DOCSLIB.ORG

Dissertation

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

DISSERTATION Titel der Dissertation „Shaping the slow winds of Asymptotic Giant Branch stars in binary systems“ Verfasser Mag. Andreas Mayer, Bakk. angestrebter akademischer Grad Doktor der Naturwissenschaften (Dr.rer.nat.) Wien, 2015 Studienkennzahl lt. Studienblatt: A 796 605 413 Dissertationsgebiet lt. Studienblatt: Astronomie Betreuerin / Betreuer: Ao. Univ.-Prof. Dr. Franz Kerschbaum Reicher Mann und armer Mann Standen da und sahn sich an. Und der Arme sagte bleich: W¨arich nicht arm, w¨arstdu nicht reich. Bertolt Brecht { \Alfabet" (1934) Contents List of Figures 7 List of Tables 8 1. Introduction 9 1.1. Herschel Space Observatory . 9 1.1.1. Spacecraft . 10 1.1.2. The Photodetector Array Camera and Spectrometer . 12 1.1.3. Data processing . 14 1.1.4. Mass-loss of Evolved StarS (MESS) program . 19 1.2. Asymptotic giant branch stars . 20 1.2.1. Stellar structure and evolution . 22 1.2.2. Dust formation & mass loss . 27 1.2.3. Observational properties . 31 1.3. AGB stars in binary systems . 34 1.3.1. Mass transfer in binary systems . 36 1.3.2. Observing binary AGB star systems . 39 1.4. Stellar winds . 42 1.4.1. Interaction of two winds: detached shells . 46 1.4.2. Interaction with the interstellar medium: bow shocks . 48 1.4.3. Interaction with a companion: Archimedean spirals . 52 2. Publications 59 2.1. Herschel's view into Mira's head . 61 2.2. Large-scale environments of binary AGB stars - I. 66 2.3. Large-scale environments of binary AGB stars - II. 82 2.4. Publications as co-author . 97 2.4.1. A far-infrared survey of bow shocks and detached shells around AGB stars and red supergiants . 97 2.4.2. Dusty shells surrounding the carbon variables S Scuti and RT Capricorni . 99 2.4.3. Improving Herschel imaging datasets . 100 2.4.4. The wonderful complexity of the Mira AB system . 101 2.4.5. Dissecting the AGB star L2 Puppis . 103 3. Conclusion & Outlook 105 3.1. Remaining binary objects of the MESS sample . 108 3.1.1. θ Apodis . 108 3.1.2. EP Aquarii . 114 3.1.3. IRC +10 216 (CW Leonis) . 118 3.1.4. o1 Orionis . 120 3.1.5. Y Lyncis . 122 3.1.6. TW Horologii . 123 3.1.7. U Camelopardis . 124 3.1.8. R Sculptoris . 126 3.1.9. V Hydræ . 129 3.1.10. VY Ursæ Majoris . 130 3.1.11. TX Camelopardis . 132 3.1.12. V Eridani . 133 3.1.13. CIT 6 (RW Leonis Minoris) . 134 3.1.14. AFGL 3068 (LL Pegasi) . 137 3.1.15. VY Canis Majoris . 139 Bibliography 141 A. Appendix 157 A.1. Kurzfassung . 157 A.2. Abstract . 158 A.3. A&A reprint permission . 159 A.4. Abbreviations . 160 A.5. Constants . 162 A.6. Observing proposal for ESO P93A . 162 B. Curriculum Vitæ 175 B.1. Publication list . 177 C. Acknowledgements 181 List of Figures 1.1. Herschel Space Observatory . 11 1.2. PACS layout and light path through the instrument . 12 1.3. Herschel's scan map technique . 13 1.4. Herschel/PACS model PSF . 18 1.5. Evolutionary track of a 1 M star on the HRD . 21 1.6. Processes in the MS and AGB phase according to mass . 24 1.7. Internal structure of a 2 M AGB star . 26 1.8. Movement of atmospheric layers . 29 1.9. Schematic view of a circumstellar envelope . 30 1.10. Evolution of a low mass binary system . 33 1.11. Orbital period distribution of nearby binary systems . 35 1.12. Roche equipotential surface . 37 1.13. Concept of a stellar wind bubble . 43 1.14. IRAS two-colour diagram of AGB stars . 44 1.15. Herschel/PACS images of S Scuti . 47 1.16. Thin shell model of a bow shock . 49 1.17. Herschel/PACS images of TX Piscium and X Herculis . 51 1.18. Velocity field of wind accretion around secondary star . 53 1.19. Model of a wide binary spiral pattern . 54 1.20. Two examples of spiral patterns around AGB stars . 55 3.1. Herschel/PACS images of θ Apodis . 109 3.2. Positional data of θ Apodis . 110 3.3. Contour plot of θ Apodis . 111 3.4. Herschel/PACS images of EP Aquarii . 115 3.5. Intensity plots of EP Aquarii . 116 3.6. Herschel/PACS & SPIRE images of IRC +10 216 . 118 3.7. Herschel/PACS images of o1 Orionis . 120 3.8. Herschel/PACS images of Y Lyncis . 122 3.9. Herschel/PACS images of TW Horologii . 123 3.10. Herschel/PACS images of U Camelopardis . 124 3.11. Illustration of the environment of R Sculptoris . 126 3.12. Herschel/PACS images of R Sculptoris . 127 7 3.13. Herschel/PACS images of V Hyadræ . 129 3.14. Herschel/PACS images of VY Ursæ Majoris . 130 3.15. Herschel/PACS images of TX Camelopardis . 132 3.16. Herschel/PACS images of V Eridani . 133 3.17. VLA velocity channel maps of CIT 6 . 134 3.18. Herschel/PACS images of CIT 6 . 135 3.19. HST image of AFGL 3068 . 137 3.20. Herschel/PACS images of AFGL 3068 . 138 3.21. Herschel/PACS images of VY Canis Majoris . 140 List of Tables 1.1. Most abundant molecules produced in AGB stars . 28 3.1. Positional data of θ Apodis . 112 3.2. Position angles of bipolar outflow and proper motion direction . 113 8 CHAPTER 1 Introduction 1.1. Herschel Space Observatory The thesis at hand is an observational study of the interactions that occur in the winds of asymptotic giant branch (AGB) stars and is based on obser- vations carried out with the Herschel Space Observatory (Herschel; Pilbratt et al. 2010). Herschel is a space mission led by the European Space Agency (ESA) and dedicated to the far-infrared (IR) and sub-millimetre wavelength range, whose exploration was included in ESA's long-term plan Horizon 2000 (Longdon 1984). By this time, it was called the Far-InfraRed and Submillime- tre space Telescope (FIRST) until it received its present name Herschel in the year 2000; named after Friedrich Wilhelm Herschel (1738{1822), the discoverer of the infrared radiation. The Herschel mission was chosen as the successor of the Infrared Space Observatory (ISO; 1995{1998) and the realisation of the mission was decided in 1993 as the fourth cornerstone mission of ESA, after the X-ray Multi-Mirror-Mission (XMM-Newton; 1999{present), the Solar and Heliospheric Observatory (SOHO; 1995{present), and Rosetta (2004{present). Shortly after, the industrial production of the spacecraft began with a budget of 1.1 billion Euro. Given the high costs of space missions, the reasons to operate a telescope outside earth must be vital and are found in the properties of the earth's atmo- sphere. On the one hand, the atmospheric windows only allow ground-based observations in certain wavelength ranges (optical, near- to mid-infrared, and radio), while photons of other energies are absorbed and scattered by several molecules like ozone, carbon dioxide, and water (vapour) in the earth's at- mosphere. On the other hand, the thermal conditions and instability of the atmosphere hinders ground-based observations. This is especially the case in the far-IR regime (λ > 15 µm), where the thermal emission of the atmosphere dominates the observations. To explore the universe in this wavelength range means to reveal its cool and dusty places. The far-infrared covers a wavelength 9 1.1. Herschel Space Observatory range of roughly 15{1000 µm, equivalent to the peaks of the black body radi- ation curve between 300 K and 3 K. This is the temperature domain of newly born stars, planets and galaxies, active galactic nuclei (AGN), and evolved stars. Prior IR space missions like the Infrared Astronomical Satellite (IRAS), ISO, Spitzer Space Observatory, and AKARI delivered spectacular results in these scientific fields. Herschel is able to add a new level of detail to the far-IR universe due to its high sensitivity and spatial resolution. With a wavelength range of 55{671 µm, it is the first mission going beyond 200 µm (besides the Cosmic Background Explorer (COBE) and Wilkinson Microwave Anisotropy Probe (WMAP), which are used solely for cosmological studies). On 14 May 2009, Herschel was finally sent to space with an Ariane 5-ECA rocket1. After the separation from the carrier rocket, Herschel was manoeuvred 9 to the second Lagrange point (L2), which is located ≈ 1:5 × 10 m behind the earth, as seen from the sun. L2 has the advantage that the sun, earth, and moon are on the same side which is handy in the sense that a sunshade is able to protect the spacecraft effectively. At this location, the spacecraft moves with the same orbital period as the earth. On 14 June 2009, while moving to L2, the Photodetector Array Camera & Spectrometer (PACS) on-board Herschel obtained first light: an image of M51, the Whirlpool Galaxy. After several commissioning phases the first routine operations were executed on 18 October 2009. In March 2013, nearly four years after launch and 3.5 years of successful observations, the liquid helium needed to cool the Herschel detectors was almost completely evaporated. This lack of helium prevented the detectors from working accurately and on 29 April 2013 ESA declared the Herschel mission to be completed. 1.1.1. Spacecraft The Herschel Space Observatory has a total size of about 4 m × 4 m × 7 m with a mass of 3400 kg at launch. This includes 600 kg of liquid helium that is used to cool the instruments2.
Recommended publications
  • Information Bulletin on Variable Stars

    Information Bulletin on Variable Stars

    COMMISSIONS AND OF THE I A U INFORMATION BULLETIN ON VARIABLE STARS Nos November July EDITORS L SZABADOS K OLAH TECHNICAL EDITOR A HOLL TYPESETTING K ORI ADMINISTRATION Zs KOVARI EDITORIAL BOARD L A BALONA M BREGER E BUDDING M deGROOT E GUINAN D S HALL P HARMANEC M JERZYKIEWICZ K C LEUNG M RODONO N N SAMUS J SMAK C STERKEN Chair H BUDAPEST XI I Box HUNGARY URL httpwwwkonkolyhuIBVSIBVShtml HU ISSN COPYRIGHT NOTICE IBVS is published on b ehalf of the th and nd Commissions of the IAU by the Konkoly Observatory Budap est Hungary Individual issues could b e downloaded for scientic and educational purp oses free of charge Bibliographic information of the recent issues could b e entered to indexing sys tems No IBVS issues may b e stored in a public retrieval system in any form or by any means electronic or otherwise without the prior written p ermission of the publishers Prior written p ermission of the publishers is required for entering IBVS issues to an electronic indexing or bibliographic system to o CONTENTS C STERKEN A JONES B VOS I ZEGELAAR AM van GENDEREN M de GROOT On the Cyclicity of the S Dor Phases in AG Carinae ::::::::::::::::::::::::::::::::::::::::::::::::::: : J BOROVICKA L SAROUNOVA The Period and Lightcurve of NSV ::::::::::::::::::::::::::::::::::::::::::::::::::: :::::::::::::: W LILLER AF JONES A New Very Long Period Variable Star in Norma ::::::::::::::::::::::::::::::::::::::::::::::::::: :::::::::::::::: EA KARITSKAYA VP GORANSKIJ Unusual Fading of V Cygni Cyg X in Early November :::::::::::::::::::::::::::::::::::::::
  • List of Easy Double Stars for Winter and Spring  = Easy  = Not Too Difficult  = Difficult but Possible

    List of Easy Double Stars for Winter and Spring  = Easy  = Not Too Difficult  = Difficult but Possible

    List of Easy Double Stars for Winter and Spring = easy = not too difficult = difficult but possible 1. Sigma Cassiopeiae (STF 3049). 23 hr 59.0 min +55 deg 45 min This system is tight but very beautiful. Use a high magnification (150x or more). Primary: 5.2, yellow or white Seconary: 7.2 (3.0″), blue 2. Eta Cassiopeiae (Achird, STF 60). 00 hr 49.1 min +57 deg 49 min This is a multiple system with many stars, but I will restrict myself to the brightest one here. Primary: 3.5, yellow. Secondary: 7.4 (13.2″), purple or brown 3. 65 Piscium (STF 61). 00 hr 49.9 min +27 deg 43 min Primary: 6.3, yellow Secondary: 6.3 (4.1″), yellow 4. Psi-1 Piscium (STF 88). 01 hr 05.7 min +21 deg 28 min This double forms a T-shaped asterism with Psi-2, Psi-3 and Chi Piscium. Psi-1 is the uppermost of the four. Primary: 5.3, yellow or white Secondary: 5.5 (29.7), yellow or white 5. Zeta Piscium (STF 100). 01 hr 13.7 min +07 deg 35 min Primary: 5.2, white or yellow Secondary: 6.3, white or lilac (or blue) 6. Gamma Arietis (Mesarthim, STF 180). 01 hr 53.5 min +19 deg 18 min “The Ram’s Eyes” Primary: 4.5, white Secondary: 4.6 (7.5″), white 7. Lambda Arietis (H 5 12). 01 hr 57.9 min +23 deg 36 min Primary: 4.8, white or yellow Secondary: 6.7 (37.1″), silver-white or blue 8.
  • Morphology and Kinematics of the Gas Envelope of the Mira Binary W Aquilae 3

    Morphology and Kinematics of the Gas Envelope of the Mira Binary W Aquilae 3

    Research in Astron. Astrophys. Vol.0 (200x) No.0, 000–000 Research in http://www.raa-journal.org http://www.iop.org/journals/raa Astronomy and Astrophysics Morphology and kinematics of the gas envelope of the Mira binary W Aquilae ⋆ D. T. Hoai, P. T. Nhung, P. N. Diep, N. T. Phuong, P. Tuan-Anh, N. T. Thao and P. Darriulat Department of Astrophysics, Vietnam National Satellite Center, VAST, 18 Hoang Quoc Viet, Cau Giay, Hanoi, Vietnam; [email protected] Abstract We analyse ALMA observations of the 12CO(3-2) emission of the circumstellar envelope (CSE) of the Mira variable binary star W Aql. These provide, for the first time, spatially resolved Doppler velocity spectra of the CSE up to angular distances to the central star of ∼ 5′′ (meaning some 2000 AU). The exploratory nature of the observations (only five minutes in each of two different configurations) does not allow for a detailed modelling of the properties of the CSE but provides important qualitative information on its morphology and kinematics. Emission is found to be enhanced along an axis moving from east/west to north-east/south-west when the angular distance from the central star projected on the plane of the sky increases from zero to four arcseconds. In parallel, the Doppler velocity distribution displays asymmetry along an axis moving from east/west to north-west/south-east. The results are discussed in the context of earlier observations, in particular of the dust morphology. Key words: stars: AGB and post-AGB − (Star:) circumstellar matter − Star: individual (W Aql) − Stars: mass-loss − radio lines: stars.
  • Agrarian Metaphors 397

    Agrarian Metaphors 397

    396 Agrarian Metaphors 397 The Bible provided homilists with a rich store of "agricultural" metaphors and symbols) The loci classici are passages like Isaiah's "Song of the Vineyard" (Is. 5:1-7), Ezekiel's allegories of the Tree (Ez. 15,17,19:10-14,31) and christ's parables of the Sower (Matt. 13: 3-23, Mark 4:3-20, Luke 8:5-15) ,2 the Good Seed (Matt. 13:24-30, Mark 4:26-29) , the Barren Fig-tree (Luke 13:6-9) , the Labourers in the Vineyard (Matt. 21:33-44, Mark 12:1-11, Luke 20:9-18), and the Mustard Seed (Matt. 13:31-32, Mark 4:30-32, Luke 13:18-19). Commonplace in Scripture, however, are comparisons of God to a gardener or farmer,5 6 of man to a plant or tree, of his soul to a garden, 7and of his works to "fruits of the spirit". 8 Man is called the "husbandry" of God (1 Cor. 3:6-9), and the final doom which awaits him is depicted as a harvest in which the wheat of the blessed will be gathered into God's storehouse and the chaff of the damned cast into eternal fire. Medieval scriptural commentaries and spiritual handbooks helped to standardize the interpretation of such figures and to impress them on the memories of preachers (and their congregations). The allegorical exposition of the res rustica presented in Rabanus Maurus' De Universo (XIX, cap.l, "De cultura agrorum") is a distillation of typical readings: Spiritaliter ... in Scripturis sacris agricultura corda credentium intelliguntur, in quibus fructus virtutuxn germinant: unde Apostolus ad credentes ait [1 Cor.
  • Molecular Line Study of the S-Type AGB Star W Aquilae ALMA Observations of CS, Sis, Sio and HCN

    Molecular Line Study of the S-Type AGB Star W Aquilae ALMA Observations of CS, Sis, Sio and HCN

    Astronomy & Astrophysics manuscript no. WAql-v6-revision_02_final c ESO 2018 October 5, 2018 Molecular line study of the S-type AGB star W Aquilae ALMA observations of CS, SiS, SiO and HCN M. Brunner1, T. Danilovich2; 3, S. Ramstedt4, I. Marti-Vidal2, E. De Beck2, W.H.T. Vlemmings2, M. Lindqvist2, and F. Kerschbaum1 1 Department for Astrophysics, University of Vienna, Türkenschanzstrasse 17, A-1180 Vienna e-mail: [email protected] 2 Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, 439 92 Onsala, Sweden 3 Department of Physics and Astronomy, Institute of Astronomy, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium 4 Department of Physics and Astronomy, Uppsala University, 75120 Uppsala, Sweden Received Month nr, YYYY; accepted Month nr, YYYY ABSTRACT Context. With the outstanding spatial resolution and sensitivity of the Atacama Large Millimeter/sub-millimeter Array (ALMA), molecular gas other than the abundant CO can be observed and resolved in circumstellar envelopes (CSEs) around evolved stars, such as the binary S-type Asymptotic Giant Branch (AGB) star W Aquilae. Aims. We aim to constrain the chemical composition of the CSE and determine the radial abundance distribution, the photospheric peak abundance, and isotopic ratios of a selection of chemically important molecular species in the innermost CSE of W Aql. The derived parameters are put into the context of the chemical evolution of AGB stars and are compared with theoretical models. Methods. We employ one-dimensional radiative transfer modeling – with the accelerated lambda iteration (ALI) radiative transfer code – of the radial abundance distribution of a total of five molecular species (CS, SiS, 30SiS, 29SiO and H13CN) and determine the best fitting model parameters based on high-resolution ALMA observations as well as archival single-dish observations.
  • The XMM-Newton View of the Yellow Hypergiant IRC+10420 And

    The XMM-Newton View of the Yellow Hypergiant IRC+10420 And

    The XMM-Newton view of the yellow hypergiant IRC +10420 and its surroundings$ M. De Becker, D. Hutsem´ekers1, E. Gosset1 Department of Astrophysics, Geophysics and Oceanography, University of Li`ege, 17, All´ee du 6 Aoˆut, B5c, B-4000 Sart Tilman, Belgium Abstract Among evolved massive stars likely in transition to the Wolf-Rayet phase, IRC +10420 is probably one of the most enigmatic. It belongs to the category of yellow hypergiants and it is characterized by quite high mass loss episodes. Even though IRC +10420 benefited of many observations in several wavelength domains, it has never been a target for an X-ray observatory. We report here on the very first dedicated observation of IRC +10420 in X-rays, using the XMM-Newton satellite. Even though the target is not detected, we derive X-ray flux upper limits of the order of 1–3 × 10−14 ergcm−2 s−1 (between 0.3 and 10.0keV), and we discuss the case of IRC +10420 in the framework of emission models likely to be adequate for such an object. Using the Optical/UV Monitor on board XMM-Newton, we present the very first upper limits of the flux density of IRC +10420 in the UV domain (between 1800 and 2250Å and between 2050 and 2450Å). Finally, we also report on the detection in this field of 10 X-ray and 7 UV point sources, and we briefly discuss their properties and potential counterparts at longer wavelengths. Key words: stars: early-type, stars: individual: IRC +10420, X-rays: stars PACS: 97.10.Me, 97.30.Sw, 95.85.Nv 1.
  • The Evening Sky Map

    The Evening Sky Map

    I N E D R I A C A S T N E O D I T A C L E O R N I G D S T S H A E P H M O O R C I . Z N O p l f e i n h d o P t O o N ) l h a r g Z i u s , o I l C t P h R I r e o R N ( O o r C r H e t L p h p E E i s t D H a ( r g T F i . O B NORTH D R e N M h t E A X O e s A H U M C T . I P N S L E E P Z “ E A N H O NORTHERN HEMISPHERE M T R T Y N H E ” K E η ) W S . T T E W U B R N W D E T T W T H h A The Evening Sky Map e MAY 2021 E . C ) Cluster O N FREE* EACH MONTH FOR YOU TO EXPLORE, LEARN & ENJOY THE NIGHT SKY r S L a o K e Double r Y E t B h R M t e PERSEUS A a A r CASSIOPEIA n e S SKY MAP SHOWS HOW Get Sky Calendar on Twitter P δ r T C G C A CEPHEUS r E o R e J s O h Sky Calendar – May 2021 http://twitter.com/skymaps M39 s B THE NIGHT SKY LOOKS T U ( O i N s r L D o a j A NE I I a μ p T EARLY MAY PM T 10 r 61 M S o S 3 Last Quarter Moon at 19:51 UT.
  • Lunar Mansion Names in South-West China

    Lunar Mansion Names in South-West China

    Onoma 51 Journal of the International Council of Onomastic Sciences ISSN: 0078-463X; e-ISSN: 1783-1644 Journal homepage: https://onomajournal.org/ Lunar mansion names in South-West China: An etymological reconstruction of ancestral astronomical designations in Moso, Pumi, and Yi cultures compared with Chinese and Tibetan contexts DOI: 10.34158/ONOMA.51/2016/6 Xu Duoduo National University of Singapore (NUS), Asia Research Institute (ARI), Singapore [email protected] To cite this article: Xu Duoduo. 2016. Lunar mansion names in South-West China: An etymological reconstruction of ancestral astronomical designations in Moso, Pumi, and Yi cultures compared with Chinese and Tibetan contexts. Onoma 51, 113–143. DOI: 10.34158/ONOMA.51/2016/6 To link to this article: https://doi.org/10.34158/ONOMA.51/2016/6 © Onoma and the author. Lunar mansion names in South-West China: An etymological reconstruction of ancestral astronomical designations in Moso, Pumi, and Yi cultures compared with Chinese and Tibetan contexts Abstract: The present study aims at an etymological reconstruction of lunar mansion designations of the Moso, Pumi, and Yi people from South-West China. Those lunar mansions are generally named after animals. A systematic examination on these astronomical names reveals frequent borrowing processes among these cultures, extended to Tibetan and Chinese contexts. Three patterns of direct borrowing of the lunar mansion names can be highlighted in addition to compatible morphological structures in some designation. This comparative research also provides innovative 114 XU DUODUO solutions to several issues still unsolved from the current studies on lunar mansions focused on specific ethnic groups.
  • Ephemerides Astronomicae. Anni...Ad Meridianum Mediolanensem

    Ephemerides Astronomicae. Anni...Ad Meridianum Mediolanensem

    Informazioni su questo libro Si tratta della copia digitale di un libro che per generazioni è stato conservata negli scaffali di una biblioteca prima di essere digitalizzato da Google nell’ambito del progetto volto a rendere disponibili online i libri di tutto il mondo. Ha sopravvissuto abbastanza per non essere più protetto dai diritti di copyright e diventare di pubblico dominio. Un libro di pubblico dominio è un libro che non è mai stato protetto dal copyright o i cui termini legali di copyright sono scaduti. La classificazione di un libro come di pubblico dominio può variare da paese a paese. I libri di pubblico dominio sono l’anello di congiunzione con il passato, rappresentano un patrimonio storico, culturale e di conoscenza spesso difficile da scoprire. Commenti, note e altre annotazioni a margine presenti nel volume originale compariranno in questo file, come testimonianza del lungo viaggio percorso dal libro, dall’editore originale alla biblioteca, per giungere fino a te. Linee guide per l’utilizzo Google è orgoglioso di essere il partner delle biblioteche per digitalizzare i materiali di pubblico dominio e renderli universalmente disponibili. I libri di pubblico dominio appartengono al pubblico e noi ne siamo solamente i custodi. Tuttavia questo lavoro è oneroso, pertanto, per poter continuare ad offrire questo servizio abbiamo preso alcune iniziative per impedire l’utilizzo illecito da parte di soggetti commerciali, compresa l’imposizione di restrizioni sull’invio di query automatizzate. Inoltre ti chiediamo di: + Non fare un uso commerciale di questi file Abbiamo concepito Google Ricerca Libri per l’uso da parte dei singoli utenti privati e ti chiediamo di utilizzare questi file per uso personale e non a fini commerciali.
  • From Supergiant to Solar-Mass Star: Study Finds HD 179821 Less Massive Than Previously Thought 8 February 2019, by Tomasz Nowakowski

    From Supergiant to Solar-Mass Star: Study Finds HD 179821 Less Massive Than Previously Thought 8 February 2019, by Tomasz Nowakowski

    From supergiant to solar-mass star: Study finds HD 179821 less massive than previously thought 8 February 2019, by Tomasz Nowakowski observations of HD 179821 have been conducted, the exact distance to this star remains a subject of debate. Some studies suggest that it is located about 19,500 light years from the Earth, while others cite a much closer distance of some 12,700 light years. Discrepancy in the distance estimates leaves uncertainties regarding the star's mass and evolutionary status. Gaia's second data release, known as Data Release 2 (DR2), has the potential to resolve such uncertainties as it offers high-precision positions, parallaxes and proper motions for more than 1.3 billion sources in the sky. A team of astronomers led by Mudumba Parthasarathy of the Indian Institute of Astrophysics in Bangalore used DR2 data to obtain the parallax of HD 179821, which allowed them to make new distance calculations. The parallax of HD 179821 was found to be approximately 0.31 mas. Employing an inference HD 179821. Credit: Hubble Legacy Archive procedure developed by other researchers in 2018, Parthasarathy's team calculated that this value corresponds to a distance of about 9,600 light years. Gaia parallax also allowed them to find that A post-asymptotic giant branch (post-AGB) star the star is located some 850 light years below the known as HD 179821 turns out to be significantly Galactic plane. less massive than previously thought, according to a new study. Using new data from ESA's Gaia Furthermore, the derived distance and other satellite, astronomers found that HD 179821 is not parameters provided by previous studies, such as a supergiant, which was suggested by previous spectral type and observed V magnitude, were observations, but is rather a solar-mass star.
  • Reduced Maximum Mass-Loss Rate of OH/IR Stars Due to Overlooked Binary Interaction

    Reduced Maximum Mass-Loss Rate of OH/IR Stars Due to Overlooked Binary Interaction

    The University of Manchester Research Reduced maximum mass-loss rate of OH/IR stars due to overlooked binary interaction DOI: 10.1038/s41550-019-0703-5 Document Version Accepted author manuscript Link to publication record in Manchester Research Explorer Citation for published version (APA): Decin, L., Homan, W., Danilovich, T., de Koter, A., Engels, D., Waters, L. B. F. M., Muller, S., Gielen, C., Garca- Hernandez, D. A., Stancliffe, R., Van de Sande, M., Molenberghs, G., Kerschbaum, F., Zijlstra, A., & El Mellah, I. (2019). Reduced maximum mass-loss rate of OH/IR stars due to overlooked binary interaction. Nature Astronomy, 3(5), 408-415. https://doi.org/10.1038/s41550-019-0703-5 Published in: Nature Astronomy Citing this paper Please note that where the full-text provided on Manchester Research Explorer is the Author Accepted Manuscript or Proof version this may differ from the final Published version. If citing, it is advised that you check and use the publisher's definitive version. General rights Copyright and moral rights for the publications made accessible in the Research Explorer are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. Takedown policy If you believe that this document breaches copyright please refer to the University of Manchester’s Takedown Procedures [http://man.ac.uk/04Y6Bo] or contact [email protected] providing relevant details, so we can investigate your claim. Download date:08. Oct. 2021 Reduced maximum mass-loss rate of OH/IR stars due to overlooked binary interaction L.
  • Molecular Line Study of the S-Type AGB Star W Aquilae: ALMA Observations of CS, Sis, Sio and HCN

    Molecular Line Study of the S-Type AGB Star W Aquilae: ALMA Observations of CS, Sis, Sio and HCN

    Molecular line study of the S-type AGB star W Aquilae: ALMA observations of CS, SiS, SiO and HCN Downloaded from: https://research.chalmers.se, 2021-10-05 12:42 UTC Citation for the original published paper (version of record): Brunner, M., Danilovich, T., Ramstedt, S. et al (2018) Molecular line study of the S-type AGB star W Aquilae: ALMA observations of CS, SiS, SiO and HCN Astronomy and Astrophysics, 617 http://dx.doi.org/10.1051/0004-6361/201832724 N.B. When citing this work, cite the original published paper. research.chalmers.se offers the possibility of retrieving research publications produced at Chalmers University of Technology. It covers all kind of research output: articles, dissertations, conference papers, reports etc. since 2004. research.chalmers.se is administrated and maintained by Chalmers Library (article starts on next page) Astronomy & Astrophysics manuscript no. WAql-v6-revision_02_final c ESO 2018 October 5, 2018 Molecular line study of the S-type AGB star W Aquilae ALMA observations of CS, SiS, SiO and HCN M. Brunner1, T. Danilovich2; 3, S. Ramstedt4, I. Marti-Vidal2, E. De Beck2, W.H.T. Vlemmings2, M. Lindqvist2, and F. Kerschbaum1 1 Department for Astrophysics, University of Vienna, Türkenschanzstrasse 17, A-1180 Vienna e-mail: [email protected] 2 Department of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, 439 92 Onsala, Sweden 3 Department of Physics and Astronomy, Institute of Astronomy, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium 4 Department of Physics and Astronomy, Uppsala University, 75120 Uppsala, Sweden Received Month nr, YYYY; accepted Month nr, YYYY ABSTRACT Context.