Given the spectacular interactions between Io and Jupiter -- the moon plays a major role in shaping the planet’s magnetic field and contributes a cloud of particles originally produced by its volcanic activity -- it’s all but inevitable that a recently discovered ‘rogue’ object would be compared to the duo. The rogue in question is SIMP J01365663+0933473, a planetary mass object of perhaps 12 Jupiter masses that is at the boundary between brown dwarf and planet. Between 12 and 13 Jupiter masses is considered to be the deuterium burning limit; i.e., above this, we would expect a gaseous object to be a deuterium-burning brown dwarf. What an intriguing situation we find here. Originally found in data collected by the Very Large Array, SIMP J01365663+0933473 (which I’ll now mercifully shorten, as per the paper, to SIMP0136) has a magnetic field some 200 times stronger than Jupiter’s. The discovery marked the first radio detection of a possibly planetary mass object beyond our Solar...

Just how important is plate tectonics for the development of complex life? We’ve learned that its continual churn, with material pushing up from ocean rifts and being subducted as it meets continental shelves, can moderate the Earth’s climate. Increasing temperatures are tamped down through the capture of excess carbon dioxide in rocks, which reduces potential greenhouse conditions. Lowering temperatures will produce the reverse effect. The result is a mechanism for maintaining stable temperatures that some have seen as necessary for life. "Volcanism releases gases into the atmosphere, and then through weathering, carbon dioxide is pulled from the atmosphere and sequestered into surface rocks and sediment," said Bradford Foley, assistant professor of geosciences at Penn State University. "Balancing those two processes keeps carbon dioxide at a certain level in the atmosphere, which is really important for whether the climate stays temperate and suitable for life." And indeed, most of...

With my time-out period over (more about this next week), I want to get back into gear with the help of Ramses Ramirez, a specialist on planetary habitability whose work has now taken him to Japan. Born and raised in New York City, Ramses tells me he is much at home in his new position as a research scientist at the Earth-Life Science Institute (ELSI) in Tokyo, where opportunities for scientific collaboration abound and the chance to learn a new language beckons. We've looked at Ramses' papers a number of times in these pages, and I was delighted when he offered this description of his work to our readership. A student of James Kasting, he received his Ph.D. from Penn State in 2014 and went on to postdoc work with Lisa Kaltenegger at Cornell's Carl Sagan Institute. A fascination with astrobiology and the issues involved in defining habitable zones continues to be a primary focus. Ramses' new paper ponders whether we are best served by looking for life similar to Earth's because this...

A cluster of stars sharing a common origin, now gravitationally unbound, is referred to as a stellar association. I’ve written before about how useful some of these groupings can be. In the form of so-called moving groups -- a stellar association that is still somewhat coherent -- they help us identify stars of similar age, an aid as we discover new objects. Now we have word of an object called 2MASS 0249 c, found in the Beta Pictoris moving group, that has striking similarities to the most famous member of that group, Beta Pictoris b. 2MASS 0249 c, like Beta Pictoris b, was found by direct imaging, meaning we’re actually looking at the object under discussion in the image below. The two objects are all but identical in mass, brightness and spectrum. Images from the Canada-France-Hawaii Telescope (CFHT) showed an object moving at a large distance from its host, which turned out to be a pair of closely spaced brown dwarfs. Follow-up observations with the Keck instrument allowed that...

Red dwarfs have a lot of things going for them when it comes to finding possibly habitable planets. A planet of Earth size in the HZ will produce a substantial transit signal because of the small size of the star (‘transit depth' refers to the amount of the star's light that is blocked by the planet), and the tight orbit the planet must follow increases the geometric probability of observing a transit. But planets that do not transit are also more readily detected because of the large size of the planet compared to the star, gravitational interactions producing a strong radial velocity signature, which is what we have in the case of Ross 128b. About 11 light years from Earth, the planet was culled out of more than a decade of radial velocity data in 2017 using the European Southern Observatory's HARPS spectrograph (High Accuracy Radial velocity Planet Searcher) at the La Silla Observatory in Chile. The location of the planet near the inner edge of its star’s habitable zone excited...

It's always a shock for me when the soft air and fecund smells of spring slam into a parched and baked July, but seasonal change is inevitable. At least it is on Earth. We get such seasonal changes because of Earth's obliquity, the angle of its spin axis relative to the plane of its orbit. For Earth, the angle has stayed pretty close to 23 degrees for a long time, although the tilt's direction wobbles over cycles of thousands of years. And this very constancy of obliquity turns up in exoplanet discussions at times because it affects conditions on a planetary surface. Some have argued that without the gravitational effects of the Moon, the tilt of the Earth would be changed by the gravitational pull of the Sun and planets, producing a potentially high degree of obliquity. Contrast our situation with that of Uranus, where we find a 90-degree tilt that leaves one pole in sunlight for half the Uranian year as the other remains in darkness. Without knowing how long the Moon has been able...