Possible nearby extrasolar planet stirs scientific and media excitement
DOI: 10.1063/PT.4.0146
The thumbnail summary for the Nature News and Views article ‘Astronomy: Meet our closest neighbour ’ announces, ‘The discovery of a possible extrasolar planet that has the same mass as Earth and orbits α Centauri B, a member of the closest star system to the Sun, is both a technical achievement and cause for excitement.’
Nature has reported that scientific achievement—which has not yet been fully confirmed—with a paper by Xavier Dumusque et al., elucidated it for scientists in the News and Views piece, and explained it for a wider audience in a news story . The international science weekly has also spread the excitement. As of early on 17 October, National Public Radio’s Morning Edition had covered the news, and though the Wall Street Journal had not yet mentioned it, stories appeared in both the New York Times and the Washington Post .
Artie Hatzes of the Thuringian State Observatory in Tautenburg, Germany, wrote Nature‘s News and Views contribution, which begins:
One big goal of astronomers studying exoplanets — planets that orbit stars other than the Sun — is the detection of an Earth-mass planet in the habitable zone of a Sun-like star. The habitable zone is usually defined as the range of distances from the parent star at which water, if present, would be liquid. Writing in a paper published on Nature‘s website today, Dumusque et al. report the discovery of a candidate exoplanet that brings this goal one step closer.
Hatzes attributes the excitement to mass and location:
[I]t has approximately the same mass as Earth, and it orbits α Centauri B, a member of the closest star system to the Sun. Because of its proximity, it would be a good target for further investigations. For example, reflected starlight or radiated light from the planet would enable us to study its atmosphere, if present, or possibly its surface composition. So far, such studies have been possible only for much larger planets. In addition, the authors’ spectral analysis of the system is a demonstration that weak planetary signals can be extracted from a star’s spectrum.
He identifies two main challenges confronting the researchers. The first was to detect ‘such a small Doppler wobble, a mere 0.51 metres per second.’ Nature‘s news article explains that ‘venerable planet-finding technique’ as one ‘that monitors a star for a subtle back-and-forth ‘wobble’ in its motion as seen from Earth, caused by the gravitational tug of an orbiting body.’ Hatzes identifies the ‘second and much more daunting challenge’ as ‘the extraction of the planet’s signal from the ‘noise’ caused by the variability of the star.’ He stipulates that only ‘if other analyses come to the same conclusion can we be sure that this planet exists.’
The research finding comes from what Nature‘s news piece calls a campaign to monitor 10 of the brightest and nearest stars that can be seen from the Southern Hemisphere by using the High Accuracy Radial Velocity Planet Searcher (HARPS) spectrograph on the European Southern Observatory’s 3.6-meter telescope at La Silla, Chile.
The New York Times‘s story mentions conjecture about ‘an international project to launch a scientific probe’ to Alpha Centauri that ‘could take hundreds of years.’ But Nature‘s news story ends with this:
Ralph McNutt, a planetary scientist at Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, has received NASA study funding to design an ‘innovative interstellar explorer’. Even when launched by one of the most powerful rockets on Earth, boosted by a gravitational slingshot around Jupiter, and further accelerated by a radioisotope thruster, that probe would take about 28,000 years to reach α Centauri. Quoting British author Douglas Adams, McNutt quips: ‘Space is big. Really big.’
Steven T. Corneliussen, a media analyst for the American Institute of Physics, monitors three national newspapers, the weeklies Nature and Science, and occasionally other publications. He has published op-eds in the Washington Post and other newspapers, has written for NASA’s history program, and is a science writer at a particle-accelerator laboratory.