– Niels Bohr Institute - University of Copenhagen

A young bipolar outflow from IRAS 15398-3359

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Context. Changing physical conditions in the vicinity of protostarsallow for a rich and interesting chemistry to occur. Heating and coolingof the gas allows molecules to be released from and frozen out on dustgrains. These changes in physics, traced by chemistry as well as thekinematical information, allows us to distinguish between differentscenarios describing the infall of matter and the launching of molecularoutflows and jets. Aims: We aim to determine the spatialdistribution of different species that are of different chemical origin.This is to examine the physical processes in play in the observedregion. From the kinematical information of the emission lines we aim todetermine the nature of the infalling and outflowing gas in the system.We also aim to determine the physical properties of the outflow. Methods: Maps from the Submillimeter Array (SMA) reveal the spatialdistribution of the gaseous emission towards IRAS 15398-3359. The lineradiative transfer code LIME is used to construct a full 3D model of thesystem taking all relevant components and scales into account. Results: CO, HCO+, and N2H+ aredetected and shown to trace the motions of the outflow. For CO, thecircumstellar envelope and the surrounding cloud also have a profoundimpact on the observed line profiles. N2H+ isdetected in the outflow, but is suppressed towards the central region,perhaps because of the competing reaction between CO andH3+ in the densest regions as well as thedestruction of N2H+ by CO.N2D+ is detected in a ridge south-west of theprotostellar condensation and is not associated with the outflow. Themorphology and kinematics of the CO emission suggests that the source isyounger than ~1000 years. The mass, momentum, momentum rate, mechanicalluminosity, kinetic energy, and mass-loss rate are also all estimated tobe low. A full 3D radiative transfer model of the system can explain allthe kinematical and morphological features in the system.
Original languageEnglish
Article numberA145
JournalAstronomy & Astrophysics
Number of pages10
StatePublished - 2016

    Research areas

  • ISM: individual objects: IRAS 15398-3359, ISM: molecules, ISM: abundances, ISM: jets and outflows, stars: winds, outflows

ID: 167802102