DOCSLIB.ORG

Gas Flow Models in the Milky Way Embedded Bars

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Gas Flow Models in the Milky Way Embedded Bars Astronomy & Astrophysics manuscript no. paper_dyna_2 c ESO 2018 October 31, 2018 Gas flow models in the Milky Way embedded bars N. J. Rodriguez-Fernandez1 and F. Combes2 1 IRAM, 300 rue de la Piscine, 38406 St. Martin d'Heres, France e-mail: [email protected] 2 LERMA, Observatoire de Paris, 61 Av de l'Observatoire, 75014 Paris, France Received September 15, 1996; accepted March 16, 1997 ABSTRACT Context. The gas distribution and dynamics in the inner Galaxy present many unknowns as the origin of the asymmetry of the lv-diagram of the Central Molecular Zone (CMZ). On the other hand, there are recent evidences in the stellar component of the presence of a nuclear bar that could be slightly lopsided. Aims. Our goal is to characterize the nuclear bar observed in 2MASS maps and to study the gas dynamics in the inner Milky Way taking into account this secondary bar. Methods. We have derived a realistic mass distribution by fitting the 2MASS star counts map of Alard (2001) with a model including three components (disk, bulge and nuclear bar) and we have simulated the gas dynamics, in the deduced gravitational potential, using a sticky-particles code. Results. Our simulations of the gas dynamics reproduce successfully the main characteristics of the Milky Way for a bulge orientation of 20◦ − 35◦ with respect to the Sun-Galactic Center (GC) line and a pattern speed of 30-40 km s−1 kpc−1. In our models the Galactic Molecular Ring (GMR) is not an actual ring but the inner parts of the spiral arms, while the 3-kpc arm and its far side counterpart are lateral arms that contour the bar. Our simulations reproduce, for the first time, the parallelogram shape of the lv-diagram of the CMZ as the gas response to the nuclear bar. This bar should be oriented by an angle of ◦ ◦ 9 ∼ 60 − 75 with respect to the Sun-GC line and its mass amounts to (2 − 5:5) 10 M . We show that the observed asymmetry of the CMZ cannot be due to lopsidedness of the nuclear bar as suggested by the 2MASS maps. Conclusions. We do not find clear evidences of lopsidedness in the stellar potential. We propose that the observed asymmetry of the central gas layer can be due to the infalling of gas into the CMZ in the l=1.3◦-complex. Key words. Galaxy: structure { Galaxy: center { Galaxy: kinematics and dynamics { ISM: kinematics and dynamics { Methods: numerical 1. Introduction Gaussians functions. Since COBE, the direct evidence of the bar has increased based on photometric surveys and Studying the structure and the dynamics of the Milky Way star counts in the near-infrared (see for instance L´opez- galaxy is necessary to understand its formation and evolu- Corredoira et al. 2000, 2005; Babusiaux & Gilmore 2005, tion. For example, the large scale star formation rate, the and references therein). Although, there is a consensus arXiv:0806.4252v1 [astro-ph] 26 Jun 2008 gas transfer to the nucleus and the fueling of the central on the triaxial nature of the bulge, the actual shape super-massive black hole are strongly influenced by the and the inclination is still under debate with currently large scale dynamics of the Galaxy. no clear agreement among different authors. The inclina- At least three components are needed to explain the tion angles found range from ∼ 10◦ − 15◦ (Binney et al. rotation curve of the Galaxy: a disc, a bulge and a mas- 1991; Freudenreich 1998; Lopez-Corredoira et al. 1997) sive dark halo. In near-infrared images, the bulge is a tri- to ∼ 30◦ − 45◦ (Weiner & Sellwood 1999; Sevenster 1999; axial structure difficult to distinguish from a bar. The L´opez-Corredoira et al. 2001) with a number of works giv- first direct evidence of the barred nature of the Milky ing values in the range 15◦ − 30◦ (Mulder & Liem 1986; Way was found by Blitz & Spergel (1991). The analysis Binney et al. 1997; Fux 1999; Englmaier & Gerhard 1999; of COBE/DIRBE data (Dwek et al. 1995; Binney et al. Bissantz & Gerhard 2002; Bissantz et al. 2003; Babusiaux 1997; Freudenreich 1998) supported Blitz & Spergel re- & Gilmore 2005; L´opez-Corredoira et al. 2005). sults. Dwek et al. (1995) found that the peanut-shaped bulge seen in the COBE image is best fitted by boxy In addition to the bar-like boxy-bulge, some recent works have also proposed the existence of another bar that Send offprint requests to: N. J. Rodriguez-Fernandez would be longer and thinner than the bulge (Picaud et al. 2 N. J. Rodriguez-Fernandez and F. Combes: Gas flow models in the Milky Way embedded bars 2003; L´opez-Corredoira et al. 2001, 2007; Benjamin et al. To our knowledge, the works by Binney et al. (1991), 2005). As the bulge, the near side of this long and thin bar Jenkins & Binney (1994) and Lee et al. (1999) are the will also be located in the first Galactic quadrant. In con- only dynamical models that have tried to interpret the trast, the long bar would be oriented at an angle of ∼ 45◦ dynamics of the complex Galactic center region (the cen- with respect to the line of sight towards Galactic center. tral 500 pc). Other models of the Galactic dynamics have In the present paper we will not discuss this component been mainly devoted to larger scales, from the works of as the mass should be dominated by the bulge. Hereafter, Mulder & Liem (1986) and Wada et al (1994) to the more we will refer to the triaxial boxy bulge as \large bar" or recent works by Fux (1999), Englmaier & Gerhard (1999), simply \bulge". Weiner & Sellwood (1999) and Bissantz et al. (2003). The Due to the difficulty to measure the stellar veloci- bar pattern rotation speed for most of those models are ties, most of our knowledge of the Galactic dynamics in the range from 40 to 60 km s−1 kpc−1. Regarding the come from spectroscopic observations of the atomic and corotation radius, it is estimated to be in the range 3-4 molecular interstellar medium (Rougoor & Oort 1960; kpc by some works (Englmaier & Gerhard 1999; Bissantz Scoville 1972; Liszt & Burton 1978; Bally et al. 1987; et al. 2003; Habing et al. 2006) and in the range 4-5 kpc Dame et al. 2001). The gas exhibit large non-circular mo- by other works (Combes 1996; Sevenster 1999; Fux 1999). tions in the inner Galaxy. Among the possible explana- In contrast, Binney et al. (1991) placed the corotation at tions for these kinematics, de Vaucouleurs (1964) proposed 2.4 kpc and found a pattern speed of 80 km s−1 kpc−1. the gas response to a bar potential. This explanation has As pointed out by Combes (1996), the discrepancy be- also been discussed in other observational works as those tween Binney et al. estimation and other estimations can of Kerr (1967), Bania (1977) or Liszt & Burton (1978). be due to the fact that the molecular gas distribution in Nevertheless, it is the comparison of the observations with the Galactic center region used by Binney et al. could be numerical simulations of the gas dynamics what have al- the response to a small nuclear bar instead of the large lowed to better understand the structure of the Galaxy bar of the Galaxy. and to derive important dynamical information as the pat- Indeed, there are recent evidences of the presence of tern speed of the bar. The first attempt was that of Mulder a distinct structure in the nuclear region of the Galaxy. & Liem (1986) solving the gas-dynamical equations to get The star counts map made by Alard (2001) with 2MASS the gas flow in a weak bar for the whole Galaxy. data shows an excess of counts in the inner four degrees of A major step in our understanding of the gas kinemat- the Galaxy that resembles a small nuclear bar. This bar ics in the Galactic Center was the paper by Binney et al. could be lopsided with the barycenter displaced to nega- (1991). These authors made a comparison of the CO(1-0) tive longitudes. Nishiyama et al. (2005) have also found and HI longitude-velocity diagrams (hereafter lv-diagram) evidence of a structure different to the large bar or bulge of Bally et al. (1987) and Burton & Liszt (1978), with the in the inner degrees of the Galaxy. lv locus of closed stellar orbits in a bar potential (x1 and In the present paper, we want to investigate the gas re- x2 orbits). The lv-diagram of the molecular gas in the in- sponse to the mass distribution inferred from the 2MASS ner ∼ 4◦ of the Galaxy shows a parallelogram shape that data. In particular, we model the central mass distribution resembles the lv locus of the cusped x1 orbit for a bar with as a small nuclear bar. We are interested in the role of this inclination of ∼ 16◦. In spite of the globally successful in- nuclear bar to explain the differences among the results of terpretation of the CO and HI lv-diagrams, the Binney previous works (Binney et al. 1991; Fux 1999; Combes et al. (1991) model cannot account for the observed asym- 1996). We also want to study whether a lopsided nuclear metry of the CO parallelogram, which is lopsided towards bar could explain the apparent lopsidedness of the molec- positive longitudes while the modeled parallelograms are ular gas distribution in the nuclear region, whose com- centered at longitude 0◦. In addition the expected upper plex dynamics are far from being understood.
Load more

Recommended publications
  • 29 Jan 2020 11Department of Physics, Faculty of Science, Hokkaido University, Kita 10 Nishi 8, Kita-Ku, Sapporo, Hokkaido 060-0810, Japan
    Publ. Astron. Soc. Japan (2014) 00(0), 1–42 1 doi: 10.1093/pasj/xxx000 FOREST Unbiased Galactic plane Imaging survey with the Nobeyama 45 m telescope (FUGIN). VI. Dense gas and mini-starbursts in the W43 giant molecular cloud complex Mikito KOHNO1∗, Kengo TACHIHARA1∗, Kazufumi TORII2∗, Shinji FUJITA1∗, Atsushi NISHIMURA1,3, Nario KUNO4,5, Tomofumi UMEMOTO2,6, Tetsuhiro MINAMIDANI2,6,7, Mitsuhiro MATSUO2, Ryosuke KIRIDOSHI3, Kazuki TOKUDA3,7, Misaki HANAOKA1, Yuya TSUDA8, Mika KURIKI4, Akio OHAMA1, Hidetoshi SANO1,9, Tetsuo HASEGAWA7, Yoshiaki SOFUE10, Asao HABE11, Toshikazu ONISHI3 and Yasuo FUKUI1,9 1Department of Physics, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan 2Nobeyama Radio Observatory, National Astronomical Observatory of Japan (NAOJ), National Institutes of Natural Sciences (NINS), 462-2, Nobeyama, Minamimaki, Minamisaku, Nagano 384-1305, Japan 3Department of Physical Science, Graduate School of Science, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan 4Department of Physics, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Ten-nodai, Tsukuba, Ibaraki 305-8577, Japan 5Tomonaga Center for the History of the Universe, University of Tsukuba, Ten-nodai 1-1-1, Tsukuba, Ibaraki 305-8571, Japan 6Department of Astronomical Science, School of Physical Science, SOKENDAI (The Graduate University for Advanced Studies), 2-21-1, Osawa, Mitaka, Tokyo 181-8588, Japan 7National Astronomical Observatory of Japan (NAOJ), National
    [Show full text]
  • Nd AAS Meeting Abstracts
    nd AAS Meeting Abstracts 101 – Kavli Foundation Lectureship: The Outreach Kepler Mission: Exoplanets and Astrophysics Search for Habitable Worlds 200 – SPD Harvey Prize Lecture: Modeling 301 – Bridging Laboratory and Astrophysics: 102 – Bridging Laboratory and Astrophysics: Solar Eruptions: Where Do We Stand? Planetary Atoms 201 – Astronomy Education & Public 302 – Extrasolar Planets & Tools 103 – Cosmology and Associated Topics Outreach 303 – Outer Limits of the Milky Way III: 104 – University of Arizona Astronomy Club 202 – Bridging Laboratory and Astrophysics: Mapping Galactic Structure in Stars and Dust 105 – WIYN Observatory - Building on the Dust and Ices 304 – Stars, Cool Dwarfs, and Brown Dwarfs Past, Looking to the Future: Groundbreaking 203 – Outer Limits of the Milky Way I: 305 – Recent Advances in Our Understanding Science and Education Overview and Theories of Galactic Structure of Star Formation 106 – SPD Hale Prize Lecture: Twisting and 204 – WIYN Observatory - Building on the 308 – Bridging Laboratory and Astrophysics: Writhing with George Ellery Hale Past, Looking to the Future: Partnerships Nuclear 108 – Astronomy Education: Where Are We 205 – The Atacama Large 309 – Galaxies and AGN II Now and Where Are We Going? Millimeter/submillimeter Array: A New 310 – Young Stellar Objects, Star Formation 109 – Bridging Laboratory and Astrophysics: Window on the Universe and Star Clusters Molecules 208 – Galaxies and AGN I 311 – Curiosity on Mars: The Latest Results 110 – Interstellar Medium, Dust, Etc. 209 – Supernovae and Neutron
    [Show full text]
  • Hi Absorption Toward Hii Regions at Small Galactic
    The Astrophysical Journal, 774:117 (18pp), 2013 September 10 doi:10.1088/0004-637X/774/2/117 C 2013. The American Astronomical Society. All rights reserved. Printed in the U.S.A. H i ABSORPTION TOWARD H ii REGIONS AT SMALL GALACTIC LONGITUDES C. Jones1, J. M. Dickey1,J.R.Dawson1,2, N. M. McClure-Griffiths2, L. D. Anderson3, and T. M. Bania4 1 School of Mathematics and Physics, Private Bag 37, University of Tasmania, Hobart 7001, Australia 2 CSIRO Astronomy and Space Science, ATNF, P.O. Box 76, Epping, NSW 1710, Australia 3 Department of Physics, West Virginia University, Morgantown, WV 26506, USA 4 Institute for Astrophysical Research, Department of Astronomy, Boston University, 725 Commonwealth Avenue, Boston, MA 02215, USA Received 2013 May 7; accepted 2013 July 16; published 2013 August 22 ABSTRACT We make a comprehensive study of H i absorption toward H ii regions located within |l| < 10◦. Structures in the extreme inner Galaxy are traced using the longitude–velocity space distribution of this absorption. We find significant H i absorption associated with the Near and Far 3 kpc Arms, the Connecting Arm, Bania’s Clump 1, and the H i Tilted Disk. We also constrain the line-of-sight distances to H ii regions, by using H i absorption spectra together with the H ii region velocities measured by radio recombination lines. Key words: Galaxy: structure – H ii regions Online-only material: color figures, figure set 1. INTRODUCTION components that dominate. However, cool gas is readily ob- served in absorption against background continuum sources, The extreme inner Galaxy (EIG) has long been the subject of where it may be disentangled from warmer material along the intense astrophysical study as it provides excellent opportunities line of sight.
    [Show full text]
  • Curriculum Vitae (Pdf)
    THOMAS M. DAME Curriculum Vitae Harvard–Smithsonian Center for Astrophysics office: (617) 495-7334 Building C-311 home: (617) 497-6163 60 Garden Street email: [email protected] Cambridge, Massachusetts 02138 CURRENT POSITIONS Senior Radio Astronomer, Smithsonian Astrophysical Observatory Lecturer on Astronomy, Harvard University EDUCATION B.A. (Magna cum Laude), Astronomy and Physics, Boston University, 1976 M.A., Astronomy, Columbia University, 1978 M. Phil., Columbia University, 1979 Ph.D., Astronomy, Columbia University, 1983 Dissertation: Molecular Clouds and Galactic Spiral Structure (Advisor: P. Thaddeus) PREVIOUS POSITIONS 1988 Teaching Fellow, Core Program, Harvard University 1985–86 Research Associate, Columbia Univ., Dept. of Astronomy 1983–84 National Research Council Resident Research Associate at the NASA Goddard Institute for Space Studies, 2880 Broadway, N.Y., N.Y. 10025 1976–80 Teaching Assistant, Columbia College HONORS AND AWARDS Secretary's Research Prize, Smithsonian Institution, 2009 Special Achievement Awards, Smithsonian Institution, 1989, 1997, 1999, 2007, 2009, 2010 Postdoctoral Associateship, National Academy of Sciences (N.R.C.), 1983–84 Columbia University Graduate Fellowship, 1976–78 College Prize for Excellence in Astronomy, Boston University, 1976 PROFESSIONAL MEMBERSHIP International Astronomical Union American Astronomical Society T. M. Dame PUBLICATIONS 1. "Molecular Clouds and Galactic Spiral Structure," R. S. Cohen, H. I. Cong, T. M. Dame, and P. Thaddeus, 1980. Astrophysical Journal, 239, L53. 2. "Columbia CO Survey: Molecular Clouds and Spiral Structure," R. S. Cohen, T. M. Dame, and P. Thaddeus, 1980, in Interstellar Molecules, ed. B. H. Andrew (IAU Symp. No. 87) (Dordrecht: Reidel), 205. 3. "The Interrelation of Cosmic γ-Rays and Interstellar Gas in the Range l = 65°–180°," K.
    [Show full text]
  • Discovery of a Pair of Classical Cepheids in an Invisible Cluster Beyond the Galactic Bulge I
    The Astrophysical Journal Letters, 799:L11 (6pp), 2015 January 20 doi:10.1088/2041-8205/799/1/L11 © 2015. The American Astronomical Society. All rights reserved. DISCOVERY OF A PAIR OF CLASSICAL CEPHEIDS IN AN INVISIBLE CLUSTER BEYOND THE GALACTIC BULGE I. Dékány1,2, D. Minniti3,1,7, G. Hajdu2,1, J. Alonso-García2,1, M. Hempel2, T. Palma1,2, M. Catelan2,1, W. Gieren4,1, and D. Majaess5,6 1 Millennium Institute of Astrophysics, Santiago, Chile 2 Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, Santiago, Chile 3 Departamento de Ciencias Físicas, Universidad Andres Bello, República 220, Santiago, Chile 4 Departamento de Astronomía, Universidad de Concepción, Casilla 160 C, Concepción, Chile 5 Department of Astronomy & Physics, Saint Mary’s University, Halifax, NS B3H 3C3, Canada 6 Mount Saint Vincent University, Halifax, NS B3M 2J6, Canada Received 2014 November 26; accepted 2014 December 29; published 2015 January 19 ABSTRACT We report the discovery of a pair of extremely reddened classical Cepheid variable stars located in the Galactic plane behind the bulge, using near-infrared (NIR) time-series photometry from the VISTA Variables in the Vía Láctea Survey. This is the first time that such objects have ever been found in the opposite side of the Galactic plane. The Cepheids have almost identical periods, apparent brightnesses, and colors. From the NIR Leavitt law, we determine their distances with ~1.5% precision and ~8% accuracy. We find that they have a same total extinction of A()V 32 mag, and are located at the same heliocentric distance of ádñ=11.4 0.9 kpc, and less than 1 pc from the true Galactic plane.
    [Show full text]
  • The Observed Spiral Structure of the Milky Way⋆⋆⋆
    A&A 569, A125 (2014) Astronomy DOI: 10.1051/0004-6361/201424039 & c ESO 2014 Astrophysics The observed spiral structure of the Milky Way, L. G. Hou and J. L. Han National Astronomical Observatories, Chinese Academy of Sciences, Jia-20, DaTun Road, ChaoYang District, 100012 Beijing, PR China e-mail: [lghou;hjl]@nao.cas.cn Received 21 April 2014 / Accepted 7 July 2014 ABSTRACT Context. The spiral structure of the Milky Way is not yet well determined. The keys to understanding this structure are to in- crease the number of reliable spiral tracers and to determine their distances as accurately as possible. HII regions, giant molecular clouds (GMCs), and 6.7 GHz methanol masers are closely related to high mass star formation, and hence they are excellent spiral tracers. The distances for many of them have been determined in the literature with trigonometric, photometric, and/or kinematic methods. Aims. We update the catalogs of Galactic HII regions, GMCs, and 6.7 GHz methanol masers, and then outline the spiral structure of the Milky Way. Methods. We collected data for more than 2500 known HII regions, 1300 GMCs, and 900 6.7 GHz methanol masers. If the photo- metric or trigonometric distance was not yet available, we determined the kinematic distance using a Galaxy rotation curve with the −1 −1 current IAU standard, R0 = 8.5 kpc and Θ0 = 220 km s , and the most recent updated values of R0 = 8.3 kpc and Θ0 = 239 km s , after velocities of tracers are modified with the adopted solar motions. With the weight factors based on the excitation parameters of HII regions or the masses of GMCs, we get the distributions of these spiral tracers.
    [Show full text]
  • 334—24October2020 Editor:Joãoalves([email protected]) List of Contents
    THE STAR FORMATION NEWSLETTER An electronic publication dedicated to early stellar/planetary evolution and molecular clouds No.334—24October2020 Editor:JoãoAlves([email protected]) List of Contents The Star Formation Newsletter Editorial ....................................... 3 Interview ...................................... 4 Editor: João Alves [email protected] Abstracts of Newly Accepted Papers ........... 7 New Jobs ..................................... 35 Editorial Board Meetings ..................................... 40 Alan Boss Summary of Upcoming Meetings .............. 41 Jerome Bouvier Lee Hartmann Short Announcements ........................ 42 Thomas Henning Paul Ho Jes Jorgensen Charles J. Lada Thijs Kouwenhoven Cover Picture Michael R. Meyer Ralph Pudritz The L1495 cloud in Taurus contains many small Luis Felipe Rodríguez groupings of young low-mass stars. The image Ewine van Dishoeck shows the region around V1096 Tau, seen as a neb- Hans Zinnecker ulous star near the center of the image, and the small compact group of young stars seen further to The Star Formation Newsletter is a vehicle for the south, including CW Tau, V773 Tau, and FM fast distribution of information of interest for as- Tau. The red nebulous object is Herbig-Haro object tronomers working on star and planet formation HH 827. and molecular clouds. You can submit material for the following sections: Abstracts of recently Image courtesy Adam Block accepted papers (only for papers sent to refereed http://adamblockphotos.com journals), Abstracts
    [Show full text]
  • Photometric Distances to Young Stars in the Inner Galactic Disk II
    A&A 548, A125 (2012) Astronomy DOI: 10.1051/0004-6361/201219653 & c ESO 2012 Astrophysics Photometric distances to young stars in the inner Galactic disk II. The region towards the open cluster Trumpler 27 at L = 355◦,, G. Perren1,R.A.Vázquez2, and G. Carraro3,4 1 Instituto de Física de Rosario, IFIR (CONICET-UNR), Parque Urquiza, 2000 Rosario, Argentina e-mail: [email protected] 2 Facultad de Ciencias Astronómicas y Geofísicas (UNLP), Instituto de Astrofísica de La Plata (CONICET, UNLP), Paseo del Bosque s/n, La Plata, Argentina e-mail: [email protected] 3 ESO, Alonso de Cordova 3107, Casilla 19100 Santiago de Chile, Chile e-mail: [email protected] 4 Dipartimento di Astronomia, Universita’ di Padova, Vicolo Osservatorio 5, 35122 Padova, Italy Received 23 May 2012 / Accepted 17 September 2012 ABSTRACT Context. The spiral structure of the Milky Way inside the solar circle is still poorly known because of the high density of the material that causes strong extinction towards the Galactic center. Aims. We present results of the first extensive and deep color–color diagram (CCD) photometric survey carried out in the field of the open cluster Trumpler 27, an object immersed in a region of extremely high visual absorption in the constellation of Sagittarius not far from the Galaxy center. The survey covers almost a quarter of square degree. Methods. We look for young stars clumps that might plausibly be associated with spiral structure. Wide-field UBVI photometry combined with infrared information allows us to reconstruct the distribution in the reddening and distance of young stars in the field using the CCD and color–magnitude diagrams (CMD).
    [Show full text]
  • The Environmental Impact of High- and Low-Mass Stars: from Formation to Main Sequence
    c 2013 by Ian William Stephens. All rights reserved. THE ENVIRONMENTAL IMPACT OF HIGH- AND LOW-MASS STARS: FROM FORMATION TO MAIN SEQUENCE BY IAN WILLIAM STEPHENS DISSERTATION Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Astronomy in the Graduate College of the University of Illinois at Urbana-Champaign, 2013 Urbana, Illinois Doctoral Committee: Associate Professor Leslie W. Looney, Chair Professor You-Hua Chu Professor Emeritus Richard M. Crutcher Associate Professor Tony Wong Abstract Throughout the entire lifetime of a star, it continuously alters the environment. Diverse processes are involved which complicates studies of stellar interaction. This thesis focuses on two different physical phenomena associated with stars: (1) the interplay of magnetic fields and collapsing clouds, and (2) the effects of radiation from massive stars. We first compare polarization measurements of 52 Galactic star-forming regions with their locations in the Galaxy. In particular, we find that there is no correlation between the average magnetic field direction of star-forming molecular clouds and the Galaxy, indicating that star formation may eventually become its own process independent of the Galaxy. Secondly, we observe the coupling of the magnetic field with the low-mass protostar L1157-mm by creating polarimetric maps at resolutions from 300 to 2500 AU. The inferred magnetic field lines show a well-defined hourglass morphology centered ∼ about the core – only the second of such morphology discovered around a low-mass protostar. Next, we focus on radiation from massive stars in the Large Magellanic Cloud. We first present a survey of H II regions around massive young stellar objects (YSOs) and explore numerous relationship between parameters measured through observations of free-free and infrared emission.
    [Show full text]
  • 254 — 13 February 2014 Editor: Bo Reipurth ([email protected]) List of Contents
    THE STAR FORMATION NEWSLETTER An electronic publication dedicated to early stellar/planetary evolution and molecular clouds No. 254 — 13 February 2014 Editor: Bo Reipurth ([email protected]) List of Contents The Star Formation Newsletter Interview ...................................... 3 My Favorite Object ............................ 5 Editor: Bo Reipurth [email protected] Perspective ................................... 10 Technical Editor: Eli Bressert Abstracts of Newly Accepted Papers .......... 13 [email protected] Abstracts of Newly Accepted Major Reviews . 54 Technical Assistant: Hsi-Wei Yen Dissertation Abstracts ........................ 60 [email protected] New Jobs ..................................... 61 Editorial Board Meetings ..................................... 63 Summary of Upcoming Meetings ............. 66 Joao Alves Alan Boss Short Announcements ........................ 67 Jerome Bouvier New Books ................................... 68 Lee Hartmann Thomas Henning Paul Ho Jes Jorgensen Charles J. Lada Cover Picture Thijs Kouwenhoven Michael R. Meyer This image shows the blueshifted outflow cav- Ralph Pudritz ity from the embedded quadruple Class I source Luis Felipe Rodr´ıguez L1551 IRS5 based on Hα and [SII] images obtained Ewine van Dishoeck with the Subaru telescope images. Two short jets, Hans Zinnecker HH 154, are seen to emerge from the source region to the upper left. The outflow cavity has burst The Star Formation Newsletter is a vehicle for through the front of the cloud, exposing the rich fast distribution of information of interest for as- and complex Herbig-Haro shock structures within. tronomers working on star and planet formation A few faint knots from the HH 30 jet (outside the and molecular clouds. You can submit material field) are visible at the top of the image. The for the following sections: Abstracts of recently field is about 7×8 arcmin, corresponding to about accepted papers (only for papers sent to refereed 0.30×0.35 pc at the assumed distance of 150 pc.
    [Show full text]
  • SEDIGISM: Structure, Excitation, and Dynamics of the Inner Galactic Interstellar Medium
    Kent Academic Repository Full text document (pdf) Citation for published version Schuller, F. and Csengeri, T. and Urquhart, J.S. and Duarte-Cabral, A. and Barnes, P. J. and Giannetti, A. and Hernandez, A. K. and Leurini, S. and Mattern, M. and Medina, S.-N. X. and Agurto, C. and Azagra, F. and Anderson, L. D. and Beltran, M. T. and Beuther, H. (2017) SEDIGISM: Structure, excitation, and dynamics of the inner Galactic interstellar medium. Astronomy & Astrophysics, DOI https://doi.org/10.1051/0004-6361/201628933 Link to record in KAR http://kar.kent.ac.uk/61366/ Document Version Publisher pdf Copyright & reuse Content in the Kent Academic Repository is made available for research purposes. Unless otherwise stated all content is protected by copyright and in the absence of an open licence (eg Creative Commons), permissions for further reuse of content should be sought from the publisher, author or other copyright holder. Versions of research The version in the Kent Academic Repository may differ from the final published version. Users are advised to check http://kar.kent.ac.uk for the status of the paper. Users should always cite the published version of record. Enquiries For any further enquiries regarding the licence status of this document, please contact: [email protected] If you believe this document infringes copyright then please contact the KAR admin team with the take-down information provided at http://kar.kent.ac.uk/contact.html Astronomy & Astrophysics manuscript no. sedigism-intro c ESO 2017 January 20, 2017 SEDIGISM: Structure, excitation, and dynamics of the inner Galactic interstellar medium⋆ F.
    [Show full text]
  • Structure, Excitation, and Dynamics of the Inner Galactic Interstellar Medium
    Faculty Scholarship 1-1-2017 Sedigism: Structure, Excitation, And Dynamics Of The nneI r Galactic Interstellar Medium F. Schuller T. Csengeri J. S. Urquhart L. D. Anderson Follow this and additional works at: https://researchrepository.wvu.edu/faculty_publications Digital Commons Citation Schuller, F.; Csengeri, T.; Urquhart, J. S.; and Anderson, L. D., "Sedigism: Structure, Excitation, And Dynamics Of The nneI r Galactic Interstellar Medium" (2017). Faculty Scholarship. 945. https://researchrepository.wvu.edu/faculty_publications/945 This Article is brought to you for free and open access by The Research Repository @ WVU. It has been accepted for inclusion in Faculty Scholarship by an authorized administrator of The Research Repository @ WVU. For more information, please contact [email protected]. LJMU Research Online Schuller, F, Csengeri, T, Urquhart, JS, Duarte-Cabral, A, Barnes, PJ, Giannetti, A, Hernandez, AK, Leurini, S, Mattern, M, Medina, SNX, Agurto, C, Azagra, F, Anderson, LD, Beltrán, MT, Beuther, H, Bontemps, S, Bronfman, L, Dobbs, CL, Dumke, M, Finger, R, Ginsburg, A, Gonzalez, E, Henning, T, Kauffmann, J, Mac- Auliffe, F, Menten, KM, Montenegro-Montes, FM, Moore, TJT, Muller, E, Parra, R, Perez-Beaupuits, JP, Pettitt, A, Russeil, D, Sánchez-Monge, A, Schilke, P, Schisano, E, Suri, S, Testi, L, Torstensson, K, Venegas, P, Wang, K, Wienen, M, Wyrowski, F and Zavagno, A SEDIGISM: Structure, excitation, and dynamics of the inner Galactic interstellar medium http://researchonline.ljmu.ac.uk/7453/ Article Citation (please note it is advisable to refer to the publisher’s version if you intend to cite from this work) Schuller, F, Csengeri, T, Urquhart, JS, Duarte-Cabral, A, Barnes, PJ, Giannetti, A, Hernandez, AK, Leurini, S, Mattern, M, Medina, SNX, Agurto, C, Azagra, F, Anderson, LD, Beltrán, MT, Beuther, H, Bontemps, S, Bronfman, L, Dobbs, CL, Dumke, M, Finger, R, Ginsburg, A, Gonzalez, E, Henning, T, LJMU has developed LJMU Research Online for users to access the research output of the University more effectively.
    [Show full text]