DOCSLIB.ORG

The Nearest (Massive) Star Forming Region in the Gould Belt

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Nearest (Massive) Star Forming Region in the Gould Belt The Sco OB 2 Association The nearest (massive) star forming region in the Gould Belt 03 Sep. 2015 Difeng Guo (API Amsterdam) Lex Kaper (API Amsterdam) Anthony Brown (Leiden Observatory) Jos de Bruijne (ESA) Outline • Motivation • The Gould Belt • Scorpius-Centaurus OB2 • Methods (what I’m doing now) • Gaia Process of Star Formation • Different scales OB association Single Binary Galaxy Process of Star Formation • Different scales Gould Belt OB Association The Gould Belt • Benjamin A. Gould 1879 • O & B stars in a big circle • Origin: Unknown The Gould Belt Sun The Gould Belt Sun The Gould Belt ~700pc (Blaauw 1991) The Gould Belt +Molecular Gas (Lindblad 1974) Perseus Orion OB2 OB1 ~ 7 Myr <12 Myr Cas-Tau 25~50 Myr Scorpius Introduction: de Geus et al. 1989 Blauww 1991 Centaurus OB2 Mamajek et al. 2002 5~20Myr Pecaut et al. 2012 Complete census: Rizzuto et al. 2015 de Zeeuw et al. 1999 The Gould Belt ~140pc Nearest Whole mass range Scorpius Young Centaurus OB2 5~20Myr OB Associations in the Gould Belt 90º L=0º 270º OB Associations in the Gould Belt Gal. Plane 90º L=0º 270º OB Associations in the Gould Belt Gould Belt Tilted ~ 20º 90º L=0º 270º Scorpius-Centaurus OB2 in the Gould Belt Upper Upper Centaurus- Scorpius Lupus Lower Centaurus- Crux 90º L=0º 270º The Age Map in Sco-Cen Upper Scorpius Upper Centaurus-Lupus Lower Centaurus-Crux Mark Pecaut, PhD Thesis 2013 Page 171 G Longitude Figure 4.9 Spatial distribution of 662 F/G/K/M-type pre-MS members (solid dots) with spatial age contours. The contours are created by evaluating the median luminosity offset relative to the luminosity uncertainties (< log(L/L⊙)> ◦ − log(L/L⊙))/σlog(L/L⊙) of stars in a 5 radius each (l, b). These contour bins are then mapped to ages using the F5 through G9 stars that fall in those bins. 171 Sequential Star Formation Adriaan Blaauw 1964, 1978, 1991 Elmegreen & Lada 1977, Thaddeus 1977 Preibisch+ 2007 Step 1: Determine Membership Step 1: Determine Membership • Measure the proper motions Photographic plate HIPPARCOS Gaia Long, long ago… 1997 ~2017 sub-arcsec/yr ~mas/yr ~50µas/yr +RV! ~1km/s Step 1: Determine Membership • Methods: convergent point + “spaghetti” µ Convergent point Spaghetti Method de Bruijne 1999 Hoogerwerf et al. 1999 de Zeeuw et al. 1999 Step 1: Determine Membership • Example - Sco OB2, 521 members Red: Members Black: Non-members Without RV! De Zeeuw et al. 1999 Step 2: Determine Age Step 2: Determine Age USco High mass Pecaut et al. 2012 Step 2: Determine Age 1Myr PMS 10Myr 5Myr 3Myr USco 20Myr Low mass Rizzuto et al. 2015 Sco OB2 • D ~ 140 pc • Long. x Lat. x π = 75º x 40º x (12 ~ 4 mas) • Age Gradient: [5~11 Myr] - [16 Myr] - [17 Myr] de Geus et al. 1989 Mamajek et al. 2002 Pecaut et al. 2012 Rizzuto et al. 2015 Kinematic • 521 Members (High & mid mass) & 100+ (Low mass) Gaia • 1st release: 20x precise PM on existing HIP PM • Complete population with PM and RV • More members, better stat. • Less error —> velocity dispersion • Expansion, velocity-mass relation, binaries, runaways, etc. • Photometry: complete HRD + • —> Origin of the Gould Belt Key Points • The Gould Belt: Origin? • configuration • Sco OB2: Start point, Sequential SF • Gaia: PM+RV, complete population in the Gould Belt Sources of illustration Pictures binary sf http://spaceref.com/astronomy/new-studies-give-strong-boost-to-binary-star-formation-theory.html single sf http://starformation.synthasite.com OB association http://home.strw.leidenuniv.nl/~spz/MODESTA/modest/SOS/PrimBin/index.html gouldbelt http://www.handprint.com/ASTRO/galaxy.html galaxy sf http://scitechdaily.com/evidence-that-local-starbursts-impact-the-bulk-of-the-gas-around-their-host-galaxy/ plates http://www.mariamitchell.org/research-and-collections/astronomy/astronomical-plates hipparcos http://www.cnes.fr/web/CNES-fr/4622-hipparcos-collectionneur-detoiles.php orion constellation http://www.constellation-guide.com/constellation-list/orion-constellation/ .
Load more

Recommended publications
  • Constructing a Galactic Coordinate System Based on Near-Infrared and Radio Catalogs
    A&A 536, A102 (2011) Astronomy DOI: 10.1051/0004-6361/201116947 & c ESO 2011 Astrophysics Constructing a Galactic coordinate system based on near-infrared and radio catalogs J.-C. Liu1,2,Z.Zhu1,2, and B. Hu3,4 1 Department of astronomy, Nanjing University, Nanjing 210093, PR China e-mail: [jcliu;zhuzi]@nju.edu.cn 2 key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education, Nanjing 210093, PR China 3 Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008, PR China 4 Graduate School of Chinese Academy of Sciences, Beijing 100049, PR China e-mail: [email protected] Received 24 March 2011 / Accepted 13 October 2011 ABSTRACT Context. The definition of the Galactic coordinate system was announced by the IAU Sub-Commission 33b on behalf of the IAU in 1958. An unrigorous transformation was adopted by the Hipparcos group to transform the Galactic coordinate system from the FK4-based B1950.0 system to the FK5-based J2000.0 system or to the International Celestial Reference System (ICRS). For more than 50 years, the definition of the Galactic coordinate system has remained unchanged from this IAU1958 version. On the basis of deep and all-sky catalogs, the position of the Galactic plane can be revised and updated definitions of the Galactic coordinate systems can be proposed. Aims. We re-determine the position of the Galactic plane based on modern large catalogs, such as the Two-Micron All-Sky Survey (2MASS) and the SPECFIND v2.0. This paper also aims to propose a possible definition of the optimal Galactic coordinate system by adopting the ICRS position of the Sgr A* at the Galactic center.
    [Show full text]
  • Eclipse Newsletter
    ECLIPSE NEWSLETTER The Eclipse Newsletter is dedicated to increasing the knowledge of Astronomy, Astrophysics, Cosmology and related subjects. VOLUMN 2 NUMBER 1 JANUARY – FEBRUARY 2018 PLEASE SEND ALL PHOTOS, QUESTIONS AND REQUST FOR ARTICLES TO [email protected] 1 MCAO PUBLIC NIGHTS AND FAMILY NIGHTS. The general public and MCAO members are invited to visit the Observatory on select Monday evenings at 8PM for Public Night programs. These programs include discussions and illustrated talks on astronomy, planetarium programs and offer the opportunity to view the planets, moon and other objects through the telescope, weather permitting. Due to limited parking and seating at the observatory, admission is by reservation only. Public Night attendance is limited to adults and students 5th grade and above. If you are interested in making reservations for a public night, you can contact us by calling 302-654- 6407 between the hours of 9 am and 1 pm Monday through Friday. Or you can email us any time at [email protected] or [email protected]. The public nights will be presented even if the weather does not permit observation through the telescope. The admission fees are $3 for adults and $2 for children. There is no admission cost for MCAO members, but reservations are still required. If you are interested in becoming a MCAO member, please see the link for membership. We also offer family memberships. Family Nights are scheduled from late spring to early fall on Friday nights at 8:30PM. These programs are opportunities for families with younger children to see and learn about astronomy by looking at and enjoying the sky and its wonders.
    [Show full text]
  • The Gould Belt
    Astrophysics, Vol. 57, No. 4, pp. 583-604, December, 2014. REVIEWS THE GOULD BELT V.V. Bobylev1,2 1Pulkovo Astronomical Observatory, St. Petersburg, Russia 2Sobolev Astronomical Institute, St. Petersburg State University, Russia AbstractThis review is devoted to studies of the Gould belt and the Local system. Since the Gould belt is the giant stellar-gas complex closest to the sun, its stellar component is characterized, along with the stellar associations and diffuse clusters, cold atomic and molecular gas, high-temperature coronal gas, and dust contained in it. Questions relating to the kinematic features of the Gould belt are discussed and the most interesting scenarios for its origin and evolution are examined. 1 Historical information Stars of spectral classes O and B that are visible to the naked eye define two large circles in the celestial sphere. One of them passes near the plane of the Milky Way, while the second is slightly inclined to it and is known as the Gould belt. The minimum galactic latitude of the Gould belt is in the region of the constellation Orion, and the maximum, in the region of Scorpio-Centaurus. Herschel noted [1] that some of the bright stars in the southern sky appear to be part of a separate structure from the Milky Way with an inclination to the galactic equator of about 20◦. Commenting on the features of the distribution of stars in the Milky Way, Struve [2] independently noted that the stars that form the largest densifications on the celestial sphere can lie in two planes with a mutual inclination of about 10◦.
    [Show full text]
  • Radio Astronomers Peer Deep Into the Stellar Nursery of the Orion Nebula 15 June 2017
    Radio astronomers peer deep into the stellar nursery of the Orion Nebula 15 June 2017 stars," says Rachel Friesen, one of the collaboration's co-Principal Investigators and, until 31 May 2017, a Dunlap Fellow at the Dunlap Institute for Astronomy & Astrophysics, University of Toronto. "But ammonia is an excellent tracer of dense, star- forming gas," says Friesen, "and these large ammonia maps will allow us to track the motions and temperature of the densest gas. This is critical to assessing whether gas clouds and filaments are stable, or are undergoing collapse on their way to forming new stars." The image accompanies the first release of results from the collaboration's Green Bank Ammonia Survey (GAS), published in the Astrophysical Journal. The collaboration's other co-Principal Investigator is Jaime Pineda, from the Max Planck Institute for Extraterrestrial Physics; the team also includes astronomers from the University of In this composite image combining GBT radio and WISE Toronto's Department of Astronomy & Astrophysics infrared observations, the filament of ammonia and Canadian Institute for Theoretical Astrophysics. molecules appears red and Orion Nebula gas appears blue. Credit: R. Friesen, Dunlap Institute; J. Pineda, The goal of GAS is to survey all the major, nearby MPIP; GBO/AUI/NSF star-forming regions in the northern half of the Gould Belt—a ring of young stars and gas clouds that circles the entire sky and runs through the Astronomers have released an image of a vast constellation Orion. The survey will eventually filament of star-forming gas, 1200 light-years away, provide a clearer picture over a larger portion of the in the stellar nursery of the Orion Nebula.
    [Show full text]
  • The System of Molecular Clouds in the Gould Belt in Details
    Astronomy Letters, 2016, Vol. 42, No. 8, pp. 544–554. The System of Molecular Clouds in the Gould Belt V.V. Bobylev Pulkovo Astronomical Observatory, St. Petersburg, Russia Abstract—Based on high-latitude molecular clouds with highly accurate distance estimates taken from the literature, we have redetermined the parameters of their spatial orientation. This system can be approximated by a 350 235 140 pc ellipsoid inclined by the angle i = 17 2◦ to the Galactic plane with× the longitude× of the ascending ◦ ± node lΩ = 337 1 . Based on the radial velocities of the clouds, we have found their ± group velocity relative to the Sun to be (u0, v0,w0) = (10.6, 18.2, 6.8) (0.9, 1.7, 1.5) km s−1. The trajectory of the center of the molecular cloud system in± the past in a time interval of 60 Myr has been constructed. Using data on masers associated with low- mass protostars,∼ we have calculated the space velocities of the molecular complexes in Orion, Taurus, Perseus, and Ophiuchus. Their motion in the past is shown to be not random. INTRODUCTION A giant stellar-gas complex known as the Gould Belt is located near the Sun (Frogel and Stothers 1977; Efremov 1989; P¨oppel 1997, 2001; Torra et al. 2000; Olano 2001). A giant cloud of neutral hydrogen called the Lindblad ring (Lindblad 1967, 2000) is associated with it; the system of nearby OB associations (de Zeeuw et al. 1999), open star clusters (Piskunov et al. 2006; Bobylev 2006), and complexes of nearby molecular clouds (Dame et al.
    [Show full text]
  • Astrophysics in 2006 3
    ASTROPHYSICS IN 2006 Virginia Trimble1, Markus J. Aschwanden2, and Carl J. Hansen3 1 Department of Physics and Astronomy, University of California, Irvine, CA 92697-4575, Las Cumbres Observatory, Santa Barbara, CA: ([email protected]) 2 Lockheed Martin Advanced Technology Center, Solar and Astrophysics Laboratory, Organization ADBS, Building 252, 3251 Hanover Street, Palo Alto, CA 94304: ([email protected]) 3 JILA, Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder CO 80309: ([email protected]) Received ... : accepted ... Abstract. The fastest pulsar and the slowest nova; the oldest galaxies and the youngest stars; the weirdest life forms and the commonest dwarfs; the highest energy particles and the lowest energy photons. These were some of the extremes of Astrophysics 2006. We attempt also to bring you updates on things of which there is currently only one (habitable planets, the Sun, and the universe) and others of which there are always many, like meteors and molecules, black holes and binaries. Keywords: cosmology: general, galaxies: general, ISM: general, stars: general, Sun: gen- eral, planets and satellites: general, astrobiology CONTENTS 1. Introduction 6 1.1 Up 6 1.2 Down 9 1.3 Around 10 2. Solar Physics 12 2.1 The solar interior 12 2.1.1 From neutrinos to neutralinos 12 2.1.2 Global helioseismology 12 2.1.3 Local helioseismology 12 2.1.4 Tachocline structure 13 arXiv:0705.1730v1 [astro-ph] 11 May 2007 2.1.5 Dynamo models 14 2.2 Photosphere 15 2.2.1 Solar radius and rotation 15 2.2.2 Distribution of magnetic fields 15 2.2.3 Magnetic flux emergence rate 15 2.2.4 Photospheric motion of magnetic fields 16 2.2.5 Faculae production 16 2.2.6 The photospheric boundary of magnetic fields 17 2.2.7 Flare prediction from photospheric fields 17 c 2008 Springer Science + Business Media.
    [Show full text]
  • Vol. 38, No. 3 September 2009 Journal of the International
    Vol. 38, No. 3 September 2009 Journal of the International Planetarium Society Darkness at Dawn in India Page 18 September 2009 Vol. 38 No. 3 Executive Editor Articles Sharon Shanks Ward Beecher Planetarium 6 Greenwich’s Public Astronomer SteveTidey Youngstown State University 10 Russia’s Only High School Planetarium One University Plaza Dr. Larry Krumenaker Youngstown, Ohio 44555 USA 18 Darkness at Dawn in India Piyush Pandey +1 330-941-3619 20 IPS 2012: Baton Rouge Jon Elvert [email protected] 22 Eugenides Script Contest Revisions Advertising Coordinator Thomas Kraupe Dr. Dale Smith, Interim Coordinator (See Publications Committee on page 3) Columns Membership 63 25 Years Ago. Thomas Wm. Hamilton Individual: $50 one year; $90 two years 60 Book Reviews. April S. Whitt Institutional: $200 first year; $100 annual renewal 67 Calendar of Events. .Loris Ramponi Library Subscriptions: $36 one year 28 Educational Horizons . Jack L. Northrup Direct membership requests and changes of 30 General Counsel . Christopher S. Reed address to the Treasurer/Membership Chairman 32 IMERSA NEWS . .Judith Rubin 4 In Front of the Console . .Sharon Shanks Back Issues of the Planetarian 38 International News. Lars Broman IPS Back Publications Repository 68 Last Light . April S. Whitt maintained by the Treasurer/Membership Chair; 48 Mobile News. .Susan Reynolds Button contact information is on next page 51 NASA Space Science News. Anita Sohus 53 Past President’s Message . Susan Reynolds Button Index 56 Planetarium Show Reviews. Steve Case A cumulative index of major articles that have 24 President’s Message . Tom Mason appeared in the Planetarian from the first issue 64 What’s New.
    [Show full text]
  • A First Look at the Auriga–California Giant Molecular Cloud with Herschel∗ and the Cso: Census of the Young Stellar Objects and the Dense Gas
    The Astrophysical Journal,764:133(14pp),2013February20 doi:10.1088/0004-637X/764/2/133 C 2013. The American Astronomical Society. All rights reserved. Printed in the U.S.A. ! A FIRST LOOK AT THE AURIGA–CALIFORNIA GIANT MOLECULAR CLOUD WITH HERSCHEL∗ AND THE CSO: CENSUS OF THE YOUNG STELLAR OBJECTS AND THE DENSE GAS Paul M. Harvey1,CassandraFallscheer2,AdamGinsburg3,SusanTerebey4,PhilippeAndre´5,TylerL.Bourke6, James Di Francesco7,VeraKonyves¨ 5,8,BrendaC.Matthews7,andDawnE.Peterson9 1 Astronomy Department, University of Texas at Austin, 1 University Station C1400, Austin, TX 78712-0259, USA; [email protected] 2 Department of Physics and Astronomy, University of Victoria, 3800 Finnerty Road, Victoria, BC V8P 5C2, Canada; [email protected] 3 Center for Astrophysics and Space Astronomy, University of Colorado, 389 UCB, Boulder, CO 80309-0389, USA; [email protected] 4 Department of Physics and Astronomy PS315, 5151 State University Drive, California State University at Los Angeles, Los Angeles, CA 90032, USA; [email protected] 5 Laboratoire AIM, CEA/DSM-CNRS-UniversiteParisDiderot,IRFU´ /Service d’Astrophysique, CEA Saclay, F-91191 Gif-sur-Yvette, France; [email protected], [email protected] 6 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA; [email protected] 7 Herzberg Institute of Astrophysics, National Research Council of Canada, 5071 West Saanich Road, Victoria, BC V9E 2E7, Canada; [email protected], [email protected] 8 Institut
    [Show full text]
  • Exploring the Origins of Earth's Nitrogen
    Exploring the Origins of Earth’s Nitrogen by Thomas Sean Rice A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy (Astronomy and Astrophysics) in the University of Michigan 2019 Doctoral Committee: Professor Edwin Bergin, Chair Professor Fred Adams Associate Professor Jes Jørgensen, Københavns Universitet Professor Michael Meyer Assistant Professor Emily Rauscher Thomas Sean Rice [email protected] ORCID iD: 0000-0002-7231-7328 c Thomas Sean Rice 2019 For John Goodricke, Annie Jump Cannon, Konstantin Tsiolkovsky, and Henrietta Swan Leavitt. For my parents, for Linda and Rick, and for Tim and Jen. And for all the Deaf people who made me and my work possible. ii ACKNOWLEDGMENTS I must give immense thanks to my advisor, Ted Bergin, for six years of careful advising, guidance, and scientific discussion. Likewise, I am incredibly grateful to Jes Jørgensen for hosting me as a guest PhD student at the Centre for Star and Planet Formation (StarPlan) in Copenhagen, Denmark, during two visits in 2017 and 2018 totaling six months, and for invaluable scientific training and collaboration. I am also grateful to the remaining members of my dissertation committee, Michael Meyer, Emily Rauscher, and Fred Adams, for useful guidance and discussion during these past few years, which have contributed to my research success. For critical help with formatting, copy-editing and proofreading of this dissertation at various stages, I thank Richard Teague, Ian Roederer, Rachael Roettenbacher, Forrest Holden, Anna Cornel, Bryan Terrazas, Wendy Carter-Veale, Erin May, Traci Johnson, Ilse Cleeves, and Kamber Schwarz. I am incredibly grateful to so many people who have been instrumental to the process of my becoming a scientist.
    [Show full text]
  • IRREGULARITIES of the VELOCITY FIELD J. Torra1
    513 YOUNG STARS: IRREGULARITIES OF THE VELOCITY FIELD 1 2 1 3 J. Torra ,A.E.G omez , F. Figueras , F. Comer on , 2 4 1 1 S. Grenier , M.O. Mennessier , M. Mestres ,D.Fern andez 1 Departament d'Astronomia i Meteorologia. Universitat de Barcelona, Spain 2 Observatoire de Paris-Meudon, D.A.S.G.A.L., France 3 Europ ean Southern Observatory, Garching b ei Munc hen, Germany 4 GRAAL. Universit e de Montp ellier I I, France interpreted as a lo cal e ect of the spiral arm Lind- ABSTRACT blad 1973, by energetic event on the galactic disk Olano 1982, Elmegreen 1982, corrugation waves in the galactic disk Nelson 1976 or by an halo-disk We present here a rst review of the structure and interaction Comer on 1992, Lepine & Duvert 1995. kinematics of the lo cal system of young stars. Hip- parcos astrometric data for a large sample of O and The velo city eld of young stars is describ ed to rst B stars have b een complemented with a careful com- order by the Oort's formulae Ogoro dnikov 1965 pilation of available radial velo cities and Stromgren relating the observed radial velo city, distance and photometry thus providing reliable distance, spatial prop er motion with the solar motion and the gra- velo city and age for each star in the sample. The dients of the velo city eld. Several works have b een fundamental parameters characterizing the structure devoted to the determination of the Oort's constants of the Gould Belt, inclination, size and age are deter- considering only di erential rotation or including mined.
    [Show full text]
  • Herschel Observations of the Filament Paradigm for Star Formation: Where Do We Stand?
    Abstract: Herschel 10 years after launch: science and celebration, ESAC, 13-14 May 2019 Herschel observations of the filament paradigm for star formation: Where do we stand? Philippe André Commissariat à l’Energie Atomique, Département d’Astrophysique CEA Saclay, Orme des Merisiers – Bât. 709 F-91191 Gif-sur-Yvette, France Herschel imaging surveys of Galactic molecular clouds have revolutionized our observational understanding of the link between the structure of the cold interstellar medium (ISM) and the star formation process. I will give an overview of the results obtained in this area as part of the Herschel Gould Belt survey and will summarize the main aspects of the new paradigm for solar-type star formation favored by Herschel observations. While interstellar filaments have been known for quite some time, Herschel results demonstrate that they are truly ubiquitous, probably make up a dominant fraction of the dense molecular gas in GMCs, present a high degree of universality in their properties, and are intimately related to the formation of prestellar cores. Overall, the available observations support a picture in which molecular filaments and prestellar cores represent two fundamental steps in the star formation process: First, multiple large-scale compressions of interstellar material in supersonic turbulent MHD flows generates a cobweb of filaments in the ISM; second, the densest filaments fragment into prestellar cores (and subsequently protostars) by gravitational instability, while simultaneously growing in mass and complexity through accretion of background cloud material. This paradigm differs from the classical gravo- turbulent picture in that it emphasizes the role of geometry and anisotropic growth of structure in the star formation process.
    [Show full text]
  • THE GOULD's BELT DISTANCE SURVEY Revista Mexicana De Astronomía Y Astrofísica, Vol
    Revista Mexicana de Astronomía y Astrofísica ISSN: 0185-1101 [email protected] Instituto de Astronomía México Loinard, L.; Mioduszewski, A. J.; Torres, R. M.; Dzib, S.; Rodríguez, L. F.; Boden, A. F. THE GOULD'S BELT DISTANCE SURVEY Revista Mexicana de Astronomía y Astrofísica, vol. 40, 2011, pp. 205-210 Instituto de Astronomía Distrito Federal, México Available in: http://www.redalyc.org/articulo.oa?id=57121297111 How to cite Complete issue Scientific Information System More information about this article Network of Scientific Journals from Latin America, the Caribbean, Spain and Portugal Journal's homepage in redalyc.org Non-profit academic project, developed under the open access initiative RevMexAA (Serie de Conferencias), 40, 205–210 (2011) THE GOULD’S BELT DISTANCE SURVEY L. Loinard,1 A. J. Mioduszewski,2 R. M. Torres,3 S. Dzib,1 L. F. Rodr´ıguez,1 and A. F. Boden4 RESUMEN Observaciones que utilizan la interferometr´ıa de muy larga l´ınea de base (VLBI por sus siglas en ingl´es) pueden proveer la posici´on de radiofuentes compactas con una precisi´on del orden de 50 micro-segundos de arco. Esto es suficiente para medir la paralaje trigonom´etrica y los movimientos propios de cualquier objeto localizado hasta 500 pc del Sol con una precisi´on mejor que unos porcientos. Por ser magn´eticamente activas, las estrellas j´ovenes a menudo emiten emisi´on radio compacta detectable usando t´ecnicas VLBI. Aqu´ı, mostraremos c´omo observaciones VLBI ya han restringido la distancia a las regiones de formaci´on estelar cercanas m´as frecuentemente estudiadas (Tauro, Ofiuco, Ori´on, etc.) y han empezado a revelar su estructura y su cinem´atica interna.
    [Show full text]