* Astronomy

Blobrana · L

RE: L1448-mm

Blobrana · L

Young star fires off extremely rapid water molecules

A team including Leiden astronomers has observed water molecules moving away from a young, sun-like star at a speed of more than 200,000 km per hour. This is 80 times as fast as a bullet fired from an AK-47 weapon.
The observations have shown that water probably reforms into hot, dense clouds of gas as an effect of the shockwaves. The conditions are so favourable that every second, 100 million times the amount of water is formed that is contained in the Amazon river! The observations shed new light on the most energetic phase in the formation of a large mass (stars with a mass smaller than our sun). Our sun also experienced this process in the first stage of its evolution. Temperatures of more than 10,000 celsius are reached in this process. Water is one of the molecules that ensure that the temperature cools down quickly so that the young star can continue to grow.
The star that was studied, L1448-MM, is located in the constellation of Perseus at a distance of some 750 light years. The HIFI space instrument was developed and constructed by a consortium of institutes and universities in Europe, Canada and the United States, led by SRON Netherlands Institute for Space Research. The data comes from the Water in Star Forming Regions with Herschel (WISH) Key Programme, that is headed by Professor Ewine van Dishoeck of the Leiden Sterrewacht.

Blobrana · L

Title: Heavy water around the L1448-mm protostar
Authors: C. Codella, C. Ceccarelli, B. Nisini, R. Bachiller, J. Cernicharo, F. Gueth, A. Fuente, B. Lefloch
(19 Oct 2010)

L1448-mm is the prototype of a low-mass Class 0 protostar driving a high-velocity jet. Given its bright H2O spectra observed with ISO, L1448-mm is an ideal laboratory to observe heavy water (HDO) emission. Aims: Our aim is to image the HDO emission in the protostar surroundings, the possible occurrence of HDO emission also investigating off L1448-mm, towards the molecular outflow. Methods: We carried out observations of L1448-mm in the HDO(1_10-1_11) line at 80.6 GHz, an excellent tracer of HDO column density, with the IRAM Plateau de Bure Interferometer. Results: We image for the first time HDO emission around L1448-mm. The HDO structure reveals a main clump at velocities close to the ambient one towards the the continuum peak that is caused by the dust heated by the protostar. In addition, the HDO map shows tentative weaker emission at about 2000 AU from the protostar towards the south, which is possibly associated with the walls of the outflow cavity opened by the protostellar wind. Conclusions: Using an LVG code, modelling the density and temperature profile of the hot-corino, and adopting a gas temperature of 100 K and a density of 1.5 10^8 cm^-3, we derive a beam diluted HDO column density of about 7 10^13 cm^-2, corresponding to a HDO abundance of about 4 10^-7. In addition, the present map supports the scenario where HDO can be efficiently produced in shocked regions and not uniquely in hot corinos heated by the newly born star.

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