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European astronomers have discovered a planet with about the mass of the Earth orbiting a star in the Alpha Centauri system — the nearest to Earth. It is also the lightest exoplanet ever discovered around a star like the Sun. The planet was detected using the HARPS instrument on the 3.6-metre telescope at ESO’s La Silla Observatory in Chile. The results will appear online in the journal Nature on 17 October 2012.

[This is cool! While the planet discovered is too hot for life, there probably are others and some might be in that orbit where water can be liquid and life can exist. So maybe with future ion drive ships, suspended animation, or whatever human colonies might be established there. Neat!] Bringing the search for another Earth about as close as it will ever get, a team of European astronomers was scheduled to announce on Wednesday that it had found a planet the same mass as Earth’s in Alpha Centauri, a triple star system that is the Sun’s closest neighbor, only...

Explanation: The glare of Alpha Centauri, one of the brightest stars in planet Earth's night sky, floods the left side of this southern skyscape. A mere 4.3 light-years distant, Alpha Centauri actually consists of two component stars similar in size to the Sun, locked in a mutual orbit. Much smaller and cooler, a third member of the same star system, Proxima Centauri, lies outside this field of view. Still, the telescopic scene does reveal often overlooked denizens of the Milky Way's crowded galactic plane that lie beyond the glare of Alpha Centauri, including a planetary nebula cataloged as Hen 2-111,...

Explanation: The closest star system to the Sun is the Alpha Centauri system. Of the three stars in the system, the dimmest -- called Proxima Centauri -- is actually the nearest star. The bright stars Alpha Centauri A and B form a close binary as they are separated by only 23 times the Earth- Sun distance - slightly greater than the distance between Uranus and the Sun. In the above picture, the brightness of the stars overwhelm the photograph causing an illusion of great size, even though the stars are really just small points of light. The Alpha Centauri system...

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...

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...

European astronomers have discovered a planet with about the mass of the Earth orbiting a star in the Alpha Centauri system -- the nearest to Earth. It is also the lightest exoplanet ever discovered around a star like the Sun. The planet was detected using the HARPS instrument on the 3.6-meter telescope at ESO's La Silla Observatory in Chile. The results will appear online in the journal Nature on 17 October 2012.

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...

What are the chances that we’ll find habitable planets around Alpha Centauri A and B? Centauri Dreams has long kept an eye on the work of Greg Laughlin (UC-Santa Cruz) and colleagues, who have been working on the Alpha Centauri question with ever more interesting results. Following their work on Greg’s systemic site has been fascinating, and for those who would like to be quickly brought up to speed, it’s useful to know that Laughlin has made their recent paper summarizing these findings available online. Anyone serious about the study of these closest stars to Earth will want to download...

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...

Results from exoplanet surveys indicate that small planets (super-Earth size and below) are abundant in our Galaxy. However, little is known about their interiors and atmospheres. There is therefore a need to find small planets transiting bright stars, which would enable a detailed characterisation of this population of objects. We present the results of a search for the transit of the Earth-mass exoplanet Alpha Centauri Bb with the Hubble Space Telescope (HST). We observed Alpha Centauri B twice in 2013 and 2014 for a total of 40 hours. We achieve a precision of 115 ppm per 6-s exposure time in...

Explanation: Located just next door, Alpha Centauri is the closest star system to the Sun. A view from our interstellar neighbor a mere 4.3 light-years away is shown in this illustration. The Sun is at the upper right, a bright star against the background of the Milky Way. The crescent in the foreground is an artist's rendering of a planet now reported orbiting Alpha Centauri B, making it the closest known exoplanet. Discovered by astronomer Xavier Dumusque et al. using the planet hunting HARPS instrument to measure minute shifts in the star's spectrum for more than four years, the planet...