootis B-C: recently astronomers would have detected hints of a brown dwarf (nearly 48 times the mass of Jupiter) in wide orbit (<10 AUs). Though a bit bizarre configuration since the 44 Boo BC is already in eccentric and not so wide orbit around 44 Boo A brighter primary.

- V471 Tauri: the most unusual system so far. A K0V+wd tight binary with third object, in substellar regime (nearly 50 Mj) in wide orbit (10.3 AUs e=0.3).

- HW Virginis: a tight sdB+late M-type dwarf binary system with multiple planets.

- VW Cephei: quite a curious systems. Latest paper about this object claims a third (stellar) body in wide and eccentric orbit around primary, plus hints of a fourth low-mass (sub?)stellar object (<<0.2 Mso) in tighter one, but possibly in resonant configuration with third star.

- BM Ursae Majoris: a third object with possibly less than 70 Jupiter masses is thought to be located within 10 AUs from W-UMa (or RS CVn, I don't remember) type system.

- BH Virginis: another 60-70 Mj third object inferred. Around 18 AUs away from EB system.

- Y Sextantis: here third object is low mass stellar but fourth putative one is likely substellar (43 Mj at nearly 60 AUs).

- OY Carinae: cataclysmic variable. Here possibly a third superplanetary object is inferred (<16 Mj at >17 AUs).

- Z Chamaeleontis: a classical CV with a putative third body with >10 Mj at >8 AUs.


I'm going to provide paper links but in next thread. This one is just too long Laughing
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Re: Planetary systems around w ursae majoris type stars.

Post by Darkness nova on 17th August 2009, 2:09 pm

Hmm....

Apparently they are always the same spectral type. I still wonder if two stars would screw the HZ up any though.....

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Re: Planetary systems around w ursae majoris type stars.

Post by Edasich on 17th August 2009, 2:44 pm

Darkness nova wrote:Hmm....

Apparently they are always the same spectral type. I still wonder if two stars would screw the HZ up any though.....

I think you should just do the math with individual luminosities of both components. For example:

LA=1 LSun ; LB= 0.8 LSun

LTotal= 1+0.8= 1.8 LSun

Then get the square root of the total luminosity and you should get the habitable zone for the system.
In this case HZ= 1.34 AUs.
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Re: Planetary systems around w ursae majoris type stars.

Post by Lazarus on 17th August 2009, 3:08 pm

Sirius_Alpha wrote:Though I don't know if the components of W UMa type stars can have radically different spectral types. I don't see why not.
The stars are in some amount of thermal contact. This tends to even things out somewhat.

I have come across this description of a research program in which it is mentioned that a model of a W UMa habitable zone has been developed, but I haven't yet found anything more about this online.
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Re: Planetary systems around w ursae majoris type stars.

Post by Darkness nova on 18th August 2009, 4:55 pm

Thanks for the equation edasich.

And lazarus for the paper. I'll see if they have anything else.....or if they have an email address so that I may ask them myself.

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Re: Planetary systems around w ursae majoris type stars.

Post by Led_Zep on 18th February 2015, 6:15 pm

Edasich wrote:

Here some examples:

V471 Tauri: the most unusual system so far. A K0V+wd tight binary with third object, in substellar regime (nearly 50 Mj) in wide orbit (10.3 AUs e=0.3).

It seems there's nothing :

http://www.eso.org/public/unitedkingdom/news/eso1506/
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Re: Planetary systems around w ursae majoris type stars.

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