Radial-velocity Searches for Planets Around Active Stars PDF Download
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Author: Raphaëlle D. Haywood
Publisher: Springer
ISBN: 3319412736
Category : Science
Languages : en
Pages : 152
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Book Description
This thesis develops new and powerful methods for identifying planetary signals in the presence of “noise” generated by stellar activity, and explores the physical origin of stellar intrinsic variability, using unique observations of the Sun seen as a star. In particular, it establishes that the intrinsic stellar radial-velocity variations mainly arise from suppression of photospheric convection by magnetic fields. With the advent of powerful telescopes and instruments we are now on the verge of discovering real Earth twins in orbit around other stars. The intrinsic variability of the host stars themselves, however, currently remains the main obstacle to determining the masses of such small planets. The methods developed here combine Gaussian-process regression for modeling the correlated signals arising from evolving active regions on a rotating star, and Bayesian model selection methods for distinguishing genuine planetary signals from false positives produced by stellar magnetic activity. The findings of this thesis represent a significant step towards determining the masses of potentially habitable planets orbiting Sun-like stars.
Author: Raphaëlle D. Haywood
Publisher: Springer
ISBN: 3319412736
Category : Science
Languages : en
Pages : 152
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Book Description
This thesis develops new and powerful methods for identifying planetary signals in the presence of “noise” generated by stellar activity, and explores the physical origin of stellar intrinsic variability, using unique observations of the Sun seen as a star. In particular, it establishes that the intrinsic stellar radial-velocity variations mainly arise from suppression of photospheric convection by magnetic fields. With the advent of powerful telescopes and instruments we are now on the verge of discovering real Earth twins in orbit around other stars. The intrinsic variability of the host stars themselves, however, currently remains the main obstacle to determining the masses of such small planets. The methods developed here combine Gaussian-process regression for modeling the correlated signals arising from evolving active regions on a rotating star, and Bayesian model selection methods for distinguishing genuine planetary signals from false positives produced by stellar magnetic activity. The findings of this thesis represent a significant step towards determining the masses of potentially habitable planets orbiting Sun-like stars.
Author: Dibyendu Nandy
Publisher: Cambridge University Press
ISBN: 9781107170056
Category : Science
Languages : en
Pages : 392
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Book Description
The variable activity of stars such as the Sun is mediated through stellar magnetic fields, radiative and energetic particle fluxes, stellar winds and magnetic storms manifested as stellar flares and coronal mass ejections. This activity influences planetary atmospheres, climate and habitability: on the one hand it drives life-sustaining processes on planets, but on the other hand can adversely impact planetary environments rendering them uninhabitable. Studies of this intimate relationship between the parent star, its astrosphere and the planets that it hosts have reached a certain level of maturity in our own Solar System. Based on this understanding, the first attempts are being made to characterize the interactions between distant stars and their planets and understand their coupled evolution, which is relevant for the search for habitable exoplanets. IAU Symposium 328 brings together diverse, interdisciplinary reviews and research papers which address the themes of star-planet interactions and habitability.
Author: Carolus J. Schrijver
Publisher: Cambridge University Press
ISBN: 1107090474
Category : Science
Languages : en
Pages : 407
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Book Description
Taking an interdisciplinary approach, this book explores what makes the conditions on Earth 'just right' to sustain life.
Author: International Astronomical Union. Symposium
Publisher:
ISBN:
Category : Habitable planets
Languages : en
Pages : 375
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Book Description
"The variable activity of stars such as the Sun is mediated through stellar magnetic fields, radiative and energetic particle fluxes, stellar winds, and magnetic storms manifested as stellar flares and coronal mass ejections. This activity influences planetary atmospheres, climate and habitability: on the one hand it drives life-sustaining processes on planets, but on the other hand can adversely impact planetary environments rendering them uninhabitable. Studies of this intimate relationship between the parent star, its astrosphere and the planets that it hosts have reached a certain level of maturity in our own Solar System. Based on this understanding, the first attempts are being made to characterize the interactions between distant stars and their planets and understand their coupled evolution, which is relevant for the search for habitable exoplanets. IAU Symposium 328 brings together diverse, interdisciplinary reviews and research papers which address the themes of star-planet interactions and habitability."-- Publisher's description.
Author: Jeffrey Linsky
Publisher: Springer
ISBN: 303011452X
Category : Science
Languages : en
Pages : 273
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Book Description
Like planets in our solar system, exoplanets form, evolve, and interact with their host stars in many ways. As exoplanets acquire material and grow to the final size, their atmospheres are subjected to intense UV and X-radiation and high-energy particle bombardment from the young host star. Whether a planet can retain its atmosphere and the conditions for significant mass loss both depend upon the strength of the host star's high-energy radiation and wind, the distance of the exoplanet from its host star, the gravitational potential of the exoplanet, and the initial chemical composition of the exoplanet atmosphere. This introductory overview describes the physical processes responsible for the emission of radiation and acceleration of winds of host stars that together control the environment of an exoplanet, focusing on topics that are critically important for understanding exoplanetary atmospheres but are usually not posed from the perspective of host stars. Accordingly, both host stars and exoplanets are not studied in isolation but are treated as integrated systems. Stellar magnetic fields, which are the energy source for activity phenomena including high-energy radiation and winds, play a critical role in determining whether exoplanets are habitable. This text is primarily for researchers and graduate students who are studying exoplanet atmospheres and habitability, but who may not have a background in the physics and phenomenology of host stars that provide the environment in which exoplanets evolve. It provides a comprehensive overview of this broad topic rather than going deeply into many technical aspects but includes a large list of references to guide those interested in pursuing these questions. Nonspecialists with a scientific background should also find this text a valuable resource for understanding the critical issues of contemporary exoplanet research.
Author: Valeria Souza
Publisher: Springer Nature
ISBN: 3030460878
Category : Science
Languages : en
Pages : 237
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Book Description
Astrobiology not only investigates how early life took hold of our planet but also life on other planets – both in our Solar System and beyond – and their potential for habitability. The book take readers from the scars on planetary surfaces made by space rocks to the history of the Solar System narrated by those space rocks as well as exoplanets in other planetary systems. But the true question is how life arose here or elsewhere. Modern comparative genomics has revealed that Darwin was correct; a set of highly conserved genes and cellular functions indicate that all life is related by common ancestry. The Last Universal Common Ancestor or LUCA sits at the base of the Tree of Life. However, once that life took hold, it started to diversify and form complex microbial communities that are known as microbial mats and stromatolites. Due to their long evolutionary history and abundance on modern Earth, research on the biological, chemical and geological processes of stromatolite formation has provided important insights into the field of astrobiology. Many of these microbialite-containing ecosystems have been used as models for astrobiology, and NASA mission analogs including Shark Bay, Pavilion and Kelly Lakes. Modern microbialites represent natural laboratories to study primordial ecosystems and provide proxies for how life could evolve on other planets. However, few viral metagenomic studies (i.e., viromes) have been conducted in microbialites, which are not only an important part of the community but also mirror its biodiversity. This book focuses on particularly interesting sites such as Andean lake microbialites, a proxy of early life since they are characterized by very high UV light, while Alchichica and Bacalar lakes are characterized by high-salt and oligotrophic waters that nurture stromatolites. However, it is only the oasis of Cuatro Ciénegas Basin in México that stored past life in its marine sediments of the Sierra de San Marcos. This particular Sierra has a magmatic pouch that moves the deep aquifer to the surface in a cycle of sun drenched life and back to the depths of the magmatic life in an ancient cycle that now is broken by the overexploitation of the surface water as well as the deep aquifer in order to irrigate alfalfa in the desert. The anthropocene, the era of human folly, is killing this unique time machine and with it the memory of the planet.
Author: Ervin Laszlo
Publisher: St. Martin's Essentials
ISBN: 1250797225
Category : Body, Mind & Spirit
Languages : en
Pages : 202
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Book Description
"By opening this Handbook for wise thinking and living, you open the door to your new identity, because across the threshold there is only the lightness of Being, and infinity in all directions."—Deepak Chopra In The Wisdom Principles, Dr. Ervin Laszlo, authority in the fields of new science, consciousness, and spirituality, bridges the chasm between our understanding of science and the truths of spirituality, bringing an essential and timely message of wisdom to the world. Laszlo offers readers principles of empowerment that will guide the choices they make for years to come and will allow them to move confidently toward a better future. This book is the distillation of Laszlo’s sixty plus years spent delving into the mysteries of science and a lifetime of keen spiritual insight. The nuggets of timely wisdom offered in The Wisdom Principles, and the timeless truths revealed on its pages, are a precious resource for wise thinking and living. As we stand at a crossroads of civilization there has never been a greater need for them than today. Deepak Chopra, Neale Donald Walsch, and Gregg Braden are among the renowned thought-leaders who lend their voices to Laszlo’s work, framing the book and underscoring the power of its life-changing principles.
Author: National Academies of Sciences, Engineering, and Medicine
Publisher: National Academies Press
ISBN: 0309463971
Category : Science
Languages : en
Pages : 133
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Book Description
The search for life is one of the most active fields in space science and involves a wide variety of scientific disciplines, including planetary science, astronomy and astrophysics, chemistry, biology, chemistry, and geoscience. In December 2016, the Space Studies Board hosted a workshop to explore the possibility of habitable environments in the solar system and in exoplanets, techniques for detecting life, and the instrumentation used. This publication summarizes the presentations and discussions from the workshop.
Author: Lawrence B. Crowell
Publisher: World Scientific
ISBN: 9812790772
Category : Science
Languages : en
Pages : 202
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Book Description
Nanotechnology is an emerging and exciting area in the field of implants. Numerous promising developments have been elucidated regarding the use of nanotechnology to regenerate tissues. This important book highlights the potential of nanophase materials to improve hard and soft tissue applications. In all cases, increased tissue regeneration has been observed for bone, cartilage, vascular, bladder, and central/peripheral nervous system tissues.
Author: Carolus J. Schrijver
Publisher: Cambridge University Press
ISBN: 1139489755
Category : Science
Languages : en
Pages :
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Book Description
Heliophysics is a fast-developing scientific discipline that integrates studies of the Sun's variability, the surrounding heliosphere, and the environment and climate of planets. Over the past few centuries, our understanding of how the Sun drives space weather and climate on the Earth and other planets has advanced at an ever increasing rate. This 2010 volume, the last in this series of three heliophysics texts, focuses on long-term variability from the Sun's decade-long sunspot cycle and considers the evolution of the planetary system over ten billion years from a climatological perspective. Topics covered range from the dynamo action of stars and planets to processes in the Earth's troposphere, ionosphere, and magnetosphere and their effects on planetary climate and habitability. Supplemented by online teaching materials, it can be used as a textbook for courses or as a foundational reference for researchers in fields from astrophysics and plasma physics to planetary and climate science.
