Außerirdischen Verhält
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Arxiv:0809.1275V2
How eccentric orbital solutions can hide planetary systems in 2:1 resonant orbits Guillem Anglada-Escud´e1, Mercedes L´opez-Morales1,2, John E. Chambers1 [email protected], [email protected], [email protected] ABSTRACT The Doppler technique measures the reflex radial motion of a star induced by the presence of companions and is the most successful method to detect ex- oplanets. If several planets are present, their signals will appear combined in the radial motion of the star, leading to potential misinterpretations of the data. Specifically, two planets in 2:1 resonant orbits can mimic the signal of a sin- gle planet in an eccentric orbit. We quantify the implications of this statistical degeneracy for a representative sample of the reported single exoplanets with available datasets, finding that 1) around 35% percent of the published eccentric one-planet solutions are statistically indistinguishible from planetary systems in 2:1 orbital resonance, 2) another 40% cannot be statistically distinguished from a circular orbital solution and 3) planets with masses comparable to Earth could be hidden in known orbital solutions of eccentric super-Earths and Neptune mass planets. Subject headings: Exoplanets – Orbital dynamics – Planet detection – Doppler method arXiv:0809.1275v2 [astro-ph] 25 Nov 2009 Introduction Most of the +300 exoplanets found to date have been discovered using the Doppler tech- nique, which measures the reflex motion of the host star induced by the planets (Mayor & Queloz 1995; Marcy & Butler 1996). The diverse characteristics of these exoplanets are somewhat surprising. Many of them are similar in mass to Jupiter, but orbit much closer to their 1Carnegie Institution of Washington, Department of Terrestrial Magnetism, 5241 Broad Branch Rd. -
1903Apj 18. .3415 the SPECTRUM of O CETL' by Joel Stebbins. On
.3415 18. 1903ApJ THE SPECTRUM OF o CETL' By Joel Stebbins. On account of the great instrumental power required for the observation of the spectra of faint objects, changes in the spectra of long-period variable stars have not been well studied. In fact, there is no star which undergoes a large variation in bright- ness whose spectrum has been systematically followed from maxi- mum to minimum, or vice versa. It is proposed to give here the results of a study of the spectrum of o Ceti> or Mira, made, at the suggestion of Director Campbell, with the thirty-six-inch refractor of the Lick Observatory, from June 1902 to January 1903. During this period the star faded in brightness from 3.8 to 9.0 magnitude. The first photograph of the spectrum was obtained about three weeks after the predicted time of maximum, and a series of plates was secured covering the interval to mini- mum. No negatives were obtained after the star had again begun to increase in brightness. The most important articles concerning the spectrum of Mira are those of Vogel,2 Sidgreaves,3 and Campbell.4 Neither Vogel nor Sidgreaves followed the star long enough to find much change in its spectrum, and Campbell’s work was mainly in con- nection with observations of the star for radial velocity, with the Mills spectrograph. INSTRUMENTS AND METHODS. The spectrograph used in my observations was the one employed rby Messrs. Campbell and Wright in their work on 1 “ Dissertation in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in the University of California,” Lick Observatory Bulletin No. -
A Terrestrial Planet Candidate in a Temperate Orbit Around Proxima Centauri
A terrestrial planet candidate in a temperate orbit around Proxima Centauri Guillem Anglada-Escude´1∗, Pedro J. Amado2, John Barnes3, Zaira M. Berdinas˜ 2, R. Paul Butler4, Gavin A. L. Coleman1, Ignacio de la Cueva5, Stefan Dreizler6, Michael Endl7, Benjamin Giesers6, Sandra V. Jeffers6, James S. Jenkins8, Hugh R. A. Jones9, Marcin Kiraga10, Martin Kurster¨ 11, Mar´ıa J. Lopez-Gonz´ alez´ 2, Christopher J. Marvin6, Nicolas´ Morales2, Julien Morin12, Richard P. Nelson1, Jose´ L. Ortiz2, Aviv Ofir13, Sijme-Jan Paardekooper1, Ansgar Reiners6, Eloy Rodr´ıguez2, Cristina Rodr´ıguez-Lopez´ 2, Luis F. Sarmiento6, John P. Strachan1, Yiannis Tsapras14, Mikko Tuomi9, Mathias Zechmeister6. July 13, 2016 1School of Physics and Astronomy, Queen Mary University of London, 327 Mile End Road, London E1 4NS, UK 2Instituto de Astrofsica de Andaluca - CSIC, Glorieta de la Astronoma S/N, E-18008 Granada, Spain 3Department of Physical Sciences, Open University, Walton Hall, Milton Keynes MK7 6AA, UK 4Carnegie Institution of Washington, Department of Terrestrial Magnetism 5241 Broad Branch Rd. NW, Washington, DC 20015, USA 5Astroimagen, Ibiza, Spain 6Institut fur¨ Astrophysik, Georg-August-Universitat¨ Gottingen¨ Friedrich-Hund-Platz 1, 37077 Gottingen,¨ Germany 7The University of Texas at Austin and Department of Astronomy and McDonald Observatory 2515 Speedway, C1400, Austin, TX 78712, USA 8Departamento de Astronoma, Universidad de Chile Camino El Observatorio 1515, Las Condes, Santiago, Chile 9Centre for Astrophysics Research, Science & Technology Research Institute, University of Hert- fordshire, Hatfield AL10 9AB, UK 10Warsaw University Observatory, Aleje Ujazdowskie 4, Warszawa, Poland 11Max-Planck-Institut fur¨ Astronomie Konigstuhl¨ 17, 69117 Heidelberg, Germany 12Laboratoire Univers et Particules de Montpellier, Universit de Montpellier, Pl. -
Thursday, December 22Nd Swap Meet & Potluck Get-Together Next First
Io – December 2011 p.1 IO - December 2011 Issue 2011-12 PO Box 7264 Eugene Astronomical Society Annual Club Dues $25 Springfield, OR 97475 President: Sam Pitts - 688-7330 www.eugeneastro.org Secretary: Jerry Oltion - 343-4758 Additional Board members: EAS is a proud member of: Jacob Strandlien, Tony Dandurand, John Loper. Next Meeting: Thursday, December 22nd Swap Meet & Potluck Get-Together Our December meeting will be a chance to visit and share a potluck dinner with fellow amateur astronomers, plus swap extra gear for new and exciting equipment from somebody else’s stash. Bring some food to share and any astronomy gear you’d like to sell, trade, or give away. We will have on hand some of the gear that was donated to the club this summer, including mirrors, lenses, blanks, telescope parts, and even entire telescopes. Come check out the bargains and visit with your fellow amateur astronomers in a relaxed evening before Christmas. We also encourage people to bring any new gear or projects they would like to show the rest of the club. The meeting is at 7:00 on December 22nd at EWEB’s Community Room, 500 E. 4th in Eugene. Next First Quarter Fridays: December 2nd and 30th Our November star party was clouded out, along with a good deal of the month afterward. If that sounds familiar, that’s because it is: I changed the date in the previous sentence from October to November and left the rest of the sentence intact. Yes, our autumn weather is predictable. Here’s hoping for a lucky break in the weather for our two December star parties. -
Pulsating Low-Mass White Dwarfs in the Frame of New Evolutionary Sequences I
A&A 569, A106 (2014) Astronomy DOI: 10.1051/0004-6361/201424352 & c ESO 2014 Astrophysics Pulsating low-mass white dwarfs in the frame of new evolutionary sequences I. Adiabatic properties A. H. Córsico1,2 andL.G.Althaus1,2 1 Grupo de Evolución Estelar y Pulsaciones. Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata, Paseo del Bosque s/n, 1900 La Plata, Argentina 2 IALP – CONICET, Argentina e-mail: acorsico,[email protected] Received 6 June 2014 / Accepted 31 July 2014 ABSTRACT Context. Many low-mass white dwarfs with masses M∗/ M ∼< 0.45, including the so-called extremely low-mass white dwarfs (M∗/ M ∼< 0.20−0.25), have recently been discovered in the field of our Galaxy through dedicated photometric surveys. The sub- sequent discovery of pulsations in some of them has opened the unprecedented opportunity of probing the internal structure of these ancient stars. Aims. We present a detailed adiabatic pulsational study of these stars based on full evolutionary sequences derived from binary star evolution computations. The main aim of this study is to provide a detailed theoretical basis of reference for interpreting present and future observations of variable low-mass white dwarfs. Methods. Our pulsational analysis is based on a new set of He-core white-dwarf models with masses ranging from 0.1554 to 0.4352 M derived by computing the non-conservative evolution of a binary system consisting of an initially 1 M ZAMS star and a 1.4 M neutron star. We computed adiabatic radial ( = 0) and non-radial ( = 1, 2) p and g modes to assess the dependence of the pulsational properties of these objects on stellar parameters such as the stellar mass and the effective temperature, as well as the effects of element diffusion. -
Boceto Revista Astronomica
El eclipse de Luna del 15 de abril de 2014 - fotografía por Alejandro Blain Año 86 Número 281 Mayo 2014 Asociación Argentina Amigos de la Astronomía Editorial Telescopio Remoto 4 Hace unas semanas estaba de docente con un grupo de estudiantes Artemio Luis Fava en Quiroga y sin internet cuando me llamó Inés (que había vuelto de CASLEO) para contarme la noticia: un grupo de investigadores había Tierra a la vista... 5 detectado el modo B de polarización… lo que confirmaba las predicciones Iván David Castillo de la teoría inflacionaria del Big Bang. Dicho de otro modo ¡el Big Bang está confirmado! Y por primera vez en mucho tiempo sentí que somos MAVEN - NASA 7 polvo de estrellas. María Agostina Gangemi Si bien mi exclamación no es del todo cierta (más que haberse confirmado el Big Bang, se ha ganado seguridad en el modelo y es posible Damas del cielo 11 explicar hasta más atrás en el tiempo), creo que es el hecho científico más María Marta Do Santos importante que haya ocurrido durante mi vida y agradezco a todos los que ayudaron a poder plasmarlo en esta revista. Contamos con un interesante En el CASLEO de campaña 17 artículo del Dr. Bengochea acompañado de una historieta de PHD Inés Simone Comics de los doctores Jorge Cham y Jon Kaufman (perteneciente al grupo de investigación de BICEP2). No dejen de visitar www.phdcomics. Zoología galáctica 19 com , www.caifa.com.ar ni www.facebook.com/ParalajeCientifico Mgter. Ezequiel Koile Más cerca de nosotros, en el planeta rojo, mientras el Curiosity sigue La inflación cósmica 22 caminando en la superficie (un poco rengo y reculando) se le aproximan Dr. -
1903Aj 23 . . . 22K 22 the Asteojsomic Al
22 THE ASTEOJSOMIC AL JOUENAL. Nos- 531-532 22K . Taking into account the smallness of the weights in- concerned. Through the use of these tables the positions . volved, the individual differences which make up the and motions of many stars not included in the present 23 groups in the preceding table agree^very well. catalogue can be brought into systematic harmony with it, and apparently without materially less accuracy for the in- dividual stars than could be reached by special compu- Tables of Systematic Correction for N2 and A. tations for these stars in conformity with the system of B. 1903AJ The results of the foregoing comparisons. have been This is especially true of the star-places computed by utilized to form tables of systematic corrections for ISr2, An, Dr. Auwers in the catalogues, Ai and As. As will be seen Ai and As. In right-ascension no distinction is necessary by reference to the catalogue the positions and motions of between the various catalogues published by Dr. Auwers, south polar stars taken from N2 agree better with the beginning with the Fundamental-G at alo g ; but in decli- results of this investigation than do those taken from As, nation the distinction between the northern, intermediate, which, in turn, are quoted from the Cape Catalogue for and southern catalogues must be preserved, so far as is 1890. SYSTEMATIC COBEECTIOEB : CEDEE OF DECLINATIONS. Eight-Ascensions ; Cokrections, ¿las and 100z//xtf. Declinations; Corrections, Æs and IOOzZ/x^. B — ISa B —A B —N2 B —An B —Ai âas 100 â[is âas 100 âgô âSs 100 -
Meteor Csillagászati Évkönyv 2015
Ár: 3000 Ft 015 2 csillagászati évkönyv r meteor o e csillagászati évkönyv t e m 2015 ISSN 0866 - 2851 9 7 7 0 8 6 6 2 8 5 0 0 2 METEOR CSILLAGÁSZATI ÉVKÖNYV 2015 METEOR CSILLAGÁSZATI ÉVKÖNYV 2015 MCSE – 2014. SZEPTEMBER–NOVEMBER METEOR CSILLAGÁSZATI ÉVKÖNYV 2015 MCSE – 2014. SZEPTEMBER–NOVEMBER meteor csillagászati évkönyv 2015 Szerkesztette: Benkõ József Mizser Attila Magyar Csillagászati Egyesület www.mcse.hu Budapest, 2014 METEOR CSILLAGÁSZATI ÉVKÖNYV 2015 MCSE – 2014. SZEPTEMBER–NOVEMBER Az évkönyv kalendárium részének összeállításában közremûködött: Bagó Balázs Görgei Zoltán Kaposvári Zoltán Kiss Áron Keve Kovács József Molnár Péter Sárneczky Krisztián Sánta Gábor Szabadi Péter Szabó M. Gyula Szabó Sándor Szöllôsi Attila A kalendárium csillagtérképei az Ursa Minor szoftverrel készültek. www.ursaminor.hu Szakmailag ellenôrizte: Szabados László A kiadvány a Magyar Tudományos Akadémia támogatásával készült. További támogatóink mindazok, akik az SZJA 1%-ával támogatják a Magyar Csillagászati Egyesületet. Adószámunk: 19009162-2-43 Felelôs kiadó: Mizser Attila Nyomdai elôkészítés: Kármán Stúdió, www.karman.hu Nyomtatás, kötészet: OOK-Press Kft., www.ookpress.hu Felelôs vezetô: Szathmáry Attila Terjedelem: 23 ív fekete-fehér + 8 oldal színes melléklet 2014. november ISSN 0866-2851 METEOR CSILLAGÁSZATI ÉVKÖNYV 2015 MCSE – 2014. SZEPTEMBER–NOVEMBER Tartalom Bevezetô ................................................... 7 Kalendárium ............................................... 13 Cikkek Kiss László: A változócsillagászat újdonságai .................... 227 Tóth Imre: Az üstökösök megismerésének mérföldkövei ........... 242 Petrovay Kristóf: Az éghajlatváltozás és a Nap ................... 265 Kovács József: A kozmológiai állandótól a sötét energiáig – 100 éves az általános relativitáselmélet ...................... 280 Szabados László: A jó „öreg” Hubble-ûrtávcsô ................... 296 Kolláth Zoltán: A fényszennyezésrôl a Fény Nemzetközi Évében 311 Beszámolók Mizser Attila: A Magyar Csillagászati Egyesület 2013. -
Basics of Astrophysics Revisited. I. Mass- Luminosity Relation for K, M and G Class Stars
Basics of astrophysics revisited. I. Mass- luminosity relation for K, M and G class stars Edgars Alksnis [email protected] Small volume statistics show, that luminosity of slow rotating stars is proportional to their angular momentums of rotation. Cause should be outside of standard solar model. Slow rotating giants and dim dwarfs are not out of „main sequence” in this concept. Predictive power of stellar mass-radius- equatorial rotation speed-luminosity relation has been offered to test in numerous examples. Keywords: mass-luminosity relation, stellar rotation, stellar mass prediction, stellar rotation prediction ...Such vibrations would proceed from deep inside the sun. They are a fast way of transporting large amounts of energy from the interior to the surface that is not envisioned in present theory.... They could stir up the material inside the sun, which current theory tends to see as well layered, and that could affect the fusion dynamics. If they come to be generally accepted, they will require a reworking of solar theory, and that carries in its train a reworking of stellar theory generally. These vibrations could reverberate throughout astronomy. (Science News, Vol. 115, April 21, 1979, p. 270). Actual expression for stellar mass-luminosity relation (fig.1) Fig.1 Stellar mass- luminosity relation. Credit: Ay20. L- luminosity, relative to the Sun, M- mass, relative to the Sun. remain empiric and in fact contain unresolvable contradiction: stellar luminosity basically is connected with their surface area (radius squared) but mass (radius in cube) appears as a factor which generate luminosity. That purely geometric difference had pressed astrophysicists to place several classes of stars outside of „main sequence” in the frame of their strange theoretic constructions. -
Double Stars at the U.S. Naval Observatory
Vol. 10 No. 1 January 1, 2014 Journal of Double Star Observations Page 12 Double Stars at the U.S. Naval Observatory Alan L. Behall1 U.S. Naval Observatory 3450 Massachusetts Avenue, NW, Washington, DC, 20392-5420 Abstract: Micrometer measures of double stars made with the 24-inch reflector and the 26- inch refractor of the U.S. Naval Observatory from 1973 to 1990 are presented. Introduction Alan Behall (1940-2009) worked at the US Naval Observatory from 1963-1975 in the Astronomy & As- trophysics Department in work primarily involving double stars. From 1968 to 1970, he made measures of 159 pairs with the 12 inch Clark refractor on the roof of Building 1 and obtained 68 mean positions with a medi- an separation of 1.39 a.s. After his “training” period with the 12 inch, Alan began work with the 26 inch Clark refractor. From 1970 to 1974 he made measures of 1295 pairs with the 26 inch and obtained 370 mean positions with a median separation of 1.20 a.s. In 1974 he also made measures of 60 pairs with the 24 inch Boller & Chivens reflector, resulting in 24 mean posi- tions with a median separation of 1.01 a.s. All of these measures are found in the second series of USNO Pub- lications (Behall 1977). However, his in-depth analysis of orbit pairs is probably of greater significance. In 1963 he determined a very accurate orbit for 13 Ceti (Behall 1963), and re- turned to it a decade later (Gatewood & Behall 1975) with George Gatewood to investigate the residuals in parallax measures due to the unseen spectroscopic com- panion in this overluminous star. -
Extrasolar Planets and Their Host Stars
Kaspar von Braun & Tabetha S. Boyajian Extrasolar Planets and Their Host Stars July 25, 2017 arXiv:1707.07405v1 [astro-ph.EP] 24 Jul 2017 Springer Preface In astronomy or indeed any collaborative environment, it pays to figure out with whom one can work well. From existing projects or simply conversations, research ideas appear, are developed, take shape, sometimes take a detour into some un- expected directions, often need to be refocused, are sometimes divided up and/or distributed among collaborators, and are (hopefully) published. After a number of these cycles repeat, something bigger may be born, all of which one then tries to simultaneously fit into one’s head for what feels like a challenging amount of time. That was certainly the case a long time ago when writing a PhD dissertation. Since then, there have been postdoctoral fellowships and appointments, permanent and adjunct positions, and former, current, and future collaborators. And yet, con- versations spawn research ideas, which take many different turns and may divide up into a multitude of approaches or related or perhaps unrelated subjects. Again, one had better figure out with whom one likes to work. And again, in the process of writing this Brief, one needs create something bigger by focusing the relevant pieces of work into one (hopefully) coherent manuscript. It is an honor, a privi- lege, an amazing experience, and simply a lot of fun to be and have been working with all the people who have had an influence on our work and thereby on this book. To quote the late and great Jim Croce: ”If you dig it, do it. -
Physical Properties of the Current Census of Northern White Dwarfs
PHYSICAL PROPERTIES OF THE CURRENT CENSUS OF NORTHERN WHITE DWARFS WITHIN 40 pc OF THE SUN M.-M. Limoges,1,3 P. Bergeron,1 and S. L´epine2,4 1D´epartement de Physique, Universit´ede Montr´eal, C.P. 6128, Succ. Centre-Ville, Montr´eal, Qu´ebec H3C 3J7, Canada 2Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30302-4106 [email protected], [email protected], [email protected] ABSTRACT We present a detailed description of the physical properties of our current census of white dwarfs within 40 pc of the Sun, based on an exhaustive spectro- scopic survey of northern hemisphere candidates from the SUPERBLINK proper motion database. Our method for selecting white dwarf candidates is based on a combination of theoretical color-magnitude relations and reduced proper motion diagrams. We reported in an earlier publication the discovery of nearly 200 new white dwarfs, and we present here the discovery of an additional 133 new white dwarfs, among which we identify 96 DA, 3 DB, 24 DC, 3 DQ, and 7 DZ stars. We further identify 178 white dwarfs that lie within 40 pc of the Sun, represent- ing a 40% increase of the current census, which now includes 492 objects. We estimate the completeness of our survey at between 66 and 78%, allowing for uncertainties in the distance estimates. We also perform a homogeneous model atmosphere analysis of this 40 pc sample and find a large fraction of massive white dwarfs, indicating that we are successfully recovering the more massive, and less luminous objects often missed in other surveys.