Flares from a candidate Galactic magnetar suggest a missing link to dim isolated neutron stars

Minutes-duration optical flares with supernova luminosities

In recent years, certain luminous extragalactic optical transients have been observed to last only a few days1. Their short observed duration implies a different powering mechanism from the most common luminous extragalactic transients (supernovae), whose timescale is weeks2. Some short-duration transients, most notably AT2018cow (ref. 3), show blue optical colours and bright radio and X-ray emission4. Several AT2018cow-like transients have shown hints of a long-lived embedded energy source5, such as X-ray variability6,7, prolonged ultraviolet emission8, a tentative X-ray quasiperiodic oscillation9,10 and large energies coupled to fast (but subrelativistic) radio-emitting ejecta11,12. Here we report observations of minutes-duration optical flares in the aftermath of an AT2018cow-like transient, AT2022tsd (the 'Tasmanian Devil'). The flares occur over a period of months, are highly energetic and are probably nonthermal, implying that they arise from a near-relativistic outflow or jet. Our observations confirm that, in some AT2018cow-like transients, the embedded energy source is a compact object, either a magnetar or an accreting black hole.

Discourses of Nature in New Perceptions of the Natural Landscape in Southern Chile

Landscapes are shaped over time by the changing imaginaries that result from new representations of nature and the value associated with it. This paper discusses the evolving discourses which have shaped the perception of the landscape in two socially and ecologically significant contexts in Chile. The first is the central-southern region of the country, a large portion of which is now devoted to commercial forestry plantations. The second is the Patagonia-Aysén region, where since the 1990s, colonization of a land defined by a tradition of livestock rearing has evolved into a process epitomized by the slogan "Aysén, Life Reserve." The representation that was made of central-southern Chile in the 50' and 60' as a deforested and degraded land was the justification for promoting a new form of land occupation: the monoculture forest, designed and executed by a specific law. Forty years on from the passing of this law, the plantations of central-southern Chile have undergone a process of naturalization. In this case, the exaltation of nature has been permanent (before and after the changes doing by this law). The only thing that changes is the definition of nature, which ended up including forest plantations. That is, discourses influence perceptions and these lead to new practices in the study area and beyond. In Patagonia-Aysén, by the other side, there has been a marked shift in the rhetoric surrounding land. This has been particularly noticeable in the case of government bodies and private ecotourism companies, which have constructed an imaginary in line with a new model of economic development for the area. In a break with tradition, both the public and private sectors are beginning to shift their investment away from agricultural and livestock exploitation and toward ecotourism and conservation projects. In both cases, we analyse the manner in which transformations in perceptions and representations of landscape bring about new forms of land use, and how new focuses of value and social interest, forged within wider environmental discourses, have brought with them unexpected social consequences, like depopulation, economic transformations, cultural changes, etc. Thus, the aim of this work is to expose and discuss the reality and scope of new green discourses and their influence on the perception of natural landscapes in the Chilean neoliberal context.

Heat and momentum transfer for magnetoconvection in a vertical external magnetic field

The scaling theory of Grossmann and Lohse [J. Fluid Mech. 407, 27 (2000)JFLSA70022-112010.1017/S0022112099007545] for turbulent heat and momentum transfer is extended to the magnetoconvection case in the presence of a (strong) vertical magnetic field. A comparison with existing laboratory experiments and direct numerical simulations in the quasistatic limit allows us to restrict the parameter space to very low Prandtl and magnetic Prandtl numbers and thus to reduce the number of unknown parameters in the model. Also included is the Chandrasekhar limit, for which the outer magnetic induction field B is large enough such that convective motion is suppressed and heat is transported by diffusion. Our theory identifies four distinct regimes of magnetoconvection that are distinguished by the strength of the outer magnetic field and the level of turbulence in the flow, respectively.