The Rare Exoplanet with a Double Sunset

Discovery News ^ | Thursday, October 21, 2010 | Ian O'Neill

[SunkenCiv]

By developing a technique called precision astrometry, the researchers have discovered a Jupiter-mass exoplanet orbiting the primary star of the binary system of HR 7162 (or HD 176051), some 49 light-years from Earth. They've called it "Inrakluk."

Astrometry is the study of the precise measurements of the positions and movement of stars. This is the first time the technique has been used to decipher the presence of an exoplanet in the complex dynamics of a binary system. The periodic variation in location of HR 7162 led to the Jupiter-like exoplanet's discovery.

But the very existence of Inrakluk has called into question our understanding about how planetary systems form.

In a one-star system like our solar system, the leading theory as to how the planets formed is through a process called accretion... This is all well and good for a single star, but what if you throw a second star into the mix, like in the HR 7162 binary? The accretion model for planetary formation simply doesn't stick.

When there's a second star orbiting the primary (more massive) star in the binary, according to planetary evolution models, the combined gravitational tugging of both stars hinder the slow accretion of the planets. The planet-building materials are ejected from the system before planets can form. This is one reason put forward that may explain why so few exoplanets have been discovered in binary systems.

However, this new discovery proves that mature Jupiter-like worlds can exist in binaries. The TSU-headed group have challenged the planetary accretion theory as the sole planet-forming mechanism in favor of a faster "gravitational collapse" model.

[Praxeologue]

Thank you. Figure 10 in the .pdf gave me pause, though.

[BenKenobi]

Ever play with one of these?

http://shop.ebay.ca/i.html?_nkw=spirograph+toy&_armrs=1&_dmd=2&_from=&_ipg=

It’s secret math. These orbits work the same way as these spirographs do.

[rdl6989]

figure 8

That's what I wonder.

[Larry Lucido]

It spend weekends and holidays with the daddy star.

[NYFreeper]

I was thinking the same thing.

[Praxeologue]

My guess would be that the spiral results from the over-rotation of the satellite. For example, the earth may have a very slight spiral in its orbit relative to the sun, but our moon would not, relative to earth.

[Vaduz]

I know people here who see the same thing after dipping beak to long.

[GeronL]

lol

[GeronL]

thanks

[KevinDavis]

[Vaquero]

It has been put forth that a binary/trinary system would wreak havoc on life forming on a rocky planet...it looks like alpha centuriAB and proxima centuri would be a wash for habitability.

[wastedyears]

Especially if a planet would have a figure 8 orbit. Being that close to any sun, especially two of them, would sanitize the surface, snuffing out most if not all life.