Spiral Arms Embrace Young Star

Gravitational forces are expected to excite spiral density waves in protoplanetary disks, the 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 ALMA, Perez et al. have 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. The authors argue that the observed spirals trace shocks of spiral density waves in the midplane of this young disk.

Image: ALMA peered into the Ophiuchus star-forming region to study the protoplanetary disk around the young star Elias 2-27. Astronomers discovered a striking spiral pattern in the disk that is the product of density waves – gravitational perturbations in the disk. Credit: L. Pérez (MPIfR), B. Saxton (NRAO/AUI/NSF), ALMA (ESO/NAOJ/NRAO), NASA/JPL Caltech/WISE Team.

Science Team: Laura M. Pérez (MPIfR), John M. Carpenter (JAO), Sean M. Andrews (CfA), Luca Ricci (CfA), Andrea Isella (Rice), Hendrik Linz (MPIfA), Anneila I. Sargent (Caltech), David J. Wilner (CfA), Thomas Henning (MPIfA), Adam T. Deller (ASTRON), Claire J. Chandler (NRAO), Cornelis P. Dullemond (Heidelberg), Joseph Lazio (JPL), Karl M. Menten (MPIfA), Stuartt A. Corder (JAO), Shaye Storm (CfA), Leonardo Testi (ESO, INAF), Marco Tazzari (ESO), Woojin Kwon (KASSI), Nuria Calvet (Michigan), Jane S. Greaves (Cardiff), Robert J. Harris (Illinois), and Lee G. Mundy (Maryland).

Publication: Spiral Density Waves in a Young Protoplanetary Disk, 2016, Science 353, 1519.

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