DOCSLIB.ORG

The Role of Stellar Feedback in the Dynamics of H Ii Regions

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Role of Stellar Feedback in the Dynamics of H Ii Regions THE ROLE OF STELLAR FEEDBACK IN THE DYNAMICS OF H II REGIONS The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Citation Lopez, Laura A., Mark R., Alberto D. Bolatto, J. Xavier Prochaska, Enrico Ramirez-Ruiz, and Daniel Castro. "THE ROLE OF STELLAR FEEDBACK IN THE DYNAMICS OF H II REGIONS." The Astrophysical Journal 795:121 (2014 November 10), p.1-18. © 2014 American Astronomical Society. As Published http://dx.doi.org/10.1088/0004-637x/795/2/121 Publisher Institute of Physics/American Astronomical Society Version Final published version Citable link http://hdl.handle.net/1721.1/93181 Terms of Use Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. The Astrophysical Journal, 795:121 (18pp), 2014 November 10 doi:10.1088/0004-637X/795/2/121 C 2014. The American Astronomical Society. All rights reserved. Printed in the U.S.A. THE ROLE OF STELLAR FEEDBACK IN THE DYNAMICS OF H ii REGIONS Laura A. Lopez1,5,6, Mark R. Krumholz2, Alberto D. Bolatto3, J. Xavier Prochaska2,4, Enrico Ramirez-Ruiz2, and Daniel Castro1 1 MIT-Kavli Institute for Astrophysics and Space Research, 77 Massachusetts Avenue, 37-664H, Cambridge, MA 02139, USA; [email protected] 2 Department of Astronomy and Astrophysics, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA 95060, USA 3 Department of Astronomy, University of Maryland, College Park, MD 20742, USA 4 University of California Observatories, Lick Observatory, 1156 High Street, Santa Cruz, CA 95064, USA Received 2013 September 20; accepted 2014 September 15; published 2014 October 21 ABSTRACT Stellar feedback is often cited as the biggest uncertainty in galaxy formation models today. This uncertainty stems from a dearth of observational constraints as well as the great dynamic range between the small scales (1 pc) where the feedback originates and the large scales of galaxies (1 kpc) that are shaped by this feedback. To bridge this divide, in this paper we aim to assess observationally the role of stellar feedback at the intermediate scales of H ii regions (∼10–100 pc). In particular, we employ multiwavelength data to examine several stellar feedback mechanisms in a sample of 32 H ii regions (with ages ∼3–10 Myr) in the Large and Small Magellanic Clouds, respectively. Using optical, infrared, radio, and X-ray images, we measure the pressures exerted on the shells from the direct stellar radiation, the dust-processed radiation, the warm ionized gas, and the hot X-ray-emitting gas. We find that the warm ionized gas dominates over the other terms in all of the sources, although two have comparable dust-processed radiation pressures to their warm gas pressures. The hot gas pressures are comparatively weak, while the direct radiation pressures are one to two orders of magnitude below the other terms. We discuss the implications of these results, particularly highlighting evidence for hot gas leakage from the H ii shells and regarding the momentum deposition from the dust-processed radiation to the warm gas. Furthermore, we emphasize that similar observational work should be done on very young H ii regions to test whether direct radiation pressure and hot gas can drive the dynamics at early times. Key words: galaxies: star clusters: general – H ii regions – stars: formation Online-only material: color figures ∼ 1. INTRODUCTION fraction ( 1%–2%) of GMC mass is converted to stars per cloud free-fall time (e.g., Zuckerman & Evans 1974; Krumholz & Tan Stellar feedback—the injection of energy and momentum by 2007; Evans et al. 2009; Heiderman et al. 2010; Krumholz et al. stars—originates at the small scales of star clusters (1 pc), yet 2012). This inefficiency can be attributed to stellar feedback it shapes the interstellar medium (ISM) on large scales (1 kpc). processes of H ii regions that act to disrupt and ultimately At large scales, stellar feedback is necessary in order to form to destroy their host clouds (e.g., Whitworth 1979; Matzner realistic galaxies in simulations and to account for observed 2002; Krumholz et al. 2006;Vazquez-Semadeni´ et al. 2010; galaxy properties. In the absence of feedback, baryonic matter Goldbaum et al. 2011;Daleetal.2005, 2012, 2013). In addition cools rapidly and efficiently forms stars, producing an order of to the pressure of the warm ionized H ii region gas itself, there magnitude too much stellar mass and consuming most available are several other forms of stellar feedback that can drive the gas in the galaxy (e.g., White & Rees 1978;Keresetal.ˇ 2009). dynamics of H ii regions and deposit energy and momentum Stellar feedback prevents this “cooling catastrophe” by heating in the surrounding ISM: the direct radiation of stars (e.g., gas as well as removing low angular momentum baryons from Krumholz & Matzner 2009;Falletal.2010;Murrayetal. galactic centers, thereby allowing only a small fraction of the 2010; Hopkins et al. 2011), the dust-processed infrared radiation baryonic budget of dark matter halos to be converted to stars. The (e.g., Thompson et al. 2005; Murray et al. 2010; Andrews removal of baryons may also flatten the dark matter mass profile, & Thompson 2011), stellar winds and supernovae (SNe; e.g., critical to form bulgeless dwarf galaxies (e.g., Mashchenko Yorke et al. 1989; Harper-Clark & Murray 2009; Rogers & et al. 2008; Governato et al. 2010, 2012). Furthermore, stellar Pittard 2013), and protostellar outflows/jets (e.g., Quillen et al. feedback possibly drives kiloparsec-scale galactic winds and 2005; Cunningham et al. 2006; Li & Nakamura 2006; Nakamura outflows (see Veilleux et al. 2005 for a review) which have been &Li2008; Wang et al. 2010). frequently observed in local galaxies (e.g., Bland & Tully 1988; From a theoretical perspective, SNe were the first feedback Martin 1999; Strickland et al. 2004) as well as in galaxies at mechanism to be considered as a means to remove gas from moderate to high redshift (e.g., Ajiki et al. 2002;Fryeetal. low-mass galaxies (e.g., Dekel & Silk 1986) and to prevent the 2002; Shapley et al. 2003; Rubin et al. 2013). cooling catastrophe (e.g., White & Frenk 1991). However, reso- At the smaller scales of star clusters and giant molecular lution limitations precluded the explicit modeling of individual clouds (GMCs), newborn stars dramatically influence their SNe in galaxy formation simulations, so phenomenological pre- environments. Observational evidence suggests that only a small scriptions were employed to account for “sub-grid” feedback (e.g., Katz 1992; Navarro & White 1993; Mihos & Hernquist 5 NASA Einstein Fellow. 1994). Since then, extensive work has been done to improve and 6 Pappalardo Fellow in Physics. to compare these sub-grid models (e.g., Thacker & Couchman 1 The Astrophysical Journal, 795:121 (18pp), 2014 November 10 Lopez et al. 2000; Springel & Hernquist 2003; Saitoh et al. 2008; Teyssier Table 1 et al. 2010; Hopkins et al. 2011; Scannapieco et al. 2012; Stinson Sample of H ii Regions et al. 2012; Aumer et al. 2013; Kim et al. 2014). Furthermore, Source Alt Name R.A. Decl. Radiusa Radiusa the use of “zoom-in” simulations (which can model feedback (J2000) (J2000) (arcmin) (pc) physics down to 1 pc scale) has enabled the modeling of sev- LMC sources eral modes of feedback simultaneously (e.g., Agertz et al. 2013; Hopkins et al. 2013; Renaud et al. 2013; Stinson et al. 2013; N4 DEM L008 04:52:09 −66:55:13 0.7 10.2 N11 DEM L034, L041 04:56:41 −66:27:19 10.0 145 Agertz & Kravtsov 2014; Ceverino et al. 2014). − While simulations are beginning to incorporate many feed- N30 DEM L105, L106 05:13:51 67:27:22 3.1 45.1 N44 DEM L150 05:22:16 −67:57:09 7.1 103 back mechanisms, most observational work focuses on the N48 DEM L189 05:25:50 −66:15:03 5.2 75.6 effects of the individual modes. Consequently, the relative con- N55 DEM L227, L228 05:32:33 −66:27:20 3.6 52.4 tribution of these components and which processes dominate N59 DEM L241 05:35:24 −67:33:22 3.9 56.7 in different conditions remains uncertain. To address this issue, N79 DEM L010 04:52:04 −69:22:34 4.4 64.0 we recently employed multiwavelength imaging of the giant N105 DEM L086 05:09:56 −68:54:03 2.9 42.2 H ii region N157 (30 Doradus; “30 Dor” hereafter) to assess N119 DEM L132 05:18:45 −69:14:03 5.9 85.8 the dynamical role of several stellar feedback mechanisms in N144 DEM L199 05:26:38 −68:49:55 4.9 71.3 driving the shell expansion (Lopez et al. 2011). In particular, we N157 30 Dor 05:38:36 −69:05:33 6.8 98.9 N160 05:40:22 −69:37:35 5.0 40.0 measured the pressures associated with the different feedback − modes across 441 regions to map the pressure components as a N180 DEM L322, L323 05:48:52 70:03:51 2.7 39.3 N191 DEM L064 05:04:35 −70:54:27 2.1 30.5 function of position; we considered the direct radiation pressure N206 DEM L221 05:30:38 −71:03:53 7.7 112 exerted by the light from massive stars, the dust-processed ra- diation pressure, the warm ionized (∼104 K) gas pressure, and SMC sources the hot shocked (∼107 K) gas pressure from stellar winds and DEM S74 00:53:14 −73:12:18 2.7 47.9 SNe.
Load more

Recommended publications
  • The Central Density of R136 in 30 Doradus
    A&A 552, A94 (2013) Astronomy DOI: 10.1051/0004-6361/201220396 & c ESO 2013 Astrophysics The central density of R136 in 30 Doradus F. J. Selman and J. Melnick European Southern Observatory, Alonso de Cordova 3107 Vitacura Casilla 7630355, Santiago, Chile e-mail: [email protected] Received 18 September 2012 / Accepted 13 February 2013 ABSTRACT The central density, ρ0, of a stellar cluster is an important physical parameter for determining its evolutionary and dynamical state. How much mass segregation there is or whether the cluster has undergone core collapse both depend on ρ0. We reanalyze the results of a previous paper that gives the mass density profile of R136 and combine them with both a conservative upper limit for the core parameter and a more uncertain recent measurement. We thus place a lower limit on ρ0 under reasonable and defensible assumptions 4 3 about the IMF, finding ρ0 ≥ 1.5 × 10 M/pc for the conservative assumption a < 0.4 pc for the cluster core parameter. If we use the 7 3 lower, but more uncertain value a = 0.025 pc, the central density estimate becomes greater than 10 M/pc . A mechanism based on the destruction of a large number of circumstellar disks is posited to explain the hitherto unexplained increase in reddening presented in that same work. Key words. circumstellar matter – galaxies: clusters: individual: R 136 – stars: luminosity function, mass function – Magellanic Clouds – dust, extinction 1. Introduction therein). The cluster R136 has been claimed to have the char- acteristics of a PCC cluster: a cuspy density profile (Mackey Owing to its nearness and extreme nature, Radcliffe 136 (Feast & Gilmore 2003), and a large number of runaway stars (see et al.
    [Show full text]
  • Formation of the Active Star Forming Region LHA 120-N 44 Triggered By
    Draft version December 24, 2018 Typeset using LATEX twocolumn style in AASTeX61 FORMATION OF THE ACTIVE STAR FORMING REGION LHA 120-N 44 TRIGGERED BY TIDALLY-DRIVEN COLLIDING HI FLOWS Kisetsu Tsuge,1 Hidetoshi Sano,1,2 Kengo Tachihara,1 Cameron Yozin,3 Kenji Bekki,3 Tsuyoshi Inoue,1 Norikazu Mizuno,4 Akiko Kawamura,4 Toshikazu Onishi,5 and Yasuo Fukui1,2 1Department of Physics, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan; [email protected] 2Institute for Advanced Research, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan 3ICRAR, M468, The University of Western Australia, 35 Stirling Highway, Crawley Western Australia 6009, Australia 4National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588, Japan 5Department of Physical Science, Graduate School of Science, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan (Accepted November 30, 2018) ABSTRACT N44 is the second active site of high mass star formation next to R136 in the Large Magellanic Cloud (LMC). We carried out a detailed analysis of Hi at 60 arcsec resolution by using the ATCA & Parkes data. We presented decomposition of the Hi emission into two velocity components (the L- and D-components) with the velocity separation of ∼60 km s−1. In addition, we newly defined the I-component whose velocity is intermediate between the L- and D-components. The D-component was used to derive the rotation curve of the LMC disk, which is consistent with the stellar rotation curve (Alves & Nelson 2000). Toward the active cluster forming region of LHA 120-N 44, the three velocity components of Hi gas show signatures of dynamical interaction including bridges and complementary spatial distributions.
    [Show full text]
  • Distributed Star Formation in the M17 Giant Molecular Cloud
    The Evolving ISM in the Milky Way & Nearby Galaxies Distributed Star Formation in the M17 Giant Molecular Cloud Matthew S. Povich1, Ed Churchwell1, and Barbara A. Whitney2, ABSTRACT We have found 269 candidate young stellar objects (YSOs) within a 0.5- degree (14 pc at 1.6 kpc) radius of the M17 H II region by fitting model spectral energy distributions (SEDs) to point-source fluxes from the GLIMPSE Archive, combined with MIPSGAL 24 and 70 µm photometry and MSX point-source fluxes where available. Bright diffuse mid-IR background emission dramatically reduces the IRAC point source sensitivity in the M17 H II region, so all but a few of the detected YSOs lie outside the H II region. Of our sample, ∼160 YSOs in the earliest stages of formation are distributed throughout the extended outer regions of M17 giant molecular cloud. YSOs appear to be located beyond the previously measured extent of the molecular gas. Our YSO sample has a power- law IMF that is complete above ∼3 M. We estimate that at least 1250 stars are currently forming in the M17 molecular cloud. High-resolution imaging of M17 in X-rays with Chandra (Broos et al. 2007) has uncovered a population of 8,000–10,000 young stars within or near NGC 6618, the central ionizing cluster; our sample represents a complementary population. The M17 giant molecular cloud continues to form stars at > 25% of the star formation rate that produced the massive NGC 6618 cluster. Subject headings: stars: formation — infrared: ISM — H II regions 1. Introduction M17 is a well-studied nearby (1.4–1.9 kpc; Povich et al.
    [Show full text]
  • Multi-Frequency Study of Supernova Remnants in the Large Magellanic Cloud Confirmation of the Supernova Remnant Status of DEM L205
    A&A 546, A109 (2012) Astronomy DOI: 10.1051/0004-6361/201219708 & c ESO 2012 Astrophysics Multi-frequency study of supernova remnants in the Large Magellanic Cloud Confirmation of the supernova remnant status of DEM L205 P. Maggi1, F. Haberl1,L.M.Bozzetto2, M. D. Filipovic´2,S.D.Points3, Y.-H. Chu4, M. Sasaki5,W.Pietsch1, R. A. Gruendl4,J.Dickel6,R.C.Smith3, R. Sturm1,E.J.Crawford2, and A. Y. De Horta2 1 Max-Planck-Institut für extraterrestrische Physik, Postfach 1312, Giessenbachstr., 85741 Garching, Germany e-mail: [email protected] 2 University of Western Sydney, Locked Bag 1797, Penrith South DC, NSW 1797, Australia 3 Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, Cassilla 603 La Serena, Chile 4 Astronomy Department, University of Illinois, 1002 West Green Street, Urbana, IL 61801, USA 5 Institut für Astronomie und Astrophysik Tübingen, Universität Tübingen, Sand 1, 72076 Tübingen, Germany 6 Physics and Astronomy Department, University of New Mexico, MSC 07-4220, Albuquerque, NM 87131, USA Received 29 May 2012 / Accepted 23 July 2012 ABSTRACT Context. The Large Magellanic Cloud (LMC) is an ideal target for the study of an unbiased and complete sample of supernova remnants (SNRs). We started an X-ray survey of the LMC with XMM-Newton, which, in combination with observations at other wavelengths, will allow us to discover and study remnants that are either even fainter or more evolved (or both) than previously known. Aims. We present new X-ray and radio data of the LMC SNR candidate DEM L205, obtained by XMM-Newton and ATCA, along with archival optical and infrared observations.
    [Show full text]
  • Herschel Observations of the Galactic HII Region RCW 79
    Astronomy & Astrophysics manuscript no. RCW79_langu_corr c ESO 2018 September 9, 2018 Herschel? observations of the Galactic H ii region RCW 79 Hong-Li Liu1;2;3, Miguel Figueira1, Annie Zavagno1, Tracey Hill4, Nicola Schneider5;6;7, Alexander Men'shchikov8, Delphine Russeil1, Fr´ed´eriqueMotte9;10, J´er´emy Tig´e1, Lise Deharveng1, L. D. Anderson11;12, Jin-Zeng Li2, Yuefang Wu13, Jing-Hua Yuan2, and Maohai Huang2 1 Aix Marseille Univ, CNRS, LAM, Laboratoire d'Astrophysique de Marseille, Marseille, France e-mail: [email protected] 2 National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, 100012, Beijing, China 3 University of Chinese Academy of Sciences, 100049, Beijing, China 4 Joint ALMA Observatory, 3107 Alonso de Cordova, Vitacura, Santiago, Chile 5 Univ. Bordeaux, LAB, CNRS, UMR 5804, 33270, Floirac, France 6 CNRS, LAB, UMR 5804, 33270, Floirac, France 7 I. Physik. Institut, University of Cologne, 50937 Cologne, Germany 8 Laboratoire AIM ParisSaclay, CEA/DSMCNRSUniversit´eParis Diderot, IRFU, Service d'Astrophysique, Centre d'Etudes de Saclay, Orme des Merisiers, 91191 Gif-sur-Yvette, France 9 Institut de Plantologie et d'Astrophysique de Grenoble (IPAG), Univ. Grenoble Alpes/CNRS-INSU, BP 53, 38041 Grenoble Cedex 9, France 10 Laboratoire AIM Paris-Saclay, CEA/IRFU - CNRS/INSU - Universit´eParis Diderot, Service d'Astrophysique, B^at. 709, CEA-Saclay, 91191, Gif-sur-Yvette Cedex, France 11 Department of Physics and Astronomy, West Virginia University, Morgantown, WV 26506, USA ; Also Adjunct Astronomer at the National Radio Astronomy Observatory, P.O. Box 2, Green Bank, WV 24944, USA 12 Adjunct Astronomer at the Green Bank Observatory 13 Department of Astronomy, Peking University, 100871 Beijing, China Preprint online version: September 9, 2018 ABSTRACT Context.
    [Show full text]
  • A Case Study of the Galactic H Ii Region M17 and Environs: Implications for the Galactic Star Formation Rate
    A Case Study of the Galactic H ii Region M17 and Environs: Implications for the Galactic Star Formation Rate by Matthew Samuel Povich A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy (Astronomy) at the University of Wisconsin – Madison 2009 ii Abstract Determinations of star formation rates (SFRs) in the Milky Way and other galaxies are fundamentally based on diffuse emission tracers of ionized gas, such as optical/near-infrared recombination lines, far- infrared continuum, and thermal radio continuum, that are sensitive only to massive OB stars. OB stars dominate the ionization of H II regions, yet they make up <1% of young stellar populations. SFRs therefore depend upon large extrapolations over the stellar initial mass function (IMF). The primary goal of this Thesis is to obtain a detailed census of the young stellar population associated with a bright Galactic H II region and to compare the resulting star formation history with global SFR tracers. The main SFR tracer considered is infrared continuum, since it can be used to derive SFRs in both the Galactic and extragalactic cases. I focus this study on M17, one of the nearest giant H II regions to the Sun (d =2.1kpc),fortwo reasons: (1) M17 is bright enough to serve as an analog of observable extragalactic star formation regions, and (2) M17 is associated with a giant molecular cloud complex, ∼100 pc in extent. The M17 complex is a significant star-forming structure on the Galactic scale, with a complicated star formation history. This study is multiwavelength in nature, but it is based upon broadband mid-infrared images from the Spitzer/GLIMPSE survey and complementary infrared Galactic plane surveys.
    [Show full text]
  • Cfa in the News ~ Week Ending 3 January 2010
    Wolbach Library: CfA in the News ~ Week ending 3 January 2010 1. New social science research from G. Sonnert and co-researchers described, Science Letter, p40, Tuesday, January 5, 2010 2. 2009 in science and medicine, ROGER SCHLUETER, Belleville News Democrat (IL), Sunday, January 3, 2010 3. 'Science, celestial bodies have always inspired humankind', Staff Correspondent, Hindu (India), Tuesday, December 29, 2009 4. Why is Carpenter defending scientists?, The Morning Call, Morning Call (Allentown, PA), FIRST ed, pA25, Sunday, December 27, 2009 5. CORRECTIONS, OPINION BY RYAN FINLEY, ARIZONA DAILY STAR, Arizona Daily Star (AZ), FINAL ed, pA2, Saturday, December 19, 2009 6. We see a 'Super-Earth', TOM BEAL; TOM BEAL, ARIZONA DAILY STAR, Arizona Daily Star, (AZ), FINAL ed, pA1, Thursday, December 17, 2009 Record - 1 DIALOG(R) New social science research from G. Sonnert and co-researchers described, Science Letter, p40, Tuesday, January 5, 2010 TEXT: "In this paper we report on testing the 'rolen model' and 'opportunity-structure' hypotheses about the parents whom scientists mentioned as career influencers. According to the role-model hypothesis, the gender match between scientist and influencer is paramount (for example, women scientists would disproportionately often mention their mothers as career influencers)," scientists writing in the journal Social Studies of Science report (see also ). "According to the opportunity-structure hypothesis, the parent's educational level predicts his/her probability of being mentioned as a career influencer (that ism parents with higher educational levels would be more likely to be named). The examination of a sample of American scientists who had received prestigious postdoctoral fellowships resulted in rejecting the role-model hypothesis and corroborating the opportunity-structure hypothesis.
    [Show full text]
  • Meeting Program
    A A S MEETING PROGRAM 211TH MEETING OF THE AMERICAN ASTRONOMICAL SOCIETY WITH THE HIGH ENERGY ASTROPHYSICS DIVISION (HEAD) AND THE HISTORICAL ASTRONOMY DIVISION (HAD) 7-11 JANUARY 2008 AUSTIN, TX All scientific session will be held at the: Austin Convention Center COUNCIL .......................... 2 500 East Cesar Chavez St. Austin, TX 78701 EXHIBITS ........................... 4 FURTHER IN GRATITUDE INFORMATION ............... 6 AAS Paper Sorters SCHEDULE ....................... 7 Rachel Akeson, David Bartlett, Elizabeth Barton, SUNDAY ........................17 Joan Centrella, Jun Cui, Susana Deustua, Tapasi Ghosh, Jennifer Grier, Joe Hahn, Hugh Harris, MONDAY .......................21 Chryssa Kouveliotou, John Martin, Kevin Marvel, Kristen Menou, Brian Patten, Robert Quimby, Chris Springob, Joe Tenn, Dirk Terrell, Dave TUESDAY .......................25 Thompson, Liese van Zee, and Amy Winebarger WEDNESDAY ................77 We would like to thank the THURSDAY ................. 143 following sponsors: FRIDAY ......................... 203 Elsevier Northrop Grumman SATURDAY .................. 241 Lockheed Martin The TABASGO Foundation AUTHOR INDEX ........ 242 AAS COUNCIL J. Craig Wheeler Univ. of Texas President (6/2006-6/2008) John P. Huchra Harvard-Smithsonian, President-Elect CfA (6/2007-6/2008) Paul Vanden Bout NRAO Vice-President (6/2005-6/2008) Robert W. O’Connell Univ. of Virginia Vice-President (6/2006-6/2009) Lee W. Hartman Univ. of Michigan Vice-President (6/2007-6/2010) John Graham CIW Secretary (6/2004-6/2010) OFFICERS Hervey (Peter) STScI Treasurer Stockman (6/2005-6/2008) Timothy F. Slater Univ. of Arizona Education Officer (6/2006-6/2009) Mike A’Hearn Univ. of Maryland Pub. Board Chair (6/2005-6/2008) Kevin Marvel AAS Executive Officer (6/2006-Present) Gary J. Ferland Univ. of Kentucky (6/2007-6/2008) Suzanne Hawley Univ.
    [Show full text]
  • Gas and Dust in the Magellanic Clouds
    Gas and dust in the Magellanic clouds A Thesis Submitted for the Award of the Degree of Doctor of Philosophy in Physics To Mangalore University by Ananta Charan Pradhan Under the Supervision of Prof. Jayant Murthy Indian Institute of Astrophysics Bangalore - 560 034 India April 2011 Declaration of Authorship I hereby declare that the matter contained in this thesis is the result of the inves- tigations carried out by me at Indian Institute of Astrophysics, Bangalore, under the supervision of Professor Jayant Murthy. This work has not been submitted for the award of any degree, diploma, associateship, fellowship, etc. of any university or institute. Signed: Date: ii Certificate This is to certify that the thesis entitled ‘Gas and Dust in the Magellanic clouds’ submitted to the Mangalore University by Mr. Ananta Charan Pradhan for the award of the degree of Doctor of Philosophy in the faculty of Science, is based on the results of the investigations carried out by him under my supervi- sion and guidance, at Indian Institute of Astrophysics. This thesis has not been submitted for the award of any degree, diploma, associateship, fellowship, etc. of any university or institute. Signed: Date: iii Dedicated to my parents ========================================= Sri. Pandab Pradhan and Smt. Kanak Pradhan ========================================= Acknowledgements It has been a pleasure to work under Prof. Jayant Murthy. I am grateful to him for giving me full freedom in research and for his guidance and attention throughout my doctoral work inspite of his hectic schedules. I am indebted to him for his patience in countless reviews and for his contribution of time and energy as my guide in this project.
    [Show full text]
  • SAA 100 Club
    S.A.A. 100 Observing Club Raleigh Astronomy Club Version 1.2 07-AUG-2005 Introduction Welcome to the S.A.A. 100 Observing Club! This list started on the USENET newsgroup sci.astro.amateur when someone asked about everyone’s favorite, non-Messier objects for medium sized telescopes (8-12”). The members of the group nominated objects and voted for their favorites. The top 100 objects, by number of votes, were collected and ranked into a list that was published. This list is a good next step for someone who has observed all the objects on the Messier list. Since it includes objects in both the Northern and Southern Hemispheres (DEC +72 to -72), the award has two different levels to accommodate those observers who aren't able to travel. The first level, the Silver SAA 100 award requires 88 objects (all visible from North Carolina). The Gold SAA 100 Award requires all 100 objects to be observed. One further note, many of these objects are on other observing lists, especially Patrick Moore's Caldwell list. For convenience, there is a table mapping various SAA100 objects with their Caldwell counterparts. This will facilitate observers who are working or have worked on these lists of objects. We hope you enjoy looking at all the great objects recommended by other avid astronomers! Rules In order to earn the Silver certificate for the program, the applicant must meet the following qualifications: 1. Be a member in good standing of the Raleigh Astronomy Club. 2. Observe 80 Silver observations. 3. Record the time and date of each observation.
    [Show full text]
  • Curriculum Vitae of You-Hua Chu
    Curriculum Vitae of You-Hua Chu Address and Telephone Number: Institute of Astronomy and Astrophysics, Academia Sinica 11F of Astronomy-Mathematics Building, AS/NTU No.1, Sec. 4, Roosevelt Rd, Taipei 10617 Taiwan, R.O.C. Tel: (886) 02 2366 5300 E-mail address: [email protected] Academic Degrees, Granting Institutions, and Dates Granted: B.S. Physics Dept., National Taiwan University 1975 Ph.D. Astronomy Dept., University of California at Berkeley 1981 Professional Employment History: 2014 Sep - present Director, Institute of Astronomy and Astrophysics, Academia Sinica 2014 Jul - present Distinguished Research Fellow, Institute of Astronomy and Astrophysics, Academia Sinica 2014 Jul - present Professor Emerita, University of Illinois at Urbana-Champaign 2005 Aug - 2011 Jul Chair of Astronomy Dept., University of Illinois at Urbana-Champaign 1997 Aug - 2014 Jun Professor, University of Illinois at Urbana-Champaign 1992 Aug - 1997 Jul Research Associate Professor, University of Illinois at Urbana-Champaign 1987 Jan - 1992 Aug Research Assistant Professor, University of Illinois at Urbana-Champaign 1985 Feb - 1986 Dec Graduate College Scholar, University of Illinois at Urbana-Champaign 1984 Sep - 1985 Jan Lindheimer Fellow, Northwestern University 1982 May - 1984 Jun Postdoctoral Research Associate, University of Wisconsin at Madison 1981 Oct - 1982 May Postdoctoral Research Associate, University of Illinois at Urbana-Champaign 1981 Jun - 1981 Aug Postdoctoral Research Associate, University of California at Berkeley Committees Served:
    [Show full text]
  • Carina Nebula Pillar Lithograph As the Initial Source of Information to Engage These Are Terms Students May Encounter While Doing Further Research on Star Formation
    Carina Nebula Pillar National Aeronautics and Space Administration Carina Nebula Pillar Hubble Captures View of ‘Mystic Mountain’ To mark the 20th anniversary of Hubble’s launch and deployment into Earth orbit, NASA and the Space Telescope Science Institute issued this stunning image. The new photograph is reminiscent of a craggy fantasy mountaintop surrounded by wispy clouds. The image captures the chaotic activity on a three-light-year-tall pillar of gas and dust that is being eaten away by the brilliant light from nearby colossal young stars. Those massive stars are located above the pillar, off the image. Streamers of hot, ionized gas can be seen flowing off the ridges of the structure, and thin veils of gas and dust, illuminated by starlight, float around its towering peaks. Scorching radiation and fast winds (streams of charged particles) from the gigantic young stars in the nebula are shaping and compressing the pillar, causing new stars to form within it. The new stars buried inside the pillar are firing off jets of Close-up view of Carina Nebula Pillar gas that can be seen streaming from towering peaks. This This image reveals long jets of gas shooting in opposite turbulent cosmic pillar lies within a tempestuous stellar directions off the tip of a giant pillar of material. The jets nursery called the Carina Nebula, located 7,500 light-years are a signature of new star birth. The young star cannot away in the southern constellation Carina. be seen because it is buried deep inside the dense pillar. The Carina Nebula is one of the largest and brightest The jets are launched by a swirling disk of gas and dust nebulas in the sky.
    [Show full text]