National Radio Astronomy Observatory 1973
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NATURE l DECEl\IBEK 28. 1899 J 1 _;. wh. 1m. of Algol 1$ Persei). followed ll\' no loss of accuracy, and thereft•re their puhlicatio:I 1:; . \'enus. Illuminated portion of <lise = o·873· is In :lccordance with th<: decisions of the Con l(r. 6h. sorn. :'llinimum nf Algol (8 . ference of Superintendents of Ephemeride;; held at _l'aris in 1(). t7h. 17m. to 17h. som. OccultatiOn of a Cancn 18<)6, I he constants of aberration, precession, and nutatron have (mag. 4'3) by the moon. _ . lreen altered from the commencement of 1901' ; but, for the con 20 12h. 46m. to 13h. 46m. Occuliatwn of IL\.C. Yenience of oh<en·ers Hill desirint-: to use the Stnl\·e-l'cter's 4006 (mag. 5 71 by the moon. constants, both been inchulcd in the present tables. 21. 1 1 h. 22m. to 12h. 26m. OccultatH>n of '/ "l'Ot•t:I.AR ,. FOR DECE:l!IIER. · -The issue of \"irnini< (mog. 57) by the moon. l'opu!ar Ash·oiiOIII)' for this month contain>, among much -J? ' ISh 3sm. to I6h. 45•11 . Occuliation cf H . .-\.C. generally interesting matter, two useful :lrticlcs by _Profs. II. C. 4722 mag. 5 ·s). \Yilsun and \V. II. Pickering. The former descnbcs a photo 2(}, 1h. Conjunction of Jupiter and the moon graph of the nebula of Andromeda obtained by at Coodsell (Jupiler z ' 3' i'l.). Observatory, the 8-inch Clarke refractor, wrth an exposure I ;h 40n1. of Jupiter'.; Sat. Ill. of twell'e hours given on three nights. -
The Axis Is Nearly Perpendicular to the Orbital Plane ; (2) the Sense Is the Same As That of the Revolution ; (3) the Period Is Longer Than That of the Revolution
No. 7.] 247 75. An Explanation of the Periodic Variable Stars. By Kiyotsugu HIRAYAMA, M.I.A. Astronomical Observatory, Azabu, Tokyo. (Comm. July 13, 1931.) The binary hypotheses, initially proposed to explain the periodic variable stars, were defective. The pulsation theory seemed more promising ; but even this is disappointing in explaining the varieties and the minor details, of the phenomena. The following explanation ,1) although qualitative, seems satisfactory for those. The hypothesis is based on the capture theory of the stars,2) recently proposed by the writer, and is inconsistent with the fission theory. Cepheid Variables. The Cepheid variable is supposed to be a contact system of a giant star and a dwarf star which is almost dark. The relative orbit is supposed to be nearly circular, in accordance with the general tendency of the binary stars. For the rotation of the primary, the following qualifications are made : (1) the axis is nearly perpendicular to the orbital plane ; (2) the sense is the same as that of the revolution ; (3) the period is longer than that of the revolution. No assumption is made for the rotation of the companion, although the libration is very probable. Taking as a model, the stars of spherical form of the masses 10 and 1 solar units, and the period of revolution, 0.02 year, the mean distance comes out as 0.16 astronomical unit, and the velocitiesrelative to the centre of gravity, as 22.3 and 223.5 km sec-1. As a consequence of the relative motion of the companion, a trail, or an abrasion, so to speak, is left on the surface of the primary, which may be recovered as the time goes on. -
Report of Contributions
Mapping the X-ray Sky with SRG: First Results from eROSITA and ART-XC Report of Contributions https://events.mpe.mpg.de/e/SRG2020 Mapping the X- … / Report of Contributions eROSITA discovery of a new AGN … Contribution ID : 4 Type : Oral Presentation eROSITA discovery of a new AGN state in 1H0707-495 Tuesday, 17 March 2020 17:45 (15) One of the most prominent AGNs, the ultrasoft Narrow-Line Seyfert 1 Galaxy 1H0707-495, has been observed with eROSITA as one of the first CAL/PV observations on October 13, 2019 for about 60.000 seconds. 1H 0707-495 is a highly variable AGN, with a complex, steep X-ray spectrum, which has been the subject of intense study with XMM-Newton in the past. 1H0707-495 entered an historical low hard flux state, first detected with eROSITA, never seen before in the 20 years of XMM-Newton observations. In addition ultra-soft emission with a variability factor of about 100 has been detected for the first time in the eROSITA light curves. We discuss fast spectral transitions between the cool and a hot phase of the accretion flow in the very strong GR regime as a physical model for 1H0707-495, and provide tests on previously discussed models. Presenter status Senior eROSITA consortium member Primary author(s) : Prof. BOLLER, Thomas (MPE); Prof. NANDRA, Kirpal (MPE Garching); Dr LIU, Teng (MPE Garching); MERLONI, Andrea; Dr DAUSER, Thomas (FAU Nürnberg); Dr RAU, Arne (MPE Garching); Dr BUCHNER, Johannes (MPE); Dr FREYBERG, Michael (MPE) Presenter(s) : Prof. BOLLER, Thomas (MPE) Session Classification : AGN physics, variability, clustering October 3, 2021 Page 1 Mapping the X- … / Report of Contributions X-ray emission from warm-hot int … Contribution ID : 9 Type : Poster X-ray emission from warm-hot intergalactic medium: the role of resonantly scattered cosmic X-ray background We revisit calculations of the X-ray emission from warm-hot intergalactic medium (WHIM) with particular focus on contribution from the resonantly scattered cosmic X-ray background (CXB). -
ASTRONOMY and ASTROPHYSICS the Elliptical Galaxy Formerly Known As the Local Group: Merging the Globular Cluster Systems
Astron. Astrophys. 358, 471–480 (2000) ASTRONOMY AND ASTROPHYSICS The elliptical galaxy formerly known as the Local Group: merging the globular cluster systems Duncan A. Forbes1,2, Karen L. Masters1, Dante Minniti3, and Pauline Barmby4 1 University of Birmingham, School of Physics and Astronomy, Edgbaston, Birmingham B15 2TT, UK 2 Swinburne University of Technology, Astrophysics and Supercomputing, Hawthorn, Victoria 3122, Australia 3 P. Universidad Catolica,´ Departamento de Astronom´ıa y Astrof´ısica, Casilla 104, Santiago 22, Chile 4 Harvard–Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA Received 5 November 1999 / Accepted 27 January 2000 Abstract. Prompted by a new catalogue of M31 globular clus- al. 1995; Minniti et al. 1996). Furthermore Hubble Space Tele- ters, we have collected together individual metallicity values for scope studies of merging disk galaxies reveal evidence for the globular clusters in the Local Group. Although we briefly de- GC systems of the progenitor galaxies (e.g. Forbes & Hau 1999; scribe the globular cluster systems of the individual Local Group Whitmore et al. 1999). Thus GCs should survive the merger of galaxies, the main thrust of our paper is to examine the collec- their parent galaxies, and will form a new GC system around tive properties. In this way we are simulating the dissipationless the newly formed elliptical galaxy. merger of the Local Group, into presumably an elliptical galaxy. The globular clusters of the Local Group are the best studied Such a merger is dominated by the Milky Way and M31, which and offer a unique opportunity to examine their collective prop- appear to be fairly typical examples of globular cluster systems erties (reviews of LG star clusters can be found in Brodie 1993 of spiral galaxies. -
Milan Dimitrijevic Avgust.Qxd
1. M. Platiša, M. Popović, M. Dimitrijević, N. Konjević: 1975, Z. Fur Natur- forsch. 30a, 212 [A 1].* 1. Griem, H. R.: 1975, Stark Broadening, Adv. Atom. Molec. Phys. 11, 331. 2. Platiša, M., Popović, M. V., Konjević, N.: 1975, Stark broadening of O II and O III lines, Astron. Astrophys. 45, 325. 3. Konjević, N., Wiese, W. L.: 1976, Experimental Stark widths and shifts for non-hydrogenic spectral lines of ionized atoms, J. Phys. Chem. Ref. Data 5, 259. 4. Hey, J. D.: 1977, On the Stark broadening of isolated lines of F (II) and Cl (III) by plasmas, JQSRT 18, 649. 5. Hey, J. D.: 1977, Estimates of Stark broadening of some Ar III and Ar IV lines, JQSRT 17, 729. 6. Hey, J. D.: Breger, P.: 1980, Stark broadening of isolated lines emitted by singly - ionized tin, JQSRT 23, 311. 7. Hey, J. D.: Breger, P.: 1981, Stark broadening of isolated ion lines by plas- mas: Application of theory, in Spectral Line Shapes I, ed. B. Wende, W. de Gruyter, 201. 8. Сыркин, М. И.: 1981, Расчеты электронного уширения спектральных линий в теории оптических свойств плазмы, Опт. Спектроск. 51, 778. 9. Wiese, W. L., Konjević, N.: 1982, Regularities and similarities in plasma broadened spectral line widths (Stark widths), JQSRT 28, 185. 10. Konjević, N., Pittman, T. P.: 1986, Stark broadening of spectral lines of ho- mologous, doubly ionized inert gases, JQSRT 35, 473. 11. Konjević, N., Pittman, T. P.: 1987, Stark broadening of spectral lines of ho- mologous, doubly - ionized inert gases, JQSRT 37, 311. 12. Бабин, С. -
Maffei 1970 the MEMBER Technology, (H
THE ASTROPHYSICAL JOURNAL, 163:L25-L31, 1971January1 @ 1971. The University of Chicago. All rights reserved. Printed in U.S.A. 1971ApJ...163L..25S MAFFEI 1: A NEW MASSIVE MEMBER OF THE LOCAL GROUP? HYRON SPINRAD,* w. L. w. SARGENT,t J.B. 0KE,t GERRY NEUGEBAUER,t ROBERT LANDAU,* IVAN R. KING,* }AMES E. GUNN,t GORDON GARMIRE,t AND NANNIELOU H. DIETER§ Received 1970 November 2 ABSTRACT An extensive collection of observational data is presented which indicates that the recently dis covered infrared object Maffei 1 is a highly reddened giant elliptical galaxy at a distance of about 1 Mpc, and thus is probably a new massive member of the Local Group. I. INTRODUCTION In 1968, Maffei (1968) discovered two infrared objects in the neighborhood of IC 1805. The objects are conspicuous as extended, elliptical sources on I-N plates, but are just barely visible on the blue 48-inch Palomar Sky Survey plates. They are located in the plane of the Galaxy at approximately zn = 136°, bII = -0.5°; the two objects are separated by about 40'. At 2.2 µ, where differences due to interstellar extinction are small, the flux from the central 8" of Maffei 1 is comparable to that from a similar area of M31. Nonthermal radio emission at 3, 4, and 9 cm has been detected from Maffei 2 by Bell, Seaquist, and Brown (1970), although no radio emisssion was observed from Maffei 1. The possibility that these objects are reddened external galaxies, and possibly even members of the Local Group of galaxies, has led to an observational program among observers at the Leuschner, Lick, and Hale Observatories which utilizes a variety of techniques covering wavelengths from 0.4 to 3.5 µ. -
On the Application of Stark Broadening Data Determined with a Semiclassical Perturbation Approach
Atoms 2014, 2, 357-377; doi:10.3390/atoms2030357 OPEN ACCESS atoms ISSN 2218-2004 www.mdpi.com/journal/atoms Article On the Application of Stark Broadening Data Determined with a Semiclassical Perturbation Approach Milan S. Dimitrijević 1,2,* and Sylvie Sahal-Bréchot 2 1 Astronomical Observatory, Volgina 7, 11060 Belgrade, Serbia 2 Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique, Observatoire de Paris, UMR CNRS 8112, UPMC, 5 Place Jules Janssen, 92195 Meudon Cedex, France; E-Mail: [email protected] (S.S.-B.) * Author to whom correspondence should be addressed; E-Mail: [email protected]; Tel.: +381-64-297-8021; Fax: +381-11-2419-553. Received: 5 May 2014; in revised form: 20 June 2014 / Accepted: 16 July 2014 / Published: 7 August 2014 Abstract: The significance of Stark broadening data for problems in astrophysics, physics, as well as for technological plasmas is discussed and applications of Stark broadening parameters calculated using a semiclassical perturbation method are analyzed. Keywords: Stark broadening; isolated lines; impact approximation 1. Introduction Stark broadening parameters of neutral atom and ion lines are of interest for a number of problems in astrophysical, laboratory, laser produced, fusion or technological plasma investigations. Especially the development of space astronomy has enabled the collection of a huge amount of spectroscopic data of all kinds of celestial objects within various spectral ranges. Consequently, the atomic data for trace elements, which had not been -
Search for Forced Oscillations in Binaries I
Astron. Astrophys. 319, 867–880 (1997) ASTRONOMY AND ASTROPHYSICS Search for forced oscillations in binaries I. The eclipsing and spectroscopic binary V 436 Persei 1 Persei?;?? ≡ P. Harmanec1, P. Hadrava1,S.Yang2, D. Holmgren1, P. North3, P. Koubsky´1,J.Kubat´ 1, and E. Poretti4 1 Astronomicky´ ustav´ Akademie vedˇ Ceskˇ e´ republiky, 251 65 Ondrejov,ˇ Czech Republic (hec(had, david, koubsky, kubat)@sunstel.asu.cas.cz) 2 Department of Physics and Astronomy, University of Victoria, P.O. Box 3055, Victoria, B.C., V8W 3P6, Canada ([email protected]) 3 Institut d’Astronomie de l’Universite´ de Lausanne, CH-1290 Chavannes-des-Bois, Switzerland ([email protected]) 4 Osservatorio Astronomico, Via E. Bianchi 46, I-22055 Merate (CO), Italy ([email protected]) Received 20 May 1996 / Accepted 21 August 1996 Abstract. Outline of a project aimed at testing the presence stable electronic spectral detectors in the seventies brought a of rapid line-profile variations in the atmospheres of hot com- real revolution to the subject. Smith (1977, 1978) discovered ponents of close binaries is presented and its first results are variable line asymmetries for several sharp-lined OB stars while described. An analysis of new electronic spectra of the eclips- Walker, Yang and Fahlman (1979) were the first to recognize ing binary V436 Per from three observatories and of photoelec- another type of variation, now known as ‘travelling sub-features’ tric observations, obtained earlier by several authors, leads to a or ‘moving bumps’: small profile disturbances which gradually unique determination of all basic physical elements of this in- move (most often from blue to red) across the line profiles. -
Astronomy 2009 Index
Astronomy Magazine 2009 Index Subject Index 1RXS J160929.1-210524 (star), 1:24 4C 60.07 (galaxy pair), 2:24 6dFGS (Six Degree Field Galaxy Survey), 8:18 21-centimeter (neutral hydrogen) tomography, 12:10 93 Minerva (asteroid), 12:18 2008 TC3 (asteroid), 1:24 2009 FH (asteroid), 7:19 A Abell 21 (Medusa Nebula), 3:70 Abell 1656 (Coma galaxy cluster), 3:8–9, 6:16 Allen Telescope Array (ATA) radio telescope, 12:10 ALMA (Atacama Large Millimeter/sub-millimeter Array), 4:21, 9:19 Alpha (α) Canis Majoris (Sirius) (star), 2:68, 10:77 Alpha (α) Orionis (star). See Betelgeuse (Alpha [α] Orionis) (star) Alpha Centauri (star), 2:78 amateur astronomy, 10:18, 11:48–53, 12:19, 56 Andromeda Galaxy (M31) merging with Milky Way, 3:51 midpoint between Milky Way Galaxy and, 1:62–63 ultraviolet images of, 12:22 Antarctic Neumayer Station III, 6:19 Anthe (moon of Saturn), 1:21 Aperture Spherical Telescope (FAST), 4:24 APEX (Atacama Pathfinder Experiment) radio telescope, 3:19 Apollo missions, 8:19 AR11005 (sunspot group), 11:79 Arches Cluster, 10:22 Ares launch system, 1:37, 3:19, 9:19 Ariane 5 rocket, 4:21 Arianespace SA, 4:21 Armstrong, Neil A., 2:20 Arp 147 (galaxy pair), 2:20 Arp 194 (galaxy group), 8:21 art, cosmology-inspired, 5:10 ASPERA (Astroparticle European Research Area), 1:26 asteroids. See also names of specific asteroids binary, 1:32–33 close approach to Earth, 6:22, 7:19 collision with Jupiter, 11:20 collisions with Earth, 1:24 composition of, 10:55 discovery of, 5:21 effect of environment on surface of, 8:22 measuring distant, 6:23 moons orbiting, -
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 -
Cluster Analysis and Unsupervised Machine Learning Applied to Find Open Star Clusters in the Milky Way
Cluster analysis and unsupervised machine learning applied to find open star clusters in the Milky Way This dissertation is submitted for the degree of physicist By Andrés Felipe Amar Lesmes Faculty of Science Physics Department Bogotá D.C. Colombia November 2020 Cluster analysis and unsupervised machine learning applied to find open star clusters in the Milky Way This dissertation is submitted for the degree of physicist By Andrés Felipe Amar Lesmes Universidad de los Andes Faculty of Science Physics Department Advisor Alejandro García Ph. D. Bogotá D.C. Colombia 2020 This project is dedicated to my family who have been a big support along this track, To my dearest Luna... Acknowledgements I would like to express thanks to Dr. Alejandro García for being a big support and good guidance along this project, thanks for the patience and for always pushing me forward in this task. I would like to express also my genuine thanks to my Mother, Grandmother, Aunt and Sister for encourage me. All my friends and colleagues, who have helped me during the degree in order to study and understand many topics, specially thanks to Juanpi, Alejo2, Roosvelt, Coco, Jorge, Ávila, Gus and Daniel Calderón. To my school teacher Hermes Ortíz who gave me a wonderfull introduction of the beauty of physics. And finally my grandad who always accompanied me in difficult moments. Abstract The main intention of this project is to characterize open clusters of the Milky Way via unsupervised machine learning with the clustering algorithm density-based spatial clustering of applications with noise (DBSCAN), the data used was retrieved from Gaia DR2 in favor of having standard data for further analysis based on literature and comparison also with it. -
The Detection of Bright Asymptotic Giant Branch Stars in the Nearby Elliptical Galaxy Maffei 1
THE DETECTION OF BRIGHT ASYMPTOTIC GIANT BRANCH STARS IN THE NEARBY ELLIPTICAL GALAXY MAFFEI 1 T. J. Davidge 1 Canadian Gemini Office, Herzberg Institute of Astrophysics, National Research Council of Canada, 5071 W. Saanich Road, Victoria, British Columbia, Canada V9E 2E7 email: [email protected] Sidney van den Bergh Dominion Astrophysical Observatory, Herzberg Institute of Astrophysics, National Research Council of Canada, 5071 W. Saanich Road, Victoria, British Columbia, Canada V9E 2E7 email: [email protected] ABSTRACT We have used the adaptive optics system on the Canada-France-Hawaii Telescope to study a field 6 arcmin from the center of the heavily obscured elliptical galaxy Maffei 1. Our near diffraction-limited H and K0 images reveal an excess population of objects with respect to a background field, and we conclude that the asymptotic giant branch tip (AGB-tip) in Maffei 1 occurs at K =20 0:25. Assuming that stars at the AGB-tip in Maffei 1 have the ± same intrinsic luminosity as those in the bulge of M31, then the actual distance modulus of Maffei 1 is 28:2 0:3ifAV =5:1, which corresponds to a distance +0:6 ± of 4:4 0:5 Mpc. This is in excellent agreement with the distance estimated from − surface brightness flucuations in the infrared, and confirms that Maffei 1 is too distant to significantly affect the dynamics of the Local Group. Subject headings: galaxies: individual (Maffei 1) – galaxies: distances and redshifts 1Visiting Astronomer, Canada-France-Hawaii Telescope, which is operated by the National Research Council of Canada, the Centre National de le Recherche Scientifique, and the University of Hawaii.