A young bipolar outflow from IRAS 15398-3359
Journal article, 2016

Context. Changing physical conditions in the vicinity of protostars allow for a rich and interesting chemistry to occur. Heating and cooling of the gas allows molecules to be released from and frozen out on dust grains. These changes in physics, traced by chemistry as well as the kinematical information, allows us to distinguish between different scenarios describing the infall of matter and the launching of molecular outflows and jets. Aims. We aim to determine the spatial distribution of different species that are of different chemical origin. This is to examine the physical processes in play in the observed region. From the kinematical information of the emission lines we aim to determine 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 spatial distribution of the gaseous emission towards IRAS 15398-3359. The line radiative transfer code LIME is used to construct a full 3D model of the system taking all relevant components and scales into account. Results. CO, HCO+, and N2H+ are detected and shown to trace the motions of the outflow. For CO, the circumstellar envelope and the surrounding cloud also have a profound impact on the observed line profiles. N2H+ is detected in the outflow, but is suppressed towards the central region, perhaps because of the competing reaction between CO and H-3(+) in the densest regions as well as the destruction of N2H+ by CO. N2D+ is detected in a ridge south-west of the protostellar condensation and is not associated with the outflow. The morphology and kinematics of the CO emission suggests that the source is younger than similar to 1000 years. The mass, momentum, momentum rate, mechanical luminosity, kinetic energy, and mass-loss rate are also all estimated to be low. A full 3D radiative transfer model of the system can explain all the kinematical and morphological features in the system.

cloud

ISM: abundances

high-velocity

objects

star-forming regions

ISM: jets and outflows

ISM: individual objects: IRAS 15398-3359

mass protostar

submillimeter continuum observations

protostellar shock l1157-b1

infall motions

stellar

molecular outflows

ISM: molecules

co

Author

Per Bjerkeli

Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics

J. K. Jorgensen

Köbenhavns Universitet

C. Brinch

Niels Bohr Institute

Astronomy and Astrophysics

0004-6361 (ISSN) 1432-0746 (eISSN)

Vol. 587

Subject Categories

Astronomy, Astrophysics and Cosmology

DOI

10.1051/0004-6361/201527310