Welcome back to the Abstract! These are the studies this week that searched for life in the dark, stood up for hedgehogs, dropped some wisdom, and died in an inexplicably epic explosion.First, aliens might be riding around interstellar space on exomoons, just in case that\u2019s of interest to you. Then: an ultrasonic solution to roadkill, the limits of metrification, and an answer to a cosmic mystery.As always, for more of my work, check out my book First Contact: The Story of Our Obsession with Aliens or subscribe to my personal newsletter the BeX Files.\u00a0bThe view from a rogue exomoonDahlb\u00fcdding, David et al. \u201cHabitability of Tidally Heated H2-Dominated Exomoons around Free-Floating Planets.\u201d\u00a0Living on a planet with a boring old Sun is for normies. In a new study, astronomers suggest that alien life could potentially emerge in a much more unexpected place\u2014\u201dexomoons\u201d that orbit free-floating planets in interstellar space.\u00a0There are likely trillions of rogue planets wandering through the Milky Way, untethered to any star, raising the tantalizing mystery of whether any of them could be habitable. Now, researchers led by David Dahlb\u00fcdding of the Max Planck Institute for Extraterrestrial Physics (MPE) extend this question to exomoons that were dragged out into interstellar space with their planets.\u00a0\u00a0\u201cThe search for exomoons within conventional stellar systems continues with no confirmed detection to date,\u201d the team said. \u201cThus, free-floating planets might offer an alternative pathway for the first discovery of an exomoon.\u201dIn other words, astronomers have never clearly seen an exomoon. But new techniques for spying free-floating worlds\u2014such as microlensing, which reveals objects through the warped light of their gravity\u2014could provide the sensitivity that is required for this long-sought detection.With regard to potential habitability, Dahlb\u00fcdding and his colleagues focused specifically on exomoons that orbit planets with thick hydrogen atmospheres. If such a pair were to be kicked out of a star system, the exomoon\u2019s orbit could become stretched out into a far more elliptical shape. This shift would cause the planet to exert more intense tidal forces onto its satellite, generating heat that could keep liquid water flowing on the moon over vast timescales.\u201cClose encounters before the final ejection even increase the ellipticity of the moon\u2019s orbit, boosting tidal heating over millions to billions of years, depending on the moon\u2019s and free-floating planet\u2019s properties,\u201d the team said. The tidal forces and atmospheric components could also \u201ccreate favourable conditions for RNA polymerisation and thus support the emergence of life.\u201d\u201cThese potentially habitable moons could be detected through a variety of techniques,\u201d including microlensing, the researchers added, though they noted that actually analyzing their atmospheres \u201cmay not be feasible with any instruments currently in operation.\u201dWhile we may not be able to spot signs of life on these worlds anytime soon, it would be exciting just to discover a planet and a moon bound together, but unbound from any star, which is a genuine near-term possibility.In other news\u2026Ultra-sonic the hedgehogRasmussen, Sophie Lund et al. \u201cHearing and anatomy of the ear of the European hedgehog Erinaceus europaeus.\u201d Biology Letters.Hedgehogs have long been ubiquitous in Europe, but cars now kill up to one-third of their population each year. Even more nightmarish, the advent of robotic lawn mowers has led to an uptick in hedgehog deaths.To help protect these iconic critters, scientists suggest testing out acoustic repellents. A series of experiments with 20 hedgehogs from a wildlife rescue established that \u201chedgehogs can perceive a broad ultrasonic range,\u201d with peak sensitivity around 40 kHz.Rasmussen, who goes by Dr. Hedgehog, with a hedgehog. Image: Joan OstenfeldtThe results \u201cshow a potential for the development of targeted ultrasonic sound repellents to deter hedgehogs temporarily from potential dangers such as the particular models of robotic lawn mowers found to be hazardous to hedgehog survival, and more importantly, cars,\u201d said researchers led by Sophie Lund Rasmussen of the University of Oxford.\u201cDesigning sound repellents for cars to reduce the high number of road-killed hedgehogs enhances animal welfare and supports conservation of this declining flagship species,\u201d the team concluded.To channel the old joke, why did the hedgehog cross the road? Answer: Ideally it didn\u2019t, due to scientific intervention. (I\u2019ll be here all night).Dropping in on science historyCornu, Armel et al. \u201cThe drop and the metric system: how an unruly unit survived revolutions.\u201d Annals of Science.The metric system has been adopted by every country except Liberia, Myanmar, and the United States. But even as metrication was rapidly embraced in the 17th and 18th centuries, a far more imprecise system\u2014the drop\u2014refused to drop out.\u00a0People have measured liquids in drop form for thousands of years, and still do in many contexts today. Researchers led by Armel Cornu of Uppsala University have now explored how such \u201cnon-standard units survive lengthy waves of standardization.\u201d The paper is worth a read for its many interesting asides, like how acids were tested \u201cby counting the number of drops\u2026that could be placed on the skin before one witnessed the effects.\u201d Gnarly.\u00a0It also gets into the political dimensions of metrication, including this proto-populist justification for standardizing units: \u201cNumerous complaints about the diversity of measurements and their lack of cross-readability\u201d were directed with \u201ca special ire at powerful lords who abused standards in order to extort the population,\u201d Cornu\u2019s team said. The metric system was one response to “the discontent of peasants and the little people against the powerful.\u201d\u00a0Anyway, a little bit of drop-related science history never hurt anyone\u2014unless you volunteered to be an acid tester.A (dead) star is born\u00a0Farah, Joseph et al. \u201cLense\u2013Thirring precessing magnetar engine drives a superluminous supernova.\u201d Nature.Astronomers have discovered the mysterious power source of rare and radiant stellar explosions called \u201cType I superluminous supernovae\u201d which are ten times brighter than regular supernovae.\u00a0The secret superluminous sauce, as it turns out, is the birth of a magnetar, a highly magnetized stellar remnant, according to a supernova first observed in December 2024. The light from this stellar explosion contained imprints of the Lense\u2013Thirring effect, in which spacetime is dragged around by massive and rapidly rotating objects, a key sign of a magnetar origin.\u00a0Artist\u2019s conception of a magnetar surrounded by an accretion disk exhibiting Lense-Thirring precession. Image: Joseph Farah and Curtis McCully\u201cOur observations are consistent with a magnetar centrally located within the expanding supernova ejecta,\u201d said researchers led by Joseph Farah of Las Cumbres Observatory. \u201cThese results provide the first observational evidence of the Lense\u2013Thirring effect in the environment of a magnetar and confirm the magnetar spin-down model as an explanation for the extreme luminosity observed in Type I superluminous supernovae.\u201d\u00a0\u201cWe anticipate that this discovery will create avenues for testing general relativity in a new regime\u2014the violent centres of young supernovae,\u201d the team concluded.\u00a0Forget \u201cstellar\u201d as slang for great; we have graduated to \u201csuperluminous.\u201d\u00a0Thanks for reading! See you next week.<\/p>\n","protected":false},"excerpt":{"rendered":"