Twin baby stars grow in complex network of gas and dust

Each star has a circumstellar disk of its own and together, the stars and their disks, have another, larger, circumbinary disk. 

The team was led by Felipe Alves, currently at the Max Planck Institute for Extraterrestrial Physics, who did his doctoral studies at the Institute of Space Sciences (CSIC), under the coordination of IEEC member Dr. Josep Miquel Girart, who is also the third author of the study.

The results appear in the journal Science.

Most stars in the Universe come in the form of pairs – binaries – or even multiple star systems. Now, the formation of such a binary star system has been observed for the first time with high-resolution ALMA (Atacama Large Millimetre/submillimetre Array) images. 

An international team of astronomers targeted the system [BHB2007] 11, the youngest member of a small cluster of young stellar objects in the Barnard 59 dark nebula, which is part of the cloud of dust and gas called the Pipe nebula. While previous observations showed a rotating and infalling envelope surrounding a circumbinary disk, the new observations now also reveal its inner structure.

“We see two compact sources, that we interpret as circumstellar disks around the two young stars,” explains Felipe Alves from the Max Planck Institute for Extraterrestrial Physics (MPE). The stars grow bigger by pulling matter from these disks. “The size of each of these disks is similar to the asteroid belt in our Solar System and their separation is slightly smaller than our Solar System as a whole.” In addition, both protostars and their circumstellar disks are surrounded by a bigger disk, called a circumbinary disk, with a total mass of about 80 Jupiter masses, which shows a complex network of dust structures distributed in spiral shapes, resembling a pretzel.

Astronomers have observed an accretion process in two stages. In the first stage, mass is transferred from the big, circumbinary disk to the circumstellar disks. In the second stage, mass is transferred from the circumstellar disks to the stars. 

“Thanks to the power of ALMA, we have managed to peer deeper into the complex system of young binary stars and gain a better understanding of how such systems form, as well as find out that the formation of rocky planets in such environments may be possible. Using this knowledge, we can now study more similar systems to further describe the conditions that allow for multiple star systems to form,” declared Dr. Josep Miquel Girart, a researcher from the Institute of Space Studies of Catalonia (IEEC) at the Institute of Space Sciences (ICE, CSIC) and third author of the study.

Observatories and Instruments

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of ESO, the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI). ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

Links

– IEEC
– ICE (CSIC)
– ALMA
– Max Planck Institute for Extraterrestrial Physics

More information

This research is presented in a paper entitled “Gas flow and accretion via spiral streamers and circumstellar disks in a young binary protostar”, by F. O. Alves, P. Caselli, J. M. Girart  et al., to appear in the journal Science on 4 October 2019.
The Institute of Space Studies of Catalonia (IEEC  — Institut d’Estudis Espacials de Catalunya) promotes and coordinates space research and technology development in Catalonia for the benefit of society. IEEC fosters collaborations both locally and worldwide and is an efficient agent of knowledge, innovation and technology transfer. As a result of over 20 years of high-quality research, done in collaboration with major international organisations, IEEC ranks among the best international research centers, focusing on areas such as: astrophysics, cosmology, planetary science, and Earth Observation. IEEC’s engineering division develops instrumentation for ground- and space-based projects, and has extensive experience in working with private or public organisations from the aerospace and other innovation sectors.  

IEEC is a private non-profit foundation, governed by a Board of Trustees composed of Generalitat de Catalunya and four other institutions that each have a research unit, which together constitute the core of IEEC R&D activity: the University of Barcelona (UB) with the research unit ICCUB — Institute of Cosmos Sciences; the Autonomous University of Barcelona (UAB) with the research unit CERES — Center of Space Studies and Research; the Polytechnic University of Catalonia (UPC) with the research unit CTE — Research Group in Space Sciences and Technologies; the Spanish Research Council (CSIC) with the research unit ICE — Institute of Space Sciences. IEEC is integrated in the CERCA network (Centres de Recerca de Catalunya).

Image
PR_Image1: The mouthpiece of the Pipe Nebula
This picture shows Barnard 59, part of a vast dark cloud of interstellar dust called the Pipe Nebula. 
Credit: ESO
License: Creative Commons 4.0

Contacts
IEEC Communication Office
Barcelona, Spain
Rosa Rodríguez Gasén
E-mail: comunicacio@ieec.cat 

Lead Scientist
Garching bei München, Germany
Felipe Alves
Center for Astrochemical Studies
Max Planck Institute for Extraterrestrial Physics
Tel: +49 89 30000 3897
Email: falves@mpe.mpg.de

Third author
Cerdanyola del Vallès, Catalonia, Spain
Josep Miquel Girart
Institute of Space Sciences (ICE, CSIC) / IEEC
Email: girart@ice.cat