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Solar Twins: Separating Look-Alikes From the Sun’s True Siblings

March 19, 2009 09:00 AM
by Haley A. Lovett
Scientists have found stars like our sun, but could a new way to recognize solar twins unlock the mysteries of the solar system and extraterrestrial life?

How to Recognize Solar Twins: A New Theory

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Astrophysicist Simon Portegies Zwart wants to find solar twins—real ones. Looking for more than just stars with similar characteristics to the sun’s, Portegies Zwart wants to identify solar twins that actually formed alongside the sun in the Centaurus constellation 4.3 billion years ago.

In a new paper, Portegies Zwart explains how he will try to figure out where a few of the sun’s siblings are now living using calculations for how the sun may have moved away from its birthplace over time, along with the chemical composition of the sun.

But other scientists doubt whether Portegies Zwart will find siblings of the sun in this way, or if he will be able to prove that any other stars are in fact true siblings. Leslie Looney, an astrophysicist at the University of Illinois at Urbana-Champaign, told Scientific American that the best that Portegies Zwart will be able to do using this method is to identify “‘likely’ kin.”

Historical Context: How many “solar twins” are there?

According to the astronomer Cayrel de Strobel, there are three types of sun-like stars. Solar-like stars are like the sun in mass and stage of evolution. Solar analogs share loosely similar properties with the sun such as temperature, age and distance from other stars. Solar twins share close similarities with the sun, and are identified using the same traits as solar analogs, such as temperature, mass, brightness and chemical makeup.

Sun-like stars may move from one category to another as we learn more about them or as scientists are better able to measure certain traits. Just because a star is identified as a solar twin, it does not mean that it originated from the Centaurus constellation like the sun. 

There are at least four known solar twins: 18 Scorpius, HD 98618, HIP 100963 and the most recently discovered and most similar to the sun, HIP 56948.

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Analysis: Solar twins make case for extraterrestrial life

According to the McDonald Observatory, scientists “cannot study the Sun the same way they do distant stars. It is too close, and too bright.” Therefore, solar twins can help us understand more about our own sun and the formation of our solar system.

But for some, solar twins may aid in other research, like the search for extraterrestrial life. “[Sun-like stars] are certainly a decent starting point,” Margaret Turnbull of the Space Telescope Science Institute told New Scientist in regard to the search for life, "given that we know of at least one civilisation around such a star.”

Discovering a star much like the sun suggests to scientists that the sun is not unique, and that perhaps the building blocks for life, such as those found on Earth, exist elsewhere.

Related Topic: Life on other planets

2008 was a big year for the search for alien life forms. Mars was found to have alkaline soil, making it capable of supporting plant life, and many planets outside our solar system were found to have structures similar enough to Earth to potentially support life.

Some of the moons in our solar system have also been thought to have the capability to support life forms. One in particular, Saturn’s moon Enceladus, was found to have carbon-based molecules in the water vapor emitted from the planet.

Discoveries on our own planet often shed light on the potential for life in the extreme conditions that exist on other planets. Scientists recently discovered algae that can survive in extreme temperatures and that transforms the poison arsenic into less harmful forms of the substance, making life possible in the area.
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