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Spring Fever Strikes
The MARCH 2002 DENVER OBSERVER Newsletter of the Denver Astronomical Society One Mile Nearer the Stars How Many in One Night?? Gearing up for the Messier Marathon? Those folks who are new to astronomy may not yet be able to relate to the sheer joy of braving the early-spring temperatures (brrrrr) for a full night (and morning—I’m talking dusk to dawn, here) of observing some of the most beautiful objects in the heavens. Why now? Because for only a few weeks during the year is it possible to see all of the Messier objects in one night. Astronomers will dig in their heels and tripods, get out the star charts (See Page 7), and knock off one object after the next. Some people actually catalog 70 of the available 110 targets and submit their achievements to the Astronomical League for the coveted Messier Certificate. Others just like to look at the beautiful celestial wonders like the one in the photo to the left. Either way, get out to the The Pleaides (M45) DSS on the weekend of the 15th and enjoy Image © Joe Gafford, 2002 the views!—PK Spring Fever Strikes President’s Corner .......... 2 MARCH SKIES 2002 f you’ve been reading your astronomy magazines, you know that by month’s Schedule of Events ......... 2 Iend, four naked-eye planets will grace the night skies. Jupiter is the main show-stopper but Saturn, Mars, and finally Venus will sparkle for all, moon or no moon. Remember that a Officers ......................... 2 little high-cloud haze can be good for telescopic planet observations. -
Planetary Nebulae
Planetary Nebulae A planetary nebula is a kind of emission nebula consisting of an expanding, glowing shell of ionized gas ejected from old red giant stars late in their lives. The term "planetary nebula" is a misnomer that originated in the 1780s with astronomer William Herschel because when viewed through his telescope, these objects appeared to him to resemble the rounded shapes of planets. Herschel's name for these objects was popularly adopted and has not been changed. They are a relatively short-lived phenomenon, lasting a few tens of thousands of years, compared to a typical stellar lifetime of several billion years. The mechanism for formation of most planetary nebulae is thought to be the following: at the end of the star's life, during the red giant phase, the outer layers of the star are expelled by strong stellar winds. Eventually, after most of the red giant's atmosphere is dissipated, the exposed hot, luminous core emits ultraviolet radiation to ionize the ejected outer layers of the star. Absorbed ultraviolet light energizes the shell of nebulous gas around the central star, appearing as a bright colored planetary nebula at several discrete visible wavelengths. Planetary nebulae may play a crucial role in the chemical evolution of the Milky Way, returning material to the interstellar medium from stars where elements, the products of nucleosynthesis (such as carbon, nitrogen, oxygen and neon), have been created. Planetary nebulae are also observed in more distant galaxies, yielding useful information about their chemical abundances. In recent years, Hubble Space Telescope images have revealed many planetary nebulae to have extremely complex and varied morphologies. -
Skytools Chart
38 Octans - Chamaleon SkyTools 3 / Skyhound.com β NGC 6025 NGC 2516 IC 2448 β β ε γ Chamaeleon Volans δ ε ε PK 315-13.1 Triangulum Australe β γ 12h δ2 α ε 3195 ζ PK 325-12.1 1 α ζ 6101 5h η θ δ α Apus 09h 2 IC 4499 γ δ1 β γ ζ 6362 η 2 2210 η 2164 18h 06h Large Magellanic Cloud Tarantula Nebulaδ Mensa 2031 NGC 2014 NGC 1962 NGC 1955 ζ NGC 1874 NGC 1829 θ 1866 κ NGC 1770 1805 Collinder 411 NGC 1814 1978 1818 1783 03h 6744 21h β ε ε γ Octans Pavo ν -80° 00h ν 1559 β α δ θ Hydrus Reticulum β γ ι δ 1313 β Small Magellanic Cloud 0° 52° x 34° -7 ε ζ κ 00h00m00.0s -90°00'00" (Skymark) Globular Cl. Dark Neb. Galaxy 8 7 6 5 4 3 2 1 Globule Planetary Open Cl. Nebula 38 Octans - Chamaleon GALASSIE Sigla Nome Cost. A.R. Dec. Mv. Dim. Tipo Distanza 200/4 80/11,5 20x60 NGC 292 Small Magellanic Cloud Tuc 00h 52m 38s +72° 48' 01” +2,80 318',0x204',0 SBm 0,2 Mly --- --- --- NGC 1313 Ret 03h 18m 15s -66° 29' 51” +9,70 9',5x7',2 Sbcd 13,5 Mly --- --- --- NGC 1559 Ret 04h 17m 36s -62° 47' 01" +11,00 4',2x2',1 SBc 34,0 Mly --- --- --- PGC 17223 Large Magellanic Cloud Dor 05h 23m 35s -69° 45' 22" +0,80 648',0x552',0 SBm 0,2 Mly --- --- --- NGC 6744 Pav 19h 09m 46s -63° 51' 28" +9,10 17',0x10',7 SABb 21,0 Mly --- --- --- AMMASSI APERTI Sigla Nome Cost. -
The Stellar Group NGC 1901 in Front of the Large Magellanic Cloud ,
A&A 466, 931–941 (2007) Astronomy DOI: 10.1051/0004-6361:20066687 & c ESO 2007 Astrophysics Observational templates of star cluster disruption The stellar group NGC 1901 in front of the Large Magellanic Cloud, G. Carraro1,2, R. de la Fuente Marcos3, S. Villanova1, C. Moni Bidin2, C. de la Fuente Marcos3,H.Baumgardt4, and G. Solivella5 1 Dipartimento di Astronomia, Università di Padova, Vicolo Osservatorio 2, 35122 Padova, Italy e-mail: [email protected] 2 Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chile 3 Suffolk University Madrid Campus, C/ Viña 3, 28003 Madrid, Spain 4 AIfA, University of Bonn, Auf dem Hügel 71, 53121 Bonn, Germany 5 Facultad de Ciencias Astronómicas y Geofísicas de la UNLP, IALP-CONICET, Paseo del Bosque s/n, La Plata, Argentina Received 3 November 2006 / Accepted 23 January 2007 ABSTRACT Context. Observations indicate that present-day star formation in the Milky Way disk takes place in stellar ensembles or clusters rather than in isolation. Bound, long-lived stellar groups are known as open clusters. They gradually lose stars and are severely disrupted in their final evolutionary stages, leaving an open cluster remnant made up of a few stars. Aims. In this paper, we study in detail the stellar content and kinematics of the poorly populated star cluster NGC 1901. This object appears projected against the Large Magellanic Cloud. The aim of the present work is to derive the current evolutionary status, binary fraction, age, and mass of this stellar group. These are fundamental quantities to compare with those from N-body models in order to study the most general topic of star cluster evolution and dissolution. -
On the Effects of Subvirial Initial Conditions and the Birth
Mon. Not. R. Astron. Soc. 000, 000–000 (0000) Printed 24 October 2018 (MN LATEX style file v2.2) On the Effects of Subvirial Initial Conditions and the Birth Temperature of R136 Daniel P. Caputo1⋆, Nathan de Vries1 and Simon Portegies Zwart1 1Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, the Netherlands 24 October 2018 ABSTRACT We investigate the effect of different initial virial temperatures, Q, on the dynamics of star clusters. We find that the virial temperature has a strong effect on many aspects of the resulting system, including among others: the fraction of bodies escaping from the system, the depth of the collapse of the system, and the strength of the mass segregation. These differences deem the practice of using “cold” initial conditions no longer a simple choice of convenience. The choice of initial virial temperature must be carefully considered as its impact on the remainder of the simulation can be profound. We discuss the pitfalls and aim to describe the general behavior of the collapse and the resultant system as a function of the virial temperature so that a well reasoned choice of initial virial temperature can be made. We make a correction to the previous theoretical estimate for the minimum radius, Rmin, of the cluster at the deepest (−1/3) moment of collapse to include a Q dependency, Rmin ≈ Q+N , where N is the number of particles. We use our numericalresults to infer more aboutthe initial conditions of the young cluster R136. Based on our analysis, we find that R136 was likely formed with a rather cool, but not cold, initial virial temperature (Q ≈ 0.13). -
The Extragalactic Distance Scale
The Extragalactic Distance Scale Published in "Stellar astrophysics for the local group" : VIII Canary Islands Winter School of Astrophysics. Edited by A. Aparicio, A. Herrero, and F. Sanchez. Cambridge ; New York : Cambridge University Press, 1998 Calibration of the Extragalactic Distance Scale By BARRY F. MADORE1, WENDY L. FREEDMAN2 1NASA/IPAC Extragalactic Database, Infrared Processing & Analysis Center, California Institute of Technology, Jet Propulsion Laboratory, Pasadena, CA 91125, USA 2Observatories, Carnegie Institution of Washington, 813 Santa Barbara St., Pasadena CA 91101, USA The calibration and use of Cepheids as primary distance indicators is reviewed in the context of the extragalactic distance scale. Comparison is made with the independently calibrated Population II distance scale and found to be consistent at the 10% level. The combined use of ground-based facilities and the Hubble Space Telescope now allow for the application of the Cepheid Period-Luminosity relation out to distances in excess of 20 Mpc. Calibration of secondary distance indicators and the direct determination of distances to galaxies in the field as well as in the Virgo and Fornax clusters allows for multiple paths to the determination of the absolute rate of the expansion of the Universe parameterized by the Hubble constant. At this point in the reduction and analysis of Key Project galaxies H0 = 72km/ sec/Mpc ± 2 (random) ± 12 [systematic]. Table of Contents INTRODUCTION TO THE LECTURES CEPHEIDS BRIEF SUMMARY OF THE OBSERVED PROPERTIES OF CEPHEID -
A Basic Requirement for Studying the Heavens Is Determining Where In
Abasic requirement for studying the heavens is determining where in the sky things are. To specify sky positions, astronomers have developed several coordinate systems. Each uses a coordinate grid projected on to the celestial sphere, in analogy to the geographic coordinate system used on the surface of the Earth. The coordinate systems differ only in their choice of the fundamental plane, which divides the sky into two equal hemispheres along a great circle (the fundamental plane of the geographic system is the Earth's equator) . Each coordinate system is named for its choice of fundamental plane. The equatorial coordinate system is probably the most widely used celestial coordinate system. It is also the one most closely related to the geographic coordinate system, because they use the same fun damental plane and the same poles. The projection of the Earth's equator onto the celestial sphere is called the celestial equator. Similarly, projecting the geographic poles on to the celest ial sphere defines the north and south celestial poles. However, there is an important difference between the equatorial and geographic coordinate systems: the geographic system is fixed to the Earth; it rotates as the Earth does . The equatorial system is fixed to the stars, so it appears to rotate across the sky with the stars, but of course it's really the Earth rotating under the fixed sky. The latitudinal (latitude-like) angle of the equatorial system is called declination (Dec for short) . It measures the angle of an object above or below the celestial equator. The longitud inal angle is called the right ascension (RA for short). -
Annual Report 1972
I I ANNUAL REPORT 1972 EUROPEAN SOUTHERN OBSERVATORY ANNUAL REPORT 1972 presented to the Council by the Director-General, Prof. Dr. A. Blaauw, in accordance with article VI, 1 (a) of the ESO Convention Organisation Europeenne pour des Recherches Astronomiques dans 1'Hkmisphtre Austral EUROPEAN SOUTHERN OBSERVATORY Frontispiece: The European Southern Observatory on La Silla mountain. In the foreground the "old camp" of small wooden cabins dating from the first period of settlement on La Silln and now gradually being replaced by more comfortable lodgings. The large dome in the centre contains the Schmidt Telescope. In the background, from left to right, the domes of the Double Astrograph, the Photo- metric (I m) Telescope, the Spectroscopic (1.>2 m) Telescope, and the 50 cm ESO and Copen- hagen Telescopes. In the far rear at right a glimpse of the Hostel and of some of the dormitories. Between the Schmidt Telescope Building and the Double Astrograph the provisional mechanical workshop building. (Viewed from the south east, from a hill between thc existing telescope park and the site for the 3.6 m Telescope.) TABLE OF CONTENTS INTRODUCTION General Developments and Special Events ........................... 5 RESEARCH ACTIVITIES Visiting Astronomers ........................................ 9 Statistics of Telescope Use .................................... 9 Research by Visiting Astronomers .............................. 14 Research by ESO Staff ...................................... 31 Joint Research with Universidad de Chile ...................... -
Name Glxy Plan Glxy Mltg Glob Glob Open Glob Glxy Glxy Glxy Open
Name 評価 コメント DSO Type Mag. Size Type/ Type/Mag V(HB) RA/Dec (5～1) CenterStar/Mag 5が最高、 V(tip)/#Star 1が最低 NGC 7814 UGC 8 CGCG 456-24 MCG +3-1-20 PGC 218 Glxy 11.6b 6.3x 2.2' 135 SA(s)ab: sp RC3 00 03 15.1 +16 08 45 NGC 40 PK 120+9.1 PNG 120.0+9.8 Plan 10.7p 70.0x60.0" 11.5 3b+3 STE 00 13 00.9 +72 31 19 NGC 55 ESO 293-50 MCG -7-1-13 PGC 1014 Glxy 8.4b 32.3x 5.6' 108 SB(s)m: sp RC3 00 15 08.1 -39 12 53 NGC 70 IC 1539 UGC 174 CGCG 499-108 Arp 113 MCG +5-1-67 PGC 1194 MltG 14.2p 1.9x 1.2' 5 SA(rs)c RC3 00 18 22.6 +30 04 46 NGC 104 Glob 4 50.0' 11.7 14.1 BAA 00 24 05.2 -72 04 51 NGC 121 Glob 1.5' BAA 00 26 41.3 -71 31 24 NGC 136 Cr 4 Open 1.2' 20 13 II 1 p LYN 00 31 31.0 +61 30 36 G 1 Glob 13.7 0.5x 0.5' MAC 00 32 46.3 +39 34 41 NGC 147 UGC 326 CGCG 550-6 MCG +8-2-5 DDO 3 PGC 2004 Glxy 10.5b 13.2x 7.7' 28 E5 pec RC3 00 33 11.6 +48 30 28 NGC 185 UGC 396 CGCG 550-9 MCG +8-2-10 IRAS 362+4803 PGC 2329 Glxy 10.1b 11.9x10.1' 35 E3 pec RC3 00 38 57.7 +48 20 14 M 110 NGC 205 UGC 426 CGCG 535-14 MCG +7-2-14 IRAS PGC 2429 Glxy 8.9b 21.9x10.9' 170 E5 pec RC3 00 40 22.9 +41 41 22 NGC 231 Open 12 1.2x 1.2' 131 15 NGC 00 41 06.5 -73 21 02 M 32 NGC 221 UGC 452 CGCG 535-16 Arp 168 MCG +7-2-15 Arak 12 Glxy 9.0b 8.7x 6.4' 170 cE2 RC3 00 42 41.8 +40 51 56 M 31 NGC 224 UGC 454 CGCG 535-17 MCG +7-2-16 PGC 2557 Glxy 4.4b 192x62' 35 SA(s)b RC3 00 42 44.4 +41 16 NGC 246 PK 118- PNG 118.8- Plan 8.0p 4.1' 11.9 3b STE 00 47 03.6 -11 52 20 NGC 247 UGCA 11 ESO 540-22 MCG -4-3-5 IRAS 446- PGC 2758 Glxy 9.1v 21.4x 6.0' SAB(s)d RC3 00 47 08.7 -20 45 38 NGC 265 Kron 24 Lind -
The Role of Evolutionary Age and Metallicity in the Formation of Classical Be Circumstellar Disks 11
< * - - *" , , Source of Acquisition NASA Goddard Space Flight Center THE ROLE OF EVOLUTIONARY AGE AND METALLICITY IN THE FORMATION OF CLASSICAL BE CIRCUMSTELLAR DISKS 11. ASSESSING THE TRUE NATURE OF CANDIDATE DISK SYSTEMS J.P. WISNIEWSKI"~'~,K.S. BJORKMAN~'~,A.M. MAGALH~ES~",J.E. BJORKMAN~,M.R. MEADE~, & ANTONIOPEREYRA' Draft version November 27, 2006 ABSTRACT Photometric 2-color diagram (2-CD) surveys of young cluster populations have been used to identify populations of B-type stars exhibiting excess Ha emission. The prevalence of these excess emitters, assumed to be "Be stars". has led to the establishment of links between the onset of disk formation in classical Be stars and cluster age and/or metallicity. We have obtained imaging polarization observations of six SMC and six LMC clusters whose candidate Be populations had been previously identified via 2-CDs. The interstellar polarization (ISP). associated with these data has been identified to facilitate an examination of the circumstellar environments of these candidate Be stars via their intrinsic ~olarization signatures, hence determine the true nature of these objects. We determined that the ISP associated with the SMC cluster NGC 330 was characterized by a modified Serkowski law with a A,,, of -4500A, indicating the presence of smaller than average dust grains. The morphology of the ISP associated with the LMC cluster NGC 2100 suggests that its interstellar environment is characterized by a complex magnetic field. Our intrinsic polarization results confirm the suggestion of Wisniewski et al. that a substantial number of bona-fide classical Be stars are present in clusters of age 5-8 Myr. -
Download the 2016 Spring Deep-Sky Challenge
Deep-sky Challenge 2016 Spring Southern Star Party Explore the Local Group Bonnievale, South Africa Hello! And thanks for taking up the challenge at this SSP! The theme for this Challenge is Galaxies of the Local Group. I’ve written up some notes about galaxies & galaxy clusters (pp 3 & 4 of this document). Johan Brink Peter Harvey Late-October is prime time for galaxy viewing, and you’ll be exploring the James Smith best the sky has to offer. All the objects are visible in binoculars, just make sure you’re properly dark adapted to get the best view. Galaxy viewing starts right after sunset, when the centre of our own Milky Way is visible low in the west. The edge of our spiral disk is draped along the horizon, from Carina in the south to Cygnus in the north. As the night progresses the action turns north- and east-ward as Orion rises, drawing the Milky Way up with it. Before daybreak, the Milky Way spans from Perseus and Auriga in the north to Crux in the South. Meanwhile, the Large and Small Magellanic Clouds are in pole position for observing. The SMC is perfectly placed at the start of the evening (it culminates at 21:00 on November 30), while the LMC rises throughout the course of the night. Many hundreds of deep-sky objects are on display in the two Clouds, so come prepared! Soon after nightfall, the rich galactic fields of Sculptor and Grus are in view. Gems like Caroline’s Galaxy (NGC 253), the Black-Bottomed Galaxy (NGC 247), the Sculptor Pinwheel (NGC 300), and the String of Pearls (NGC 55) are keen to be viewed. -
Lopsided Spiral Galaxies: Evidence for Gas Accretion
A&A 438, 507–520 (2005) Astronomy DOI: 10.1051/0004-6361:20052631 & c ESO 2005 Astrophysics Lopsided spiral galaxies: evidence for gas accretion F. Bournaud1, F. Combes1,C.J.Jog2, and I. Puerari3 1 Observatoire de Paris, LERMA, 61 Av. de l’Observatoire, 75014 Paris, France e-mail: [email protected] 2 Department of Physics, Indian Institute of Science, Bangalore 560012, India 3 Instituto Nacional de Astrofísica, Optica y Electrónica, Calle Luis Enrique Erro 1, 72840 Tonantzintla, Puebla, Mexico Received 3 January 2005 / Accepted 15 March 2005 Abstract. We quantify the degree of lopsidedness for a sample of 149 galaxies observed in the near-infrared from the OSUBGS sample, and try to explain the physical origin of the observed disk lopsidedness. We confirm previous studies, but for a larger sample, that a large fraction of galaxies have significant lopsidedness in their stellar disks, measured as the Fourier amplitude of the m = 1 component normalised to the average or m = 0 component in the surface density. Late-type galaxies are found to be more lopsided, while the presence of m = 2 spiral arms and bars is correlated with disk lopsidedness. We also show that the m = 1 amplitude is uncorrelated with the presence of companions. Numerical simulations were carried out to study the generation of m = 1viadifferent processes: galaxy tidal encounters, galaxy mergers, and external gas accretion with subsequent star formation. These simulations show that galaxy interactions and mergers can trigger strong lopsidedness, but do not explain several independent statistical properties of observed galaxies. To explain all the observational results, it is required that a large fraction of lopsidedness results from cosmological accretion of gas on galactic disks, which can create strongly lopsided disks when this accretion is asymmetrical enough.