Habitability on Local, Galactic and Cosmological Scales
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The Ubvri and Infrared Colour Indices of the Sun and Sun-Like Stars
The 19th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun Edited by G. A. Feiden THE UBVRI AND INFRARED COLOUR INDICES OF THE SUN AND SUN-LIKE STARS Mehmet TANRIVER1, Ferhat Fikri ÖZEREN1 1 Erciyes University, Astronomy and Space Sciences Department, 38039, Kayseri, Turkey Abstract The Sun is not a point source, the photometric observational techniques that are utilised for observing other stars cannot be utilised for the Sun, meaning that it is dicult to derive its colours accurately for astronomical work from direct measurements in dierent passbands. The solar twins are the best choices because they are the stars that are ideally the same as the Sun in all parameters, and also, their colours are highly similar to those of the Sun. From the 60 articles on the Sun and Sun-like stars in the literature from 1964 until today, the solar colour indices in the optic and infrared regions have been estimated. 1 INTRODUCTION Table 1: The obtained average colour indices values of the The Sun is an average-low-mass star in the main sequence Sun with standart deviation (±σ)( Tanrıver (2012), Tanrıver of the Hertzsprung-Russell diagram. Moreover, the Sun is (2014a), Tanrıver (2014b) ). not a point source, the photometric observational techniques that are utilised for observing other stars cannot be utilised B-V 0.6457 ± 0.0421 V-J 1.1413 ± 0.1063 for the Sun. Therefore, the colours and colour indices of the H-K 0.0572 ± 0.0351 U-B 0.1463 ± 0.0596 sun-like stars are used in order to determine the sun’s colour V-H 1.4613 ± 0.1183 J-K 0.3777 ± 0.0494 indices. -
Magnetism, Dynamo Action and the Solar-Stellar Connection
Living Rev. Sol. Phys. (2017) 14:4 DOI 10.1007/s41116-017-0007-8 REVIEW ARTICLE Magnetism, dynamo action and the solar-stellar connection Allan Sacha Brun1 · Matthew K. Browning2 Received: 23 August 2016 / Accepted: 28 July 2017 © The Author(s) 2017. This article is an open access publication Abstract The Sun and other stars are magnetic: magnetism pervades their interiors and affects their evolution in a variety of ways. In the Sun, both the fields themselves and their influence on other phenomena can be uncovered in exquisite detail, but these observations sample only a moment in a single star’s life. By turning to observa- tions of other stars, and to theory and simulation, we may infer other aspects of the magnetism—e.g., its dependence on stellar age, mass, or rotation rate—that would be invisible from close study of the Sun alone. Here, we review observations and theory of magnetism in the Sun and other stars, with a partial focus on the “Solar-stellar connec- tion”: i.e., ways in which studies of other stars have influenced our understanding of the Sun and vice versa. We briefly review techniques by which magnetic fields can be measured (or their presence otherwise inferred) in stars, and then highlight some key observational findings uncovered by such measurements, focusing (in many cases) on those that offer particularly direct constraints on theories of how the fields are built and maintained. We turn then to a discussion of how the fields arise in different objects: first, we summarize some essential elements of convection and dynamo theory, includ- ing a very brief discussion of mean-field theory and related concepts. -
The Large Scale Universe As a Quasi Quantum White Hole
International Astronomy and Astrophysics Research Journal 3(1): 22-42, 2021; Article no.IAARJ.66092 The Large Scale Universe as a Quasi Quantum White Hole U. V. S. Seshavatharam1*, Eugene Terry Tatum2 and S. Lakshminarayana3 1Honorary Faculty, I-SERVE, Survey no-42, Hitech city, Hyderabad-84,Telangana, India. 2760 Campbell Ln. Ste 106 #161, Bowling Green, KY, USA. 3Department of Nuclear Physics, Andhra University, Visakhapatnam-03, AP, India. Authors’ contributions This work was carried out in collaboration among all authors. Author UVSS designed the study, performed the statistical analysis, wrote the protocol, and wrote the first draft of the manuscript. Authors ETT and SL managed the analyses of the study. All authors read and approved the final manuscript. Article Information Editor(s): (1) Dr. David Garrison, University of Houston-Clear Lake, USA. (2) Professor. Hadia Hassan Selim, National Research Institute of Astronomy and Geophysics, Egypt. Reviewers: (1) Abhishek Kumar Singh, Magadh University, India. (2) Mohsen Lutephy, Azad Islamic university (IAU), Iran. (3) Sie Long Kek, Universiti Tun Hussein Onn Malaysia, Malaysia. (4) N.V.Krishna Prasad, GITAM University, India. (5) Maryam Roushan, University of Mazandaran, Iran. Complete Peer review History: http://www.sdiarticle4.com/review-history/66092 Received 17 January 2021 Original Research Article Accepted 23 March 2021 Published 01 April 2021 ABSTRACT We emphasize the point that, standard model of cosmology is basically a model of classical general relativity and it seems inevitable to have a revision with reference to quantum model of cosmology. Utmost important point to be noted is that, ‘Spin’ is a basic property of quantum mechanics and ‘rotation’ is a very common experience. -
Exoplanet Community Report
JPL Publication 09‐3 Exoplanet Community Report Edited by: P. R. Lawson, W. A. Traub and S. C. Unwin National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Pasadena, California March 2009 The work described in this publication was performed at a number of organizations, including the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (NASA). Publication was provided by the Jet Propulsion Laboratory. Compiling and publication support was provided by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not constitute or imply its endorsement by the United States Government, or the Jet Propulsion Laboratory, California Institute of Technology. © 2009. All rights reserved. The exoplanet community’s top priority is that a line of probeclass missions for exoplanets be established, leading to a flagship mission at the earliest opportunity. iii Contents 1 EXECUTIVE SUMMARY.................................................................................................................. 1 1.1 INTRODUCTION...............................................................................................................................................1 1.2 EXOPLANET FORUM 2008: THE PROCESS OF CONSENSUS BEGINS.....................................................2 -
Looking for New Earth in the Coming Decade
Detection of Earth-like Planets with NWO With discoveries like methane on Mars (Mumma et al. 2009) and super-Earth planets orbiting nearby stars (Howard et al. 2009), the fields of exobiology and exoplanetary science are breaking new ground on almost a weekly basis. These two fields will one day merge, with the high goal of discovering Earth-like planets orbiting nearby stars and the subsequent search for signs of life on those planets. The Kepler mission will soon place clear bounds on the frequency of terrestrial-sized planets (Basri et al. 2008). Beyond that, the great challenge is to determine their true natures. Are terrestrial exoplanets anything like Earth, with life forms able to thrive even on the surface? What is the range of conditions under which Earth-like and other habitable worlds can arise? Every stellar system in the solar neighborhood is entirely unique, and it is almost certain that anything that can happen, will. With current and near-term technology, we can make great strides in finding and characterizing planets in the habitable zones of nearby stars. Given reasonable mission specifications for the New Worlds Observer, the layout of the stars in the solar neighborhood, and their variable characteristics (especially exozodiacal dust) a direct imaging mission can detect and characterize dozens of Earths. Not only does direct imaging achieve detection of planets in a single visit, but photometry, spectroscopy, polarimetry and time-variability in those signals place strong constraints on how those planets compare to our own, including plausible ranges in planet mass and atmospheric and internal structure. -
Detection and Characterization of Circumstellar Material with a WFIRST Or EXO-C Coronagraphic Instrument: Simulations and Observational Methods
Detection and characterization of circumstellar material with a WFIRST or EXO-C coronagraphic instrument: simulations and observational methods Glenn Schneider Dean C. Hines Glenn Schneider, Dean C. Hines, “Detection and characterization of circumstellar material with a WFIRST or EXO-C coronagraphic instrument: simulations and observational methods,” J. Astron. Telesc. Instrum. Syst. 2(1), 011022 (2016), doi: 10.1117/1.JATIS.2.1.011022. Downloaded From: http://astronomicaltelescopes.spiedigitallibrary.org/ on 01/14/2017 Terms of Use: http://spiedigitallibrary.org/ss/termsofuse.aspx Journal of Astronomical Telescopes, Instruments, and Systems 2(1), 011022 (Jan–Mar 2016) Detection and characterization of circumstellar material with a WFIRST or EXO-C coronagraphic instrument: simulations and observational methods Glenn Schneidera,* and Dean C. Hinesb aThe University of Arizona, Steward Observatory and the Department of Astronomy, North Cherry Avenue, Tucson, Arizona 85712, United States bSpace Telescope Science Institute, 3700 San Martin Drive, Baltimore, Maryland 21218, United States Abstract. The capabilities of a high (∼10−9 resel−1) contrast narrow-field coronagraphic instrument (CGI) on a space-based WFIRST-C or probe-class EXO-C/S mission are particularly and importantly germane to symbiotic studies of the systems of circumstellar material from which planets have emerged and interact with throughout their lifetimes. The small particle populations in “disks” of co-orbiting materials can trace the presence of planets through dynamical -
Monthly Newsletter of the Durban Centre - March 2018
Page 1 Monthly Newsletter of the Durban Centre - March 2018 Page 2 Table of Contents Chairman’s Chatter …...…………………….……….………..….…… 3 Andrew Gray …………………………………………...………………. 5 The Hyades Star Cluster …...………………………….…….……….. 6 At the Eye Piece …………………………………………….….…….... 9 The Cover Image - Antennae Nebula …….……………………….. 11 Galaxy - Part 2 ….………………………………..………………….... 13 Self-Taught Astronomer …………………………………..………… 21 The Month Ahead …..…………………...….…….……………..…… 24 Minutes of the Previous Meeting …………………………….……. 25 Public Viewing Roster …………………………….……….…..……. 26 Pre-loved Telescope Equipment …………………………...……… 28 ASSA Symposium 2018 ………………………...……….…......…… 29 Member Submissions Disclaimer: The views expressed in ‘nDaba are solely those of the writer and are not necessarily the views of the Durban Centre, nor the Editor. All images and content is the work of the respective copyright owner Page 3 Chairman’s Chatter By Mike Hadlow Dear Members, The third month of the year is upon us and already the viewing conditions have been more favourable over the last few nights. Let’s hope it continues and we have clear skies and good viewing for the next five or six months. Our February meeting was well attended, with our main speaker being Dr Matt Hilton from the Astrophysics and Cosmology Research Unit at UKZN who gave us an excellent presentation on gravity waves. We really have to be thankful to Dr Hilton from ACRU UKZN for giving us his time to give us presentations and hope that we can maintain our relationship with ACRU and that we can draw other speakers from his colleagues and other research students! Thanks must also go to Debbie Abel and Piet Strauss for their monthly presentations on NASA and the sky for the following month, respectively. -
The Chemical Composition of Solar-Type Stars and Its Impact on the Presence of Planets
The chemical composition of solar-type stars and its impact on the presence of planets Patrick Baumann Munchen¨ 2013 The chemical composition of solar-type stars and its impact on the presence of planets Patrick Baumann Dissertation der Fakultat¨ fur¨ Physik der Ludwig-Maximilians-Universitat¨ Munchen¨ durchgefuhrt¨ am Max-Planck-Institut fur¨ Astrophysik vorgelegt von Patrick Baumann aus Munchen¨ Munchen,¨ den 31. Januar 2013 Erstgutacher: Prof. Dr. Achim Weiss Zweitgutachter: Prof. Dr. Joachim Puls Tag der mündlichen Prüfung: 8. April 2013 Zusammenfassung Wir untersuchen eine mogliche¨ Verbindung zwischen den relativen Elementhaufig-¨ keiten in Sternatmospharen¨ und der Anwesenheit von Planeten um den jeweili- gen Stern. Um zuverlassige¨ Ergebnisse zu erhalten, untersuchen wir ausschließlich sonnenahnliche¨ Sterne und fuhren¨ unsere spektroskopischen Analysen zur Bestim- mung der grundlegenden Parameter und der chemischen Zusammensetzung streng differenziell und relativ zu den solaren Werten durch. Insgesamt untersuchen wir 200 Sterne unter Zuhilfenahme von Spektren mit herausragender Qualitat,¨ die an den modernsten Teleskopen gewonnen wurden, die uns zur Verfugung¨ stehen. Mithilfe der Daten fur¨ 117 sonnenahnliche¨ Sterne untersuchen wir eine mogliche¨ Verbindung zwischen der Oberflachenh¨ aufigkeit¨ von Lithium in einem Stern, seinem Alter und der Wahrscheinlichkeit, dass sich ein oder mehrere Sterne in einer Um- laufbahn um das Objekt befinden. Fur¨ jeden Stern erhalten wir sehr exakte grundle- gende Parameter unter Benutzung einer sorgfaltig¨ zusammengestellten Liste von Fe i- und Fe ii-absorptionslinien, modernen Modellatmospharen¨ und Routinen zum Erstellen von Modellspektren. Die Massen und das Alter der Objekte werden mithilfe von Isochronen bestimmt, was zu sehr soliden relativen Werten fuhrt.¨ Bei jungen Sternen, fur¨ die die Isochronenmethode recht unzuverlssig¨ ist, vergleichen wir verschiedene alternative Methoden. -
THE KINEMATICS and AGES of STARS in GLIESE's CATALOGUE 1. Introduction This Contribution Gives Some Results on the Kinematics An
THE KINEMATICS AND AGES OF STARS IN GLIESE'S CATALOGUE R. WIELEN Astronomisches Rechen-Institut, Heidelberg, F.R.G. 1. Introduction This contribution gives some results on the kinematics and ages of stars near the Sun. These results are mainly based on the catalogue of nearby stars compiled by Gliese (1957, 1969 and minor recent modifications). Table I shows the number of objects under consideration. While the old catalogue (1957) contained only stars with distances r up to 20 pc, the new edition (1969) includes many stars with slightly larger distances. In Table I, a 'system' is either a single star or a binary or a multiple system. The number of systems with known space velocities nearer than 20 pc has increased by about 30% from 1957 to 1969. The first edition of Gliese's catalogue (1957) has been analyzed in detail by Gliese (1956) and von Hoerner (1960). TABLE I Gliese's Catalogue of Nearby Stars Number Edition 1969 1957 All j-s=20pc r<20 pc Stars 1890 1277 1095 Systems 1529 1036 916 Systems with known space velocity 1131 770 598 Although Gliese's catalogue is the most complete collection of stars within 20 pc, this sample of stars is severely biased by selection effects and is not fully representative for all the nearby stars. Only the stars brighter than M„~ +7 are almost completely known within 20 pc. For the fainter stars, the following selection effects occur: (a) The southern sky is deficient in detected faint nearby stars; (b) Since most of the faint nearby stars are found by their high proper motions, the sample is deficient in stars with small tangential components of their space velocities (measured with respect to the Sun); (c) Due to incomplete detection, the apparent space density of faint stars decreases rapidly with increasing distance r, and this effect becomes stronger with increasing M„. -
Particle Dark Matter in the Solar System
Particle Dark Matter in the Solar System Annika H. G. Peter A Dissertation Presented to the Faculty of Princeton University in Candidacy for the Degree of Doctor of Philosophy Recommended for Acceptance by the Department of Physics June, 2008 c Copyright 2008 by Annika H. G. Peter. All rights reserved. Abstract Particle dark matter in the Galactic halo may be bound to the solar system either by elastic scattering through weak interactions with nucleons in the Sun (weak scattering) or by gravitational interactions with the planets, mainly Jupiter (gravitational capture). In this thesis, I simulate weak scattering, gravitational capture, and the subsequent evolution of the bound orbits to determine the distribution of bound dark matter at the position of the Earth. Previous work on this subject suggested that the event rate in dark matter detection experiments due to bound particles could be of order the event rate of halo particles in direct detection experiments, and several orders of magnitude higher for neutrinos arising from dark matter annihilation in the Earth. I use direct integration of orbits in a simplified solar system consisting of the Sun and Jupiter. I follow bound orbits until the particles are either rescattered in the Sun onto orbits that no longer intersect the Earth, ejected from the solar system, or reach the lifetime of the solar system tSS = 4.5 Gyr. Since many aspects of the particle orbits pose severe problems for traditional orbit integration methods, I develop a novel integration scheme for this problem, which has only small and oscillatory energy errors even for highly eccentric orbits over very long times. -
Taking the Measure of the Universe: Precision Astrometry with SIM
Accepted for publication in PASP, January 2008 issue A Preprint typeset using LTEX style emulateapj v. 08/22/09 TAKING THE MEASURE OF THE UNIVERSE: PRECISION ASTROMETRY WITH SIM PLANETQUEST Stephen C. Unwin1, Michael Shao2, Angelle M. Tanner2, Ronald J. Allen3, Charles A. Beichman4, David Boboltz5, Joseph H. Catanzarite2, Brian C. Chaboyer6, David R. Ciardi4, Stephen J. Edberg2, Alan L. Fey5, Debra A. Fischer7, Christopher R. Gelino8, Andrew P. Gould9, Carl Grillmair8, Todd J. Henry10, Kathryn V. Johnston11,12, Kenneth J. Johnston5, Dayton L. Jones2, Shrinivas R. Kulkarni4, Nicholas M. Law4, Steven R. Majewski13, Valeri V. Makarov2, Geoffrey W. Marcy14, David L. Meier2, Rob P. Olling15, Xiaopei Pan2, Richard J. Patterson13, Jo Eliza Pitesky2, Andreas Quirrenbach16, Stuart B. Shaklan2, Edward J. Shaya15, Louis E. Strigari17, John A. Tomsick18,19, Ann E. Wehrle20, and Guy Worthey21 Accepted for publication in PASP, January 2008 issue ABSTRACT Precision astrometry at microarcsecond accuracy has application to a wide range of astrophysical problems. This paper is a study of the science questions that can be addressed using an instrument with flexible scheduling that delivers parallaxes at about 4 microarcsec (µas) on targets as faint as V = 20, and differential accuracy of 0.6 µas on bright targets. The science topics are drawn primarily from the Team Key Projects, selected in 2000, for the Space Interferometry Mission PlanetQuest (SIM PlanetQuest). We use the capabilities of this mission to illustrate the importance of the next level of astrometric precision in modern astrophysics. SIM PlanetQuest is currently in the detailed design phase, having completed in 2005 all of the enabling technologies needed for the flight instrument. -
The Oort Cloud As a Dynamical System
Monograf´ıas de la Real Academia de Ciencias de Zaragoza 30, 1–9, (2006). The Oort cloud as a dynamical system S. Breiter Astronomical Observatory, Adam Mickiewicz University S loneczna 36, 60-286 Pozna´n, Poland. ∗ Abstract The Oort cloud is a formally simple dynamical system if we restrict its study to the heliocentric Kepler problem perturbed by the quadratic tidal potential of the Galaxy. Nonintegrability of this system leads to rich dynamics, shaped by the resonances of various nature. A new perturbation solution has helped to identify a class of resonances between the precessing nodes and the rotation of the Galaxy. 1 Introduction In 1950, J. H. Oort [10] proposed a hypothesis that long-periodic comets observed in the Solar System come from a cloud surrounding the Sun, instead of being some captured interstellar objects. This bold hypothesis, although initially backed up by the observations of merely 19 objects, has nowadays gained a common acceptance: the cloud is assumed to be a shell ranging from 50 to 100 kAU, populated by 1012 objects. What changed since the times of Oort, is the identification of the mechanism responsible for the transport of comets to the inner Solar System. Curiously, Oort – an expert in galactic dynamics – thought about the sporadic encounters with passing-by stars, whereas today the Galactic potential is considered the primary factor. The influence of our Galaxy is the only signif- icant factor of systematic nature that can influence cometary orbits. Other phenomena, like encounters with other stars and molecular clouds are by no means negligible, but they happen occasionally as a quasi-random forcing superimposed on the steady Galactic force background.