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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). -
TSP 2004 Telescope Observing Program
THE TEXAS STAR PARTY 2004 TELESCOPE OBSERVING CLUB BY JOHN WAGONER TEXAS ASTRONOMICAL SOCIETY OF DALLAS RULES AND REGULATIONS Welcome to the Texas Star Party's Telescope Observing Club. The purpose of this club is not to test your observing skills by throwing the toughest objects at you that are hard to see under any conditions, but to give you an opportunity to observe 25 showcase objects under the ideal conditions of these pristine West Texas skies, thus displaying them to their best advantage. This year we have planned a program called “Starlight, Starbright”. The rules are simple. Just observe the 25 objects listed. That's it. Any size telescope can be used. All observations must be made at the Texas Star Party to qualify. All objects are within range of small (6”) to medium sized (10”) telescopes, and are available for observation between 10:00PM and 3:00AM any time during the TSP. Each person completing this list will receive an official Texas Star Party Telescope Observing Club lapel pin. These pins are not sold at the TSP and can only be acquired by completing the program, so wear them proudly. To receive your pin, turn in your observations to John Wagoner - TSP Observing Chairman any time during the Texas Star Party. I will be at the outside door leading into the TSP Meeting Hall each day between 1:00 PM and 2:30 PM. If you finish the list the last night of TSP, or I am not available to give you your pin, just mail your observations to me at 1409 Sequoia Dr., Plano, Tx. -
Annual Report 2009-2010
ICRAR AnnuAl RepoRt 2009-2010 Annual Report 2009/10 Document ICRAR-DOC-0016 ICRAR Annual Report 2009/10 11 August 2010 FRONT COVER: Top Left: A group photo of some members of the ICRAR Board, ICRAR Executive and Professor Richard Schilizzi (Director SKA Program Development Office) at the launch of ICRAR, 1 September 2009 – photo Jurgen Lunsmann Top Right: The Murchison Wide-field Array 32 tile system on the Murchison Radio- astronomy Observatory June 2010 – photo Paul Bourke and Jonathan Knispel, WASP Middle Left: Three-dimensional supercomputer model of supernovae 1987a – image Toby Potter, ICRAR Middle: Year 10 students attending the “Out There” SKA event in March 2009 - photo Paul Ricketts, Centre for Learning Technology UWA Middle Right: Supercomputer simulation of hydrogen gas in the early Universe – image Dr Alan Duffy, ICRAR Bottom Left: Radio emission from the inner core of the galaxy Centaurus A as seen by the first disk of the ASKAP telescope coupled to a dish in New Zealand 5500 km away – image Prof Steven Tingay (ICRAR) / ICRAR, CSIRO and AUT Bottom Right: Stars and gas in the colliding galaxy NGC 922 – image Prof Gerhardt Meurer (ICRAR) and Dr Kenji Bekki (ICRAR) 2 ICRAR Annual Report 2009/10 11 August 2010 Table of Contents 1.0 Executive Summary ..............................................................................................5! 1.1 Major Developments and Highlights of 2009/10 ................................................5! 1.2 National and International Collaborations..........................................................6! -
NGC 3125−1: the Most Extreme Wolf-Rayet Star Cluster Known in the Local Universe1
NGC 3125−1: The Most Extreme Wolf-Rayet Star Cluster Known in the Local Universe1 Rupali Chandar and Claus Leitherer Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, Maryland 21218 [email protected] & [email protected] and Christy A. Tremonti Steward Observatory, 933 N. Cherry Ave., Tucson, AZ, 85721 [email protected] ABSTRACT We use Space Telescope Imaging Spectrograph long-slit ultraviolet spec- troscopy of local starburst galaxies to study the massive star content of a represen- tative sample of \super star" clusters, with a primary focus on their Wolf-Rayet (WR) content as measured from the He II λ1640 emission feature. The goals of this work are three-fold. First, we quantify the WR and O star content for selected massive young star clusters. These results are compared with similar estimates made from optical spectroscopy and available in the literature. We conclude that the He II λ4686 equivalent width is a poor diagnostic measure of the true WR content. Second, we present the strongest known He II λ1640 emis- sion feature in a local starburst galaxy. This feature is clearly of stellar origin in the massive cluster NGC 3125-1, as it is broadened (∼ 1000 km s−1). Strong N IV] λ1488 and N V λ1720 emission lines commonly found in the spectra of individual Wolf-Rayet stars of WN subtype are also observed in the spectrum of NGC 3125-1. Finally, we create empirical spectral templates to gain a basic understanding of the recently observed strong He II λ1640 feature seen in Lyman Break Galaxies (LBG) at redshifts z ∼ 3. -
The Large Scale Distribution of Radio Continuum in Ε and So Galaxies
THE LARGE SCALE DISTRIBUTION OF RADIO CONTINUUM IN Ε AND SO GALAXIES R.D. Ekers, Kapteyn Astronomical Institute, University of Groningen If we look at the radio properties of the nearby ellipticals we find a situation considerably different from that just described by van der Kruit for the spiral galaxies. For example NGC 5128 (Cen A), the nearest giant elliptical galaxy, is a thousand times more powerful a radio source than the brightest spiral galaxies and furthermore its radio emission comes from a multiple lobed radio structure which bears no resemblance to the optical light distribution (e.g. Ekers, 1975). The other radio emitting elliptical galaxies in our neighbourhood, NGC 1316 (Fornax A), IC 4296 (1333-33), have similar morphology. A question which then arises is whether at lower levels we can detect radio emission coming from the optical image of the elliptical galaxies and which may be more closely related to the kind of emission seen in the spiral galaxies. Since elliptical galaxies are less numerous than spiral galaxies we have to search out to the Virgo cluster to obtain a good sample. Some results from a Westerbork map of the central region of the Virgo cluster at 1.4 GHz (Kotanyi and Ekers, in preparation) is given in the Table. Radio Emission from Galaxies in the core of the Virgo Cluster Name Hubble m Flux density NGC Type Ρ (JO"29 W m-2 Hz-1) 4374 El 10.8 6200 3C 272.1 4388 Sc 12.2 140 4402 Sd 13.6 60 4406 E3 10.9 < 4 4425 SO 13.3 < 4 4435 SO 1 1.9 < 5 4438 S pec 12.0 150 This result is typical for spiral and elliptical galaxies and illustrates the different properties quite well. -
X-Ray Luminosities for a Magnitude-Limited Sample of Early-Type Galaxies from the ROSAT All-Sky Survey
Mon. Not. R. Astron. Soc. 302, 209±221 (1999) X-ray luminosities for a magnitude-limited sample of early-type galaxies from the ROSAT All-Sky Survey J. Beuing,1* S. DoÈbereiner,2 H. BoÈhringer2 and R. Bender1 1UniversitaÈts-Sternwarte MuÈnchen, Scheinerstrasse 1, D-81679 MuÈnchen, Germany 2Max-Planck-Institut fuÈr Extraterrestrische Physik, D-85740 Garching bei MuÈnchen, Germany Accepted 1998 August 3. Received 1998 June 1; in original form 1997 December 30 Downloaded from https://academic.oup.com/mnras/article/302/2/209/968033 by guest on 30 September 2021 ABSTRACT For a magnitude-limited optical sample (BT # 13:5 mag) of early-type galaxies, we have derived X-ray luminosities from the ROSATAll-Sky Survey. The results are 101 detections and 192 useful upper limits in the range from 1036 to 1044 erg s1. For most of the galaxies no X-ray data have been available until now. On the basis of this sample with its full sky coverage, we ®nd no galaxy with an unusually low ¯ux from discrete emitters. Below log LB < 9:2L( the X-ray emission is compatible with being entirely due to discrete sources. Above log LB < 11:2L( no galaxy with only discrete emission is found. We further con®rm earlier ®ndings that Lx is strongly correlated with LB. Over the entire data range the slope is found to be 2:23 60:12. We also ®nd a luminosity dependence of this correlation. Below 1 log Lx 40:5 erg s it is consistent with a slope of 1, as expected from discrete emission. -
Astronomical Coordinate Systems
Appendix 1 Astronomical Coordinate Systems A basic requirement for studying the heavens is being able to determine where in the sky things are located. To specify sky positions, astronomers have developed several coordinate systems. Each sys- tem uses a coordinate grid projected on the celestial sphere, which is similar to the geographic coor- dinate 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 The equatorial coordinate system is probably the most widely used celestial coordinate system. It is also the most closely related to the geographic coordinate system because they use the same funda- mental plane and poles. The projection of the Earth’s equator onto the celestial sphere is called the celestial equator. Similarly, projecting the geographic poles onto the celestial sphere defines the north and south celestial poles. However, there is an important difference between the equatorial and geographic coordinate sys- tems: the geographic system is fixed to the Earth and 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 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 Mass of the Centaurus a Group of Galaxies
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by CERN Document Server The Mass of the Centaurus A Group of Galaxies Sidney van den Bergh Dominion Astrophysical Observatory National Research Council 5071 West Saanich Road Victoria, British Columbia, V8X 4M6 Canada [email protected] ABSTRACT The mass M, and the radius Rh, of the Centaurus A group are estimated from the positions and radial velocities of 30 probable cluster members. For an assumed distance of 3.9 Mpc it is found that Rh 640 kpc. The velocity 1 ∼ dispersion in the Cen A group is 114 21 km s− . From this value, and ± R = 640 kpc, the virial theorem yields a total mass of 1:4 1013 M for the h × Cen A group. The projected mass method gives a mass of 1:8 1013 M .These × values suggest that the Cen A group is about seven times as massive as the Local Group. The Cen A mass-to-light ratio is found to be M/L = 155 200 B − in solar units. The cluster has a zero-velocity radius R0 =2:3Mpc. Subject headings: Galaxies: clusters: individual (Centaurus A) 1. Introduction The loose clustering of galaxies surrounding Centaurus A was called the NGC 5128 Group by de Vaucouleurs (1975), who designated it G4 because it was the fourth closest group of galaxies in his compilation. This group is primarily of interest because its brightest member is the galaxy NGC 5128, which contains the radio source Centaurus A. This object is also [with the exception of Maffei 1 (van den Bergh 1971, Huchtmeier, Karachentsev & Karachentsev 1999)] the nearest early-type giant galaxy. -
Making a Sky Atlas
Appendix A Making a Sky Atlas Although a number of very advanced sky atlases are now available in print, none is likely to be ideal for any given task. Published atlases will probably have too few or too many guide stars, too few or too many deep-sky objects plotted in them, wrong- size charts, etc. I found that with MegaStar I could design and make, specifically for my survey, a “just right” personalized atlas. My atlas consists of 108 charts, each about twenty square degrees in size, with guide stars down to magnitude 8.9. I used only the northernmost 78 charts, since I observed the sky only down to –35°. On the charts I plotted only the objects I wanted to observe. In addition I made enlargements of small, overcrowded areas (“quad charts”) as well as separate large-scale charts for the Virgo Galaxy Cluster, the latter with guide stars down to magnitude 11.4. I put the charts in plastic sheet protectors in a three-ring binder, taking them out and plac- ing them on my telescope mount’s clipboard as needed. To find an object I would use the 35 mm finder (except in the Virgo Cluster, where I used the 60 mm as the finder) to point the ensemble of telescopes at the indicated spot among the guide stars. If the object was not seen in the 35 mm, as it usually was not, I would then look in the larger telescopes. If the object was not immediately visible even in the primary telescope – a not uncommon occur- rence due to inexact initial pointing – I would then scan around for it. -
Ngc Catalogue Ngc Catalogue
NGC CATALOGUE NGC CATALOGUE 1 NGC CATALOGUE Object # Common Name Type Constellation Magnitude RA Dec NGC 1 - Galaxy Pegasus 12.9 00:07:16 27:42:32 NGC 2 - Galaxy Pegasus 14.2 00:07:17 27:40:43 NGC 3 - Galaxy Pisces 13.3 00:07:17 08:18:05 NGC 4 - Galaxy Pisces 15.8 00:07:24 08:22:26 NGC 5 - Galaxy Andromeda 13.3 00:07:49 35:21:46 NGC 6 NGC 20 Galaxy Andromeda 13.1 00:09:33 33:18:32 NGC 7 - Galaxy Sculptor 13.9 00:08:21 -29:54:59 NGC 8 - Double Star Pegasus - 00:08:45 23:50:19 NGC 9 - Galaxy Pegasus 13.5 00:08:54 23:49:04 NGC 10 - Galaxy Sculptor 12.5 00:08:34 -33:51:28 NGC 11 - Galaxy Andromeda 13.7 00:08:42 37:26:53 NGC 12 - Galaxy Pisces 13.1 00:08:45 04:36:44 NGC 13 - Galaxy Andromeda 13.2 00:08:48 33:25:59 NGC 14 - Galaxy Pegasus 12.1 00:08:46 15:48:57 NGC 15 - Galaxy Pegasus 13.8 00:09:02 21:37:30 NGC 16 - Galaxy Pegasus 12.0 00:09:04 27:43:48 NGC 17 NGC 34 Galaxy Cetus 14.4 00:11:07 -12:06:28 NGC 18 - Double Star Pegasus - 00:09:23 27:43:56 NGC 19 - Galaxy Andromeda 13.3 00:10:41 32:58:58 NGC 20 See NGC 6 Galaxy Andromeda 13.1 00:09:33 33:18:32 NGC 21 NGC 29 Galaxy Andromeda 12.7 00:10:47 33:21:07 NGC 22 - Galaxy Pegasus 13.6 00:09:48 27:49:58 NGC 23 - Galaxy Pegasus 12.0 00:09:53 25:55:26 NGC 24 - Galaxy Sculptor 11.6 00:09:56 -24:57:52 NGC 25 - Galaxy Phoenix 13.0 00:09:59 -57:01:13 NGC 26 - Galaxy Pegasus 12.9 00:10:26 25:49:56 NGC 27 - Galaxy Andromeda 13.5 00:10:33 28:59:49 NGC 28 - Galaxy Phoenix 13.8 00:10:25 -56:59:20 NGC 29 See NGC 21 Galaxy Andromeda 12.7 00:10:47 33:21:07 NGC 30 - Double Star Pegasus - 00:10:51 21:58:39 -
Multiwavelength Observations of the Peculiar Planetary Nebula Ic 2149 R
The Astrophysical Journal, 576:860–869, 2002 September 10 # 2002. The American Astronomical Society. All rights reserved. Printed in U.S.A. MULTIWAVELENGTH OBSERVATIONS OF THE PECULIAR PLANETARY NEBULA IC 2149 R. Va´zquez,1 L. F. Miranda,2 J. M. Torrelles,3 L. Olguı´n,4 G. Benı´tez,1,5 L. F. Rodrı´guez,6 and J. A. Lo´pez1 Received 2001 August 18; accepted 2002 May 15 ABSTRACT We report high- and low-dispersion spectroscopy, optical imaging, and high-resolution Very Large Array- A 3.6 cm continuum observations of the peculiar planetary nebula IC 2149. These observations show that ‘‘ bipolar ’’ is a suitable morphological classification for IC 2149. Most nebular material is concentrated in a knotty, bright ring seen edge-on, embedded in an apparently oblate ellipsoidal shell from which remnant or incipient bipolar lobes emerge. We confirm the previously reported depletion in heavy elements and deduce a very low ejected nebular mass d0.03 M . All this information indicates that the formation of IC 2149 is the result of the evolution of a low-mass central star. Subject headings: ISM: kinematics and dynamics — planetary nebulae: individual (IC 2149) — stars: AGB and post-AGB 1. INTRODUCTION ula. IC 2149 hosts a very bright central star (V ’ 11:34, Ciardullo et al. 1999) with a stellar wind indicated by the In the last 10 yr, the commonly accepted theory on forma- presence of P Cygni profiles in the UV spectrum that indi- tion of planetary nebulae (PNs), involving the interaction of cate a wind velocity of V 1000–1600 km sÀ1 and a mass- stellar winds (Kwok, Purton, & Fitzgerald 1978), has been w ’ loss rate of M_ 10À8 M yrÀ1 (Perinotto, Benvenuti, & constantly revised in order to take into account a variety of w ’ Cerruti-Sola 1982; Feibelman et al. -
A MODEST Review
Varri et al. MEETING REPORT A MODEST review Anna Lisa Varri1*, Maxwell Xu Cai2, Francisca Concha-Ram´ırez2, Frantiˇsek Dinnbier3, Nora L¨utzgendorf4, V´aclav Pavl´ık5,6, Sara Rastello7, Antonio Sollima8, Long Wang9 and Alice Zocchi10,11 *Correspondence: [email protected] 1Institute for Astronomy, Abstract University of Edinburgh, Royal Observatory, Blackford Hill, EH9 We present an account of the state of the art in the fields explored by the 3HJ Edinburgh, United Kingdom research community invested in “Modeling and Observing DEnse STellar Full list of author information is systems” . For this purpose, we take as a basis the activities of the MODEST-17 available at the end of the article conference, which was held at Charles University, Prague, in September 2017. Reviewed topics include recent advances in fundamental stellar dynamics, numerical methods for the solution of the gravitational N-body problem, formation and evolution of young and old star clusters and galactic nuclei, their elusive stellar populations, planetary systems, and exotic compact objects, with timely attention to black holes of different classes of mass and their role as sources of gravitational waves. Such a breadth of topics reflects the growing role played by collisional stellar dynamics in numerous areas of modern astrophysics. Indeed, in the next decade many revolutionary instruments will enable the derivation of positions and velocities of individual stars in the Milky Way and its satellites, and will detect signals from a range of astrophysical sources in different portions of the electromagnetic and gravitational spectrum, with an unprecedented sensitivity. On the one hand, this wealth of data will allow us to address a number of long-standing open questions in star cluster studies; on the other hand, many unexpected properties of these systems will come to light, stimulating further progress of our understanding of their formation and evolution.