title: Spiral density waves in a young protoplanetary disk.
abstract: Gravitational forces are expected to excite spiral density waves in protoplanetary disks, disks of gas and dust orbiting young stars. However, previous observations that showed spiral structure were not able to probe disk midplanes, where most of the mass is concentrated and where planet formation takes place. Using the Atacama Large Millimeter/submillimeter Array, we detected a pair of trailing symmetric spiral arms in the protoplanetary disk surrounding the young star Elias 2-27. The arms extend to the disk outer regions and can be traced down to the midplane. These millimeter-wave observations also reveal an emission gap closer to the star than the spiral arms. We argue that the observed spirals trace shocks of spiral density waves in the midplane of this young disk.
authors.affiliation: Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany. lperez@mpifr-bonn.mpg.de.
authors.forename: Laura M
authors.initials: LM
authors.lastname: Pérez
authors.affiliation: Joint Atacama Large Millimeter/submillimeter Array (ALMA) Observatory, Avenida Alonso de Córdova 3107, Vitacura, Santiago, Chile.
authors.forename: John M
authors.initials: JM
authors.lastname: Carpenter
authors.affiliation: Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA.
authors.forename: Sean M
authors.initials: SM
authors.lastname: Andrews
authors.affiliation: Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA.
authors.forename: Luca
authors.initials: L
authors.lastname: Ricci
authors.affiliation: Rice University, 6100 Main Street, Houston, TX 77005, USA.
authors.forename: Andrea
authors.initials: A
authors.lastname: Isella
authors.affiliation: Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany.
authors.forename: Hendrik
authors.initials: H
authors.lastname: Linz
authors.affiliation: California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA.
authors.forename: Anneila I
authors.initials: AI
authors.lastname: Sargent
authors.affiliation: Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA.
authors.forename: David J
authors.initials: DJ
authors.lastname: Wilner
authors.affiliation: Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Henning
authors.affiliation: Netherlands Institute for Radio Astronomy (ASTRON), 7990-AA Dwingeloo, Netherlands.
authors.forename: Adam T
authors.initials: AT
authors.lastname: Deller
authors.affiliation: National Radio Astronomy Observatory, Post Office Box O, Socorro, NM 87801, USA.
authors.forename: Claire J
authors.initials: CJ
authors.lastname: Chandler
authors.affiliation: Heidelberg University, Center for Astronomy, Albert Ueberle Strasse 2, Heidelberg, Germany.
authors.forename: Cornelis P
authors.initials: CP
authors.lastname: Dullemond
authors.affiliation: Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91106, USA.
authors.forename: Joseph
authors.initials: J
authors.lastname: Lazio
authors.affiliation: Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany.
authors.forename: Karl M
authors.initials: KM
authors.lastname: Menten
authors.affiliation: Joint Atacama Large Millimeter/submillimeter Array (ALMA) Observatory, Avenida Alonso de Córdova 3107, Vitacura, Santiago, Chile.
authors.forename: Stuartt A
authors.initials: SA
authors.lastname: Corder
authors.affiliation: Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA.
authors.forename: Shaye
authors.initials: S
authors.lastname: Storm
authors.affiliation: European Southern Observatory, Karl Schwarzschild Strasse. 2, 85748 Garching, Germany. Istituto Nazionale di Astrofisica (INAF)-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Testi
authors.affiliation: European Southern Observatory, Karl Schwarzschild Strasse. 2, 85748 Garching, Germany.
authors.forename: Marco
authors.initials: M
authors.lastname: Tazzari
authors.affiliation: Korea Astronomy and Space Science Institute, 776 Daedeokdae-ro, Yuseong-gu, Daejeon 34055, Republic of Korea. Korea University of Science and Technology, 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea.
authors.forename: Woojin
authors.initials: W
authors.lastname: Kwon
authors.affiliation: University of Michigan, 830 Dennison Building, 500 Church Street, Ann Arbor, MI 48109, USA.
authors.forename: Nuria
authors.initials: N
authors.lastname: Calvet
authors.affiliation: Cardiff University, School of Physics and Astronomy, 4 The Parade, Cardiff CF24 3AA, UK.
authors.forename: Jane S
authors.initials: JS
authors.lastname: Greaves
authors.affiliation: University of Illinois, 1002 West Green Street, Urbana, IL 61801, USA.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Harris
authors.affiliation: Department of Astronomy, University of Maryland, College Park, MD 20742, USA.
authors.forename: Lee G
authors.initials: LG
authors.lastname: Mundy