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Over twenty percent of the planets we’ve found around other stars inhabit binary systems. It’s intriguing to take a close look at these. Most of the planet-bearing binaries are what is known as ‘wide S-types,’ meaning that the companion star orbits the inner star/planet system at a distance of over 100 AU. But take a good look at GJ86b, γ Cephei b and HD41004b. Here we’re looking at three planets in close binary systems with a separation between the component stars of 20 AU or less. That separation raises the eyebrows, for Alpha Centauri A and B form a close...

The nearest Earth out there in space? It might be right next door, galactically speaking. Two teams of astronomers, one from the United States and one from Europe, are in a race to find a planet orbiting our near neighbors Alpha Centauri A and Alpha Centauri B, twin stars that appear from Earth as a single point of light.

Earth may have a twin orbiting one of our nearest stellar neighbors, a new study suggests. University of California, Santa Cruz graduate student Javiera Guedes used computer simulations of planet formation to show that terrestrial planets are likely to have formed around one of the stars in the Alpha Centauri star system, our closest stellar neighbors. Guedes' model showed planets forming around the star Alpha Centauri B (its sister star, Proxima Centauri, is actually our nearest neighbor) in what is called the "habitable zone," or the region around a star where liquid water can exist on a planet's surface. The...

Earth may have a twin orbiting one of our nearest stellar neighbors, a new study suggests. University of California, Santa Cruz graduate student Javiera Guedes used computer simulations of planet formation to show that terrestrial planets are likely to have formed around one of the stars in the Alpha Centauri star system, our closest stellar neighbors. Guedes' model showed planets forming around the star Alpha Centauri B (its sister star, Proxima Centauri, is actually our nearest neighbor) in what is called the "habitable zone," or the region around a star where liquid water can exist on a planet's surface. The...

This coming January, Ad Astra Rocket Company will test the VX-200, a full-scale ground prototype of the variable specific impulse magnetoplasma rocket (VASIMIR), first conceived in 1979 by the company's president and CEO, astronaut and plasma physicist Franklin Chang Diaz. The rocket is an attempt to improve on current space-propulsion technologies, and it would use hot plasma, heated by radio waves and controlled by a magnetic field, for propulsion. Chang Diaz believes that the system would allow rockets to travel through space at higher speeds, with greater fuel efficiency. If the prototype demonstrates sufficient efficiency, thrust, and specific impulse on...

If we’re finding planets in places 1500 light years away, as the TrES project just did, why don’t we know more about planets in the Alpha Centauri system? One problem is that Centauri A and B are relatively close to each other, with a semimajor axis of 23.4 AU. Leaving Proxima Centauri out of the picture (at 12,000 AU, its short-term effects can be disregarded), it’s still true that radial velocity studies have to take the complicated and varying spectra that binaries produce into account. In other words, getting a read on binaries like these in terms of the slight...

Newly-Discovered Star may be Third-Closest Jet Propulsion Laboratory, Pasadena, Calif. Goddard Space Flight Center, Greenbelt, Md. The local celestial neighborhood just got more crowded with a discovery of a star that may be the third closest to the Sun. The star, "SO25300.5+165258," is a faint red dwarf star estimated to be about 7.8 light-years from Earth in the direction of the constellation Aries. "Our new stellar neighbor is a pleasant surprise, since we weren't looking for it," said Dr. Bonnard Teegarden, an astrophysicist at NASA's Goddard Space Flight Center, Greenbelt, Md. Teegarden is lead author of a paper announcing...

Astronomy Picture of the Day Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2002 April 25 Southern Cross in Mauna Loa Skies Credit & Copyright Barney Magrath Explanation: Gazing across this gorgeous skyscape, the Southern Cross and stars of the constellation Centaurus are seen above the outline of Mauna Loa (Long Mountain), planet Earth's largest volcano. Unfamiliar to sky gazers north of about 25 degrees north latitude, the Southern Cross, constellation Crux, is near the horizon to the left of Mauna...