DOCSLIB.ORG

1959Apj. . .130 . . 178W an INFRARED SURVEY of a REGION

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
1959Apj. . .130 . . 178W an INFRARED SURVEY of a REGION 178W . AN INFRARED SURVEY OF A REGION IN AQUILA .130 . B. Westerlund* Warner and Swasey Observatory, Case Institute of Technology Received December 4, 1958; revised February 4, 1959 1959ApJ. ABSTRACT Spectral classes on the Case infrared system, infrared magnitudes, and red minus infrared colors for 478 red stars are presented. The limiting infrared magnitude of the survey is about 13.0. The data are believed to be complete to 12.25 for the early M stars and 12.75 for the late M stars. The search for M stars was carried out in three areas at galactic longitude 12° and latitudes —8°, — 6?5, and —5°, covering 2 square degrees each. The whole field covered by the plates, of about 20 square degrees, was searched for carbon stars. Only one was found. The surface distribution of the stars shows a latitude effect for the early and intermediate M stars which is hardly apparent for the late M stars. The red minus infrared colors show a marked reddening at 2.5 kpc from the sun but no additional reddening at larger distances. The present analysis deals with stars beyond this distance. A tentative density analysis has been made for the M2-M4 stars. I. INTRODUCTION The present investigation deals with a study of the relatively cool stars in a region in Aquila. The methods are identical with those used in the analysis of a region in Cygnus (Westerlund 1958; hereafter referred to as “Paper I”), with the exception that red minus infrared colors have been measured for this investigation. The fields primarily searched for red stars are three rectangles of 2 square degrees each within the region LF1 discussed for the determination of the luminosity function by McCuskey and Seyfert (1947) and McCuskey (1956). The observational data for the blue classification were given by McCuskey (1949). LF1 is centered at R.A. = 19h27m; Dec. = +6?9; / = 12°; £ = — 7Q (Lund pole). The three rectangles have their bases paral- lel to the galactic equator and the heights equal to Io. They are centered at ¿ = 12° and ¿> = —8° (region A), —6?5 (region B), and —5° (region C), respectively. In the whole area only one carbon star has been identified with certainty. The three rectangles contain a few stars suspected of S-type characteristics and several red variables. II. OBSERVATIONAL MATERIAL The study was carried out on red-sensitive 103a-E and infrared-sensitive I-N Kodak Spectroscopic plates. For spectral classification most of the I-N plates were hypersensi- tized as described in Paper I. Table 1 gives the data of the plates. In the last column “88A,” ‘W/’ and “89B” refer to Wratten filters and “RGl” to the Schott filter. All the plates were taken with the Schmidt telescope of the Warner and Swasey Observatory except U 70, which was taken with the Uppsala Schmidt telescope at Mount Stromlo Observatory. The dispersion in the Uppsala Schmidt spectra is about 2200 A/mm at the A band, which makes it possible to follow the classification system of the 4° prism Case plates. III. APPARENT AND ABSOLUTE MAGNITUDES: SPECTRAL CLASSIFICATION The red and infrared magnitude sequences were primarily based on 30 stars of spectral types B and A for which photographic (wPg) and red (wv) magnitudes had been deter- mined by McCuskey (1949). The method of Paper I was used to derive the infrared magnitudes (wir) and to correct for the differences between filters 88A and 89. * Now at Uppsala Southern Station, Mount Stromlo Observatory, Canberra, Australia. 178 © American Astronomical Society • Provided by the NASA Astrophysics Data System 178W . INFRARED SURVEY 179 .130 . The red magnitude scale was extended to wpr =15 mag. by aid of one plate exposed with a neutral half-filter. It has been shown (Westerlund 1956) that filter constants may vary from one plate to the other and from one half of the plate to the other (Nassau 1959ApJ. and Burger 1946). Therefore, the extension was carried out for each half of the plate 1 by aid of the relation derived for that half for stars brighter than mpr = 13. The magnitudes of most of the stars are mean values from measurements on three plates. For most of the variables details are given in Table 6. The probable error of a single magnitude determination was found to be ±0.07 mag. in the infrared. The error in color for the catalogue stars is ± 0*07 mag. for stars brighter than miV = 12.0 mag. and ±0.10 mag. for the fainter ones. As the infrared TABLE 1 Data of the Plates Plate No. Exposure and Prism (minutes) Filter Spectral Plates 914-4.. 1947, June 18 2708-2, 1951, Aug. 10 3457-2, 1953, July 24 4268-4 1956, June 12 4273-4. 1956, July 29 4301-4. 1956, Sept. 2 7 U 70... 1957, July 18 Direct Plates 2996. 1952, May 29 89 3706. 1956, June 9 88A 3709. 1956, June 10 RG1 3710. 1956, June 10 RGl±neutral 3712. 1956, July 17 RG1 3715. 1956, July 17 88A absolute magnitudes of the early M stars, —3.0 mag. has been adopted and, for the late M stars, —4.0 mag., in agreement with Paper I. The spectral classification follows the Case system, referred to in Paper I. IV. THE INTRINSIC COLORS According to Kron and Smith (1951), the zero point of the Case red system (rar) does not deviate appreciably from their photoelectric system, R. The methods used for the determination of the zero points and the scales of the infrared magnitudes, Wir and /, respectively, are such as to make a fairly close agreement between the color indices wr — Wir and R — I likely. It therefore seems worthwhile to try to obtain the intrinsic colors (wr — Wir)o from the more accurate photoelectric measurements. For this the 1 Experience shows that the characteristic curves of the plates will be straight lines over a considerable magnitude interval when measured in a suitably set Haffner-type iris-diaphragm photometer. For the present red plates, straight lines could be expected to wpr = 16 mag. The extended magnitude scale gives a characteristic curve completely coinciding with the extrapolated line. This may be taken as a proof of the accuracy of the extension. © American Astronomical Society • Provided by the NASA Astrophysics Data System 178W . 180 B. WESTERLUND .130 . value oí R — / is needed for unreddened bright stars. However, in the existing catalogues on the R, I system no measurements for M giants are available (Kron and Smith 1951; Kxon 1953; Kron and Gascoigne 1953; Kron, White, and Gascoigne 1953; Kron, Gas- 1959ApJ. coigne, and White 1957). In the six-color photometry (Stebbins and Whitford 1945; Stebbins and Kron 1956) red and infrared measures, R§ and /e, are available for a number of M giants. The colors {R — /)e can be reduced to — / by aid of the ÑPS stars in common to the two systems. The following relation has been used: R — I = 0.69 {R — I) 6+0.24 . The Mount Wilson spectral types used in the six-color photometry have been reduced to the Case system by aid of the relation given by Nassau and van Albada (1949). The mean colors for ordinary giant stars of classes M2, M3, M4, and M5 thus derived, (R — /)o, are given in Table 9, line 4. No consideration of eventual variations of the color within the range of the luminosity of the giant class has been taken, the only luminosity classification possible in the Case system being the separation of supergiants. An independent determination of the intrinsic colors (tnx — Wir)o of the M2-M5 stars is discussed in Section VII. V. THE CATALOGUE Tables 2, 3, and 4 give the data for all red stars identified in regions A, B, and C. The first column gives the number of the star for its identification on the charts (Figs, la, 1£, 1c) ; the second, the spectral type with the letter M omitted; the third, the infrared magnitude; the fourth, the red minus infrared color index. The stars are listed in order of galactic longitude. For the orientation of the charts a number of bright BD stars have been identified and marked (Table 5). Also, some stars common to both McCuskey’s catalogue (1949) and the present one are noted in the “Remarks” to the catalogue. The asterisks indicate new or earlier known variables (relisted in Table 6) ; the symbol f suspected variables of type M6.5 and earlier. VI. THE VARIABLES The whole field seems rich in variables and worth observing for spectral variations as well as magnitude and color variations over a longer period. At present the discussion is limited to the presentation of the available data for the stars known to be variables or suspected of variability according to the General Catalogue of Variable Stars (8 stars) and for 28 other stars showing pronounced variation in spectral type or magnitude (Table 6). Most stars of types M7 and later are certainly variables (cf. Paper I). VII. THE INTERSTELLAR ABSORPTION The total photographic absorption (APg) in LF1 amounts to 2.8 mag. at a distance from the sun of 2.5 kpc (McCuskey and Seyfert 1947; McCuskey 1956). With a ratio of total infrared absorption (Air) to the photographic of 3:8 we find Air = 1.05 mag. at that distance. Table 7 gives the observed distribution of the M2-M4, M5-M6.5, and M7-M10 stars for the three regions; N(m) = number of stars per square degree brighter than the magnitude miT. Figure 2 shows the corresponding cumulative Wolf diagrams for the M2-M4 stars.
Load more

Recommended publications
  • Early Stages of Massive Star Formation
    Early Stages of Massive Star Formation Vlas Sokolov Munchen¨ 2018 Early Stages of Massive Star Formation Vlas Sokolov Dissertation an der Fakultat¨ fur Physik der Ludwig–Maximilians–Universitat¨ Munchen¨ vorgelegt von Vlas Sokolov aus Kyjiw, Ukraine Munchen,¨ den 13 Juli 2018 Erstgutachter: Prof. Dr. Paola Caselli Zweitgutachter: Prof. Dr. Markus Kissler-Patig Tag der mundlichen¨ Prufung:¨ 27 August 2018 Contents Zusammenfassung xv Summary xvii 1 Introduction1 1.1 Overview......................................1 1.2 The Interstellar Medium..............................2 1.2.1 Molecular Clouds..............................5 1.3 Low-mass Star Formation..............................9 1.4 High-Mass Star and Cluster Formation....................... 12 1.4.1 Observational perspective......................... 14 1.4.2 Theoretical models............................. 16 1.4.3 IRDCs as the initial conditions of massive star formation......... 18 1.5 Methods....................................... 20 1.5.1 Radio Instrumentation........................... 20 1.5.2 Radiative Processes in the Dark Clouds.................. 22 1.5.3 Blackbody Dust Emission......................... 23 1.5.4 Ammonia inversion transitions....................... 26 1.6 This Thesis..................................... 28 2 Temperature structure and kinematics of the IRDC G035.39–00.33 31 2.1 Abstract....................................... 31 2.2 Introduction..................................... 32 2.3 Observations.................................... 33 2.3.1 GBT observations............................
    [Show full text]
  • The Galaxy in Context: Structural, Kinematic & Integrated Properties
    The Galaxy in Context: Structural, Kinematic & Integrated Properties Joss Bland-Hawthorn1, Ortwin Gerhard2 1Sydney Institute for Astronomy, School of Physics A28, University of Sydney, NSW 2006, Australia; email: [email protected] 2Max Planck Institute for extraterrestrial Physics, PO Box 1312, Giessenbachstr., 85741 Garching, Germany; email: [email protected] Annu. Rev. Astron. Astrophys. 2016. Keywords 54:529{596 Galaxy: Structural Components, Stellar Kinematics, Stellar This article's doi: 10.1146/annurev-astro-081915-023441 Populations, Dynamics, Evolution; Local Group; Cosmology Copyright c 2016 by Annual Reviews. Abstract All rights reserved Our Galaxy, the Milky Way, is a benchmark for understanding disk galaxies. It is the only galaxy whose formation history can be stud- ied using the full distribution of stars from faint dwarfs to supergiants. The oldest components provide us with unique insight into how galaxies form and evolve over billions of years. The Galaxy is a luminous (L?) barred spiral with a central box/peanut bulge, a dominant disk, and a diffuse stellar halo. Based on global properties, it falls in the sparsely populated \green valley" region of the galaxy colour-magnitude dia- arXiv:1602.07702v2 [astro-ph.GA] 5 Jan 2017 gram. Here we review the key integrated, structural and kinematic pa- rameters of the Galaxy, and point to uncertainties as well as directions for future progress. Galactic studies will continue to play a fundamen- tal role far into the future because there are measurements that can only be made in the near field and much of contemporary astrophysics depends on such observations. 529 Redshift (z) 20 10 5 2 1 0 1012 1011 ) ¯ 1010 M ( 9 r i 10 v 8 M 10 107 100 101 102 ) c p 1 k 10 ( r i v r 100 10-1 0.3 1 3 10 Time (Gyr) Figure 1 Left: The estimated growth of the Galaxy's virial mass (Mvir) and radius (rvir) from z = 20 to the present day, z = 0.
    [Show full text]
  • The Supernova Remnant W49B As Seen with H.E.S.S
    PUBLISHED VERSION H.E.S.S. Collaboration: H. Abdalla … R. Blackwell … P. DeWilt … J. Hawkes … J. Lau … N. Maxted … G. Rowell … F. Voisin … et al. The supernova remnant W49B as seen with H.E.S.S. and Fermi-LAT Astronomy and Astrophysics, 2018; 612:A5-1-A5-10 © ESO 2018 Originally published: http://dx.doi.org/10.1051/0004-6361/201527843 PERMISSIONS https://www.aanda.org/index.php?option=com_content&view=article&id=863&Itemid=2 95 Green Open Access The Publisher and A&A encourage arXiv archiving or self-archiving of the final PDF file of the article exactly as published in the journal and without any period of embargo. 19 September 208-18 http://hdl.handle.net/2440/112084 A&A 612, A5 (2018) Astronomy DOI: 10.1051/0004-6361/201527843 & c ESO 2018 Astrophysics H.E.S.S. phase-I observations of the plane of the Milky Way Special issue The supernova remnant W49B as seen with H.E.S.S. and Fermi-LAT? H.E.S.S. Collaboration: H. Abdalla1, A. Abramowski2, F. Aharonian3,4,5, F. Ait Benkhali3, A. G. Akhperjanian5; 6,y, T. Andersson10, E. O. Angüner7, M. Arrieta15, P. Aubert24, M. Backes8, A. Balzer9, M. Barnard1, Y. Becherini10, J. Becker Tjus11, D. Berge12, S. Bernhard13, K. Bernlöhr3, R. Blackwell14, M. Böttcher1, C. Boisson15, J. Bolmont16, P. Bordas3, J. Bregeon17, F. Brun26,??, P. Brun18, M. Bryan9, T. Bulik19, M. Capasso29, J. Carr20, S. Casanova21,3, M. Cerruti16, N. Chakraborty3, R. Chalme-Calvet16, R.C. G. Chaves17,22, A. Chen23, J. Chevalier24, M. Chrétien16, S.
    [Show full text]
  • Pga 183525.Pdf
    Condensed Technical Program USNC/URSI 15-19 May 1978 MONDAY, 15 MAY Room 0900-1200 B-1 Electromagnetics 0105 B-2 SEM 0109 E-1 Lightning, Spherics and Noise (Joint with F and H) 1105 1330-1700 B-3 Thin Wires 0105 B-4 Inverse Scattering and Profile Reconstruction 0109 E-2 CCIR Panel Discussion (Joint with F) 1105 F-1 Oceanography 1109 1700 Commission E Business Meeting 1105 1715 Commission B Business Meeting 0105 TUESDAY, 16 MAY 0830-1200 B-5 Scattering 0109 C-1 Impairments to Earth-Satellite Transmission 1101 F-2 Remote Sensing of the Atmosphere from Space 1109 1330-1700 B-6 Transmission Lines 0109 C-2 System Aspects of Antennas and Dual Polarization 1101 Transmission F-3 Scattering by Random Media and Rough Surfaces (Joint with 1109 AP-S and B) G-1 HF Radio Wave Absorption and Heating Effects 0123 1700 Commission C Business Meeting 1101 Commission F Business Meeting 0123 Commission H Business Meeting 0123 (continued on inside back cover) United States National Connnittee INTERNATIONAL UNION.OF RADIO SCIENCE PROGRAM AND ABSTRACTS 1978 Spring Meeting May 15-19 Held Jointly with ANTENNAS AND PROPAGATION SOCIETY INSTITUTE OF ELECTRICAL AND ELECTRONICS ENGINEERS Washington, D.C. ]!Q:!!: Programs and Abstracts of the USNC/URSI Meetings are available from: USNC/URSI National Academy of Sciences 2101 Constitution Avenue, N.W. Washington, D.C. 20418 at $2 for meetings prior to 1970, $3 for 1971-75 meetings, and $5 for 1976-78 meetings. The full papers are not published in any collected format; requests for them should be addressed to the authors who may have them published on their own initiative.
    [Show full text]
  • VI. Dense Gas and Mini-Starbursts in the W43 Giant Molecular Cloud Complex
    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 FUJITA1,3∗, Atsushi NISHIMURA1,3, Nario KUNO4,5,12, Tomofumi UMEMOTO2,6, Tetsuhiro MINAMIDANI2,6,7, Mitsuhiro MATSUO2, Ryosuke KIRIDOSHI3, Kazuki TOKUDA3,7, Misaki HANAOKA1, Yuya TSUDA8, Mika KURIKI4, Akio OHAMA1, Hidetoshi SANO1,7,9, 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),
    [Show full text]
  • Structure and Kinematics of the Clouds Surrounding the Galactic Mini-Starburst W43 MM1 T
    A&A 595, A66 (2016) Astronomy DOI: 10.1051/0004-6361/201628653 & c ESO 2016 Astrophysics Structure and kinematics of the clouds surrounding the Galactic mini-starburst W43 MM1 T. Jacq1, J. Braine1, F. Herpin1, F. van der Tak2; 4, and F. Wyrowski3 1 Laboratoire d’Astrophysique de Bordeaux, Univ. Bordeaux, CNRS, B18N, Allée Geoffroy Saint-Hilaire, 33615 Pessac, France e-mail: [email protected] 2 SRON Netherlands Institute for Space Research, PO Box 800, 9700AV Groningen, The Netherlands 3 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany 4 Kapteyn Astronomical Institute, University of Groningen, 9712 CP Groningen, The Netherlands Received 6 April 2016 / Accepted 28 July 2016 ABSTRACT Massive stars have a major influence on their environment, yet their formation is difficult to study as they form quickly in highly obscured regions and are rare, hence more distant than lower mass stars. Westerhout 43 (W43) is a highly luminous galactic massive star-forming region at a distance of 5.5 kpc and the MM1 part hosts a particularly massive dense core (1000 M within 0.05 pc). We present new Herschel HIFI maps of the W43 MM1 region covering the main low-energy water lines at 557, 987, and 1113 GHz; 18 13 18 their H2 O counterparts; and other lines such as CO (10–9) and C O (9–8), which trace warm gas. These water lines are, with the exception of line wings, observed in absorption. Herschel SPIRE and JCMT 450 µm data have been used to make a model of the continuum emission at the HIFI wavelengths.
    [Show full text]
  • RADIO EMISSION from 16 POSSIBLE SUPERNOVA REMNANTS by D. K. MILNE* and E. R. HILL* 1. INTRODUCTION There Are Some 40 Radio Sourc
    RADIO EMISSION FROM 16 POSSIBLE SUPERNOVA REMNANTS By D. K. MILNE* and E. R. HILL* [Manuscript received August 29, 1968] Summary Sixteen radio sources, thought to be supernova remnants, have been observed at several frequencies between 408 and 2700 MHz. These data, together with previously published observations, have been used to derive spectra for these sources. The validity of the supernova remnant classification of certain of these sources is questioned. 1. INTRODUCTION There are some 40 radio sources classified in the literature as remnants of galactic supernovae. T:Q.e identification of these objects has generally followed the rules: (1) The radio spectrum is nonthermal. (2) The angular size is large enough to exclude identification as an external galaxy. (3) The object should be a population I member (i.e. within 250 pc of the galactic plane). (4) If the source is visible optically, then it should not be an HII region, and preferably should show some of the characteristic filamentary structure usually associated with supernova remnants. (5) A radio brightness distribution indicating a shell structure. To date the radio data available for these objects have been scant, particularly for certain of the southern sources. Within the range of the Parkes 210 ft radio telescope (declination +27° to -90°) there are 24 radio sources classified as galactic supernova remnants. Some of these have been examined using the Parkes facilities (e.g. Gardner and Milne 1965; Hill 1967 ; Whiteoak and Gardner 1967; Milne 1968a) whilst for the other remnants often the only data available are from the low-resolution galactic surveys (e.g.
    [Show full text]
  • Structure and Kinematics of the Clouds Surrounding the Galactic Mini-Starburst W43 MM1 Jacq, T.; Braine, J.; Herpin, F.; Van Der Tak, F.; Wyrowski, F
    University of Groningen Structure and kinematics of the clouds surrounding the Galactic mini-starburst W43 MM1 Jacq, T.; Braine, J.; Herpin, F.; van der Tak, F.; Wyrowski, F. Published in: Astronomy and astrophysics DOI: 10.1051/0004-6361/201628653 IMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite from it. Please check the document version below. Document Version Publisher's PDF, also known as Version of record Publication date: 2016 Link to publication in University of Groningen/UMCG research database Citation for published version (APA): Jacq, T., Braine, J., Herpin, F., van der Tak, F., & Wyrowski, F. (2016). Structure and kinematics of the clouds surrounding the Galactic mini-starburst W43 MM1. Astronomy and astrophysics, 595(November 2016 ), [A66]. https://doi.org/10.1051/0004-6361/201628653 Copyright Other than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons). The publication may also be distributed here under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license. More information can be found on the University of Groningen website: https://www.rug.nl/library/open-access/self-archiving-pure/taverne- amendment. Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal.
    [Show full text]
  • The Bones of the Milky Way.Pdf (6.732Mb)
    The Bones of the Milky Way The Harvard community has made this article openly available. Please share how this access benefits you. Your story matters Citation Goodman, Alyssa A., João Alves, Christopher N. Beaumont, Robert A. Benjamin, Michelle A. Borkin, Andreas Burkert, Thomas M. Dame et al. "The bones of the Milky Way." The Astrophysical Journal 797, no. 1 (2014): 53. Published Version doi:10.1088/0004-637X/797/1/53 Citable link http://nrs.harvard.edu/urn-3:HUL.InstRepos:12655583 Terms of Use This article was downloaded from Harvard University’s DASH repository, and is made available under the terms and conditions applicable to Open Access Policy Articles, as set forth at http:// nrs.harvard.edu/urn-3:HUL.InstRepos:dash.current.terms-of- use#OAP The Bones of the Milky Way Alyssa A. Goodman Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 Jo~aoAlves University of Vienna, 1180 Vienna, Austria Christopher N. Beaumont Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 Robert A. Benjamin University of Wisconsin-Whitewater, Whitewater, WI 53190 Michelle A. Borkin Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 Andreas Burkert University of Munich, Munich, Germany Thomas M. Dame Smithsonian Astrophysical Observatory, Cambridge, MA 02138 James Jackson Boston University, Boston, MA 02215 Jens Kauffmann California Institute of Technology, Pasadena, CA 91125 Thomas Robitaille Max Planck Institute for Astronomy, Heidelberg, Germany Received ; accepted To appear in The Astrophysical Journal (ApJ) –2– ABSTRACT The very long and thin infared dark cloud “Nessie” is even longer than had been previously claimed, and an analysis of its Galactic location suggests that it lies directly in the Milky Way’s mid-plane, tracing out a highly elongated bone- like feature within the prominent Scutum-Centaurus spiral arm.
    [Show full text]
  • The O-And B-Type Stellar Population in W3: Beyond the High-Density Layer
    Accepted to ApJ: 30 August 2015 A Preprint typeset using LTEX style emulateapj v. 08/22/09 THE O- AND B-TYPE STELLAR POPULATION IN W3: BEYOND THE HIGH-DENSITY LAYER Megan M. Kiminki1, Jinyoung Serena Kim1, Micaela B. Bagley1,2, William H. Sherry3,4, and George H. Rieke1 Accepted to ApJ: 30 August 2015 ABSTRACT We present the first results from our survey of the star-forming complex W3, combining V RI pho- tometry with multiobject spectroscopy to identify and characterize the high-mass stellar population across the region. With 79 new spectral classifications, we bring the total number of spectroscopically- confirmed O- and B-type stars in W3 to 105. We find that the high-mass slope of the mass function in W3 is consistent with a Salpeter IMF, and that the extinction toward the region is best characterized by an RV of approximately 3.6. B-type stars are found to be more widely dispersed across the W3 giant molecular cloud (GMC) than previously realized: they are not confined to the high-density layer (HDL) created by the expansion of the neighboring W4 H II region into the GMC. This broader B-type population suggests that star formation in W3 began spontaneously up to 8–10 Myr ago, although at a lower level than the more recent star formation episodes in the HDL. In addition, we describe a method of optimizing sky subtraction for fiber spectra in regions of strong and spatially-variable nebular emission. Subject headings: dust, extinction — open clusters and associations: individual (Westerhout 3) — stars: early-type — stars: formation — stars: luminosity function, mass function 1.
    [Show full text]
  • Star Formation and Molecular Clouds Towards the Galactic Anti-Center
    Handbook of Star Forming Regions Vol. I Astronomical Society of the Pacific, c 2008 Bo Reipurth, ed. Star Formation and Molecular Clouds towards the Galactic Anti-Center Bo Reipurth Institute for Astronomy, University of Hawaii 640 N. Aohoku Place, Hilo, HI 96720, USA Chi-Hung Yan Institute of Astronomy and Astrophysics, Academia Sinica P.O. Box 23-141, Taipei 10617, Taiwan National Taiwan Normal University 88 Sec. 4, Tingzhou Road, Taipei, 11766, Taiwan Abstract. The Galactic Anticenter region hosts a a number of massive molecular cloud complexes, some of which are currently actively forming stars. Two major OB associations, Gem OB1 and Aur OB1, are found in this direction, each with numerous massive stars and a supernova remnant. The dominant region of star formation is cen- tered around the Sh 2-235 complex and the nearby regions AFGL 5142, 5144, and 5157 towards Aur OB1. Studies of these regions have long been affected by relatively poor distance determinations, although there is general consensus that most regions are lo- cated at distances between 1.5 and 2 kpc. A number of well-known, relatively isolated Herbig Ae/Be stars are found in this general direction, including RR Tau, HD 250550, and LkHα 208. 1. Overview The region towards the Galactic Anticenter is rich in molecular clouds and star forma- tion activity, although most is located at a considerable distance. In this chapter, we summarize key features of the principal regions of star formation out to approximately 2 kpc. A number of very interesting regions exist at larger distances, but those are be- yond the scope of this review.
    [Show full text]
  • Submitted to the Combined Faculties for the Natural Sciences and For
    Dissertation submitted to the Combined Faculties for the Natural Sciences and for Mathematics of the Ruperto-Carola University of Heidelberg, Germany for the degree of Doctor of Natural Sciences presented by Diplom-Physikerin Jessica Agarwal Born in Kiel, Germany Oral examination: 26 July 2007 The Emission of Large Dust Particles from Comet 67P/Churyumov-Gerasimenko Constrained by Observation and Modelling of its Dust Trail Referees: Prof. Dr. Eberhard Grun¨ Simon F. Green, PhD Zusammenfassung. Gegenstand der Arbeit ist die Untersuchung von Staubteilchen des Kometen 67P/Chur- yumov-Gerasimenko, die großer¨ als 60µm sind. Zu diesem Zweck werden astronomische Bilder des Staub-Trails dieses Kometen ausgewertet. Solche Teilchen stellen den großten¨ Teil der Staubmasse dar, die von Kometen in den interplanetaren Raum eingetragen wer- den. Im Gegensatz zu kleineren Teilchen verbleiben sie auf Trajektorien, die der des Ko- meten sehr ahnlich¨ sind. Dem Beobachter erscheinen sie als eine schmale Struktur entlang des projizierten Kometenorbits, die als Staub-Trail bezeichnet wird. Die erste im Rahmen dieser Arbeit untersuchte Beobachtung wurde im April 2004 in sichtbarem Licht mit dem Wide Field Imager am ESO/MPG-2.2m-Teleskop auf La Silla (Chile) durchgefuhrt.¨ Der Abstand des Kometen von der Sonne betrug zu diesem Zeitpunkt 4.7 A.E. Zwei weitere Beobachtungen wurden im August 2005 und im April 2006 im mittleren Infrarot (24 µm) ausgefuhrt¨ mit der MIPS-Kamera auf dem Spitzer-Weltraumteleskop. In beiden Fallen¨ war der Komet 5.7 A.E. von der Sonne entfernt. In der dazwischenliegenden Zeit, im No- vember 2005, hatte er das Aphel passiert. Zur Interpretation der Daten werden simulierte Trailbilder erzeugt.
    [Show full text]