Imaging planets around other stars is challenging enough because their light is overwhelmed by the proximity of the parent star. But what about comets? We may not be able to see them directly, but minute variations in light can mark their passage across the stellar disk. Nearly 500 comets have been detected around the star Beta Pictoris using these methods. New work led by Flavien Kiefer (IAP/CNRS/UPMC) analyzes this cometary hoard to give us a look at what is happening in a young planetary system. Using the HARPS instrument at the European Southern Observatory’s site at La Silla in Chile, Kiefer and team have compiled what the ESO is calling ‘the most complete census of comets around another star ever created.’ Beta Pictoris is becoming an old friend, a young star some 63 light years from the Sun that is no older than 20 million years. The star is surrounded by a disk of material that has been the subject of intense study as we watch the interaction between gas, dust and the...

A physicist and writer well-versed in the intricacies of the exoplanet hunt, Andrew LePage now turns his attention to the question of planets around Centauri B, and in particular the controversy over whether the highly publicized Centauri Bb does in fact exist. Today is the second anniversary of the discovery announcement, and we still have work to do to resolve whether 'noise' in the data -- explained below -- may account for what seems to be a planet. The good news is that multiple teams continue to work on Alpha Centauri, and we should expect answers within several years, or just possibly, as LePage explains, a bit sooner than that. by Andrew LePage Time certainly seems to fly at times. It has already been two years since the October 16, 2012 announcement by a Geneva-based team of astronomers of the discovery of a planet orbiting our Sun-like neighbor, α Centauri B, using precision radial velocity measurements. While this planet, designated α Centauri Bb, was hardly...

On Friday I mentioned transmission spectroscopy, the technique of analyzing the light of a parent star as it is filtered through a planetary atmosphere. We've used it on various 'hot Jupiters' before now -- think of the much studied planet HD 209458b, where water vapor, carbon dioxide and methane have been detected and fierce upper atmosphere winds revealed. And while we wait to see if the method can be applied to the interesting WASP-94 system, we can look at its uses in another hot Jupiter whose weather has now been mapped. WASP-43b has twice Jupiter's mass and a breathtaking 19-hour year. Scientists using the Hubble Space Telescope have used transmission spectroscopy to determine the abundance of water in the atmosphere at the terminator between night and day on this tidally locked world. The team also used so-called emission spectroscopy -- in which much of the light of the parent star is subtracted -- to measure water abundance and temperature at different points in its orbit....

The WASP Consortium (Wide Angle Search for Planets) has come up with an interesting find: Two new Jupiter-class worlds, one around each star in a binary star system. Both are 'hot Jupiters,' a class of planets that is susceptible to discovery by transit methods, as in this case, and radial velocity as well. Consisting of two robotic observatories, one on La Palma (Canary Islands) and the other in South Africa, WASP has a proven track record, having found over 100 planets since 2006. WASP-94A and WASP-94B, like all WASP candidates, were confirmed by radial velocity techniques through a collaboration with the Geneva Observatory. The two stars are about 600 light years away in the constellation Microscopium. In this case, it was the WASP-South survey team that noticed dips in the light of WASP-94A, the mark of a likely hot Jupiter, with WASP-94B being found by the Geneva team during the confirmation process for the first planet. "We observed the other star by accident, and then found a...

Centauri Dreams welcomes Ravi Kopparapu, a research associate in the Department of Geosciences at Pennsylvania State University. He obtained his Ph.D in Physics from Louisiana State University, working with the LIGO (Laser Interferometer Gravitational-wave Observatory) collaboration. After a brief stint as a LIGO postdoc at Penn State, Ravi switched to the exoplanet field and started working with Prof. James Kasting. His current research work includes estimating habitable zones around different kinds of stars, calculating the occurrence of exoplanets using the data from NASA's Kepler space telescope, and understanding the bio-signatures that can potentially be detected by future space telescope missions. Dr. Kopparapu's website is http://www3.geosc.psu.edu/~ruk15/index.shtml. by Ravi Kopparapu Imagine this scenario: You are planning to buy a new house in a nice neighborhood. The schools in the area are good, the neighborhood is very safe, but you want to know the 'kid friendly'...

Like most people, I'm highly interested in the hunt for habitable worlds, planets that could truly be called Earth 2.0. But sometimes we need to step back from the 'habitable' preoccupation and think about the extraordinary range of worlds we've been finding. I'm reminded of something Caleb Scharf says in his new book The Copernicus Complex (Farrar, Straus and Giroux, 2014), in a chapter where he describes the work of Johannes Kepler and other astronomical pioneers. Kepler's laws of planetary motion first told us that planetary orbits are ellipses rather than the perfect circles envisioned by the school of Ptolemy. The implications are striking and lead us to expect just the kind of wild variety we find in the exoplanet hunt, where we're uncovering everything from 'hot Jupiters' to 'super-Earths' and a wide variety of Neptune-like worlds. Says Scharf: If planets follow elliptical paths as a general rule, and those paths need not be all within a single plane around a centrally massive...