Astro2020 Science White Paper Unlocking the Secrets of Late-Stage Stellar Evolution and Mass Loss Through Radio Wavelength Imaging
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Cometary Panspermia a Radical Theory of Life’S Cosmic Origin and Evolution …And Over 450 Articles, ~ 60 in Nature
35 books: Cosmic origins of life 1976-2020 Physical Sciences︱ Chandra Wickramasinghe Cometary panspermia A radical theory of life’s cosmic origin and evolution …And over 450 articles, ~ 60 in Nature he combined efforts of generations supporting panspermia continues to Prof Wickramasinghe argues that the seeds of all life (bacteria and viruses) Panspermia has been around may have arrived on Earth from space, and may indeed still be raining down some 100 years since the term of experts in multiple fields, accumulate (Wickramasinghe et al., 2018, to affect life on Earth today, a concept known as cometary panspermia. ‘primordial soup’, referring to Tincluding evolutionary biology, 2019; Steele et al., 2018). the primitive ocean of organic paleontology and geology, have painted material not-yet-assembled a fairly good, if far-from-complete, picture COMETARY PANSPERMIA – cultural conceptions of life dating back galactic wanderers are normal features have argued that these could not into living organisms, was first of how the first life on Earth progressed A SOLUTION? to the ideas of Aristotle, and that this of the cosmos. Comets are known to have been lofted from the Earth to a coined. The question of how from simple organisms to what we can The word ‘panspermia’ comes from the may be the source of some of the have significant water content as well height of 400km by any known process. life’s molecular building blocks see today. However, there is a crucial ancient Greek roots ‘sperma’ meaning more hostile resistance the idea of as organics, and their cores, kept warm Bacteria have also been found high in spontaneously assembled gap in mainstream understanding - seed, and ‘pan’, meaning all. -
Extremely Extended Dust Shells Around Evolved Intermediate Mass Stars: Probing Mass Loss Histories,Thermal Pulses and Stellar Evolution
EXTREMELY EXTENDED DUST SHELLS AROUND EVOLVED INTERMEDIATE MASS STARS: PROBING MASS LOSS HISTORIES,THERMAL PULSES AND STELLAR EVOLUTION A Thesis presented to the Faculty of the Graduate School at the University of Missouri In Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy by BASIL MENZI MCHUNU Dr. Angela K. Speck December 2011 The undersigned, appointed by the Dean of the Graduate School, have examined the dissertation entitled: EXTREMELY EXTENDED DUST SHELLS AROUND EVOLVED INTERMEDIATE MASS STARS PROBING MASS LOSS HISTORIES, THERMAL PULSES AND STELLAR EVOLUTION USING FAR-INFRARED IMAGING PHOTOMETRY presented by Basil Menzi Mchunu, a candidate for the degree of Doctor of Philosophy and hereby certify that, in their opinion, it is worthy of acceptance. Dr. Angela K. Speck Dr. Sergei Kopeikin Dr. Adam Helfer Dr. Bahram Mashhoon Dr. Haskell Taub DEDICATION This thesis is dedicated to my family, who raised me to be the man I am today under challenging conditions: my grandfather Baba (Samuel Mpala Mchunu), my grandmother (Ma Magasa, Nonhlekiso Mchunu), my aunt Thembeni, and my mother, Nombso Betty Mchunu. I would especially like to thank my mother for all the courage she gave me, bringing me chocolate during my undergraduate days to show her love when she had little else to give, and giving her unending support when I was so far away from home in graduate school. She passed away, when I was so close to graduation. To her, I say, ′′Ulale kahle Macingwane.′′ I have done it with the help from your spirit and courage. I would also like to thank my wife, Heather Shawver, and our beautiful children, Rosemary and Brianna , for making me see life with a new meaning of hope and prosperity. -
Red Giant Mass-Loss: Studying Evolved Stellar Winds with FUSE and HST/STIS
Red Giant Mass-Loss: Studying Evolved Stellar Winds with FUSE and HST/STIS A dissertation submitted to the University of Dublin for the degree of Doctor of Philosophy Cian Crowley Supervisor: Dr. Brian R. Espey Trinity College Dublin, July 2006 School of Physics University of Dublin Trinity College Dublin ii For Mam and Dad Declaration I hereby declare that this thesis has not been submitted as an exercise for a degree at this or any other University and that it is entirely my own work. I agree that the Library may lend or copy this thesis upon request. Signed, Cian Crowley July 25, 2006. Publications Crowley, C., Espey, B. R.,. & McCandliss, S. R., 2006, In prep., ‘FUSE and HST/STIS Observations of the Eclipsing Symbiotic Binary EG Andromedae’ Acknowledgments I wish to acknowledge and thank Brian Espey, Stephan McCandliss and Peter Hauschildt for their contributions to this work. Most especially I would like to express my gratitude to my supervisor Brian Espey for his enthusiastic supervision, patience and encourage- ment. His help, support and advice is very much appreciated. In addition, the helpful and insightful comments and advice from numerous people, inlcuding, Graham Harper, Philip Bennett, Alex Brown, Gary Ferland, Tom Ake, B-G Anderson and Dugan With- erick, were invaluable and again, very much appreciated. Also, a special word of thanks for their viva comments and feedback for Alex Brown and Peter Gallagher. This work was supported by Enterprise Ireland Basic Research grant SC/2002/370 from EU funded NDP. The FUSE data were obtained under the Guest Investigator Pro- gram and supported by NASA grants NAG5-8994 and NAG5-10403 to the Johns Hopkins University (JHU). -
Evolutionary Processes Transpiring in the Stages of Lithopanspermia Ian Von Hegner
Evolutionary processes transpiring in the stages of lithopanspermia Ian von Hegner To cite this version: Ian von Hegner. Evolutionary processes transpiring in the stages of lithopanspermia. 2020. hal- 02548882v2 HAL Id: hal-02548882 https://hal.archives-ouvertes.fr/hal-02548882v2 Preprint submitted on 5 Aug 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. HAL archives-ouvertes.fr | CCSD, April 2020. Evolutionary processes transpiring in the stages of lithopanspermia Ian von Hegner Aarhus University Abstract Lithopanspermia is a theory proposing a natural exchange of organisms between solar system bodies as a result of asteroidal or cometary impactors. Research has examined not only the physics of the stages themselves but also the survival probabilities for life in each stage. However, although life is the primary factor of interest in lithopanspermia, this life is mainly treated as a passive cargo. Life, however, does not merely passively receive an onslaught of stress from surroundings; instead, it reacts. Thus, planetary ejection, interplanetary transport, and planetary entry are only the first three factors in the equation. The other factors are the quality, quantity, and evolutionary strategy of the transported organisms. -
Astronomy & Astrophysics on the Properties of Massive Population III
A&A 382, 28–42 (2002) Astronomy DOI: 10.1051/0004-6361:20011619 & c ESO 2002 Astrophysics On the properties of massive Population III stars and metal-free stellar populations D. Schaerer Observatoire Midi-Pyr´en´ees, Laboratoire d’Astrophysique, UMR 5572, 14 Av. E. Belin, 31400 Toulouse, France Received 2 July 2001 / Accepted 13 November 2001 Abstract. We present realistic models for massive Population III stars and stellar populations based on non-LTE model atmospheres, recent stellar evolution tracks and up-to-date evolutionary synthesis models, with the aim to study their spectral properties, including their dependence on age, star formation history, and IMF. A comparison of plane parallel non-LTE model atmospheres and comoving frame calculations shows that even in the presence of some putative weak mass loss, the ionising spectra of metal-free populations differ little or negligibly from those obtained using plane parallel non-LTE models. As already discussed by Tumlinson & Shull (2000), the main salient property of Pop III stars is their increased ionising flux, especially in the He+ continuum (>54 eV). The main result obtained for individual Pop III stars is the following: due to their redward evolution off the zero age main sequence (ZAMS) the spectral hardness measured by the He+/H ionising flux is decreased by a factor ∼2 when averaged over their lifetime. If such stars would suffer strong mass loss, their spectral appearance could, however, remain similar to that of their ZAMS position. The main results regarding integrated stellar populations are: – for young bursts and the case of a constant SFR, nebular continuous emission – neglected in previous studies – dominates the spectrum redward of Lyman-α if the escape fraction of ionising photons out of the considered region is small or negligible. -
Aerosols in Astrophysics Stars Complete Their Cycle of Existence, There R.E.Stencel, C.A
Aerosols in Astrophysics stars complete their cycle of existence, there R.E.Stencel, C.A. Jurgenson & is a wholesale return of modified material T.A. Ostrowski-Fukuda back to the interstellar medium, affecting the The Observatories, University of Denver, next generation of star and planet formation. Department of Physics & Astronomy, Denver, Colorado 80208, USA Submitted: Evolved stars are characterized by surface 2002December30, Email: [email protected] temperatures low enough to allow molecules and solid-phase particles to exist in their ABSTRACT: atmospheres. In contrast to the nearly 6000K surface temperature of the Sun, the Solid phase material exists in low density kinetic temperatures of evolved stars may astrophysical environments, from stellar range between 2000K near their “surfaces” atmospheres to interstellar clouds, from to a few hundred K in their circumstellar current times to early phases of the universe. envelopes [CSE] at a few stellar radii We consider the origin, composition and distance. Time-dependent phase transitions evolution of solid phase materials in the from ionized plasma to cold, solid state are particular case of stellar outer atmospheres, observed, spectroscopically, to exist. as representative of many conditions. Also considered are the dynamics and interactions Some terminology may be helpful for the in circumstellar and galactic environments. reader not already acquainted with stellar Finally, new observational prospects for evolution. Solar mass stars are predicted to spectroscopy, polarimetry and leave the hydrogen-fusing “main sequence” interferometry are discussed. after approximately ten billion years, and progress through a rapid series of internal changes during what is known as the red 1.0 INTRODUCTION giant and asymptotic giant branch [RGB, AGB] phases, lasting one percent of the Solid phase material can be found nearly main sequence lifetime. -
THE PROGENITORS of TYPE IIP SUPERNOVAE Emma R. Beasor
THE PROGENITORS OF TYPE IIP SUPERNOVAE Emma R. Beasor A thesis submitted in partial fulfilment of the requirements of Liverpool John Moores University for the degree of Doctor of Philosophy. April 2019 Declaration The work presented in this thesis was carried out at the Astrophysics Research Insti- tute, Liverpool John Moores University. Unless otherwise stated, it is the original work of the author. While registered as a candidate for the degree of Doctor of Philosophy, for which sub- mission is now made, the author has not been registered as a candidate for any other award. This thesis has not been submitted in whole, or in part, for any other degree. Emma R. Beasor Astrophysics Research Institute Liverpool John Moores University IC2, Liverpool Science Park 146 Brownlow Hill Liverpool L3 5RF UK ii Abstract Mass-loss prior to core collapse is arguably the most important factor affecting the evolution of a massive star across the Hertzsprung-Russel (HR) diagram, making it the key to understanding what mass-range of stars produce supernova (SN), and how these explosions will appear. It is thought that most of the mass-loss occurs during the red supergiant (RSG) phase, when strong winds dictate the onward evolutionary path of the star and potentially remove the entire H-rich envelope. Uncertainty in the driving mechanism for RSG winds means the mass-loss rate (M_ ) cannot be determined from first principles, and instead, stellar evolution models rely on empirical recipes to inform their calculations. At present, the most commonly used M_ -prescription comes from a literature study, whereby many measurements of mass- loss were compiled. -
The Star Newsletter
THE HOT STAR NEWSLETTER ? An electronic publication dedicated to A, B, O, Of, LBV and Wolf-Rayet stars and related phenomena in galaxies No. 41 June/July 1998 editor: Philippe Eenens http://www.astro.ugto.mx/∼eenens/hot/ [email protected] http://www.star.ucl.ac.uk/∼hsn/index.html Contents of this newsletter From the Editor . 1 Abstracts of 24 accepted papers . 2 Abstracts of 2 submitted paper . 16 Abstracts of 2 proceedings papers . 17 Book ......................................................................18 Meetings ...................................................................20 From the editor This issue covers two months of publications and is dominated by η Car, other LBVs and B[e] stars. Other papers tell us about massive stars in the Galactic Center and R136, OB stars, polarimetry, wind models and [WC] central stars of Planetary Nebulae. We also present a book and remind readers about future meetings: two special sessions during IAU symposium 193 in Mexico (on HD5980 and on the XMEGA campaign) as well as IAU colloquium 175 in Spain in June 1999 (on Be stars). 1 Accepted Papers On the Multiplicity of η Carinae Henny J.G.L.M. Lamers1,2, Mario Livio1, Nino Panagia1,3, & Nolan R. Walborn1 1 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA 2 Astronomical Institute and SRON Laboratory for Space Research, Princetonplein 2, 3584CC Utrecht, The Netherlands 3 On assignment from the Astrophysics Division, Space Science Department of ESA. The nebula around the luminous blue variable η Car is extremely N-rich and C,O-poor, indicative of CNO-cycle products. On the other hand, the recent HST-GHRS observation of the nucleus of η Car shows the spectrum of a star with stellar-wind lines of C ii,C iv, Si ii, Si iv etc. -
Orbital Separation Amplification in Fragile Binaries with Evolved
Publications 11-22-2011 Orbital Separation Amplification in rF agile Binaries with Evolved Components K. B. Johnston Florida Institute of Technology, [email protected] Terry D. Oswalt Florida Institute of Technology, [email protected] Follow this and additional works at: https://commons.erau.edu/publication Part of the Stars, Interstellar Medium and the Galaxy Commons Scholarly Commons Citation Johnston, K. B., & Oswalt, T. D. (2011). Orbital Separation Amplification in rF agile Binaries with Evolved Components. New Astronomy, 17(4). https://doi.org/10.1016/j.newast.2011.11.004 This Article is brought to you for free and open access by Scholarly Commons. It has been accepted for inclusion in Publications by an authorized administrator of Scholarly Commons. For more information, please contact [email protected]. Orbital Separation Amplification in Fragile Binaries with Evolved Components K.B. Johnston and T. D. Oswalt∗ D.Valls-Gabaudy November 8, 2018 Abstract The secular stellar mass-loss causes an amplification of the orbital separation in fragile, common proper motion, binary systems with separations of the order of 1000 A.U. In these systems, companions evolve as two independent coeval stars as they experience negligible mutual tidal interactions or mass transfer. We present models for how post-main sequence mass-loss statistically distorts the frequency distribution of separations in fragile binaries. These models demonstrate the expected increase in orbital seapration resulting from stellar mass-loss, as well as a perturbation of associated orbital parameters. Comparisons between our models and observations resulting from the Luyten survey of wide visual binaries, specif- ically those containing MS and white-dwarf pairs, demonstrate a good agreement between the calculated and the observed angular separation distribution functions. -
Identifying Stars of Mass> 150 Msun from Their Eclipse by a Binary
Mon. Not. R. Astron. Soc. 000, 1–1 (2012) Printed 24 September 2018 (MN LATEX style file v2.2) Identifying Stars of Mass > 150M⊙ from Their Eclipse by a Binary Companion Tony Pan1, Abraham Loeb1 1Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA 24 September 2018 ABSTRACT We examine the possibility that very massive stars greatly exceeding the com- monly adopted stellar mass limit of 150M⊙ may be present in young star clusters in the local universe. We identify ten candidate clusters, some of which may host stars with masses up to 600M⊙ formed via runaway collisions. We estimate the probabilities of these very massive stars being in eclipsing binaries to be & 30%. Although most of these systems cannot be resolved at present, their transits can be detected at distances of 3 Mpc even under the contamination of the background cluster light, due to the 7 6 large associated luminosities ∼ 10 L⊙ and mean transit depths of ∼ 10 L⊙. Discov- ery of very massive eclipsing binaries would flag possible progenitors of pair-instability supernovae and intermediate-mass black holes. Key words: binaries: general – galaxies: star clusters 1 INTRODUCTION The most accurate method of constraining the stellar masses of distant stars is by measuring the radial velocity Many observations support the statistical argument that and light curves of the star in an eclipsing binary (Bonanos the upper limit to initial stellar masses is ∼ 150M⊙ for 2009; Torres, Andersen & Gim´enez 2010). The light curve Pop II/I stars (Figer 2005; Zinnecker & Yorke 2007). How- provides a wealth of information about the binary, includ- ever, this common notion is challenged by the recent spec- ing its orbital period, inclination, eccentricity, as well as the troscopic analyses of Crowther et al. -
Parameters of Selected Central Stars of Planetary Nebulae from Consistent Optical and Uv Spectral Analysis
PARAMETERS OF SELECTED CENTRAL STARS OF PLANETARY NEBULAE FROM CONSISTENT OPTICAL AND UV SPECTRAL ANALYSIS Cornelius Bernhard Kaschinski PARAMETERS OF SELECTED CENTRAL STARS OF PLANETARY NEBULAE FROM CONSISTENT OPTICAL AND UV SPECTRAL ANALYSIS Dissertation Ph.D. Thesis an der Ludwig–Maximilians–Universitat¨ (LMU) Munchen¨ at the Ludwig–Maximilians–University (LMU) Munich fur¨ den Grad des for the degree of Doctor rerum naturalium vorgelegt von submitted by Cornelius Bernhard Kaschinski Munchen,¨ 2013 1st Evaluator: Prof. Dr. A. W. A. Pauldrach 2nd Evaluator: Prof. Dr. Barbara Ercolano Date of oral exam: 25.4.2013 Contents Contents vii List of Figures xii List of Tables xiii Zusammenfassung xv Abstract xvii 1 Introduction 1 1.1 Hot Stars . 1 1.1.1 Evolution of hot stars . 1 1.2 Impact of massive stars on the evolution of stellar clusters . 5 1.3 Motivation of this thesis . 5 1.4 Organization of this thesis . 8 2 Radiation-driven winds of hot luminous stars 11 XVII. Parameters of selected central stars of PN from consistent optical and UV spectral analysis and the universality of the mass–luminosity relation 2.1 Introduction . 12 2.2 Methods . 15 2.2.1 Parameter determination using hydrodynamic models and the UV spectrum . 15 2.2.2 Parameter determination using optical H and He lines . 18 2.2.3 Combined analysis . 19 2.3 Implementation of Stark broadening in the model atmosphere code WM-basic . 19 2.4 CSPN observational material . 25 2.5 Consistent optical and UV analysis of the CSPNs NGC 6826 and NGC 2392 . 25 2.5.1 NGC 6826 . -
Viruses, ET and the Octopus from Space: the Return of | Cosmos 26/04/2018, 4:37 AM
Viruses, ET and the octopus from space: the return of | Cosmos 26/04/2018, 4:37 AM Viruses, ET and the octopus from space: the return of panspermia A major paper revives the oft-mocked theory that life on Earth began in a rain of cosmic microbes. Stephen Fleischfresser reports. The search for ET, say researchers, could start and end with the octopus. CREDIT: VIZERSKAYA/GETTY IMAGES The peer-reviewed journal Progress in Biophysics and Molecular Biology recently published a most remarkable scientific paper[1]. With 33 authors from a wide range of reputable universities and research institutes, the paper makes a seemingly incredible claim. https://cosmosmagazine.com/biology/viruses-et-and-the-octopus-from-space-the-return-of-panspermia Page 1 of 14 Viruses, ET and the octopus from space: the return of | Cosmos 26/04/2018, 4:37 AM A claim that if true, would have the most profound consequences for our understanding of the universe. Life, the paper argues, did not originate on the planet Earth. The response? Near silence. The reasons for this are as fascinating as the evidence and claims advanced by the paper itself. Entitled Cause of the Cambrian Explosion – Terrestrial or Cosmic?, the publication revives a controversial idea concerning the origin of life, an idea stretching back to Ancient Greece, known as panspermia. The scientific orthodoxy concerning the origin of life is called abiogenesis[2]. This suggests that at some point in the earth’s early history, conditions were favourable for the creation of complex organic chemistry that, in turn, led to the self-organisation of the first primitive life forms.