I always keep an eye on the Phase I and Phase II studies in the pipeline at the NASA Innovative Advanced Concepts (NIAC) program. The goal is to support ideas in their early stages, with the 2022 awards going out to 17 different researchers to the tune of a combined $5.1 million. Of these, 12 are Phase I studies, which deliver $175,000 for a nine-month period, while the five Phase II awards go to $600,000 over two years. We looked at one of the Phase I studies, Jason Benkoski's solar-thermal engine and shield concept, in the last post. Today we go hunting exoplanets with a starshade. This particular iteration of the starshade concept is called Hybrid Observatory for Earth-like Exoplanets (HOEE), as proposed by John Mather (NASA GSFC). Here the idea is to leverage the resources of the huge ground-based telescopes that should define the next generation of such instruments - the Giant Magellan Telescope, the Extremely Large Telescope, etc. - by using a starshade to block the glare of...

The apparent discovery of a new planet around Proxima Centauri moves what would have been today’s post (on laser-thermal interstellar propulsion concepts) to early next week. Although not yet confirmed, the data analysis on what will be called Proxima Centauri d seems strong, in the hands of João Faria (Instituto de Astrofísica e Ciências do Espaço, Portugal) and colleagues. The work has just been published in Astronomy & Astrophysics. It’s good to hear that Faria describes Proxima Centauri as being “within reach of further study and future exploration.” That last bit, of course, is a nod to the fact that this is the nearest star to the Sun, and while 4.2 light years is its own kind of immensity, any future interstellar probe will naturally focus either here or on Centauri A and B. Years are short on Proxima d – the putative planet circles Proxima every five days. That’s a tenth of Mercury’s distance from the Sun, closer to the star than to the inner edge of the habitable zone....

It would explain a lot if two recent discoveries involving 'mini-Neptunes' turned out to be representative of what happens to their entire class. For Michael Zhang (Caltech) and colleagues, in two just published papers, have found that mini-Neptunes can lose gas to their parent star, possibly indicating their transformation into a 'super-Earth.' If such changes are common, then we have a path to get from a dense but Neptune-like world to a super-Earth, a planet roughly 1.6 times the size of the Earth and part of a category of worlds we do not see represented in our Solar System. As we drill down toward finding smaller worlds, we've been finding a lot of mini-Neptunes as well as super-Earths, with the former two to four times the size of the Earth. Thus we have a bimodal gap in exoplanet observation. Where are the worlds between 1.6 and 2-4 times the size of Earth? The new work examines two mini-Neptunes around the TESS object TOI 560, located about a hundred light-years from Earth,...

Given our recent discussion of exomoon candidate Kepler-1708 b-i, a possible moon 2.6 times the mass of Earth orbiting a gas giant, I want to be sure to work in Miki Nakajima’s work on how moons form. Nakajima (University of Rochester) is first author of the paper describing this work. It’s a significant contribution because it points to a way to refine the target list for exomoon searches, one that may help us better understand where to look as we begin to flesh out a catalog of these objects.. And flesh it out we will, as the precedent of the rapidly growing exoplanet count makes clear. What I want to do today is consider how we’ve thus far proceeded. You’ll recall that when David Kipping and team performed their deep analysis of the data leading to Kepler-1708 b-i, they chose gas giants on orbits with a period of 400 days or more, so-called ‘cool worlds’ more like Jupiter than the ‘hot Jupiters’ found so frequently in early exoplanet studies. The method produced a strong candidate...

Half a century ago, we were wondering if other stars had planets, and although we assumed so, there was always the possibility that planets were rare. Now we know that they’re all over the place. In fact, recent research out of Katholieke Universiteit Leuven in Belgium suggests that under certain circumstances, planets can form around stars that are going through their death throes, beginning the transition from red giant to white dwarf. The new work homes in on certain binary stars, and therein hangs a tale. After a red giant star has gone through the stage of helium burning at its core, it is referred to as an asymptotic giant branch star (AGB), on a path that takes it through a period of expansion and cooling prior to its becoming a white dwarf. These expanding stars lose mass as the result of stellar wind, up to 50 to 70 percent of the total mass of the star. The result: An extended envelope of material collecting around the object that will become a planetary nebula, a glowing...

We started finding a lot of 'hot Jupiters' in the early days of planet hunting simply because, although their existence was not widely predicted, they were the most likely planetary types to trigger our radial velocity detection methods. These star-hugging worlds produced a Doppler signal that readily showed the effects of planet on star, while smaller worlds, and planets farther out in their orbits, remained undetected. David Kipping (Columbia University) uses hot Jupiters as an analogy when describing his own indefatigable work hunting exomoons. We already have one of these - Kepler-1625 b-i - but it remains problematic and unconfirmed. If this turned out to be the first in a string of exomoons, we might well expect all the early finds to be large moons simply because using transit methods, these would be the easiest to detect. Kepler-1625 b-i is problematic because the data could be showing the effects of other planets in its system. If real, it would be a moon far larger than any...