Site Map
Contacts
Follow us on Facebook Follow us on Twitter YouTube channel
Centro de Astrofísica da Universidade do Porto

The Excitation and Kinematical Properties of H2 and [Fe II] in the HH 46/47 Bipolar Outflow

A. J. L. Fernandes

Abstract
Long-slit spectra of the molecular outflow Herbig-Haro (HH) 46/47 have been taken in the J and K near-infrared bands. The observed H2 line emission confirms the existence of a bright and extended redshifted counter-jet outflow south-west of HH 46. In contrast with the optical appearance of this object, we show that this outflow seems to be composed of two different emission regions characterized by distinct heliocentric velocities. This implies an acceleration of the counter-jet. The observed [Feii] emission suggests an average extinction of 7-9 visual magnitudes for the region associated with the counter-jet. Through position-velocity diagrams, we show the existence of different morphologies for the H2 and [Feii] emission regions in the northern part of the HH 46/47 outflow. We have detected for the first time high-velocity (-250kms-1) [Feii] emission in the region bridging HH 46 to HH 47A. The two strong peaks detected can be identified with the optical positions B8 and HH 47B. The H2 excitation diagrams for the counter-jet shock suggest an excitation temperature for the gas of Tex~2600K. The lack of emission from the higher energy H2 lines, such as the 4-3 S(3) transition, suggests a thermal excitation scenario for the origin of the observed emission. Comparison of the H2 line ratios with various shock models yielded useful constraints about the geometry and type of these shocks. Planar shocks can be ruled out whereas curved or bow shocks (both J- and C-type) can be parametrized to fit our data.

Monthly Notices of the Royal Astronomical Society
Volume 315, Page 657
July 2000

>> PDF>> ADS

Institute of Astrophysics and Space Sciences

Institute of Astrophysics and Space Sciences (IA) is a new but long anticipated research infrastructure with a national dimension. It embodies a bold but feasible vision for the development of Astronomy, Astrophysics and Space Sciences in Portugal, taking full advantage and fully realizing the potential created by the national membership of the European Space Agency (ESA) and the European Southern Observatory (ESO). IA resulted from the merging the two most prominent research units in the field in Portugal: the Centre for Astrophysics of the University of Porto (CAUP) and the Center for Astronomy and Astrophysics of the University of Lisbon (CAAUL). It currently hosts more than two-thirds of all active researchers working in Space Sciences in Portugal, and is responsible for an even greater fraction of the national productivity in international ISI journals in the area of Space Sciences. This is the scientific area with the highest relative impact factor (1.65 times above the international average) and the field with the highest average number of citations per article for Portugal.

Proceed on CAUP's website|Go to IA website