Densified Pupil Spectrograph as High-precision Radial Velocimetry: From Direct Measurement of the Universe’s Expansion History to Characterization of Nearby Habitable Planet Candidates

The direct measurement of the universe’s expansion history and the search for terrestrial planets in habitable zones around solar-type stars require extremely high-precision radial-velocity measures over a decade. This study proposes an approach for enabling high-precision radial-velocity measurements from space. The concept presents a combination of a high-dispersion densified pupil spectrograph and a novel line-of-sight monitor for telescopes. The precision of the radial-velocity measurements is determined by combining the spectrophotometric accuracy and the quality of the absorption lines in the recorded spectrum. Therefore, a highly dispersive densified pupil spectrograph proposed to perform stable spectroscopy can be utilized for high-precision radial-velocity measures. A concept involving the telescope’s line-of-sight monitor is developed to minimize the change of the telescope’s line of sight over a decade. This monitor allows the precise measurement of long-term telescope drift without any significant impact on the Airy disk when the densified pupil spectra are recorded. We analytically derive the uncertainty of the radial-velocity measurements, which is caused by the residual offset of the lines of sight at two epochs. We find that the error could be reduced down to approximately 1 cm s−1, and the precision will be limited by another factor (e.g., wavelength calibration uncertainty). A combination of the high-precision spectrophotometry and the high spectral resolving power could open a new path toward the characterization of nearby non-transiting habitable planet candidates orbiting late-type stars. We present two simple and compact highly dispersed densified pupil spectrograph designs for cosmology and exoplanet sciences.

Venus’ light slab hinders its development of planetary-scale subduction and habitability

Terrestrial planets Venus and Earth have similar sizes, masses, and bulk compositions, but only Earth developed planetary-scale plate tectonics. Plate tectonics generates weatherable fresh rocks and transfers surface carbon back to Earth’s interior, which provides a long-term climate feedback, serving as a thermostat to keep Earth a habitable planet. Yet Venus shares a few common features with early Earth, such as stagnant-lid tectonics and the possible early development of a liquid ocean. Given all these similarities with early Earth, why would Venus fail to develop global-scale plate tectonics? In this study, we explore solutions to this problem by examining Venus’ slab densities under hypothesized subduction-zone conditions. Our petrologic simulations show that eclogite facies may be reached at greater depths on Venus than on Earth, and Venus’ slab densities are consistently lower than Earth’s. We suggest that the lack of sufficient density contrast between the high-pressure metamorphosed slab and mantle rocks may have impeded self-sustaining subduction. Although plume-induced crustal downwelling exists on Venus, the dipping of Venus’ crustal rocks to mantle depth fails to transition into subduction tectonics. As a consequence, the supply of fresh silicate rocks to the surface has been limited. This missing carbon sink eventually diverged the evolution of Venus’ surface environment from that of Earth.

More Future? Straight Ecologies in British Climate-Change Theatre

Attempts to convey the urgency of the climate crisis often rely on the figure of the child. From Greta Thunberg via school-striking students to the grandchildren invoked in the titles of bestselling books about global warming, appearances of children seem especially effective in protesting the loss of a habitable planet. The iconic child that needs saving (or becomes the planet’s saviour) is equally prominent in British plays about climate change. Drawing on queer critiques of the conceptual short circuit between the child and the future, this article identifies two waves of UK eco-theatre: the first wave endorses hetero-nuclear family bonds and future-oriented thinking; the second wave traces alternative relations to nonhuman, ageing, or ailing Others in the present. The first part of the article revisits critiques of reproductive futurism; the second examines the straight ecologies that characterise the first wave of eco-theatre, based on a detailed analysis of Duncan Macmillan’s play Lungs (Studio Theatre, Washington, DC/Sheffield Crucible, 2011). The final part considers climate-change plays that sever reproductive timelines, as exemplified by Caryl Churchill’s Escaped Alone, Lucy Kirkwood’s The Children, and Stef Smith’s Human Animals (all Royal Court, 2016).

FinTech and Sustainable Development

The landscape of the financial industry has witnessed a massive revolution in recent years as a result of the growth of IT. The potential of FinTech innovations is a game changer allowing a scope to align itself to meet the needs of environmental sustainability. The increasing levels of human consumption are unsustainable for the world which needs to be addressed. The world needs to lead the way by rethinking many of its industries which are causing havoc for the survival of ecosystems and ensure that they operate in accordance with the 17 Sustainable Development Goals of the United Nations. The synergy of FinTech and sustainability will help to offer a tradable, measurable, and allocable venue to move citizens towards a sustainable and financially stable future. This chapter aims to justify that the future of finance is FinTech and study the ecosystem of FinTech in India and China to understand its implications, which can help for the development in the financial sector and in making the world a sustainable, habitable planet.

How to Assemble a Habitable Planet

Hydrogen is a colorless, odorless gas that, when given enough time, changes into people. How much time? 13.7 billion years! A good way to present the information in this book is to pose a question, provide an answer, and then go on to ask and...

How to Assemble a Habitable Planet

Hydrogen is a colorless, odorless gas that, when given enough time, changes into people. How much time? 13.7 billion years! A good way to present the information in this book is to pose a question, provide an answer, and then go on to ask and...

Habitable Zones in Binary Star Systems: A Zoology

Several concepts have been brought forward to determine where terrestrial planets are likely to remain habitable in multi-stellar environments. Isophote-based habitable zones, for instance, rely on insolation geometry to predict habitability, whereas radiative habitable zones take the orbital motion of a potentially habitable planet into account. Dynamically informed habitable zones include gravitational perturbations on planetary orbits, and full scale, self consistent simulations promise detailed insights into the evolution of select terrestrial worlds. All of the above approaches agree that stellar multiplicity does not preclude habitability. Predictions on where to look for habitable worlds in such environments can differ between concepts. The aim of this article is to provide an overview of current approaches and present simple analytic estimates for the various types of habitable zones in binary star systems.