Thesisthesis We Analyzed a Large Sample of Young Stars,, Coveringcovering Aa Massmass Rangerange of ~2 to ~20 Solar Masses

Total Page:16

File Type:pdf, Size:1020Kb

Thesisthesis We Analyzed a Large Sample of Young Stars,, Coveringcovering Aa Massmass Rangerange of ~2 to ~20 Solar Masses UvA-DARE (Digital Academic Repository) Dusty disks around young stars Verhoeff, A. Publication date 2009 Document Version Final published version Link to publication Citation for published version (APA): Verhoeff, A. (2009). Dusty disks around young stars. General rights 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), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. UvA-DARE is a service provided by the library of the University of Amsterdam (https://dare.uva.nl) Download date:06 Oct 2021 Dusty Disks around Dusty Disks around Stars are formed through the collapse of giant molecular clouds.. During this contraction the matter spins up and naturally forms a circumstellar disk.. OnceOnce accretionaccretion comescomes toto aa halt,halt, thesethese disksdisks arare relatively stable.. SomeSome disksdisks areare kknown to last up to 10 Myrs.. MostMost disks however,, dissipatedissipate onon shorshorter time scales under the inuence of photoevaporation and planet formation. These disks,, consistingconsisting of 99% gas and 1% dust, have revealed a high variety of dust composition and geometry.. IIt is not clear what determines this variety and if higher mass stars also display this variety.. InIn thisthis thesisthesis we analyzed a large sample of young stars,, coveringcovering aa massmass rangerange of ~2 to ~20 solar masses.. MMidid infraredinfrared imagingimaging andand specspectroscopy have been obtained, to determine their composition and geometry. The results were placed in a multi-wavelength context as provided Y Y oung Stars oung Stars by the literature and a survey for any possible trends was carried out. In addition, case studies were perfoformed of two special stars.. Comprehensive data sets were gathered and a radiative transfer code was used to create detailed models of their disk geometry. Arjan Arjan Dusty Disks around Dusty Disks around Verhoe Verhoe Y Y oung Stars oung Stars Arjan Arjan Verhoe Verhoe Dusty Disks around Young Stars Arjan Verhoe Dusty Disks around Young Stars Academisch Proefschrift ter verkrijging van de graad van doctor aan de Universiteit van Amsterdam op gezag van de Rector Magnificus prof. dr. D. C. van den Boom ten overstaan van een door het college voor promoties ingestelde commissie, in het openbaar te verdedigen in de Agnietenkapel op dinsdag 10 november 2009, te 12:00 uur door Arjan Verhoeff geboren te Soest Promotiecommissie Promotores Prof. dr. L. B. F. M. Waters Prof. dr. A. G. G. M. Tielens Co-promotor Prof. dr. J. W. Pel Overige leden Dr. E. Pantin Dr. M. Min Dr. M. van den Ancker Prof. dr. A. de Koter Prof. dr. C. Dominik Prof. dr. M. B. M. van der Klis Faculteit der Natuurwetenschappen, Wiskunde en Informatica Cover Illustration: Artist impression of a dusty disk around a young star. Credit: NASA/JPL- Caltech. Contents 1 Introduction 9 1.1 Homo Astronomiae . 9 1.2 Star and Planet Formation . 9 1.3 Protoplanetary Disks . 10 1.3.1 Structure . 12 1.3.2 Composition . 14 1.3.3 Evolution . 16 1.4 Diagnostics . 18 1.4.1 Observations . 18 1.4.2 VISIR . 20 1.5 Questions . 24 2 VISIR spectroscopic and spatial survey of Herbig Ae stars 27 2.1 Introduction . 28 2.2 Sample . 30 2.2.1 Selection . 30 2.2.2 Stellar parameters . 31 2.2.3 SEDs and IR-excess . 31 2.3 Observations . 33 2.3.1 VISIR . 33 2.3.2 ISO, Spitzer & TIMMI2 . 33 2.4 Data Reduction . 34 2.4.1 Spectral extraction . 34 2.4.2 FWHM extraction . 35 2.5 The PSF . 36 2.6 Results . 41 2.6.1 Spectra . 41 2.6.2 Spatial extension of science targets . 44 2.6.3 Comparing flux and extent . 47 2.7 Analysis . 47 2.7.1 Feature strength . 47 2.7.2 Deconvolution of the continuum . 52 2.7.3 Deconvolution of the PAH-features . 52 2.8 Discussion of individual stars . 54 2.9 Discussion . 60 5 6 Contents 2.9.1 PAH and silicate strength . 62 2.9.2 Disk sizes in the continuum . 63 2.9.3 Disk sizes in PAH emission . 64 2.10 Conclusions . 65 3 A mid IR study of Herbig Be stars 67 3.1 Introduction . 67 3.2 Sample . 69 3.2.1 Selection . 69 3.2.2 SEDs . 72 3.2.3 Stellar parameters . 72 3.3 Observations . 75 3.3.1 Imaging . 75 3.3.2 Spectroscopy . 76 3.4 Data reduction . 76 3.5 Analysis of the images . 79 3.5.1 Photometry . 79 3.5.2 Spatial emission profile . 84 3.6 Analysis of the spectra . 88 3.6.1 Extinction correction . 88 3.6.2 Compositional fits . 88 3.6.3 Spatial extent . 90 3.6.4 Differential extractions . 93 3.7 Discussion . 95 3.7.1 IR-excess . 95 3.7.2 PAHs . 97 3.7.3 Silicates . 99 3.7.4 IR extent . 101 3.7.5 Relation to B[e] and classical Be stars . 101 3.7.6 Emerging picture . 102 3.8 Conclusions . 103 4 HD 95881: A gas rich to gas poor transition disk? 105 4.1 Introduction . 105 4.2 Stellar parameters . 108 4.3 Observations . 108 4.3.1 AMBER . 108 4.3.2 VISIR imaging . 109 4.3.3 VISIR spectroscopy . 109 4.3.4 MIDI . 109 Contents 7 4.3.5 Additional data . 110 4.4 Analysis . 110 4.4.1 AMBER . 110 4.4.2 [O I] data . 112 4.4.3 Spitzer . 113 4.4.4 VISIR imaging . 113 4.4.5 VISIR spectroscopy . 115 4.4.6 MIDI . 117 4.4.7 Observational picture . 118 4.5 Modeling . 120 4.5.1 Initial constraints . 120 4.5.2 Fitting the SED . 121 4.5.3 Spatial distribution of the gas . 122 4.5.4 Final model . 123 4.6 Discussion . 124 4.6.1 Comparison of the model with the observations . 124 4.6.2 The distribution of gas and dust . 126 4.6.3 Context . 126 4.6.4 PAH emission . 127 4.7 Conclusions . 127 5 The complex circumstellar environment of HD 142527 129 5.1 Introduction . 129 5.2 Stellar Parameters . 130 5.3 Observations and data reduction . 132 5.3.1 SEST . 132 5.3.2 ATCA . 133 5.3.3 VISIR imaging . 134 5.3.4 VISIR spectroscopy . 135 5.3.5 Additional data . 136 5.4 Analysis of the millimeter data . 136 5.5 Analysis of the Spitzer spectrum . 137 5.6 VISIR imaging analysis . 138 5.6.1 The observed images . 138 5.6.2 Central component subtraction . 139 5.6.3 18.72 versus 24.5 µm . 140 5.6.4 Deconvolution . 141 5.7 VISIR spectroscopy analysis . 144 5.7.1 N-band . 144 8 Contents 5.7.2 Q-band . 145 5.8 Modeling . 148 5.8.1 Fitting the observations . 148 5.8.2 Final Model . 150 5.9 Discussion . 151 5.9.1 Comparison of the model with the observations . 151 5.9.2 General picture . ..
Recommended publications
  • Spiral Arms in Disks: Planets Or Gravitational Instability?
    Spiral Arms in Disks: Planets or Gravitational Instability? Item Type Article Authors Dong, Ruobing; Najita, Joan R.; Brittain, Sean Citation Ruobing Dong et al 2018 ApJ 862 103 DOI 10.3847/1538-4357/aaccfc Publisher IOP PUBLISHING LTD Journal ASTROPHYSICAL JOURNAL Rights © 2018. The American Astronomical Society. Download date 27/09/2021 14:50:30 Item License http://rightsstatements.org/vocab/InC/1.0/ Version Final published version Link to Item http://hdl.handle.net/10150/631109 The Astrophysical Journal, 862:103 (19pp), 2018 August 1 https://doi.org/10.3847/1538-4357/aaccfc © 2018. The American Astronomical Society. Spiral Arms in Disks: Planets or Gravitational Instability? Ruobing Dong (董若冰)1,2 , Joan R. Najita3, and Sean Brittain3,4 1 Department of Physics & Astronomy, University of Victoria, Victoria BC V8P 1A1, Canada 2 Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721, USA; [email protected] 3 National Optical Astronomical Observatory, 950 North Cherry Avenue, Tucson, AZ 85719, USA; [email protected] 4 Department of Physics & Astronomy, 118 Kinard Laboratory, Clemson University, Clemson, SC 29634-0978, USA; [email protected] Received 2018 May 8; revised 2018 June 2; accepted 2018 June 13; published 2018 July 27 Abstract Spiral arm structures seen in scattered-light observations of protoplanetary disks can potentially serve as signposts of planetary companions. They can also lend unique insights into disk masses, which are critical in setting the mass budget for planet formation but are difficult to determine directly. A surprisingly high fraction of disks that have been well studied in scattered light have spiral arms of some kind (8/29), as do a high fraction (6/11) of well- studied Herbig intermediate-mass stars (i.e., Herbig stars >1.5 Me).
    [Show full text]
  • TESTING MODELS of LOW-EXCITATION PHOTODISSOCIATION REGIONS with FAR-INFRARED OBSERVATIONS of REFLECTION NEBULAE Rolaine C
    The Astrophysical Journal, 578:885–896, 2002 October 20 # 2002. The American Astronomical Society. All rights reserved. Printed in U.S.A. TESTING MODELS OF LOW-EXCITATION PHOTODISSOCIATION REGIONS WITH FAR-INFRARED OBSERVATIONS OF REFLECTION NEBULAE Rolaine C. Young Owl Department of Physics and Astronomy, University of California at Los Angeles, Mail Code 156205, Los Angeles, CA 90095-1562 Margaret M. Meixner1 and David Fong Department of Astronomy, University of Illinois, Urbana, IL 61801; [email protected], [email protected] Michael R. Haas NASA Ames Research Center, MS 245-6, Moffett Field, CA 94035-1000; [email protected] Alexander L. Rudolph1 Department of Physics, Harvey Mudd College, 301 East 12th Street, Claremont, CA 91711; [email protected] and A. G. G. M. Tielens Kapteyn Astronomical Institute, P.O. Box 800, 9700 AV Groningen, Netherlands; [email protected] Received 2001 August 2; accepted 2002 June 24 ABSTRACT This paper presents Kuiper Airborne Observatory observations of the photodissociation regions (PDRs) in nine reflection nebulae. These observations include the far-infrared atomic fine-structure lines of [O i]63 and 145 lm, [C ii] 158 lm, and [Si ii]35lm and the adjacent far-infrared continuum to these lines. Our analysis of these far-infrared observations provides estimates of the physical conditions in each reflection nebula. In our sample of reflection nebulae, the stellar effective temperatures are 10,000–30,000 K, the gas densities are 4 Â 102 2 Â 104 cmÀ3, the gas temperatures are 200–690 K, and the incident far-ultraviolet intensities are 300–8100 times the ambient interstellar radiation field strength (1:2 Â 10À4 ergs cmÀ2 sÀ1 srÀ1).
    [Show full text]
  • The Epsilon Chamaeleontis Young Stellar Group and The
    The ǫ Chamaeleontis young stellar group and the characterization of sparse stellar clusters Eric D. Feigelson1,2, Warrick A. Lawson2, Gordon P. Garmire1 [email protected] ABSTRACT We present the outcomes of a Chandra X-ray Observatory snapshot study of five nearby Herbig Ae/Be (HAeBe) stars which are kinematically linked with the Oph-Sco-Cen Association (OSCA). Optical photometric and spectroscopic followup was conducted for the HD 104237 field. The principal result is the discovery of a compact group of pre-main sequence (PMS) stars associated with HD 104237 and its codistant, comoving B9 neighbor ǫ Chamaeleontis AB. We name the group after the most massive member. The group has five confirmed stellar systems ranging from spectral type B9–M5, including a remarkably high degree of multiplicity for HD 104237 itself. The HD 104237 system is at least a quintet with four low mass PMS companions in nonhierarchical orbits within a projected separation of 1500 AU of the HAeBe primary. Two of the low- mass members of the group are actively accreting classical T Tauri stars. The Chandra observations also increase the census of companions for two of the other four HAeBe stars, HD 141569 and HD 150193, and identify several additional new members of the OSCA. We discuss this work in light of several theoretical issues: the origin of X-rays from HAeBe stars; the uneventful dynamical history of the high-multiplicity HD arXiv:astro-ph/0309059v1 2 Sep 2003 104237 system; and the origin of the ǫ Cha group and other OSCA outlying groups in the context of turbulent giant molecular clouds.
    [Show full text]
  • A Photometric Study of Be Stars Located in the Seismology fields of COROT
    A&A 476, 927–933 (2007) Astronomy DOI: 10.1051/0004-6361:20078252 & c ESO 2007 Astrophysics A photometric study of Be stars located in the seismology fields of COROT J. Gutiérrez-Soto1,2,J.Fabregat1,2,J.Suso3, M. Lanzara3, R. Garrido4, A.-M. Hubert2, and M. Floquet2 1 Observatorio Astronómico, Universidad de Valencia, edificio Institutos de Investigación, polígono la Coma, 46980 Paterna, Valencia, Spain e-mail: [email protected] 2 GEPI, Observatoire de Paris, CNRS, Université Paris Diderot; place Jules Janssen 92195 Meudon Cedex, France 3 GACE-ICMUV, edificio Institutos de Investigación, polígono la Coma, 46980 Paterna, Valencia, Spain 4 Instituto de Astrofísica de Andalucía (CSIC), calle Camino Bajo de Huétor, 24. 18008, Granada, Spain Received 10 July 2007 / Accepted 28 September 2007 ABSTRACT Context. In preparation for the COROT mission, an exhaustive photometric study of Be stars located in the seismology fields of the mission has been performed. The very precise and long-time-spanned photometric observations gathered by the COROT satellite will give important clues on the origin of the Be phenomenon. Aims. The aim of this work is to find short-period variable Be stars located in the seismology fields of COROT, and to study and characterise their pulsational properties. Methods. Light curves obtained at the Observatorio de Sierra Nevada, together with data from Hipparcos and ASAS-3 for a total of 84 Be stars, were analysed in order to search for short-term variations. We applied standard Fourier techniques and non-linear least-square fitting to the time series. Results. We found 7 multiperiodic, 21 mono-periodic and 26 non-variable Be stars.
    [Show full text]
  • Information Bulletin on Variable Stars
    COMMISSIONS AND OF THE I A U INFORMATION BULLETIN ON VARIABLE STARS Nos November July EDITORS L SZABADOS K OLAH TECHNICAL EDITOR A HOLL TYPESETTING K ORI ADMINISTRATION Zs KOVARI EDITORIAL BOARD L A BALONA M BREGER E BUDDING M deGROOT E GUINAN D S HALL P HARMANEC M JERZYKIEWICZ K C LEUNG M RODONO N N SAMUS J SMAK C STERKEN Chair H BUDAPEST XI I Box HUNGARY URL httpwwwkonkolyhuIBVSIBVShtml HU ISSN COPYRIGHT NOTICE IBVS is published on b ehalf of the th and nd Commissions of the IAU by the Konkoly Observatory Budap est Hungary Individual issues could b e downloaded for scientic and educational purp oses free of charge Bibliographic information of the recent issues could b e entered to indexing sys tems No IBVS issues may b e stored in a public retrieval system in any form or by any means electronic or otherwise without the prior written p ermission of the publishers Prior written p ermission of the publishers is required for entering IBVS issues to an electronic indexing or bibliographic system to o CONTENTS C STERKEN A JONES B VOS I ZEGELAAR AM van GENDEREN M de GROOT On the Cyclicity of the S Dor Phases in AG Carinae ::::::::::::::::::::::::::::::::::::::::::::::::::: : J BOROVICKA L SAROUNOVA The Period and Lightcurve of NSV ::::::::::::::::::::::::::::::::::::::::::::::::::: :::::::::::::: W LILLER AF JONES A New Very Long Period Variable Star in Norma ::::::::::::::::::::::::::::::::::::::::::::::::::: :::::::::::::::: EA KARITSKAYA VP GORANSKIJ Unusual Fading of V Cygni Cyg X in Early November :::::::::::::::::::::::::::::::::::::::
    [Show full text]
  • Stars Chien-De Lee (李建德)1, Wen-Ping Chen (陳文屏)1, 2, and Sheng-Yuan Liu (呂聖元)3
    A&A 592, A130 (2016) Astronomy DOI: 10.1051/0004-6361/201628332 & c ESO 2016 Astrophysics Evolutionary status of isolated B[e] stars Chien-De Lee (Nú·)1, Wen-Ping Chen (s文O)1; 2, and Sheng-Yuan Liu (BVC)3 1 Graduate Institute of Astronomy, National Central University, 300 Jhongda Road, 32001 Jhongli, Taiwan e-mail: [email protected] 2 Department of Physics, National Central University, 300 Jhongda Road, 32001 Jhongli, Taiwan 3 Institute of Astronomy and Astrophysics, Academia Sinica, 10617 Taipei, Taiwan Received 18 February 2016 / Accepted 18 May 2016 ABSTRACT Aims. We study a sample of eight B[e] stars with uncertain evolutionary status to shed light on the origin of their circumstellar dust. Methods. We performed a diagnostic analysis on the spectral energy distribution beyond infrared wavelengths, and conducted a census of neighboring region of each target to ascertain its evolutionary status. Results. In comparison to pre-main sequence Herbig stars, these B[e] stars show equally substantial excess emission in the near- infrared, indicative of existence of warm dust, but much reduced excess at longer wavelengths, so the dusty envelopes should be compact in size. Isolation from star-forming regions excludes the possibility of their pre-main sequence status. Six of our targets, including HD 50138, HD 45677, CD−24 5721, CD−49 3441, MWC 623, and HD 85567, have been previously considered as FS CMa stars, whereas HD 181615/6 and HD 98922 are added to the sample by this work. We argue that the circumstellar grains of these isolated B[e] stars, already evolved beyond the pre-main sequence phase, should be formed in situ.
    [Show full text]
  • Optical, Infrared and Millimetre-Wave Properties of Vega-Like Systems ± IV
    Mon. Not. R. Astron. Soc. 313, 73±86 (2000) Optical, infrared and millimetre-wave properties of Vega-like systems ± IV. Observations of a new sample of candidate Vega-like sources Roger J. Sylvester1w and Vincent Mannings2 1Department of Physics & Astronomy, University College London, Gower Street, London WC1E 6BT 2Jet Propulsion Laboratory, California Institute of Technology, MS 169-327, 4800 Oak Grove Drive, Pasadena, CA 91109, USA Accepted 1999 October 21. Received 1999 October 20; in original form 1999 July 1 ABSTRACT Photometric observations at optical and near-infrared wavelengths are presented for members of a new sample of candidate Vega-like systems, or main sequence stars with excess infrared emission due to circumstellar dust. The observations are combined with IRAS fluxes to define the spectral energy distributions of the sources. Most of the sources show only photospheric emission at near-IR wavelengths, indicating a lack of hot (,1000 K) dust. Mid-infrared spectra are presented for four sources from the sample. One of them, HD 150193, shows strong silicate emission, while another, HD 176363, was not detected. The spectra of two stars from our previous sample of Vega-like sources both show UIR-band emission, attributed to hydrocarbon materials. Detailed comparisons of the optical and IRAS positions suggest that in some cases the IRAS source is not physically associated with the visible star. Alternative associations are suggested for several of these sources. Fractional excess luminosities are derived from the observed spectral energy distributions. The values found are comparable to those measured previously for other Vega-like sources. Key words: circumstellar matter ± planetary systems ± infrared: stars.
    [Show full text]
  • Exótico Cielo Profundo 12
    12 Y el astrónomo armó su Árbol Celestial Monoceros (Mon) Monocerotis. El Unicornio. · Exótico Cielo Profundo 12 de Rodolfo Ferraiuolo y Enzo De Bernardini Constelación Monoceros (Mon) Época Verano Austral Alessi 14 LDN 1601 Cr 95 IC 447 IC 446 NGC 2245 B 37 B 38 Objetos IC 448 NGC 2247 Basel 8 NGC 2251 NGC 2254 LDN 1603 Basel 7 Tr 5 B 39 NGC 2259 NGC 2261 NGC 2264 Nuevamente, hacia el anticentro de la Vía Láctea, moviéndonos sobre la atrayente zona del ecuador galáctico que cruza al mítico Unicornio, nos abocaremos a la exploración de estos fascinantes campos donde predominan vastas zonas de hidrógeno y polvo interestelar, combinados con ricos campos estelares. Por el noroeste de Monoceros, limitando con las constelaciones de Gemini y Orion, esta área seleccionada abarca unos 9º cuadrados e, incluye varias nebulosidades brillantes y oscuras, y también cúmulos galácticos. En total, indagaremos veinte objetos de cielo profundo de variada dificultad que, como siempre, recomendamos observar desde lugares oscuros, fuera de las luminosas ciudades. Para situarnos en la zona, primero localizaremos la estrella amarilla de mag. 3,4, xi (ξ) Geminorum, Alzir y, desde allí nos moveremos unos 3º al sudsudoeste para hallar NGC 2264, nuestro primer objetivo de la noche, el cúmulo Árbol de Navidad. Con mag. 4,1 y un tamaño de 45'x30', este conocido cúmulo estelar con nebulosidad asociada, fue descubierto, el 18 de enero de 1784, por W. Herschel, quién casi dos años después detectó la fina nebulosidad. Está compuesto por más de 40 estrellas destacadas, entre más de 200, a una distancia de 2450 años luz, siendo su clasificación es III 3 r n.
    [Show full text]
  • University of Hawai'i, Institute for Astronomy Publications in Calendar
    University of Hawai‘i, Institute for Astronomy Publications in Calendar Year 2004 The names of authors listed as affiliated with IfA in each ar- &Wainscoat, R. J. Twenty-Three High-Redshift Super- ticle are in boldface. novae from the Institute for Astronomy Deep Survey: Doubling the Supernova Sample at z > 0.7. ApJ, 602, Abazajian, K., et al., including Siegmund, W. A., & Sza- 571–594 (2004) pudi, I. The Second Data Release of the Sloan Digital Sky Survey. AJ, 128, 502–512 (2004) Bendo, G. J., & Joseph, R. D. Nuclear Stellar Populations in the Infrared Space Observatory Atlas of Bright Spiral Abbas, M. M., LeClair, A., Owen, T., et al. The Nitrogen Galaxies. AJ, 127, 3338–3360 (2004) Isotopic Ratio in Jupiter’s Atmosphere from Observations by the Composite Infrared Spectrometer on the Cassini Bettoni, D., Mazzei, P., Della Valle, A., Franceschini, G. D. Spacecraft. ApJ, 602, 1063–1074 (2004) A., & Aussel, H. Optical and Spectroscopic Follow-Up of the Deeper FIR Selected Sample. Mem. Soc. Astron. Abel, N. P., Brogan, C. L., Ferland, G. J., O’Dell, C. R., Italiana Suppl., 5, 267–271 (2004) Shaw, G., & Troland, T. H. Physical Conditions in Orion’s Veil. ApJ, 609, 247–260 (2004) Beuzit, J.-L., et al., including Roddier, C., Roddier, F., & Mart´ın, E. L. New Neighbours. III. 21 New Compan- Allen, S. W., Schmidt, R. W., Ebeling, H., Fabian, A. C., ions to Nearby Dwarfs, Discovered with Adaptive Optics. &van Speybroeck, L. Constraints on Dark Energy from A&A, 425, 997–1008 (2004) Chandra Observations of the Largest Relaxed Galaxy Clusters.
    [Show full text]
  • THE STAR FORMATION NEWSLETTER an Electronic Publication Dedicated to Early Stellar Evolution and Molecular Clouds
    THE STAR FORMATION NEWSLETTER An electronic publication dedicated to early stellar evolution and molecular clouds No. 131 — 8 September 2003 Editor: Bo Reipurth ([email protected]) Abstracts of recently accepted papers The pre-main sequence spectroscopic binary AK Sco revisited S.H.P. Alencar1,2, C.H.F. Melo3, C.P. Dullemond4, J. Andersen5, C. Batalha6, L.P.R. Vaz1, and R.D. Mathieu7 1 Departamento de Fsica, ICEx-UFMG, CP. 702, Belo Horizonte - MG, 30123-970, Brazil 2 Departamento de Astronomia, IAG, USP, Rua do Mat˜ao,1226, S˜aoPaulo, 05508-900, Brazil 3 European Southern Observatory, Casilla 19001, Santiago 19, Chile 4 Max Planck Institut f¨urAstrophysik, Postfach 1317, D-85741 Garching, Germany 5 Niels Bohr Institute for Astronomy, Physics, and Geophysics, Astronomical Observatory, Juliane Maries Vej 30, 2100 Copenhagen, Denmark 6 Observat´orio Nacional, Departamento de Astrof´ısica, Rua General Jos´eCristino 77, S˜aoCrist´ov˜ao, Rio de Janeiro, 20921-400, Brazil 7 Department of Astronomy, University of Wisconsin-Madison, 475 North Charter Street, Madison, WI, 53706, USA E-mail contact: silvia@fisica.ufmg.br We present an analysis of 32 high-resolution echelle spectra of the pre-main sequence spectroscopic binary AK Sco obtained during 1998 and 2000, as well as a total of 72 photoelectric radial-velocity observations from the period 1986- 1994. These data allow considerable improvement of the period and other orbital parameters of AK Sco. Our analysis also includes eight series of photometric observations in the uvby and Geneva seven-color systems from 1987, 1989, 1990, 1992, 1994 and 1997.
    [Show full text]
  • COMMISSIONS 27 and 42 of the I.A.U. INFORMATION BULLETIN on VARIABLE STARS Nos. 4101{4200 1994 October { 1995 May EDITORS: L. SZ
    COMMISSIONS AND OF THE IAU INFORMATION BULLETIN ON VARIABLE STARS Nos Octob er May EDITORS L SZABADOS and K OLAH TECHNICAL EDITOR A HOLL TYPESETTING K ORI KONKOLY OBSERVATORY H BUDAPEST PO Box HUNGARY IBVSogyallakonkolyhu URL httpwwwkonkolyhuIBVSIBVShtml HU ISSN 2 CONTENTS 1994 No page E F GUINAN J J MARSHALL F P MALONEY A New Apsidal Motion Determination For DI Herculis ::::::::::::::::::::::::::::::::::::: D TERRELL D H KAISER D B WILLIAMS A Photometric Campaign on OW Geminorum :::::::::::::::::::::::::::::::::::::::::::: B GUROL Photo electric Photometry of OO Aql :::::::::::::::::::::::: LIU QUINGYAO GU SHENGHONG YANG YULAN WANG BI New Photo electric Light Curves of BL Eridani :::::::::::::::::::::::::::::::::: S Yu MELNIKOV V S SHEVCHENKO K N GRANKIN Eclipsing Binary V CygS Former InsaType Variable :::::::::::::::::::: J A BELMONTE E MICHEL M ALVAREZ S Y JIANG Is Praesep e KW Actually a Delta Scuti Star ::::::::::::::::::::::::::::: V L TOTH Ch M WALMSLEY Water Masers in L :::::::::::::: R L HAWKINS K F DOWNEY Times of Minimum Light for Four Eclipsing of Four Binary Systems :::::::::::::::::::::::::::::::::::::::::: B GUROL S SELAN Photo electric Photometry of the ShortPeriod Eclipsing Binary HW Virginis :::::::::::::::::::::::::::::::::::::::::::::: M P SCHEIBLE E F GUINAN The Sp otted Young Sun HD EK Dra ::::::::::::::::::::::::::::::::::::::::::::::::::: ::::::::::::: M BOS Photo electric Observations of AB Doradus ::::::::::::::::::::: YULIAN GUO A New VR Cyclic Change of H in Tau ::::::::::::::
    [Show full text]
  • Download This Article in PDF Format
    A&A 464, 687–695 (2007) Astronomy DOI: 10.1051/0004-6361:20065509 & c ESO 2007 Astrophysics Optical spectroscopy of close companions to nearby Herbig Ae/Be and T Tauri stars, A. Carmona1,2,M.E.vandenAncker2, and Th. Henning1 1 Max-Planck-Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany e-mail: [email protected] 2 European Southern Observatory, Karl Schwarzschild Strasse 2 , 85748 Garching bei München, Germany Received 26 April 2006 / Accepted 18 December 2006 ABSTRACT We present VLT-FORS2 optical (5700–9400 Å) spectroscopy of close (r < 1.5) companions to three nearby (d < 200 pc) Herbig Ae/Be stars (HD 144432, HD 150193, KK Oph) and one T Tauri star (S CrA). We report the detection of Li I (6707 Å) in absorption and emission lines (Hα, Ca II triplet) in the spectra of the companions. Our observations strongly suggest that the companions are physically associated pre-main-sequence stars. The spectral type derived for the companions is K5Ve for HD 144432 B, F9Ve for HD 150193 B, and G6Ve for KK Oph B. S CrA A and B were observed simultaneously. The spatially resolved spectra indicate that S CrA A (primary, north) is a G star and that S CrA B (secondary, south) is a K star. Using photometry from the literature and estimations of the R and I magnitude derived from the spectra, we localized primaries and companions in the HR diagram, derived their masses and assuming coevality constrained the age of the systems. KK Oph B (7 Myr) and S CrA B (2 Myr) are actively accreting T Tauri stars and are very likely surrounded by disks.
    [Show full text]