DOCSLIB.ORG

GALEX and Star Formation

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
GALEX and Star Formation GALEX and Star Formation Luciana Bianchi Abstract Wide-field far-UV (FUV, 1344-1786A)˚ and 1 Introduction near-UV (NUV, 1771-2831A)˚ imaging from GALEX provides a deep, comprehensive view of the young stel- The GalaxyEvolutionExplorer(GALEX) has imaged lar populations in hundreds of nearby galaxies, shed- in far-UV and near-UV a wide portion of the sky. Cat- ding new light on the process of star formation (SF) in alogs of hundreds of millions UV sources enable ad- different environments, and on the interplay between vances in a variety of fields, from hot stellar objects in dust and SF. GALEX’s FUV-NUV color is extremely the Milky Way to QSOs (Bianchi et al. 2009) and star- sensitive to stellar populations of ages up to a few hun- forming galaxies, and provide a roadmap for future UV dred Myrs, unambiguously probing their presence and missions (see http://dolomiti.pha.jhu.edu/uvsky). enabling age-dating and stellar mass estimate, together A deep, comprehensive view of the young stellar pop- with the characterization of interstellar dust extinction. ulations in hundreds of nearby galaxies, afforded by The deep sensitivity, combined with the wide field-of- GALEX’s wide-field UV imaging, allows us to char- view, made possile in particular the discovery and char- acterize their spatially-resolved and time-resolved re- acterization of star formation in extremely low-density, cent star formation. In addition, star formation was diffuse gas environments such as outer galaxy disks, revealed in extreme low-density environments, where it tidal tails, low-surface-brightness galaxies (LSB) and is elusive at other wavelengths. UV measurements of dwarf Irregular galaxies, and of rejuvenation episodes in millions of more distant galaxies probe their evolution early-type galaxies. Such results provide several miss- and the Universe’s star-formation history (SFH) since ing links for interpreting galaxy classes in an evolution- redshift ∼2. ary context, extend our knowledge of the star-formation In this review, we first recall the basic characteristics process to previously unexplored conditions, constrain of GALEX data (Section 2.1) and of the UV-emitting models of galaxy disk formation, and clarify the mu- young stellar populations which trace SF sites (Section tual role of dust and star formation. We review a vari- 2.2), and we discuss dust extinction correction (Sec- ety of star-forming environments studied by GALEX, tion 2.3). We review a number of environments where and provide some model analysis tools useful for inter- pretation of GALEX measurements, and potentially SF was discovered from UV imaging and was previ- as basic science planning tools for next-generation UV ously elusive, or thought to not possibly happen (low instruments. gas density conditions) in Section 3. We mention a few starburst places (Section 4) without attempting to be Keywords Astronomical surveys — stars: star forma- complete, which would be impossible. We do not ad- tion — galaxies: evolution — galaxies: stellar popula- dress the abundant statistical studies of distant galaxy tions — ultraviolet: galaxies — interstellar dust: ex- samples, aiming at reconstructing the star-formation tinction history of the universe, because these are described else- where in this book. We provide, instead, a few sample Luciana Bianchi diagnostic plots that may be of general use for a first Johns Hopkins University, Dept. of Physics & Astronomy, Balti- interpretation of GALEX data, in particular for SF more, MD, USA studies in nearby galaxies (Section 2.4), as well as for planning new UV and multi-wavelength observations. 2 2 UV imaging of young stellar populations now included in the GALEX imaging surveys, i.e. over 80% of the total number listed in Hyperleda 2.1 GALEX data database within such velocity limit and no culling cri- teria (Thilker, priv. comm.). GALEX performs wide-field (1.2◦ diameter) imaging in two Ultraviolet (UV) bands simoultaneously: FUV 2.2 The UV-emitting young populations (λeff =1539A,˚ ∆λ = 1344 - 1786A)˚ and NUV (λeff = 2316A,˚ ∆λ = 1771 - 2831A),˚ with a spatial resolu- Why is UV data sensitive to star formation? Young ′′ tion of 4.2/5.3 (FUV/NUV) (Morrissey et al. 2007), massive stars, hot, luminous, and short-lived, are the ′′ ′′ sampled with 1.5 ×1.5 pixels. Its sensitivity reaches unambiguous tracers of star formation. They are lu- ′′ ∼27.5mag/ with ≈1,500sec exposures. GALEX has minous enough that they can be seen in distant galax- also a spectroscopic observing mode, which will not be ies. They evolve on fast timescales (.10 Myrs for O- addressed here. type stars), therefore they also trace the original spatial The photometric system used in the GALEX archive structure of the star-formation episode, before the large 1 is based on the AB magnitude scale (see Morrissey et complexes and stellar associations dissolve. They are al. 2007). For most science analyses it is useful to com- very hot, therefore the UV wavelength range is ideal bine GALEX data with corollary data at other wave- to detect and study them, because (i) UV colors are lengths, especially the optical range where the Vega more sensitive to the temperatures of the hottest stars, magnitude system is often used, therefore we give in enabling e.g. to discern O-types from late-O/early-B, Table 1 the transformation between the two systems in while optical colors are saturated in this regime (e.g. commonly used passbands, as computed by us from the Bianchi 2007), and (ii) UV colors provide precise age- filters’ transmission curves, and the Vega spectrum. dating of integrated stellar populations for ages less than 1Gyr. UV images give therefore an instant snap- Table 1 Vega - AB magnitude transformation shot of young star-forming sites, uncomplicated by pre- vious star-formation history, unlike longer wavelengths Filter magV ega − magAB [mag] GALEX FUV -2.223 where multiple stellar generations contribute signifi- GALEX NUV -1.699 cantly to the light (Fig.s 1 and 2). Finally, UV fluxes SDSS u -0.944 are more sensitive to dust, which plays a major role in SDSS g 0.116 star formation, as will be discussed in Section 2.3. SDSS r -0.131 Massive stars drive the chemical evolution of the SDSS i -0.354 Universe, enriching the interstellar medium (ISM) with SDSS z -0.524 nucleosynthesis products via supenova explosions and Landolt U -0.694 intense mass loss during AGB and planetary nebula Landolt B2/B3 0.125/ 0.123 phases, and driving the dynamical evolution of the ISM Landolt V 0.004 through highly supersonic stellar winds and mass loss ∼ −5 −1 Landolt R 0.180 up to 10 M⊙ yr in their main sequence lifetime. Landolt I -0.423 Therefore, understanding their formation and charac- 2MASSJ -0.901 terizing them in a wide variety of environmental phys- 2MASSH -1.384 ical conditions (galaxy type, metallicity, gas content, 2MASSKs -1.852 dynamics including interaction events) helps our un- derstanding of the overall evolution of the universe. GALEX performs nested surveys with differing sky 2.3 Characterizing dust extinction coverage and depth, see Bianchi (2009) for a summary, Bianchi et al (2010, 2011a), Conti et al. (2011), and 2.3.1 The mutual influence of dust and star formation (Hutchings & Bianchi 2010a) for a description of the source content of currently released catalogs and sample Dust is a minor component of the ISM, yet it has a ma- science applications. jor role in the formation of stars. In turn, hard UV ra- In total, with any level of exposure, over 46,000 1 diation from massive stars can modify the dust grains’ galaxies within 100Mpc (velocity ≤ 7000 km s− ) are size distribution or coating. Extinction properties in the far-UV give information about the distribution of 1 mUV (AB)=-2.5×log(CTRUV )+ZP, and zero-points small dust grains in particular. It is important to un- ZPF UV =18.82 and ZPNUV =20.08; the countrate CTR is derstand the role of dust in the star-formation and ISM the dead-time-corrected, flat-fielded count rate in counts s−1 3 Fig. 1 GALEX (left, FUV: blue and NUV: yellow) and optical (right, on the same scale) color-composite images of selected objects examplifying the power of UV imaging for revealing young stellar populations. In particular, examples of dwarfs and tidal dwarfs inconsipcuous in the optical are also shown, near bright galaxies. From the top: NGC 4656, M81, and M101. 4 Fig. 2 GALEX (left) and optical (right) color-composite images giving typical examples of: extended UV-disks (top, NGC5474), UV-emitting rings around early-type galaxies (middle, the SB0/a galaxy NGC5701) and halo UV emission (bottom: M 82, see Hoopes et al. 2005) 5 enrichment history of galaxies, and the relation of ex- with age and metallicity (Fig. 5), and (ii) that far-IR tinction to local and global galaxy properties such as fluxes and UV fluxes trace the same populations, which metallicity and starburst intensity. It is also neccessary is mostly not the case (Fig. 3, also e.g. Efremova et al. to characterize dust extinction in various conditions, in 2011, Bianchi 2007). As a more detailed discussion is order to interpret integrated properties of distant galax- not possible here, we only mentioned the main caveats ies such as those measured by the GALEX surveys, to of such methods. properly unredden observed fluxes and correctly mea- sure their energy budget and physical properties. Extinction is a combination of scattering and absorp- tion. Geometry, density, grain composition and UV ra- diation from hot stars are relevant parameters. Spectro- scopic studies in the UV range show that in our Galaxy, an average extinction law can reproduce observed ex- tinction curves (range 1250A˚ –3.5µ) in a variety of dust environments (e.g.
Load more

Recommended publications
  • In-Flight PSF Calibration of the Nustar Hard X-Ray Optics
    In-flight PSF calibration of the NuSTAR hard X-ray optics Hongjun Ana, Kristin K. Madsenb, Niels J. Westergaardc, Steven E. Boggsd, Finn E. Christensenc, William W. Craigd,e, Charles J. Haileyf, Fiona A. Harrisonb, Daniel K. Sterng, William W. Zhangh aDepartment of Physics, McGill University, Montreal, Quebec, H3A 2T8, Canada; bCahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125, USA; cDTU Space, National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby, Denmark; dSpace Sciences Laboratory, University of California, Berkeley, CA 94720, USA; eLawrence Livermore National Laboratory, Livermore, CA 94550, USA; fColumbia Astrophysics Laboratory, Columbia University, New York NY 10027, USA; gJet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA; hGoddard Space Flight Center, Greenbelt, MD 20771, USA ABSTRACT We present results of the point spread function (PSF) calibration of the hard X-ray optics of the Nuclear Spectroscopic Telescope Array (NuSTAR). Immediately post-launch, NuSTAR has observed bright point sources such as Cyg X-1, Vela X-1, and Her X-1 for the PSF calibration. We use the point source observations taken at several off-axis angles together with a ray-trace model to characterize the in-orbit angular response, and find that the ray-trace model alone does not fit the observed event distributions and applying empirical corrections to the ray-trace model improves the fit significantly. We describe the corrections applied to the ray-trace model and show that the uncertainties in the enclosed energy fraction (EEF) of the new PSF model is ∼<3% for extraction ′′ apertures of R ∼> 60 with no significant energy dependence.
    [Show full text]
  • Cosmic Origins Newsletter, September 2016, Vol. 5, No. 2
    National Aeronautics and Space Administration Cosmic Origins Newsletter September 2016 Volume 5 Number 2 Summer 2016 Cosmic Origins Program Inside this Issue Update Summer 2016 Cosmic Origins Program Update ............................1 Mansoor Ahmed, COR Program Manager Hubble Reveals Stellar Fireworks in ‘Skyrocket’ Galaxy ................2 Message from the Astrophysics Division Director .........................2 Susan Neff, COR Program Chief Scientist Light Echoes Give Clues to Protoplanetary Disk ............................3 Far-IR Surveyor Study Status .............................................................5 Welcome to the September 2016 Cosmic Origins (COR) newslet- LUVOIR Study Status .........................................................................5 ter. In this issue, we provide updates on several activities relevant to Strategic Astrophysics Technology (SAT) Selections the COR Program objectives. Some of these activities are not under for ROSES-2015 ...................................................................................6 the direct purview of the program, but are relevant to COR goals, Technology Solicitations to Enable Astrophysics Discoveries ......6 therefore we try to keep you informed about their progress. Cosmic Origins Suborbital Program: Balloon Program – BETTII ................................................................7 In January 2016, Paul Hertz (Director, NASA Astrophysics) News from SOFIA ...............................................................................8 presented his
    [Show full text]
  • Nustar Observatory Guide
    NuSTAR Guest Observer Program NuSTAR Observatory Guide Version 3.2 (June 2016) NuSTAR Science Operations Center, California Institute of Technology, Pasadena, CA NASA Goddard Spaceflight Center, Greenbelt, MD nustar.caltech.edu heasarc.gsfc.nasa.gov/docs/nustar/index.html i Revision History Revision Date Editor Comments D1,2,3 2014-08-01 NuSTAR SOC Initial draft 1.0 2014-08-15 NuSTAR GOF Release for AO-1 Addition of more information about CZT 2.0 2014-10-30 NuSTAR SOC detectors in section 3. 3.0 2015-09-24 NuSTAR SOC Update to section 4 for release of AO-2 Update for NuSTARDAS v1.6.0 release 3.1 2016-05-10 NuSTAR SOC (nusplitsc, Section 5) 3.2 2016-06-15 NuSTAR SOC Adjustment to section 9 ii Table of Contents Revision History ......................................................................................................................................................... ii 1. INTRODUCTION ................................................................................................................................................... 1 1.1 NuSTAR Program Organization ..................................................................................................................................................................................... 1 2. The NuSTAR observatory .................................................................................................................................... 2 2.1 NuSTAR Performance ........................................................................................................................................................................................................
    [Show full text]
  • Building the Coolest X-Ray Satellite
    National Aeronautics and Space Administration Building the Coolest X-ray Satellite 朱雀 Suzaku A Video Guide for Teachers Grades 9-12 Probing the Structure & Evolution of the Cosmos http://suzaku-epo.gsfc.nasa.gov/ www.nasa.gov The Suzaku Learning Center Presents “Building the Coolest X-ray Satellite” Video Guide for Teachers Written by Dr. James Lochner USRA & NASA/GSFC Greenbelt, MD Ms. Sara Mitchell Mr. Patrick Keeney SP Systems & NASA/GSFC Coudersport High School Greenbelt, MD Coudersport, PA This booklet is designed to be used with the “Building the Coolest X-ray Satellite” DVD, available from the Suzaku Learning Center. http://suzaku-epo.gsfc.nasa.gov/ Table of Contents I. Introduction 1. What is Astro-E2 (Suzaku)?....................................................................................... 2 2. “Building the Coolest X-ray Satellite” ....................................................................... 2 3. How to Use This Guide.............................................................................................. 2 4. Contents of the DVD ................................................................................................. 3 5. Post-Launch Information ........................................................................................... 3 6. Pre-requisites............................................................................................................. 4 7. Standards Met by Video and Activities ...................................................................... 4 II. Video Chapter 1
    [Show full text]
  • Software Error Doomed Japanese Hitomi Spacecraft!
    Software error doomed Japanese Hitomi spacecraft! ! Space agency declares the astronomy satellite a loss.! ! Japan’s flagship Hitomi astronomical satellite, which launched successfully on 17 February but tumbled out of control five weeks later, may have been doomed by a basic engineering error. Confused about how it was oriented in space and trying to stop itself from spinning, Hitomi's software apparently fired a thruster jet in the wrong direction — accelerating rather than slowing the craft's rotation.! ! http://www.nature.com/news/software-error-doomed-japanese-hitomi- spacecraft-1.19835! 1! Gamma-Ray Bursts- Longair 22.7! • Are bright flashes of γ-rays- for a short period of time (<100 sec )! • fluxes of ~0.1-100 photon/cm2/sec/keV emitted primarily in the 20-500 keV band.! – Distribution is isotropic on the sky! • Because of these properties it took ~30 years from their discovery (1967) to their identification! – They are at very large distances (z up to 8 (!)) with apparent luminosities of 3x1054 erg/sec! – Rate is ~10-7/yr/galaxy ! • What are they??- short timescales imply compact object ; what could the 2 33 energy reservoir be- Mc implies M~10 gms~ Msun if total conversion of mass into energy How does all this energy end up as γ-rays ?! – Location of long γRBs is in and near star forming regions in smallish galaxies- associated with star formation! – a few γRBs have been associated with a type Ic supernova! 2! 3! Gamma-Ray Bursts ! • Cosmic γ-ray bursts (GRBs) were first reported in 1973 by Klebesadel et al (l973) but were first seen
    [Show full text]
  • The Evolving Launch Vehicle Market Supply and the Effect on Future NASA Missions
    Presented at the 2007 ISPA/SCEA Joint Annual International Conference and Workshop - www.iceaaonline.com The Evolving Launch Vehicle Market Supply and the Effect on Future NASA Missions Presented at the 2007 ISPA/SCEA Joint International Conference & Workshop June 12-15, New Orleans, LA Bob Bitten, Debra Emmons, Claude Freaner 1 Presented at the 2007 ISPA/SCEA Joint Annual International Conference and Workshop - www.iceaaonline.com Abstract • The upcoming retirement of the Delta II family of launch vehicles leaves a performance gap between small expendable launch vehicles, such as the Pegasus and Taurus, and large vehicles, such as the Delta IV and Atlas V families • This performance gap may lead to a variety of progressions including – large satellites that utilize the full capability of the larger launch vehicles, – medium size satellites that would require dual manifesting on the larger vehicles or – smaller satellites missions that would require a large number of smaller launch vehicles • This paper offers some comparative costs of co-manifesting single- instrument missions on a Delta IV/Atlas V, versus placing several instruments on a larger bus and using a Delta IV/Atlas V, as well as considering smaller, single instrument missions launched on a Minotaur or Taurus • This paper presents the results of a parametric study investigating the cost- effectiveness of different alternatives and their effect on future NASA missions that fall into the Small Explorer (SMEX), Medium Explorer (MIDEX), Earth System Science Pathfinder (ESSP), Discovery,
    [Show full text]
  • Spherex: New NASA MIDEX All-Sky 1-5 Um Spectral Survey
    SPHEREx: New NASA MIDEX All-Sky 1-5 um Spectral Survey Designed to Explore ▪ The Origin of the Universe ▪ The Origin and History of Galaxies ▪ The Origin of Water in Planetary Systems ▪ PI Jamie Bock, CalTech The First All-Sky Near-IR Spectral Survey A Rich Legacy Archive for the Astronomy Community with 100s of Millions of Stars and Galaxies Low-Risk Implementation ▪ 2022 NASA MIDEX Launch ▪ Single Observing Mode ▪ Large Design Margins Co-I Carey Lisse, SES/SRE ▪ No Moving Optics NASA SBAG Jun 25, 2019 Copyright 2017 California Institute of Technology. U.S. Government sponsorship acknowledged. New MIDEX SPHEREx (2022-2025): All-Sky 0.8 – 5.0 µm Spectral Legacy Archives Medium- High- Accuracy Accuracy Detected Spectra Spectra Clusters > 1 billion > 100 million 10 million 25,000 All-Sky surveys demonstrate high Galaxies scientiFic returns with a lasting Main data legacy used across astronomy Sequence Brown Spectra Dust-forming Dwarfs Cataclysms For example: > 100 million 10,000 > 400 > 1,000 COBE J IRAS J Stars GALEX Asteroid WMAP & Comet Galactic Quasars Quasars z >7 Spectra Line Maps Planck > 1.5 million 1 – 300? > 100,000 PAH, HI, H2 WISE J Other More than 400,000 total citations! SPHEREx Data Products & Tools: A spectrum (0.8 to 5 micron) for every 6″ pixel on the sky Planned Data Releases Survey Data Date (Launch +) Associated Products Survey 1 1 – 8 mo S1 spectral images Survey 2 8 – 14 mo S1/2 spectral images Early release catalog Survey 3 14 – 20 mo S1/2/3 spectral images Survey 4 20 – 26 mo S1/2/3/4 spectral images Final Release
    [Show full text]
  • A Thin Diffuse Component of the Galactic Ridge X-Ray Emission and Heating of the Interstellar Medium Contributed by the Radiation of Galactic X-Ray Binaries
    A&A 564, A107 (2014) Astronomy DOI: 10.1051/0004-6361/201323332 & c ESO 2014 Astrophysics A thin diffuse component of the Galactic ridge X-ray emission and heating of the interstellar medium contributed by the radiation of Galactic X-ray binaries Margherita Molaro1, Rishi Khatri1, and Rashid A. Sunyaev1,2 1 Max Planck Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85741 Garching, Germany e-mail: [email protected] 2 Space Research Institute, Russian Academy of Sciences, Profsoyuznaya 84/32, 117997 Moscow, Russia Received 23 December 2013 / Accepted 14 January 2014 ABSTRACT We predict athindiffuse component of the Galactic ridge X-ray emission (GRXE) arising from the scattering of the radiation of bright X-ray binaries (XBs) by the interstellar medium. This scattered component has the same scale height as that of the gaseous disk (∼80 pc) and is therefore thinner than the GRXE of stellar origin (scale height ∼130 pc). The morphology of the scattered component is furthermore expected to trace the clumpy molecular and HI clouds. We calculate this contribution to the GRXE from known Galactic XBs assuming that they are all persistent. The known XBs sample is incomplete, however, because it is flux limited and spans the lifetime of X-ray astronomy (∼50 years), which is very short compared with the characteristic time of 1000−10 000 years that would have contributed to the diffuse emission observed today due to time delays. We therefore also use a simulated sample of sources, to estimate the diffuse emission we should expect in an optimistic case assuming that the X-ray luminosity of our Galaxy is on average similar to that of other galaxies.
    [Show full text]
  • The Future of X-Rayastronomy
    The Future of X-rayAstronomy Keith Arnaud [email protected] High Energy Astrophysics Science Archive Research Center University of Maryland College Park and NASA’s Goddard Space Flight Center Themes Politics Efficient high resolution spectroscopy Mirrors Polarimetry Other missions Interferometry Themes Politics Efficient high resolution spectroscopy Mirrors Polarimetry Other missions Interferometry How do we get a new X-ray astronomy experiment? A group of scientists and engineers makes a proposal to a national (or international) space agency. This will include a science case and a description of the technology to be used (which should generally be in a mature state). In principal you can make an unsolicited proposal but in practice space agencies have proposal rounds in the same way that individual missions have observing proposal rounds. NASA : Small Explorer (SMEX) and Medium Explorer (MIDEX): every ~2 years alternating Small and Medium, three selected for study for one year from which one is selected for launch. RXTE, GALEX, NuSTAR, Swift, IXPE Arcus, a high resolution X-ray spectroscopy mission was a finalist in the latest MIDEX round but was not selected. Missions of Opportunity (MO): every ~2 years includes balloon programs, ISS instruments and contributions to foreign missions. Suzaku, Hitomi, NICER, XRISM Large missions such as HST, Chandra, JWST are not selected by such proposals but are decided as national priorities through the Astronomy Decadal process. Every ten years a survey is run by the National Academy of Sciences to decide on priorities for both land-based and space-based astronomy. 1960: HST; 1970: VLA; 1980: VLBA; 1990: Chandra and SIRTF; 2000: JWST and ALMA; 2010 WFIRST and LSST.
    [Show full text]
  • A Search for Anomalous Tails of Short-Period Comets
    Probable Optical Identification of LMC X-4 Claude Chevalier and Sergio A. I/ovaisky, Observatoire de Meudon Among the five X-ray sources known to exist in the Large of the sky by the UHURU satellite; it was also detected by Magellanic Cloud, none has up to now been positively the Ariel 5 and SAS-3 satellites and there is now definite idenlified with an optical object. However, this situation evidence for variability, including flares. The rotating mo­ may change in the near future as X-ray satellites point to dulation collimator system aboard SAS-3 determined the the source known as LMC X-4. The existence of this source position of LMC X-4 to one are minute. Inside the error box was announced in 1972 as a result of the first X-ray survey a large number of stars are visible on the ESO ass plate (field 86). Very deep objective-prism Schmidt plates taken at Cerro Tololo by N. Sanduleak and A. G. D. Philip showed an OS star near the centre of the error box. A spectrum of DELTA 13 l Me x- 'I pr; 1 ,llt1U D this star was taken by E. Maurice in January 1977 with the l' 3i'1~.(Jb Echelec spectrograph of the 1.5-m telescope at La Si lIa; it showed the star to be indeed an early-type luminous ob­ 3.3 ject. Du ri ng our runs at La Silla in February and March 1977 ......,', ......,', we started a systematic study of this object. One of us (C.C.) ,.....
    [Show full text]
  • ROSAT All-Sky Survey
    ROSAT All-Sky Survey S. R. Kulkarni July 22, 2020{July 27, 2020 The Russian-German mission, Spektr-R¨ongtenGamma (SRG) is on the verge of revolution- izing X-ray astronomy. One of the instruments, eROSITA, will be undertaking an imaging survey of the X-ray sky. Each six-month the entire sky will be covered to a sensitivity which is ten times better than the previous such survey (ROSAT). After eight semesters SRG will undertake pointed observations. I provide a condensed history so that a young student can appreciate the importance of SRG/eROSITA. The first all sky survey was undertaken by the Uhuru (aka SAS-1; 1970) satellite. This was followed up by HEAO-1 (aka HEAO-A; 1977) surveys. These surveys detected 339 and 843 sources in the 2{10 keV band. For those interested in arcana, 1 Uhuru count/s is 1:7 × 10−11 erg cm−2 s−1 in the 2{6 keV band. The next major mission was HEAO-2 (aka Einstein; launched in 1978). This was a game changer since, unlike the past missions which used essentially collimators or shadow cam- eras, the centerpiece of Einstein was a true imaging telescope. Furthermore the mission carried an amazing complement of imagers and spectrometers in the focal plane. The mission coincided with my graduate school (1978-1983). R¨ontgensatellit (ROSAT) was a German mission to undertake an X-ray imaging survey of the entire sky { the first such survey. Launched in 1990 it lasted for eight years. It carried two Positional Sensitive Proportional Counter (PSPC; 0.1{2.4 keV), a High Resolution Imager (HRI) and the Wide Field Camera (WFC; 60{300 A).˚ The PSPC, with a field-of- view of 2 degrees, was the primary work horse for the X-ray sky survey and was > 100 more sensitive than the pioneering Uhuru and HEAO-A1 surveys.
    [Show full text]
  • Abundances 164 ACE (Advanced Composition Explorer) 1, 21, 60, 71
    Index abundances 164 CIR (corotating interaction region) 3, ACE (Advanced Composition Explorer) 1, 14À15, 32, 36À37, 47, 62, 108, 151, 21, 60, 71, 170À171, 173, 175, 177, 254À255 200, 251 energetic particles 63, 154 SWICS 43, 86 Climax neutron monitor 197 ACRs (anomalous cosmic rays) 10, 12, 197, CME (coronal mass ejection) 3, 14À15, 56, 258À259 64, 86, 93, 95, 123, 256, 268 CIRs 159 composition 268 pickup ions 197 open flux 138 termination shock 197, 211 comets 2À4, 11 active longitude 25 ComptonÀGetting effect 156 active region 25 convection equation tilt 25 diffusion 204 activity cycle (see also solar cycle) 1À2, corona 1À2 11À12 streamers 48, 63, 105, 254 Advanced Composition Explorer see ACE temperature 42 Alfve´n waves 116, 140, 266 coronal hole 30, 42, 104, 254, 265 AMPTE (Active Magnetospheric Particle PCH (polar coronal hole) 104, 126, 128 Tracer Explorer) mission 43, 197, coronal mass ejections see CME 259 corotating interaction regions see CIR anisotropy telescopes (AT) 158 corotating rarefaction region see CRR Cosmic Ray and Solar Particle Bastille Day see flares Investigation (COSPIN) 152 bow shock 10 cosmic ray nuclear composition (CRNC) butterfly diagram 24À25 172 cosmic rays 2, 16, 22, 29, 34, 37, 195, 259 Cassini mission 181 anomalous 195 CELIAS see SOHO charge state 217 CH see coronal hole composition 196, 217 CHEM 43 convection–diffusion model 213 282 Index cosmic rays (cont.) Energetic Particle Composition Experiment drift 101, 225 (EPAC) 152 force-free approximation 213 energetic particle 268 galactic 195 anisotropy 156,
    [Show full text]