What happens when giant objects collide? We know the result will be catastrophic, as when we consider the possibility that the Moon was formed by a collision between the Earth and a Mars-sized object in the early days of the Solar System. But Sarah Stewart (UC-Davis) and Simon Lock (a graduate student at Harvard University) have produced a different possible outcome. Perhaps an impact between two infant planets would produce a single, disk-shaped object like a squashed doughnut, made up of vaporized rock and having no solid surface. Call it a 'synestia,' a coinage invoking the Greek goddess Hestia (goddess of the hearth, family, and domestic life, although the authors evidently drew on Hestia's mythological connections to architecture). Stewart and Lock got interested in the possibility of such structures by asking about the effects of angular momentum, which would be conserved in any collision. Thus two giant bodies smashing into each other should result in the angular momentum of...

One of the worst things we can do is to get so wedded to a concept that we fail to see conflicting information. That’s true whether the people involved are scientists, or stock brokers, or writers. It’s all too easy to distort the surrounding facts because we want to get a particular result, a process that is often subtle enough that we don’t notice it. Thus I was interested in what Rodrigo Luger said about his recent work on the outermost planet of TRAPPIST-1: “It had me worried for a while that we were seeing what we wanted to see. Things are almost never exactly as you expect in this field — there are usually surprises around every corner, but theory and observation matched perfectly in this case.” And that’s just it -- in exoplanet research, we’ve come to expect the unexpected. So when Luger (a doctoral student at the University of Washington) went to work on this intriguing star some 40 light years from Earth, and its seven now famous planets, he was understandably edgy. Would...

Although many of the nearby stars we will study for signs of life are older than the Sun, we do not know how long it takes life to emerge or, for that matter, how likely it is to emerge at all. As we saw yesterday, that means plugging values into Drake-like equations to estimate the possibility of detecting an alien civilization. We can't rule out the possibility that we are surrounded by planets teeming with non-sentient life, fecund worlds that have no heat-producing technologies to observe. Fortunately, we are developing the tools for detecting life of the simplest kinds, so that while a telescope of Colossus class can be used to detect technology-based heat signatures, it can also be put to work looking for simpler biomarkers. Svetlana Berdyugina (Kiepenheuer Institut für Sonnenphysik and the University of Freiburg), now a visiting scientist at the University of Hawaii, has been leading a team on such detections and spoke about surface imaging of Earth-like planets at the recent...

Let me call your attention to the PLANETS telescope, now seeking a funding boost through an ongoing Kickstarter campaign. Currently about halfway built, the PLANETS (Polarized Light from Atmospheres of Nearby ExtraTerrestrial Systems) instrument is located on the 10,000 foot Haleakala volcano on the island of Maui. When completed, it will be the world's largest off-axis telescope (at 1.85 meters) for night-time planetary and exoplanetary science. And it's part of a much larger, scalable effort to find life around nearby stars in as little as a decade. https://www.youtube.com/watch?v=Y3f-q-hKff0&w=500&h=416 An off-axis design removes obstructions to the light path like the secondary mirror supports that can cause diffraction effects and lower image quality in axially symmetric reflective telescopes. Here light from the primary mirror is deflected slightly out of the incoming lightpath, limiting diffraction and scattered light. The PLANETS Foundation, the international collaboration of...

The boundary between brown dwarf and planet is poorly defined, although objects over about 13 Jupiter masses (and up to 75 Jupiter masses) are generally considered brown dwarfs. Brown dwarfs do not reside, like most stars, on the main sequence, being not massive enough to sustain nuclear fusion of hydrogen in their cores, although deuterium and lithium fusion is a possibility. But new work on a brown dwarf called SIMP J013656.5+093347 (mercifully shortened to SIMP0136) is giving us fresh insights into the planet/dwarf frontier. The intriguing object is found in the constellation Pisces, the subject of previous studies that focused on its variability, which has been interpreted as a signature of weather patterns moving into and out of view during its rotation period of 2.4 hours. Now Jonathan Gagné (Carnegie Institution for Science) and an international team of researchers have put new constraints on SIMP0136, finding it to be an object of planetary mass. Image: Lead author...

Nine years ago in a piece titled Asteroid Belts, Possible Planets Around Epsilon Eridani, I discussed work that Massimo Marengo was doing on the nearby star, examining rings of material around Epsilon Eridani and considering the possibilities with regard to planets. Marengo (now at Iowa State University) has recently been working with Kate Su (University of Arizona) and other colleagues, using the SOFIA telescope (Stratospheric Observatory for Infrared Astronomy) to help us refine our understanding of the evolving planetary system. Image: Astronomers (left to right) Massimo Marengo, Andrew Helton and Kate Su study images of epsilon Eridani during their SOFIA mission. Credit: Massimo Marengo. The researchers used the 2.5-meter telescope aboard the Boeing 747SP jetliner to collect data about the star, working at 45,000 feet in a region above most of the atmospheric water vapor that absorbs the infrared light being studied. Epsilon Eridani is a bit over 10 light years from the Sun, and...