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Quasistellar Objects: Overview ENCYCLOPEDIA of ASTRONOMY and ASTROPHYSICS
eaa.iop.org DOI: 10.1888/0333750888/1585 Quasistellar Objects: Overview Patrick Osmer From Encyclopedia of Astronomy & Astrophysics P. Murdin © IOP Publishing Ltd 2006 ISBN: 0333750888 Institute of Physics Publishing Bristol and Philadelphia Downloaded on Thu Mar 02 22:43:08 GMT 2006 [131.215.103.76] Terms and Conditions Quasistellar Objects: Overview ENCYCLOPEDIA OF ASTRONOMY AND ASTROPHYSICS Quasistellar Objects: Overview Quasistellar objects, or quasars, were defined originally as star-like objects of large redshift. Quasars are believed to be powered by the accretion of matter onto massive black holes at the centers of galaxies, a process that emits more energy than thermonuclear reactions. Today, quasars are considered to be the most luminous members of the general class of objects called active galactic nuclei, or AGNs. Quasars are the most luminous objects in the universe. This article begins with a brief history of the discovery of quasars. Next it describes their main properties and the concepts that have been developed to explain them. It continues with a description of their nature and theoretical models. Then additional properties and topics are considered: absorption lines, host galaxies, Figure 1. Optical image of 3C273. The object looks stellar in and luminosity functions and evolution. this image except that it is accompanied by a jet of radiation extending to the lower right. (Credit National Optical Astronomy Observatories/National Science Foundation. History Copyright Association of Universities for Research in In 1960 Mathews and Sandage identified the radio source Astronomy Inc (AURA), all rights reserved.) 3C 48 (the 48th object in the 3rd Cambridge catalog of radio sources) with a star-like object of 16th magnitude. -
Pos(Westerbork)006 S 4.0 International License (CC BY-NC-ND 4.0)
Exploring the time-varying Universe PoS(Westerbork)006 Richard Strom ASTRON Oude Hoogeveensedijk 4, 7991 PD Dwingeloo, The Netherlands E-mail: [email protected] Lodie Voûte ASTRON, Anton Pannekoek Inst. Of Astronomy, University of Amsterdam, Postbus 94249, 1090 GE Amsterdam, The Netherlands E-mail: [email protected] Benjamin Stappers School of Phys. & Astron., Alan Turing Bldg., University of Manchester, Oxford Road, Manchester M13 9PL, UK E-mail: [email protected] Gemma Janssen ASTRON Oude Hoogeveensedijk 4, 7991 PD Dwingeloo, The Netherlands E-mail: [email protected] Jason Hessels ASTRON Oude Hoogeveensedijk 4, 7991 PD Dwingeloo, The Netherlands E-mail: [email protected] 50 Years Westerbork Radio Observatory, A Continuing Journey to Discoveries and Innovations Richard Strom, Arnold van Ardenne, Steve Torchinsky (eds) Published with permission of the Netherlands Institute for Radio Astronomy (ASTRON) under the terms of the Creative CommonsAttribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0). Exploring the time-varying Universe Chapter 5.1 The earliest start Richard Strom* Introduction The WSRT interferometrically measures Fourier components of the sky bright- ness distribution from a region set by the primary beam of the telescope ele- ments, at a radio frequency determined by the receiver. This information is used to construct a two-dimensional image of radio emission from the piece of sky observed. Because it is an east-west interferometer array, the information obtained at any instant of time can only be used to construct a one-dimensional map (the telescope so synthesized has the response of a fan beam – narrow in one direction, but orthogonally very elongated). -
Accurate Positions of Pluto and Asteroids Observed in Bucharest During the Year 1932
ACCURATE POSITIONS OF PLUTO AND ASTEROIDS OBSERVED IN BUCHAREST DURING THE YEAR 1932 GHEORGHE BOCŞA, PETRE POPESCU, MIHAELA LICULESCU Astronomical Institute of the Romanian Academy Str. Cuţitul de Argint 5, 040557 Bucharest, Romania E-mail: [email protected] Abstract. The paper contains the observations of minor planets performed in Bucharest Astronomical Observatory in the year 1932 with the 380/6000 mm astrograph. Both Turner’s (constants) and Schlesinger’s (dependences) methods were used in the computation of the normal coordinates of the objects. Keywords: photographic astrometry – minor planets. 1. INTRODUCTION The article is a continuation of the complete investigation of Bucharest Wide-Field Plates Archive initiated in 2010; it contains the plates with asteroids observed in 1932. That year 185 plates were exposed and were stored in the archive, but were not reduced. After analysing them, 98 plates were detected to contain measurable minor planets. The first observed positions in this year were of planet Pluto. They were exposed on 1318cm plates, with 52 minutes exposure .The observations were performed by the famous Romanian astronomer Professor Gheorghe Demetrescu. The most difficult problem was the identification of the planet, the three plates obtained in 1932 having dozens of stars with up to 15 magnitudes. As all the observations were performed in the same month and the planet did not have a great proper motion, it was possible to superpose two plates and to identify Pluto. The values (O–C)α and (O–C)δ were calculated by M. Svechnikov from the Institute of Applied Astronomy in Sankt Petersburg on the basis of precise positions obtained in Bucharest, which we integrated in Pluto’s orbit. -
A Horse of a Different Color
A Horse of a National Aeronautics and Different Color Space Administration A Horse of a Different Color To celebrate the 23rd anniversary of the Hubble Space Telescope, NASA released a new view of the Horsehead Nebula that provides an intriguing astronomical variation on the phrase, “a horse of a different color.” The Horsehead Nebula, also known as Barnard 33, was first recorded in 1888 by Williamina Fleming at the Harvard College Observatory. Visible-light images show a black silhouette, a “dark nebula,” that resembles a horse’s head. Dark nebulae are generally most noticeable because they block the light from background stars. Two views of Horsehead Nebula To see deeper into dark nebulae, astronomers use infrared These two images reveal different views of the Horsehead Nebula. The visible-light image on the left was taken by a ground-based light. Hubble’s infrared image of the Horsehead transforms telescope. The near-infrared image on the right was taken by the the dark nebula into a softly glowing landscape. The image Hubble Space Telescope. reveals more structure and detail in the clouds. In the image at left, the gas around the Horsehead Nebula shines Many parts of the Horsehead Nebula are still opaque at infrared a bright pink, in contrast to the darkness of the Horsehead itself. This pink glow occurs along the edge of the dark cloud and is wavelengths, showing that the gas is dense and cold. Within created by the bright star, Sigma Orionis, above the Horsehead, such cold and dense clouds are regions where stars are born. -
Aqueous Alteration on Main Belt Primitive Asteroids: Results from Visible Spectroscopy1
Aqueous alteration on main belt primitive asteroids: results from visible spectroscopy1 S. Fornasier1,2, C. Lantz1,2, M.A. Barucci1, M. Lazzarin3 1 LESIA, Observatoire de Paris, CNRS, UPMC Univ Paris 06, Univ. Paris Diderot, 5 Place J. Janssen, 92195 Meudon Pricipal Cedex, France 2 Univ. Paris Diderot, Sorbonne Paris Cit´e, 4 rue Elsa Morante, 75205 Paris Cedex 13 3 Department of Physics and Astronomy of the University of Padova, Via Marzolo 8 35131 Padova, Italy Submitted to Icarus: November 2013, accepted on 28 January 2014 e-mail: [email protected]; fax: +33145077144; phone: +33145077746 Manuscript pages: 38; Figures: 13 ; Tables: 5 Running head: Aqueous alteration on primitive asteroids Send correspondence to: Sonia Fornasier LESIA-Observatoire de Paris arXiv:1402.0175v1 [astro-ph.EP] 2 Feb 2014 Batiment 17 5, Place Jules Janssen 92195 Meudon Cedex France e-mail: [email protected] 1Based on observations carried out at the European Southern Observatory (ESO), La Silla, Chile, ESO proposals 062.S-0173 and 064.S-0205 (PI M. Lazzarin) Preprint submitted to Elsevier September 27, 2018 fax: +33145077144 phone: +33145077746 2 Aqueous alteration on main belt primitive asteroids: results from visible spectroscopy1 S. Fornasier1,2, C. Lantz1,2, M.A. Barucci1, M. Lazzarin3 Abstract This work focuses on the study of the aqueous alteration process which acted in the main belt and produced hydrated minerals on the altered asteroids. Hydrated minerals have been found mainly on Mars surface, on main belt primitive asteroids and possibly also on few TNOs. These materials have been produced by hydration of pristine anhydrous silicates during the aqueous alteration process, that, to be active, needed the presence of liquid water under low temperature conditions (below 320 K) to chemically alter the minerals. -
Horsehead Nebula, in Infrared Light, from Hubble
Horsehead Nebula, in Infrared Light, from Hubble Hubble, the orbiting space telescope, turned 23 years old in April of 2013. To celebrate the anniversary of its launch, NASA released this amazingly detailed image of the Horsehead Nebula which Hubble took in infrared light. NASA provides a more detailed description of this stunning image: While drifting through the cosmos, a magnificent interstellar dust cloud became sculpted by stellar winds and radiation to assume a recognizable shape. Fittingly named the Horsehead Nebula, it is embedded in the vast and complex Orion Nebula (M42). A potentially rewarding but difficult object to view personally with a small telescope, the above gorgeously detailed image was recently taken in infrared light by the orbiting Hubble Space Telescope in honor of the 23rd anniversary of Hubble's launch. The dark molecular cloud, roughly 1,500 light years distant, is cataloged as Barnard 33 and is seen above primarily because it is backlit by the nearby massive star Sigma Orionis. The Horsehead Nebula will slowly shift its apparent shape over the next few million years and will eventually be destroyed by the high energy starlight. Click on the image to enjoy a much-larger-and-clearer view. Credits: Image of the Horsehead Nebula, taken by Hubble in infrared light, by NASA, ESA, and The Hubble Heritage Team (STSci / AURA). Online, courtesy NASA. See Alignments to State and Common Core standards for this story online at: http://www.awesomestories.com/asset/AcademicAlignment/Horsehead-Nebula-in-Infrared-Light-from-Hubble-0 See Learning Tasks for this story online at: http://www.awesomestories.com/asset/AcademicActivities/Horsehead-Nebula-in-Infrared-Light-from-Hubble-0. -
Planck Highlights the Complexity of Star Formation 26 April 2010
Planck highlights the complexity of star formation 26 April 2010 The first image covers much of the constellation of Orion. The nebula is the bright spot to the lower centre. The bright spot to the right of centre is around the Horsehead Nebula, so called because at high magnifications a pillar of dust resembles a horse's head. The giant red arc of Barnard's Loop is thought to be the blast wave from a star that blew up inside the region about two million years ago. The bubble it created is now about 300 light-years across. In contrast to Orion, the Perseus region is a less vigorous star-forming area but, as Planck shows in the other image, there is still plenty going on. The images both show three physical processes This is an active star-formation region in the Orion taking place in the dust and gas of the interstellar Nebula, as seen By Planck. This image covers a region medium. Planck can show us each process of 13x13 degrees. It is a three-color combination separately. At the lowest frequencies, Planck maps constructed from three of Planck's nine frequency emission caused by high-speed electrons channels: 30, 353 and 857 GHz. Credit: ESA/LFI & HFI interacting with the Galaxy's magnetic fields. An Consortia additional diffuse component comes from spinning dust particles emitting at these frequencies. New images from ESA's Planck space observatory reveal the forces driving star formation and give astronomers a way to understand the complex physics that shape the dust and gas in our Galaxy. -
[CII] 158M Emission from L1630 in Orion B
[CII] 158 µm emission from L1630 in Orion B Cornelia Pabst Leiden Observatory November 29, 2017 in collaboration with: J. R. Goicoechea, D. Teyssier, O. Bern´e,B. B. Ochsendorf, M. G. Wolfire, R. D. Higgins, D. Riquelme, C. Risacher, J. Pety, F. LePetit, E. Roueff, E. Bron, A. G. G. M. Tielens Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 Introduction PhD student under supervision of Xander Tielens Leiden Observatory, Netherlands Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 1 / 30 [CII] 158 µm emission [CII] fine-structure line one of the brightest far-infrared cooling lines of the ISM, 1% of total FIR continuum ∼ [CII] line can be observed in distant galaxies correlation of SFR and [CII] intensity: [1] for 46 nearby galaxies, [2] on Galactic scale origin of [CII] emission: dense PDRs, cold HI gas, ionized gas, CO-dark gas on Galactic scale cf. GOT C+ [2] need to spatially resolve the ISM Orion molecular cloud as template region velocity-resolved mapping allows to form a 3D picture [1] Herrera-Camus et al. (2015) ApJ 800:1, [2] Pineda et al. (2014) A&A 570:A121 Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 2 / 30 The optical window Image Credit: NASA/ESA/Hubble Heritage Team; M. Robberto/Hubble Space Telescope Orion Treasury Project Team Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 3 / 30 The infrared window Left: visible light. Right: infrared light (IRAS). Image Credit: Akira Fujii/NASA/IRAS Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 4 / 30 L1630 in the Orion B molecular cloud - visible Alnilam Flame Nebula (NGC 2024) Alnitak NGC 2023 σ Ori Horsehead Nebula IC 434 Image Credit: ESO, Digitized Sky Survey 2 Cornelia Pabst, Leiden Observatory SOFIA tele-talk, November 29, 2017 5 / 30 L1630 in the Orion B molecular cloud - infrared Flame Nebula (NGC 2024) NGC 2023 σ Ori Horsehead Nebula IC 434 Image Credit: NASA/JPL-Caltech (WISE) blue: 3.4 µm, cyan: 4.6 µm, green: 12 µm, red: 22 µm. -
The Minor Planet Bulletin
THE MINOR PLANET BULLETIN OF THE MINOR PLANETS SECTION OF THE BULLETIN ASSOCIATION OF LUNAR AND PLANETARY OBSERVERS VOLUME 35, NUMBER 3, A.D. 2008 JULY-SEPTEMBER 95. ASTEROID LIGHTCURVE ANALYSIS AT SCT/ST-9E, or 0.35m SCT/STL-1001E. Depending on the THE PALMER DIVIDE OBSERVATORY: binning used, the scale for the images ranged from 1.2-2.5 DECEMBER 2007 – MARCH 2008 arcseconds/pixel. Exposure times were 90–240 s. Most observations were made with no filter. On occasion, e.g., when a Brian D. Warner nearly full moon was present, an R filter was used to decrease the Palmer Divide Observatory/Space Science Institute sky background noise. Guiding was used in almost all cases. 17995 Bakers Farm Rd., Colorado Springs, CO 80908 [email protected] All images were measured using MPO Canopus, which employs differential aperture photometry to determine the values used for (Received: 6 March) analysis. Period analysis was also done using MPO Canopus, which incorporates the Fourier analysis algorithm developed by Harris (1989). Lightcurves for 17 asteroids were obtained at the Palmer Divide Observatory from December 2007 to early The results are summarized in the table below, as are individual March 2008: 793 Arizona, 1092 Lilium, 2093 plots. The data and curves are presented without comment except Genichesk, 3086 Kalbaugh, 4859 Fraknoi, 5806 when warranted. Column 3 gives the full range of dates of Archieroy, 6296 Cleveland, 6310 Jankonke, 6384 observations; column 4 gives the number of data points used in the Kervin, (7283) 1989 TX15, 7560 Spudis, (7579) 1990 analysis. Column 5 gives the range of phase angles. -
The Angular Size of Objects in the Sky
APPENDIX 1 The Angular Size of Objects in the Sky We measure the size of objects in the sky in terms of degrees. The angular diameter of the Sun or the Moon is close to half a degree. There are 60 minutes (of arc) to one degree (of arc), and 60 seconds (of arc) to one minute (of arc). Instead of including – of arc – we normally just use degrees, minutes and seconds. 1 degree = 60 minutes. 1 minute = 60 seconds. 1 degree = 3,600 seconds. This tells us that the Rosette nebula, which measures 80 minutes by 60 minutes, is a big object, since the diameter of the full Moon is only 30 minutes (or half a degree). It is clearly very useful to know, by looking it up beforehand, what the angular size of the objects you want to image are. If your field of view is too different from the object size, either much bigger, or much smaller, then the final image is not going to look very impressive. For example, if you are using a Sky 90 with SXVF-M25C camera with a 3.33 by 2.22 degree field of view, it would not be a good idea to expect impressive results if you image the Sombrero galaxy. The Sombrero galaxy measures 8.7 by 3.5 minutes and would appear as a bright, but very small patch of light in the centre of your frame. Similarly, if you were imaging at f#6.3 with the Nexstar 11 GPS scope and the SXVF-H9C colour camera, your field of view would be around 17.3 by 13 minutes, NGC7000 would not be the best target. -
Understanding the Bizarre Shapes of Radio Supernova Remnants
Barrels, jets and smoke-rings: Understanding the bizarre shapes of radio supernova remnants Bryan Malcolm Gaensler A thesis submitted for the degree of Doctor of Philosophy at the University of Sydney February 1999 To Dr Michael Bishop, For showing me where to start 1 Abstract This thesis considers the various morphologies of radio supernova remnants (SNRs), and attempts to determine whether their appearance results from the properties of the progenitor star and its supernova explosion, or from the structure of the inter- stellar medium (ISM) and ambient magnetic field into which a SNR consequently expands. High-resolution observations of Supernova 1987A show a young remnant whose appearance and evolution are completely dominated by the structure of its progenitor wind. A statistical study of the Galactic population of bilateral SNRs demonstrates that the symmetry axes of these remnants run parallel to the Galac- tic Plane. This result can be explained by the interaction of main sequence stellar wind-bubbles with the ambient magnetic field; expansion of SNRs into the resulting elongated cavities results in a bilateral appearance with the observed alignment. Radio observations of SNR G296.8{00.3 show a double-ringed morphology which is best explained by expansion either into an anisotropic main-sequence progenitor wind or into multiple cavities in the ISM. Data on SNRs G309.2{00.6 and G320.4{ 01.2 (MSH 15{52) make a strong case that the appearance of both remnants is significantly affected by collimated outflows from a central source; for G309.2{00.6 the source itself is not detected, but for G320.4{01.2 there is now compelling evi- dence that the remnant is associated with and is interacting with the young pulsar PSR B1509{58. -
RADIO STARS and THEIR LIVES in the GALAXY Lynn D
Accepted to PASP A Preprint typeset using LTEX style emulateapj v. 12/16/11 RADIO STARS AND THEIR LIVES IN THE GALAXY Lynn D. Matthews1 Accepted to PASP ABSTRACT This paper summarizes the three-day international workshop Radio Stars and Their Lives in the Galaxy, held at the Massachusetts Institute of Technology Haystack Observatory on 2012 October 3-5. The workshop was organized to provide a forum for the presentation and discussion of advances in stellar and solar astrophysics recently (or soon to be) enabled by the latest generation of state-of-the- art observational facilities operating from meter to submillimeter wavelengths. The meeting brought together both observers and theorists to discuss how radio wavelength observations are providing new and unique insights into the workings of stars and their role in the Galactic ecosystem. Topics covered included radio emission from hot and cool stars (from the pre- to post-main-sequence), the Sun as a radio star, circumstellar chemistry, planetary nebulae, white dwarf binaries and novae, supernova progenitors, and radio stars as probes of the Galaxy. Subject headings: meeting summary, Stars — stars: AGB and post-AGB – stars: winds, outflows – circumstellar matter – radio lines: stars 1. BACKGROUND AND MOTIVATION FOR THE precision astrometry, and the routine study of sources at WORKSHOP a level of a few tens of µJy. We also heard how develop- Radio emission has now been detected from stars ments in theory, modeling, and laboratory astrophysics across the entire Hertzsprung-Russell (H-R) diagram, are improving our ability to interpret results. This paper spanning virtually every stage of stellar evolution.