Strongly misaligned triple system in SR 24 revealed by ALMA

Abstract

We report the detection of the 1.3 mm continuum and the molecular emission of the disks of the young triple system SR24 by analyzing ALMA (The Atacama Large Millimeter/Submillimter Array) subarcsecond archival observations. We estimate the mass of the disks (0.025 solar masses and 4E-5 earth masses for SR24S and SR24N, respectively) and the dynamical mass of the protostars (1.5 and 1.1 solar masses). A kinematic model of the SR24S disk to fit its C18O (2-1) emission allows us to develop an observational method to learn what is the tilt of a rotating and accreting disk. We derive the size, the inclination, the position angle and the sense of rotation of each disk, finding that they are strongly misaligned (108 degrees) and possibly rotate in opposite directions as seen from Earth, in projection. We compare the ALMA observations with 12CO SMA archival observations, which are more sensitive to extended structures. We find three extended structures and estimate their masses: a molecular bridge joining the disks of the system, a molecular gas reservoir associated with SR24N and a gas streamer associated with SR24S. Finally we discuss on the possible origin of the misaligned SR24 system, pointing out that a closer inspection of the northern gas reservoir is needed to better understand it.

14 pages, 9 figures, 4 tables; accepted in ApJ

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• A Possible Alignment Between the Orbits of Planetary Systems and their Visual Binary Companions
• An Asymmetric Keplerian Disk Surrounding the O-type Protostar IRAS16547$-$4247
• The ALMA-PILS survey: Gas dynamics in IRAS 16293$-$2422 and the connection between its two protostars
• A high resolution mid-infrared survey of water emission from protoplanetary disks
• An Inner Disk in the Large Gap of the Transition Disk SR 24S
• On the frequencies of circumbinary discs in protostellar systems
• Disk Evolution Study Through Imaging of Nearby Young Stars (DESTINYS): Diverse outcomes of binary-disk interactions
• SUBARU Near-Infrared Imaging Polarimetry of Misaligned Disks Around The SR24 Hierarchical Triple System
• Saturation level of turbulence in collapsing gas clouds
• Gas distribution in ODISEA sources from ALMA long-baseline observations in ${}^{12}$CO(2-1)
• A new formation scenario of a counter-rotating circumstellar disk: spiral-arm accretion from a circumbinary disk in a triple protostar system