54 research outputs found
Herschel-HIFI detections of hydrides towards AFGL 2591 (Envelope emission versus tenuous cloud absorption)
The Heterodyne Instrument for the Far Infrared (HIFI) onboard the Herschel
Space Observatory allows the first observations of light diatomic molecules at
high spectral resolution and in multiple transitions. Here, we report deep
integrations using HIFI in different lines of hydrides towards the high-mass
star forming region AFGL 2591. Detected are CH, CH+, NH, OH+, H2O+, while NH+
and SH+ have not been detected. All molecules except for CH and CH+ are seen in
absorption with low excitation temperatures and at velocities different from
the systemic velocity of the protostellar envelope. Surprisingly, the CH(JF,P =
3/2_2,- - 1/2_1,+) and CH+(J = 1 - 0, J = 2 - 1) lines are detected in emission
at the systemic velocity. We can assign the absorption features to a foreground
cloud and an outflow lobe, while the CH and CH+ emission stems from the
envelope. The observed abundance and excitation of CH and CH+ can be explained
in the scenario of FUV irradiated outflow walls, where a cavity etched out by
the outflow allows protostellar FUV photons to irradiate and heat the envelope
at larger distances driving the chemical reactions that produce these
molecules.Comment: Accepted for publication in Astronomy and Astrophysics (HIFI first
results issue
Science and society in education
This booklet is for teachers who want to expand their
teaching approaches to include socio-scientific issues
which enrich and give meaning to core scientific principles.
It is meant to enhance young peopleâs curiosity about the
social and scientific world and raise important questions
about issues which affect their lives. We call this approach
Socio-Scientific Inquiry-Based Learning, or âSSIBLâ for
short. Chapters 1 and 2 present an introduction to the
theoretical background of SSIBL. In chapter 3, SSIBL will
be approached from a classroom perspective, providing a
simplified version of the framework and showing teaching
examples
A Calanais myth and an alignment of the east stone-row with both the rising of the Pleiades and crossovers of Venus at sunrise on the summer solstices
Acknowledgements My thanks to Stefan Sagrott of Historic Environment Scotland for his help in obtaining Patrick Ashmoreâs data and to David Forrest, School of Geographical and Earth Sciences, University of Glasgow, for providing a copy of David Taitâs map of Calanais.Peer reviewedPublisher PD
Monolithic lumped-element unequal branch-line coupler for the use in asymmetrical Doherty amplifiers
Monolithic lumped-element unequal branch-line coupler for the use in asymmetrical Doherty amplifiers
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